@article{sun_choi_yu_lee_ryu_zate_jo_2024, title={Enhanced polarization retention and softening in [001]-oriented Pb(Mg1/3Nb2/3)-PbTiO3 single crystals through corona poling}, volume={4}, ISSN={["2234-0491"]}, DOI={10.1007/s43207-024-00390-0}, journal={JOURNAL OF THE KOREAN CERAMIC SOCIETY}, author={Sun, Jeong-Woo and Choi, Woo-Jin and Yu, Hye-Lim and Lee, Sang-Goo and Ryu, Jong Eun and Zate, Temesgen Tadeyos and Jo, Wook}, year={2024}, month={Apr} }
@article{perera_black_islam_ryu_corder_khan_2024, title={Rheological Behavior and Roll Coating Properties of PDMS Enhanced with Multi-Walled Carbon Nanotubes and Fumed Silica}, url={https://doi.org/10.1021/acsaenm.3c00698}, DOI={10.1021/acsaenm.3c00698}, abstractNote={Scalable manufacturing of micro- and nanoscale textured surfaces from polymer composites is desirable in many applications from drag reduction in ship applications to energy-efficient radiative cooling of infrastructure. Creation of such surfaces, however, remains a challenge. By exploiting the ribbing phenomena that arise when viscous forces dominate over surface tension forces, we can create topographic patterns using roll-to-roll manufacturing techniques. In this work, we analyze how the rheology of yield stress fluids impacts the morphology of roll-coated surfaces using polydimethylsiloxane (PDMS) samples enhanced to varying degrees with multiwalled carbon nanotubes (CNTs) and fumed silica. We observe that CNTs increasingly dominate the large amplitude oscillatory shear response of PDMS composites. However, their impact is modified by the presence of fumed silica, which introduces a transition from intracycle strain softening to hardening behavior. The roll coating behavior of these PDMS composites is examined using image processing to link the rheological properties with the resulting surface morphologies, specifically focusing on two parameters defining surface morphology─ribbing wavenumber and branching patterns. While both types of PDMS composites display comparable wavenumbers, they exhibit different degrees of branching. The deviation in branching can be attributed to the intracycle strain hardening behavior seen at low CNT loadings in PDMS composites containing fumed silica. The study provides insights into the interactions occurring between CNTs and fumed silica in PDMS composites and highlights the significance of analyzing rheological parameters that are relevant at the high strains and strain rates experienced during roll coating, advancing our understanding of ribbing stability in yield stress fluids.}, journal={ACS Applied Engineering Materials}, author={Perera, Himendra and Black, Benjamin and Islam, Md D. and Ryu, Jong E. and Corder, Ria D. and Khan, Saad A.}, year={2024}, month={Mar} }
@article{al shibli_chaturvedi_kanagaraj_zaghari_choi_ryu_2024, title={Sol-gel fabricated one-dimensional LiFePO4 microstructures for carbon nanotube-based nanocomposite freestanding sheet as cathode material for Li ion batteries}, volume={1}, ISSN={["1530-793X"]}, url={https://doi.org/10.1177/00219983231225703}, DOI={10.1177/00219983231225703}, abstractNote={ Lithium Iron Phosphate (LiFePO4) microstructures have been synthesized using the sol-gel process. One-dimensional (1D) LiFePO4 microstructures were fabricated using tissue paper as a template under different temperatures to form pure phase microstructures. XRD analysis confirmed the single phase nature of orthorhombic olivine-structured LiFePO4 with Pnma space group. SEM analysis authenticated the formation of 1D LiFePO4 microstructures along with some clusters of particles. LiFePO4-multi-walled carbon nanotubes (MWCNT) freestanding sheets were prepared using a tape-casting process. Further, the electrochemical properties of LiFePO4-MWCNT freestanding sheet were analyzed through electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge analysis. }, journal={JOURNAL OF COMPOSITE MATERIALS}, author={Al Shibli, Hamda and Chaturvedi, Prerna and Kanagaraj, Amarsingh Bhabu and Zaghari, Pouria and Choi, Daniel S. and Ryu, Jong Eun}, year={2024}, month={Jan} }
@article{sun_zate_choi_lee_lee_ryu_jo_2024, title={Understanding thermal depolarization via thermally stimulated depolarization current measurement}, volume={4}, ISSN={["2234-0491"]}, DOI={10.1007/s43207-024-00392-y}, journal={JOURNAL OF THE KOREAN CERAMIC SOCIETY}, author={Sun, Jeong-Woo and Zate, Temesgen Tadeyos and Choi, Woo-Jin and Lee, Geon-Ju and Lee, Sang-Goo and Ryu, Jong Eun and Jo, Wook}, year={2024}, month={Apr} }
@article{liu_sui_harbinson_pudlo_perera_zhang_liu_ku_islam_liu_et al._2023, title={A scalable microstructure photonic coating fabricated by roll-to-roll “defects” for daytime sub-ambient passive radiative cooling}, volume={23}, ISSN={["1530-6992"]}, url={https://doi.org/10.1021/acs.nanolett.3c00111}, DOI={10.1021/acs.nanolett.3c00111}, abstractNote={The deep space's coldness (∼4 K) provides a ubiquitous and inexhaustible thermodynamic resource to suppress the cooling energy consumption. However, it is nontrivial to achieve subambient radiative cooling during daytime under strong direct sunlight, which requires rational and delicate photonic design for simultaneous high solar reflectivity (>94%) and thermal emissivity. A great challenge arises when trying to meet such strict photonic microstructure requirements while maintaining manufacturing scalability. Herein, we demonstrate a rapid, low-cost, template-free roll-to-roll method to fabricate spike microstructured photonic nanocomposite coatings with Al2O3 and TiO2 nanoparticles embedded that possess 96.0% of solar reflectivity and 97.0% of thermal emissivity. When facing direct sunlight in the spring of Chicago (average 699 W/m2 solar intensity), the coatings show a radiative cooling power of 39.1 W/m2. Combined with the coatings' superhydrophobic and contamination resistance merits, the potential 14.4% cooling energy-saving capability is numerically demonstrated across the United States.}, number={17}, journal={Nano Letters}, author={Liu, S. and Sui, C. and Harbinson, M. and Pudlo, M. and Perera, Himendra and Zhang, Zhenzhen and Liu, Ruguan and Ku, Zahyun and Islam, Md Didarul and Liu, Yuxuan and et al.}, editor={Ryu, JongEditor}, year={2023}, pages={7767–7774} }
@article{lee_hong_jun_liu_ryu_kim_kim_lee_2023, title={Numerical and experimental studies on design of multi-lumen tube extruded with drawing and air flow}, volume={106}, ISSN={["2212-4616"]}, DOI={10.1016/j.jmapro.2023.09.074}, abstractNote={This study represents the design and optimization procedure of a multi-lumen tube used for endoscopic retrograde cholangiopancreatography (ERCP) catheter. The geometry of tip and die for the multi-lumen tube is designed based on numerical analysis of molten polymer and air flow. In particular, this numerical study consider the interaction between the molten polymer and the air flow in the lumen which is the main process variable of extrusion, and analyze the heat transfer and pressure distribution through the air flow for the first time. In addition, to reflect the reality of the multi-lumen extrusion process, the velocity is controlled at the end of the tube ejected to the free surface in consideration of the extrusion process, which is drawn by the puller downstream of the extruder. The shear rate and temperature dependent viscosity of PEBAX 7233 SA01 MED is measured for non-isothermal numerical simulations. The extrusion process for multi-lumen tubes with drawing is simulated using ANSYS Polyflow. The profile of extrudate is numerically predicted with the initial design of the tip and die with the manufacturing parameter is optimized. The predicted profile of extrudate is compared to the target profile with dimensional requirements. The design of the tip and die is modified based on numerical results following the design procedure. To suppress the die swell phenomena, the flow area of molten polymer is increased, and the velocity difference is reduced. Finally, the multi-lumen tube with the optimized tip and die is experimentally extruded and compared to the target profile of the extrudate. It has a good agreement with the target profile and satisfies the dimensional requirements. This design procedure and numerical analysis help achieve the desired target profile of extrudate.}, journal={JOURNAL OF MANUFACTURING PROCESSES}, author={Lee, Han Chang and Hong, Seong Geun and Jun, Wonjin and Liu, Sipan and Ryu, Jong Eun and Kim, Gyu Man and Kim, Woojin and Lee, Euntaek}, year={2023}, month={Nov}, pages={88–101} }
@article{phillips_chen_islam_ryu_zikry_2023, title={Predicting and Controlling Ribbing Instabilities of Carbon Nanotube-PDMS Thin-Film Systems for Multifunctional Applications}, volume={7}, ISSN={["1527-2648"]}, url={http://dx.doi.org/10.1002/adem.202300582}, DOI={10.1002/adem.202300582}, abstractNote={The manufacturing of thin films with structured surfaces by large‐scale rolling has distinct advantages over other techniques, such as lithography, due to scalability. However, it is not well understood or quantified how processing conditions can affect the microstructure at different physical scales. Hence, the objective of this investigation is to develop a validated computational model of the symmetric forward‐roll coating process to understand, predict, and control the morphology of carbon nanotube (CNT)–polydimethylsiloxane (PDMS) pastes. The effects of the thin‐film rheological properties and the roller gap on the ribbing behavior are investigated and a ribbing instability prediction model is formulated from experimental measurements and computational predictions. The CNT–PDMS thin‐film system is modeled by a nonlinear implicit dynamic finite‐element method that accounts for ribbing instabilities, large displacements, rolling contact, and material viscoelasticity. Dynamic mechanical analysis is used to obtain the viscoelastic properties of the CNT–PDMS paste for various CNT weight distributions. Furthermore, a Morris sensitivity analysis is conducted to obtain insights on the dominant predicted characteristics pertaining to the ribbing microstructure. Based on the sensitivity analysis, a critical ribbing aspect ratio is identified for the CNT–PDMS system corresponding to a critical roller gap.}, journal={ADVANCED ENGINEERING MATERIALS}, publisher={Wiley}, author={Phillips, Matthew and Chen, Muh-Jang and Islam, Md Didarul and Ryu, Jong and Zikry, Mohammed}, year={2023}, month={Jul} }
@article{harbinson_pudlo_liu_chaudhry_liu_sui_zhu_hsu_ryu_2023, title={Template-free scalable roll-to-roll fabrication of textured transparent film for passive radiation cooling of photovoltaics}, volume={35}, ISSN={["2213-8463"]}, DOI={10.1016/j.mfglet.2023.08.006}, abstractNote={Solar panels contributed to over 115,000 GWh of energy being produced in the United States and solar panel energy consumption has increased by 27 % at the start of the 21st century. Given the decrease of photovoltaic efficiency at higher temperatures and the increasing demand for clean energy, the development of an economical technology for solar panel cooling is necessary. Passive cooling can be achieved by infrared radiating into space. Typical solar arrays require large functional areas in order to supply a significant amount of power as compared to other sources. As such, any method to help reduce the temperature of the solar panel surfaces needs to maintain manufacturing scalability for sustainable use. We demonstrate a rapid, low-cost, template-free roll coating method to fabricate photonic composite film with SiO2 nanoparticles which possess high emissivity in the atmospheric transparent window while passing visible and near infrared light to photovoltaics beneath. When facing direct sunlight at summer noon, the coatings show a 3.5°C temperature decrease without loss of photovoltaic efficiency while having hydrophobic and contamination-resistance merits.}, journal={MANUFACTURING LETTERS}, author={Harbinson, Myers and Pudlo, Michael and Liu, Sipan and Chaudhry, Taimur and Liu, Yuxuan and Sui, Chenxi and Zhu, Yong and Hsu, Po-Chun and Ryu, Jong E.}, year={2023}, month={Aug}, pages={166–173} }
@inproceedings{zaghari_sinha_ryu_franzon_hopkins_2023, title={Thermal Cycling and Fatigue Life Analysis of a Laterally Conducting GaN-based Power Package}, ISSN={["2164-0157"]}, url={http://dx.doi.org/10.1109/3dic57175.2023.10154901}, DOI={10.1109/3DIC57175.2023.10154901}, abstractNote={Thermal reliability is a critical factor in ensuring the performance and efficiency of GaN-based electronic devices. In this paper, the fatigue life assessment of a laterally conducting GaN power package that uses a two-solder hierarchy of SAC305 and Sn63/Pb37 on a 120μm thick dielectric for device attach was conducted using an FEA. The double-sided package structure also introduced thick Cu as integrated baseplate layers for mechanical mounting into higher packaging levels while providing surfaces for double-sided cooling. The internal structure varied spacer thicknesses for planarization and inclusion of package-integrated decoupling capacitors. The solder materials were simulated by using the Anand viscoplastic constitutive model. Coffin-Manson, Engelmaier, and Solomon empirical strain-based models were utilized to predict the cyclic life of the package. Based on the results, the critical solder joint location was predicted in the Sn63/Pb37 solder layer between the GaN and Cu spacer, with a strain range of 0.02797. The worst-case life prediction for the module was 150 cycles using the Coffin-Manson model.}, booktitle={2023 IEEE International 3D Systems Integration Conference (3DIC)}, publisher={IEEE}, author={Zaghari, Pouria and Sinha, Sourish S. and Ryu, Jong Eun and Franzon, Paul D. and Hopkins, Douglas C.}, year={2023}, month={May} }
@article{black_chockalingam_islam_liu_perera_khan_ryu_2022, title={Fabrication of Bioinspired Micro/Nano-Textured Surfaces Through Scalable Roll Coating Manufacturing}, volume={10}, ISSN={2166-0468 2166-0476}, url={http://dx.doi.org/10.1115/1.4056732}, DOI={10.1115/1.4056732}, abstractNote={Abstract}, number={2}, journal={Journal of Micro and Nano-Manufacturing}, publisher={ASME International}, author={Black, Benjamin and Chockalingam, Sekkappan and Islam, Md Didarul and Liu, Sipan and Perera, Himendra and Khan, Saad and Ryu, Jong Eun}, year={2022}, month={Jun}, pages={021006} }
@inproceedings{liu_kim_chang_huang_jiang_ryu_2022, title={Multiphysics FEA Simulation for Polymer Nanocomposite Laser Ultrasound Transducer}, booktitle={2022 IEEE 22nd International Conference on Nanotechnology (NANO)}, author={Liu, Sipan and Kim, Howuk and Chang, Wei-Yi and Huang, Wenbin and Jiang, Xiaoning and Ryu, Jong Eun}, year={2022}, pages={249–252} }
@article{liu_kim_huang_chang_jiang_ryu_2022, title={Multiscale and multiphysics FEA simulation and materials optimization for laser ultrasound transducers}, volume={31}, ISSN={["2352-4928"]}, url={http://dx.doi.org/10.1016/j.mtcomm.2022.103599}, DOI={10.1016/j.mtcomm.2022.103599}, abstractNote={The relationship between the nanocomposite design and the laser ultrasound transducer (LUT) characteristics was investigated through simulations in multiple scale levels for material behavior, device response, and acoustic wave propagation in media. First, the effects of the nanoparticle size and concentration on the effective properties of composites were quantitatively investigated with the finite element analysis (FEA) method. Second, the effective properties of the nanocomposite were assigned to the layer, which is modeled as a homogeneous material, in the FEA for the LUT simulating the energy conversion from the incident laser to the acoustic wave. Finally, the ultrasound propagation in the water was calculated by a theoretical wave propagation model. The FEA-based prediction was compared with the experimental data in the literature and a theoretical analysis for LUT based on Thermal-Acoustic coupling. As a result, the ultrasound waves on the transducer surface and at a distance in the water could be predicted. Based on the hierarchically integrated prediction procedure, the optimal conditions of the photoacoustic nanocomposites were investigated through the parametric study with the particle size and concentration as variables. The results guide the material designs optimized for different device characteristics, such as high pressure and broad bandwidth.}, journal={MATERIALS TODAY COMMUNICATIONS}, publisher={Elsevier BV}, author={Liu, Sipan and Kim, Howuk and Huang, Wenbin and Chang, Wei-Yi and Jiang, Xiaoning and Ryu, Jong Eun}, year={2022}, month={Jun} }
@article{islam_liu_choi_guo_ryu_2022, title={Physics-based Computational Method Predicting the Dielectric Properties of Polymer Nanocomposites}, volume={29}, ISSN={["1573-4897"]}, url={https://doi.org/10.1007/s10443-022-10026-3}, DOI={10.1007/s10443-022-10026-3}, number={4}, journal={APPLIED COMPOSITE MATERIALS}, publisher={Springer Science and Business Media LLC}, author={Islam, Md Didarul and Liu, Sipan and Choi, Daniel and Guo, Zhanhu and Ryu, Jong Eun}, year={2022}, month={Apr} }
@article{didarul islam_perera_chockalingam_phillips_chen_liu_khan_zhu_zikry_eun ryu_2022, title={Template-free scalable fabrication of linearly periodic microstructures by controlling ribbing defects phenomenon during forward roll coating}, volume={33}, ISSN={2213-8463}, url={http://dx.doi.org/10.1016/j.mfglet.2022.08.001}, DOI={10.1016/j.mfglet.2022.08.001}, abstractNote={Linear periodic microstructures are of significant importance in various applications, including drag-reduction, biofouling, self-cleaning, and superhydrophobicity. However, practical applications of such surfaces require mass manufacturing techniques, which are highly limited. This study demonstrated a simple template-free scalable manufacturing technique to fabricate linearly periodic microstructure by controlling the ribbing defects in forward roll coating. A viscoelastic polymer nanocomposite with tailored properties was synthesized and utilized as the coating material. The ribbing instabilities were controlled with process parameters that resulted in variable periodicity of the linearly aligned microstructures with a spacing of 114 – 700 µm. The microstructure arrangement also had a linear to random transition as the instabilities increased. The manufactured surface has a high Wenzel roughness factor that ranges from 1.6 to 3.6, which results in water contact angles of 128o to 150o. The linear microstructure films can have critical applications in the mass manufacturing of drag reduction surfaces. The high aspect-ratio microstructure films can also have applications in superhydrophobic, self-cleaning, anti-icing, and anti-biofouling surfaces.}, journal={Manufacturing Letters}, publisher={Elsevier BV}, author={Didarul Islam, Md and Perera, Himendra and Chockalingam, Sekkappan and Phillips, Matthew and Chen, Muh-Jang and Liu, Yuxuan and Khan, Saad and Zhu, Yong and Zikry, Mohammed and Eun Ryu, Jong}, year={2022}, month={Sep}, pages={153–160} }
@article{islam_perera_black_phillips_chen_hodges_jackman_liu_kim_zikry_et al._2022, title={Template‐Free Scalable Fabrication of Linearly Periodic Microstructures by Controlling Ribbing Defects Phenomenon in Forward Roll Coating for Multifunctional Applications}, volume={9}, ISSN={2196-7350 2196-7350}, url={http://dx.doi.org/10.1002/admi.202201237}, DOI={10.1002/admi.202201237}, abstractNote={Abstract}, number={27}, journal={Advanced Materials Interfaces}, publisher={Wiley}, author={Islam, Md Didarul and Perera, Himendra and Black, Benjamin and Phillips, Matthew and Chen, Muh‐Jang and Hodges, Greyson and Jackman, Allyce and Liu, Yuxuan and Kim, Chang‐Jin and Zikry, Mohammed and et al.}, year={2022}, month={Aug}, pages={2201237} }
@article{liu_islam_ku_boyd_zhong_urbas_smith_derov_nguyen_kim_et al._2021, title={Novel computational design of high refractive index nanocomposites and effective refractive index tuning based on nanoparticle morphology effect}, volume={223}, ISSN={["1879-1069"]}, url={http://dx.doi.org/10.1016/j.compositesb.2021.109128}, DOI={10.1016/j.compositesb.2021.109128}, abstractNote={This study introduces a method to predict the refractive index (RI) of nanocomposites with the Finite Elements Analysis (FEA) based on the Fabry-Pérot interference. The efficacy was verified by comparing the estimated composites' RI with the available data in the literature. In the experimental verification, the FEA-based prediction showed closer results with the measurement as compared to the effective medium approximation (EMA) approaches, which are prevalently used to predict the physical properties of nanocomposites. Due to the modeling capability, the FEA-method could investigate the effect of the nanoparticle morphology (particle size, shape, and orientation) and distribution. Large particle size, particle agglomeration in high electric-field amplitude region, and particle elongation along the light oscillating direction are found to be the major factors to enhance the RI of composites. The underlying mechanism of RI changing is attributed to the light scattering by embedded nanoparticles, which provides one potential real-time RI tuning schematic.}, journal={COMPOSITES PART B-ENGINEERING}, publisher={Elsevier BV}, author={Liu, Sipan and Islam, Md Didarul and Ku, Zahyun and Boyd, Darryl A. and Zhong, Yaxu and Urbas, Augustine M. and Smith, Evan and Derov, John and Nguyen, Vinh Q. and Kim, Woohong and et al.}, year={2021}, month={Oct} }
@article{liu_islam_ku_urbas_boyd_kim_sanghera_ryu_2021, title={The polymer nanocomposites embedded particles size and agglomeration effect on the effective refractive index tuning}, volume={11802}, ISSN={["1996-756X"]}, url={http://dx.doi.org/10.1117/12.2594382}, DOI={10.1117/12.2594382}, abstractNote={The polymer nanocomposites have attracted increasing attention in the optical components that are miniaturized and integrated with wearable or portable electronics due to the polymer processibility and the tunability of the refractive index (RI) by adding nanoparticles. However, the lack of models predicting the composites’ RI attributed to the morphology, physical properties, as well as volume fraction of the nanoparticles poses difficulties in the design. This study investigates the effect of the size and agglomeration condition of the nanoparticles on the effective RI based on a Finite Element Analysis (FEA) method simulating the Fabry-Pérot resonance within the composite film. The result showed that larger particles (or particle clusters) could reinforce the RI of nanocomposites compared with the well-dispersed small particles. The particle-cluster model had lower RI than the single-solid-particle model with the same effective particle diameter, demonstrating that the particle cluster provides less scattering intensity than the single-solid-particle.}, journal={NANOENGINEERING: FABRICATION, PROPERTIES, OPTICS, THIN FILMS, AND DEVICES XVIII}, publisher={SPIE}, author={Liu, Sipan and Islam, Md Didarul and Ku, Zahyun and Urbas, Augustine M. and Boyd, Darryl A. and Kim, Woohong and Sanghera, Jasbinder S. and Ryu, Jong E.}, editor={Park, Wounjhang and Attias, André-Jean and Panchapakesan, BalajiEditors}, year={2021} }
@article{meng_yang_salcedo_baek_ryu_lu_zhang_2020, title={A Combined Modeling and Experimental Study of Tensile Properties of Additively Manufactured Polymeric Composite Materials}, volume={29}, ISBN={1544-1024}, ISSN={1059-9495 1544-1024}, url={http://dx.doi.org/10.1007/s11665-020-04746-5}, DOI={10.1007/s11665-020-04746-5}, abstractNote={In this study, the mechanical properties, in terms of stress–strain curves, of additively manufactured polymeric composite materials, Tango black plus (TB+), vero white plus (VW ), and their intermediate materials with different mixing ratios, are reported. The ultimate tensile strength and elongation at break are experimentally measured using ASTM standard tensile test. As the content of VM+ increases, the strength of the polymeric materials increases and elongation decreases. Additionally, the Shore A hardness of the materials increases with reduced TB+ concentration. In parallel to the experiment, hyperelastic models are employed to fit the experimental stress–strain curves. The shear modulus of the materials is obtained from the Arruda–Boyce model, and it increases with reduced concentration of TB+. Due to the good quality of the fitted data, it is suggested that the Arruda–Boyce model is the best model for modeling the additively manufactured polymeric materials. With the well characterized and modeled mechanical properties of these hyperelastic materials, designers can conduct computational study for application in flexible electronics field.}, number={4}, journal={Journal of Materials Engineering and Performance}, publisher={Springer Science and Business Media LLC}, author={Meng, Lingbin and Yang, Xuehui and Salcedo, Eduardo and Baek, Dong-Cheon and Ryu, Jong E. and Lu, Zhe and Zhang, Jing}, year={2020}, month={Apr}, pages={2597–2604} }
@article{chen_zhu_huang_zhang_pan_zhou_ryu_umar_guo_2020, title={Advances in Responsively Conductive Polymer Composites and Sensing Applications}, volume={61}, ISSN={1558-3724 1558-3716}, url={http://dx.doi.org/10.1080/15583724.2020.1734818}, DOI={10.1080/15583724.2020.1734818}, abstractNote={Abstract Conductive polymer composites (CPCs) have attracted intensive attention for several decades because they can endow the materials with not only good processability but also various functionalities except the electrical conductivity. It is known that the electrical resistance of the CPCs is dominated by the conductive networks in the polymer matrix. Therefore, tiny change of the conductive networks can lead to remarkable changes in the output electrical signal of the CPCs. Utilizing this stimulus-response behavior of conductive networks to the environment conditions, CPCs can be used to design sensitive sensors to detect or monitor the environment conditions, such as the strain/stress, pressure, temperature, solvent or vapor. This review systematically outlines the preparation, microstructures, properties, and the stimulus-response mechanisms to the environment conditions of the CPCs as well as their applications in various sensitive sensors, including strain sensors, pressure sensors, liquid sensors, vapor sensors, and temperature sensors. Finally, the open question and future challenge of utilizing the stimulus-response behavior of CPCs to design versatile sensors are discussed.}, number={1}, journal={Polymer Reviews}, publisher={Informa UK Limited}, author={Chen, Jianwen and Zhu, Yutian and Huang, Jinrui and Zhang, Jiaoxia and Pan, Duo and Zhou, Juying and Ryu, Jong E. and Umar, Ahmad and Guo, Zhanhu}, year={2020}, month={Mar}, pages={157–193} }
@article{mosey_yue_gaire_ryu_cheng_2020, title={Controlled short time large scale synthesis of magnetic cobalt nanoparticles on carbon nanotubes by flash annealing}, volume={127}, ISSN={["1089-7550"]}, url={https://doi.org/10.1063/1.5131579}, DOI={10.1063/1.5131579}, abstractNote={Nanopatterned arrays of discrete cobalt nanostructures showing characteristic parameter-dependent sizes are formed from continuous thin films on a carbon nanotube substrate using millisecond pulsed intense UV light. The nanoparticles exhibit ferromagnetic behavior with magnetic remanence and coercivity depending on the particle size. The end-state particle size is shown to be a function of initial thin film thickness and excitation energy and is therefore tunable. The evolutionary process from continuous thin films to a discrete morphology is thermodynamically driven by the large surface energy difference between metastable thin films and the underlying carbon nanotube substrate. Evidence of the Danielson model of the dewetting process is observed. These arrays can find applications as platforms for the self-assembly of magnetically susceptible materials, such as iron or nickel nanostructures, into a conduction matrix for applications in energy extraction from a latent heat storage device.}, number={4}, journal={JOURNAL OF APPLIED PHYSICS}, author={Mosey, Aaron and Yue, Lanping and Gaire, Babu and Ryu, Jong Eun and Cheng, Ruihua}, year={2020}, month={Jan} }
@article{islam_kim_ko_ku_boyd_smith_nguyen_myers_baker_kim_et al._2020, title={Design of High Efficient Mid‐Wavelength Infrared Polarizer on ORMOCHALC Polymer}, volume={305}, ISSN={1438-7492 1439-2054}, url={http://dx.doi.org/10.1002/mame.202000033}, DOI={10.1002/mame.202000033}, abstractNote={Abstract}, number={5}, journal={Macromolecular Materials and Engineering}, publisher={Wiley}, author={Islam, Md Didarul and Kim, Jun Oh and Ko, Yeongun and Ku, Zahyun and Boyd, Darryl A. and Smith, Evan M. and Nguyen, Vinh Q. and Myers, Jason D. and Baker, Colin C. and Kim, Woohong and et al.}, year={2020}, month={Mar}, pages={2000033} }
@article{zhang_mcnall_kanagaraj_park_ryu_choi_2020, title={Electrochemical characterization of LiMn2O4 nanowires fabricated by sol-gel for lithium-ion rechargeable batteries}, volume={273}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2020.127923}, abstractNote={A layer of one-dimensional (1D) LiMn2O4 nanowires (NWs) was coated on a cathode of Li-ion rechargeable battery. Nanoporous anodized aluminum oxide (AAO) integrated on silicon/silicon dioxide (Si/SiO2) substrates were employed as a template for fabrication of LiMn2O4 NWs with a sol–gel method. Purified LiMn2O4 NWs were spin-coated on a platinum (Pt) deposited Si/SiO2 substrate for electrochemical characterizations. Their electrochemical tests show that the discharge capacity of about 40 mAh/g is maintained during a few cycles at the high discharge/charge rate. Electrochemical characterization reveals that the thin-film surface with LiMn2O4 NWs is rougher than the surface without NWs. A change in surface of LiMn2O4 NWs after charging and discharging cycles was investigated by Scanning Electron Microscopy (SEM). SEM images show that diameter of the nanowires was increased by about 10–20% owing to a volume change by charging with Li ions.}, journal={MATERIALS LETTERS}, author={Zhang, Zhikan and McNall, Brady and Kanagaraj, Amarsingh Bhabu and Park, Jung-Rae and Ryu, Jong Eun and Choi, Daniel}, year={2020}, month={Aug} }
@article{islam_liu_boyd_zhong_nahid_henry_taussig_ko_nguyen_myers_et al._2020, title={Enhanced mid-wavelength infrared refractive index of organically modified chalcogenide (ORMOCHALC) polymer nanocomposites with thermomechanical stability}, volume={108}, ISSN={["1873-1252"]}, url={http://dx.doi.org/10.1016/j.optmat.2020.110197}, DOI={10.1016/j.optmat.2020.110197}, abstractNote={Abstract Organically modified chalcogenide (ORMOCHALC) polymers have proven to be alternatives to the conventional inorganic materials for mid-wavelength infrared (MWIR, λ = 3–5 μm) optical components. While the refractive index of ORMOCHALC can be reinforced by the content of chalcogenides such as sulfur (S) and selenium (Se), the increased portion of the S or Se deteriorate the thermomechanical stabilities. As a remedy, this study utilizes ZnS nanoparticles to reinforce both optical and thermomechanical properties of the sulfur-based ORMOCHALC polymer, poly(S-random-1,3-diisopropenylbenzene). The refractive index n and extinction coefficient k of the nanocomposites were characterized by Infrared Variable Angle Spectroscopic Ellipsometry (IR-VASE). The results show a significant increment in the refractive index of Δn = 6.58% at the wavelength of 4 μm by adding 20 wt% ZnS (or 7.29 vol%) in the ORMOCHALC polymer. The low extinction coefficient of the nanocomposites (}, journal={OPTICAL MATERIALS}, author={Islam, Md Didarul and Liu, Sipan and Boyd, Darryl A. and Zhong, Yaxu and Nahid, Masrur Morshed and Henry, Reece and Taussig, Laine and Ko, Yeongun and Nguyen, Vinh Q. and Myers, Jason D. and et al.}, year={2020}, month={Oct} }
@article{seo_ryu_2020, title={Influence of Reflow Profile on Thermal Fatigue Behaviors of Solder Ball Joints}, volume={29}, ISSN={["1544-1024"]}, url={https://doi.org/10.1007/s11665-020-04899-3}, DOI={10.1007/s11665-020-04899-3}, abstractNote={In electronic package design, solder joints are critical in providing electrical connections and mechanical support. The mechanical reliability of interconnection is dependent on the microstructure evolution that occurs within the solder due to the temperature changes primarily from transportation, storage, and device usage. In this study, two solder alloys, eutectic 63Sn37Pb and lead-free 95.5Sn4.0Ag0.5Cu, were tested for their thermal fatigue reliability and were observed for changes in microstructure. The different microstructures of each sample were created by controlling the cooling rate, fast or slow, during reflow. To characterize reliability, the samples endured thermal cycling − 40-125 °C until electrical failure. Finite element analysis was used to predict the primary deformation mechanism. The microstructure was inspected by cross-sectioning the solder samples using scanning electron microscopy with energy-dispersive x-ray spectroscopy. It was found that by controlling the microstructure development through the reflow rate, the solder joint’s thermal fatigue life can be extended, and concurrently, the reliability of the electronic package can be enhanced.}, number={6}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, publisher={Springer Science and Business Media LLC}, author={Seo, Eunice Y. and Ryu, Jong E.}, year={2020}, month={Jun}, pages={4095–4104} }
@article{lu_liu_murugadoss_seok_huang_ryu_guo_2020, title={Polyethylene Glycol/Carbon Black Shape-Stable Phase Change Composites for Peak Load Regulating of Electric Power System and Corresponding Thermal Energy Storage}, volume={9}, ISSN={2576-988X 2576-9898}, url={http://dx.doi.org/10.30919/es8d901}, DOI={10.30919/es8d901}, abstractNote={DOI: 10.30919/es8d901 In this work, a unique electrically conductive polyethylene glycol (PEG)/carbon black (CB) shape-stable phase change composite (SSPCC) for peak load regulating of electric power system was prepared via a vacuum impregnation approach. Scanning electron microscope (SEM), differential scanning calorimeter (DSC) and X-ray diffraction (XRD) were used to study the micro morphology, crystallization behavior, crystallization structure and thermal properties. Leakage test and DSC results showed that when the PEG content in PEG/CB SSPCC was as high as 86 wt%, the phase change enthalpy and relative enthalpy efficiency were up to 147.7 J/g and 95.1%, respectively. Fourier transform infrared (FTIR) and XRD showed no chemical reaction between CB and PEG. Thermal cycling test showed that the PEG/CB SSPCC had excellent thermal stability and thermal reliability. Moreover, the good electro-tothermal conversion ability of PEG/CB SSPCC (0.2 S/m) provided rich possibilities for peak load regulating of electric power system and corresponding thermal energy storage.}, journal={Engineered Science}, publisher={Engineered Science Publisher}, author={Lu, Xiang and Liu, Huanyu and Murugadoss, Vignesh and Seok, Ilwoo and Huang, Jintao and Ryu, Jong E. and Guo, Zhanhu}, year={2020}, pages={25–34} }
@article{zhou_wu_ma_zhang_zeng_wu_liu_ryu_guo_2020, title={Recent Advances in Organic/Composite Phase Change Materials for Energy Storage}, volume={9}, ISSN={2578-0646 2578-0654}, url={http://dx.doi.org/10.30919/esee8c150}, DOI={10.30919/esee8c150}, abstractNote={Phase change materials (PCMs) store and release energy in the phase change processes. In recent years, PCMs have gained increasing attention due to their excellent properties such as high latent heat storage capacity, appropriate solid-liquid phase change temperature, thermal reliability, and low cost. Herein, classification, characteristics, and evaluation criteria of organic/composite PCMs are systematically illustrated, and some typical preparation methods are introduced, such as in-situ polymerization, interfacial polymerization, spray drying method, porous materials adsorption method, sol-gel method, meltimpregnated and mixing method, electrospinning method, vacuum infiltration and ultrasonic method are introduced. In addition, this review presents some applications of PCMs in the utilization of solar energy, building materials, air conditioning, industrial waste heat recovery, and military camouflage and stealth. Finally, the development tendency of PCMs is discussed.}, journal={ES Energy & Environment}, publisher={Engineered Science Publisher}, author={Zhou, Yongcun and Wu, Siqi and Ma, Yu and Zhang, Hang and Zeng, Xiaoliang and Wu, Feixiang and Liu, Feng and Ryu, Jong E. and Guo, Zhanhu}, year={2020}, pages={28–40} }
@article{wang_liu_wang_liu_zhang_lin_fan_ding_ryu_guo_2020, title={Significantly Enhanced Ultrathin NiCo-based MOF Nanosheet Electrodes Hybrided with Ti3C2Tx MXene for High Performance Asymmetric Supercapacitors}, volume={9}, ISSN={2576-988X 2576-9898}, url={http://dx.doi.org/10.30919/es8d903}, DOI={10.30919/es8d903}, abstractNote={DOI: 10.30919/es8d903 In situ synthesis of NiCo based metal-organic framework (MOF) nanosheets and the exfoliation of Ti3C2Tx into isolated nanosheets (MXene), called, NiCo-MOF/Ti3C2Tx hybrid nanosheets, are simultaneously achieved by a facile ultrasonic method. This method can effectively avoid the oxidation and restacking of Ti3C2Tx nanosheets, and also make them uniformly disperse on the surface of NiCo-MOF. The formed NiCo-MOF/Ti3C2Tx hybrid nanosheets achieve a high specific capacitance of 815.2 A g at 1 A g. The practical asymmetric supercapacitor (ASC) is fabricated using activated carbon and NiCo-MOF/Ti3C2Tx hybrid nanosheets. The ASC device achieves an energy density of 39.5 Wh kg at a power density of 562.5 W kg, and also demonstrates a suitable cycling stability with 82.3 % of capacitance retention after 10000 continuous cycles at 5 Ag. The enhanced electrochemical property of NiCo-MOF/Ti3C2Tx is attributed to the nanosheet-like and mesoporous structure, high electronic conductivity, and synergistic effect of hybrid electroactive components.}, journal={Engineered Science}, publisher={Engineered Science Publisher}, author={Wang, Yanzhong and Liu, Yuexin and Wang, Chao and Liu, Hu and Zhang, Jiaoxia and Lin, Jing and Fan, Jincheng and Ding, Tao and Ryu, Jong E. and Guo, Zhanhu}, year={2020}, pages={50–59} }
@article{sun_zhuang_liu_xu_horne_wujcik_liu_ryu_wu_guo_2019, title={Development and Application of Hot Embossing in Polymer Processing: A Review}, volume={6}, ISSN={2578-0611 2578-062X}, url={http://dx.doi.org/10.30919/esmm5f605}, DOI={10.30919/esmm5f605}, abstractNote={Hot embossing of polymer materials is a promising technology for the fabrication of high quality and precision patterns on the micro/nano-scales. There are three basic forms of hot embossing including, plate-to-plate (P2P), roll-to-plate (R2P), and roll-to-roll (R2R) hot embossing. It also can be divided into isothermal and non-isothermal hot embossing according to the different temperature control modes of polymer substrates and structured molds. This review reports recent progress made of hot embossing methods in polymer processing and the efforts to shorten its processing period for commercial applications. Research and innovations in simulation of hot embossing process and mold fabrication are also comprehensively summarized. Within this review, microfluidics, light guide plate (LGP), and other novel applications of hot embossing are systematically cataloged. Finally, challenges and future trends of hot embossing in polymer processing are presented and forecasted.}, journal={ES Materials & Manufacturing}, publisher={Engineered Science Publisher}, author={Sun, Jingyao and Zhuang, Jian and Liu, Ying and Xu, Hong and Horne, Jesse and Wujcik, Evan K. and Liu, Haichao and Ryu, Jong E. and Wu, Daming and Guo, Zhanhu}, year={2019}, pages={3–17} }
@article{kanagaraj_chaturvedi_al yassi_orabi_ryu_park_choi_2019, title={Electrochemically grown vertical CdTe nanowire arrays on a flexible/transparent substrate}, volume={253}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2019.06.051}, abstractNote={Vertical cadmium telluride (CdTe) nanowires were grown on flexible/transparent substrates by sputtering ITO and aluminum thin films on Parylene substrates, anodizing aluminum to form porous alumina, followed by electrodeposition of CdTe nanowires from ITO seed layer. The pore size of anodized alumina was controlled by oxalic acid concentration and applied voltage. The composition of CdTe nanowires were tuned by adjusting applied deposition potential and solution composition. I-V characteristics of a single 50 nm in diameter CdTe nanowire was examined using a conductive atomic force microscope (CAFM) at room temperature which indicates that the electrical resistivity of electrodeposited CdTe nanowires are similar to thin-film counterpart.}, journal={MATERIALS LETTERS}, author={Kanagaraj, Amarsingh Bhabu and Chaturvedi, Prerna and Al Yassi, Hamad and Orabi, Lina and Ryu, Jong Eun and Park, Jung-Rae and Choi, Daniel S.}, year={2019}, month={Oct}, pages={113–116} }
@article{seok_al-hossain_waliullah_ryu_2019, title={Fabrication of Nano-Patterned Arrays Using Pulsed Light Technique}, volume={7}, ISSN={2576-988X 2576-9898}, url={http://dx.doi.org/10.30919/es8d506}, DOI={10.30919/es8d506}, abstractNote={Pulsed light aided thin film de-wetting process to fabricate nano-patterned array is introduced. Being compared to thermal annealing process, highly intense pulsed light with millisecond duration plays a role to transform solid-state thin-film to metastable and provides enough energy as a driving force to form island-like pattern. Topological analysis using SEM and AFM was performed to confirm fabricated structures. In addition, optical performance regarding surface-plasmon resonance and light absorption was studied by experimental UV-VIS spectroscopy and computer aided electromagnetics (EM) simulation. This research will benefit to the real-time roll-to-roll fabrication for the fabrication of nanostructures without using of thermal soaking and vacuum process.}, journal={Engineered Science}, publisher={Engineered Science Publisher}, author={Seok, Ilwoo and Al-Hossain, Aktaruzzaman and Waliullah, Mohammad and Ryu, Jong Eun}, year={2019}, pages={59–64} }
@article{an_park_yassi_lee_park_kim_ryu_choi_2019, title={Fabrication of graphene-magnetite multi-granule nanocluster composites for microwave absorption application}, volume={53}, ISSN={["1530-793X"]}, DOI={10.1177/0021998319853032}, abstractNote={ Ferrite multi-granule nanoclusters are fabricated for microwave absorption materials in different sized particles and granules by modified polyol process. Various sizes of ferrite nanoclusters are placed on graphene-based composites and the behavior of their microwave absorbing properties is studied. The absorbing properties are measured using the free-space method with two horn antennas for X-band range (8.2 GHz–12.4 GHz). Relative permittivity and permeability values are calculated in measured frequency domain. The absorption coefficient changes by forming ferrite-graphene composites are presented as well. }, number={28-30}, journal={Journal of Composite Materials}, author={An, Boo H. and Park, Bum C. and Yassi, Hamad A. and Lee, Ji S. and Park, Jung-Rae and Kim, Young K. and Ryu, Jong E. and Choi, Daniel S.}, year={2019}, month={Dec}, pages={4097–4103} }
@article{islam_yassi_dong_choi_seok_liu_guo_ryu_2019, title={Hierarchical Assembly of CuO Nano-Dandelions on 3-D Printed Template}, volume={6}, ISSN={2576-988X 2576-9898}, url={http://dx.doi.org/10.30919/es8d503}, DOI={10.30919/es8d503}, abstractNote={We report a two-phase chemical synthesis of various copper (Cu) nanostructures throughout complex 3-dimensional (3-D) printed substrates. We present dandelion-like CuO nano-rods grown on a 3-D model. 1 mm x 1 mm x 10 mm bars are cross-stacked to form a cubic log-pile structure. Ni thin-film was electrolessly deposited, and subsequently Cu layer was electroplated on the 3-D log-pile structure. In order to grow nanostructures, the Cu layer was reacted with an alkali solution (NH OH). The surface morphology and chemistry were characterized by field 4}, journal={Engineered Science}, publisher={Engineered Science Publisher}, author={Islam, Md Didarul and Yassi, Hamad Al and Dong, Mengyao and Choi, Daniel S. and Seok, Ilwoo and Liu, Chuntai and Guo, Zhanhu and Ryu, Jong Eun}, year={2019}, pages={86–89} }
@article{ryu_salcedo_lee_jang_jang_yassi_baek_choi_lee_2019, title={Material models and finite analysis of additively printed polymer composites}, volume={53}, url={https://doi.org/10.1177/0021998318785672}, DOI={https://doi.org/10.1177/0021998318785672}, abstractNote={ There are urgent needs to characterize and model the mechanical property of additively manufactured composite materials, known as the digital materials, for the computational design and simulation. In this study, most utilized digital material samples, which are the mixture of base polymers, Tango Black+ and Vero White+, by PolyJet (Stratasys) are chosen. Four polynomial models (Neo Hookean model, and two-, three-, and five-parameter Mooney–Rivlin models) are used to fit mechanical tensile test results up to 30% of strain. The material models were adopted in the finite element analysis simulating the tensile test to validate their accuracy. The simulation results based on the two-parameter Mooney–Rivlin model predict the stress at 30% strain with small errors (8.2, 10.5, 0.9, 5.0, and 8.0 for Tango Black+, DM40, DM50, DM60, and DM70, respectively). Additionally, scanning electron microscopy was utilized to analyze the fracture surface of the base materials (Tango Black+ and Vero White+) and the digital materials. }, number={3}, journal={Journal of Composite Materials}, publisher={Sage Journal}, author={Ryu, J. E. and Salcedo, E. and Lee, H. J. and Jang, S. J. and Jang, E. Y. and Yassi, H. A. and Baek, D. and Choi, D. and Lee, E.}, year={2019}, month={Feb}, pages={361–371} }
@article{an_park_kanagaraj_chaturvedi_al yassi_park_kim_ryu_sanduleanu_choi_2019, title={Microwave absorption properties of magnetite multi-granule nanocluster–multiwall carbon nanotube composites}, volume={12}, DOI={10.1142/S1793604719500115}, abstractNote={ Fe3O4 multi-granule nanocluster–multiwall carbon nanotube composites for microwave absorbing applications are fabricated by the surface-engineered tape-casting method. The multi-granule nanoclusters are synthesized by a modified polyol hydrothermal method and characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. The complex permittivity and permeability of the composites with different granule size of nanoclusters are characterized in X-band range with the reflection method. The absorption peak of the composites are shifted from 11.1[Formula: see text]GHz to 11.51[Formula: see text]GHz as granule size increased from 18[Formula: see text]nm to 35[Formula: see text]nm. }, number={2}, journal={Functional Materials Letters}, author={An, Boo Hyun and Park, Bum Chul and Kanagaraj, Amarsingh Bhabu and Chaturvedi, Prerna and Al Yassi, Hamad and Park, Jung-Rae and Kim, Young Keun and Ryu, Jong Eun and Sanduleanu, Mihai and Choi, Daniel Sunghoi}, year={2019}, pages={1950011} }
@article{berndt_hwang_islam_sihn_urbas_ku_lee_czaplewski_dong_shao_et al._2019, title={Poly(sulfur-random-(1,3-diisopropenylbenzene)) based mid-wavelength infrared polarizer: Optical property experimental and theoretical analysis}, volume={176}, ISSN={["1873-2291"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85066071701&partnerID=MN8TOARS}, DOI={10.1016/j.polymer.2019.05.036}, abstractNote={Development of polymer based mid-wavelength infrared (MWIR) optics has been limited mainly due to high optical loss of organic polymers used in general optical components. In this study, a MWIR polarization grating based on a sulfuric polymer poly(sulfur-random-(1,3-diisopropenylbenzene)) with a low loss in the MWIR range was fabricated using a simple two-step process: imprint and metal deposition. Fourier-transform infrared (FTIR) spectroscopy measurement showed that this polymeric MWIR polarizer selectively transmitted the polarized IR in transverse magnetic (TM) mode over the transverse electric (TE) mode at normal incidence. The measured extinction ratios (η = The ratio of transmissions in TM and TE) were 208, 176, and 212 at the wavelength of 3, 4, and 5 μm, respectively. The computational simulation and analytical model confirmed that the enhanced TM transmission efficiency and η followed a Fabry-Pérot (FP) resonance mode within the created sulfuric polymer film. This polymeric MWIR polarizer demonstrated a great potential for broader applications in IR photonics to realize low-cost and durable optical components.}, journal={POLYMER}, publisher={Elsevier BV}, author={Berndt, Aaron J. and Hwang, Jehwan and Islam, Md Didarul and Sihn, Amy and Urbas, Augustine M. and Ku, Zahyun and Lee, Sang Jun and Czaplewski, David A. and Dong, Mengyao and Shao, Qian and et al.}, year={2019}, month={Aug}, pages={118–126} }
@article{pan_schubert_ryu_wujick_liu_shen_liu_2018, title={Dynamic oscillatory rheological properties of polystyrene/poly(methyl methacrylate) blends and their composites in the presence of carbon black}, volume={1}, ISSN={2576-988X 2576-9898}, url={http://dx.doi.org/10.30919/es.180402}, DOI={10.30919/es.180402}, abstractNote={86 | Eng. Sci., 2018, 1, 86–94 © Engin 1 National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University, Zhengzhou, 450002, China. E-mail: xianhu.liu@zzu.edu.cn 2 Institute of Polymer Materials, Friedrich-Alexander University Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen, Germany. E-mail: xianhu.liu@zzu.edu.cn Department of Mechanical Engineering and Integrated Nanosystems Development Institute, Indiana University-Purdue University Indianapolis, 723 W. Michigan St, Indianapolis, IN 46202, USA Materials Engineering and Nanosensor [MEAN] Laboratory, Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, USA Dynamic oscillatory rheological properties of polystyrene/poly(methyl methacrylate) blends and their composites in the presence of carbon black}, journal={Engineered Science}, publisher={Engineered Science Publisher}, author={Pan, Yamin and Schubert, Dirk W. and Ryu, Jong Eun and Wujick, Evan and Liu, Chuntai and Shen, Changyu and Liu, Xianhu}, year={2018}, pages={86–94} }
@article{choi_yang_gill_berndt_park_ryu_2018, title={Fabrication and electrochemical characterization of super-capacitor based on three-dimensional composite structure of graphene and a vertical array of carbon nanotubes}, volume={52}, ISSN={0021-9983 1530-793X}, url={http://dx.doi.org/10.1177/0021998318760154}, DOI={10.1177/0021998318760154}, abstractNote={ We have demonstrated a three-dimensional composite structure of graphene and carbon nanotubes as electrodes for super-capacitors. The goal of this study is to fabricate and test the vertically grown carbon nanotubes on the graphene layer acting as a spacer to avoid self-aggregation of the graphene layers while realizing high active surface area for high energy density, specific capacitance, and power density. A vertical array of carbon nanotubes on silicon substrates was grown by a low-pressure chemical vapor deposition process using anodized aluminum oxide nanoporous template fabricated on silicon substrates. Subsequently, a graphene layer was grown by another low-pressure chemical vapor deposition process on top of a vertical array of carbon nanotubes. The Raman spectra confirmed the successful growth of carbon nanotubes followed by the growth of high-quality graphene. The average measured capacitance of the three-dimensional composite structure of graphene-carbon nanotube was 780 µFcm−2 at 100 mVs−1. }, number={22}, journal={Journal of Composite Materials}, publisher={SAGE Publications}, author={Choi, Daniel and Yang, Eui-Hyeok and Gill, Waqas and Berndt, Aaron and Park, Jung-Rae and Ryu, Jong Eun}, year={2018}, month={Feb}, pages={3039–3044} }
@article{mansouri_an_al shibli_al yassi_alkindi_lee_kim_ryu_choi_2018, title={Fabrication of three-dimensional electrical patterns by swollen-off process: An evolution of the lift-off process}, volume={18}, ISSN={1567-1739}, url={http://dx.doi.org/10.1016/j.cap.2018.06.001}, DOI={10.1016/j.cap.2018.06.001}, abstractNote={We present a novel process to fabricate three-dimensional (3D) metallic patterns from 3D printed polymeric structures utilizing different hygroscopic swelling behavior of two different polymeric materials. 3D patterns are printed with two different polymers as cube shape. The surface of the 3D printed polymeric structures is plated with nickel by an electroless plating method. The nickel patterns on the surface of the 3D printed cube shape structure are formed by removing sacrificial layers using the difference in the rate of hygroscopic swelling between two printing polymer materials. The hygroscopic behavior on the interfaced structure was modeled with COMSOL Multiphysics. The surface and electrical properties of the fabricated three-dimensional patterns were analyzed and characterized.}, number={11}, journal={Current Applied Physics}, publisher={Elsevier BV}, author={Mansouri, Mariam S. and An, Boo Hyun and Al Shibli, Hamda and Al Yassi, Hamad and Alkindi, Tawaddod Saif and Lee, Ji Sung and Kim, Young Keun and Ryu, Jong Eun and Choi, Daniel S.}, year={2018}, month={Nov}, pages={1235–1239} }
@article{kim_hwang_oh_kim_silva_czaplewski_ryu_kim_urbas_zhou_et al._2018, title={Fabry-Perot cavity resonance enabling highly polarization-sensitive double-layer gold grating}, volume={8}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-018-32158-y}, abstractNote={Abstract}, number={14787}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Kim, Jun Oh and Hwang, Jehwan and Oh, Boram and Kim, Yeongho and Silva, Sinhara and Czaplewski, David A. and Ryu, Jong Eun and Kim, Fun Kyu and Urbas, Augustine and Zhou, Jiangfeng and et al.}, year={2018} }
@article{park_berndt_kim_lee_ryu_choi_2018, title={Formation of high aspect ratio fused silica nanowalls by fluorine-based deep reactive ion etching}, volume={15}, ISSN={2352-507X}, url={http://dx.doi.org/10.1016/j.nanoso.2017.10.004}, DOI={10.1016/j.nanoso.2017.10.004}, abstractNote={Even though fused silica was considered as a good mold material for nanoimprint lithography due to the properties of UV-transparent and high strength, fabrication of high aspect ratio nanometer-scale mold was challenging. A fabrication process for 120 nm-wide fused silica ‘nano-walls’ with high aspect ratio has been developed by using fluorine-based deep reactive ion etching (DRIE). The optimum conditions of the DRIE process to result in anisotropic vertical sidewalls with high-aspect ratio and good etch rate control were demonstrated as a function of bias power, process pressure, and argon percentage of the gas mixture. One of the vast applications of this process is the fabrication of the mold for UV nanoimprint lithography (NIL). Due to the fact that the resist is cured using UV-light, it is critical that the mold is transparent. A thin aluminum layer is used as a conducting layer for e-beam lithography, then used as an etch mask for fused silica etch. In the presented study, the etch rate increases with higher bias power and lower gas pressure. The existence of Ar makes the vertical surface smoother.}, journal={Nano-Structures & Nano-Objects}, publisher={Elsevier BV}, author={Park, Jung-Rae and Berndt, Aaron and Kim, Young Keun and Lee, Ji Sung and Ryu, Jong Eun and Choi, Daniel Sunghoi}, year={2018}, month={Jul}, pages={212–215} }
@article{zhao_wu_zhang_li_jiang_wang_zhao_ryu_guo_2018, title={Ionic liquid-assisted synthesis of Yb3+-Tm3+ codoped Y7O6F9 petal shaped microcrystals with enhanced upconversion emission}, volume={103}, ISSN={0025-5408}, url={http://dx.doi.org/10.1016/j.materresbull.2018.03.003}, DOI={10.1016/j.materresbull.2018.03.003}, abstractNote={Petal-like Yb3+-Tm3+ codoped Y7O6F9 microparticles were achieved via ionic liquid-assisted (IL) hydrothermal process. The emission efficiency of Y7O6F9:Yb3+/Tm3+ powders is much stronger than that of Y2O3:Yb3+/Tm3+ sample. Under excitation at 980 nm with an unfocused laser beam under weak pump density of ∼0.1 W/cm2 (pump power 10 mW), the UC emission of the sample can been seen clearly. Four emission bands at 477, 540, 647 and 692 nm are observed and correspond to the 1G4 state to 3H6 state, 1D2 state to 3H5 state, 1G4 sate to 3F4 state, and 3F3 state to 3H6 state transition of Tm3+ ions. The enhanced UC emission is related to high crystallinity and lower effective phonon energy of oxyfluorides. The ionic liquid (IL) of [BMIM][BF4] is used both as the reaction medium and the source of F−.}, journal={Materials Research Bulletin}, publisher={Elsevier BV}, author={Zhao, Jinbo and Wu, Lili and Zhang, Chuanjiang and Li, Tingxi and Jiang, Qinglong and Wang, Feng and Zhao, Ping and Ryu, Jong Eun and Guo, Zhanhu}, year={2018}, month={Jul}, pages={19–24} }
@article{zhao_meng_ma_ma_yang_huang_ryu_shankar_li_yan_et al._2018, title={Layer-by-layer grafting CNTs onto carbon fibers surface for enhancing the interfacial properties of epoxy resin composites}, volume={154}, ISSN={0266-3538}, url={http://dx.doi.org/10.1016/j.compscitech.2017.11.002}, DOI={10.1016/j.compscitech.2017.11.002}, abstractNote={An effective method for bonding carbon nanotubes (CNTs) onto carbon fibers (CFs) surface via layer-by-layer (LBL) grafting method is reported here. The CNTs have been chemically grafted as confirmed by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) indicates that this LBL method can increase the dispersion quality of the CNTs on CF surface. The polarity, wettability and roughness of the CFs have been significantly increased after the CNTs modifying. The interfacial shear strength (IFSS) and impact strength test suggest that the hierarchical structure can result in a remarkable improvement for the interfacial properties. The results also indicate that this LBL method is a promising technique to modify CFs with the high interfacial performance.}, journal={Composites Science and Technology}, publisher={Elsevier BV}, author={Zhao, Min and Meng, Linghui and Ma, Lichun and Ma, Lina and Yang, Xiaobing and Huang, Yudong and Ryu, Jong Eun and Shankar, Akash and Li, Tingxi and Yan, Chao and et al.}, year={2018}, month={Jan}, pages={28–36} }
@article{ryu_salcedo_lee_jang_jang_yassi_baek_choi_lee_2018, title={Material models and finite analysis of additively printed polymer composites}, volume={53}, ISSN={0021-9983 1530-793X}, url={http://dx.doi.org/10.1177/0021998318785672}, DOI={10.1177/0021998318785672}, abstractNote={ There are urgent needs to characterize and model the mechanical property of additively manufactured composite materials, known as the digital materials, for the computational design and simulation. In this study, most utilized digital material samples, which are the mixture of base polymers, Tango Black+ and Vero White+, by PolyJet (Stratasys) are chosen. Four polynomial models (Neo Hookean model, and two-, three-, and five-parameter Mooney–Rivlin models) are used to fit mechanical tensile test results up to 30% of strain. The material models were adopted in the finite element analysis simulating the tensile test to validate their accuracy. The simulation results based on the two-parameter Mooney–Rivlin model predict the stress at 30% strain with small errors (8.2, 10.5, 0.9, 5.0, and 8.0 for Tango Black+, DM40, DM50, DM60, and DM70, respectively). Additionally, scanning electron microscopy was utilized to analyze the fracture surface of the base materials (Tango Black+ and Vero White+) and the digital materials. }, number={3}, journal={Journal of Composite Materials}, publisher={SAGE Publications}, author={Ryu, Jong Eun and Salcedo, Eduardo and Lee, Hyeok Jong and Jang, Sung Jun and Jang, Eun Young and Yassi, Hamad Al and Baek, Dongcheon and Choi, Daniel and Lee, Euntaek}, year={2018}, month={Jul}, pages={361–371} }
@article{salcedo_baek_berndt_ryu_2018, title={Simulation and validation of three dimension functionally graded materials by material jetting}, volume={22}, ISSN={2214-8604}, url={http://dx.doi.org/10.1016/j.addma.2018.05.027}, DOI={10.1016/j.addma.2018.05.027}, abstractNote={The goal of this work is to validate the material models for parts created with a Material Jetting 3-dimensional printer through the comparison of Finite Element Analysis (FEA) simulations and physical tests. The strain maps generated by a video extensometer for multi-material samples are compared to the FEA results based on our material models. Two base materials (ABS-like and rubber-like) and their composites are co-printed in the graded tensile test samples. The graded islands are embedded in the rubber-like test specimens. The simulations were conducted utilizing previously fitted material models, a two-parameter Mooney-Rivlin model for the elastic materials (Tango Black+, DM95, and DM60) and a bilinear model for the rigid material (Vero White+). The results show that the simulation results based on our material models can predict the deformation behaviors of the multi-material samples during a uniaxial tensile test. Our simulation results are able to predict the maximum strain in the matrix material (TB+) within 5% error. Both global deformation pattern and local strain level confirm the validity of the simulated material models.}, journal={Additive Manufacturing}, publisher={Elsevier BV}, author={Salcedo, Eduardo and Baek, Dongcheon and Berndt, Aaron and Ryu, Jong Eun}, year={2018}, month={Aug}, pages={351–359} }
@article{sun_xie_wang_su_shao_ryu_zhang_guo_shankar_li_et al._2017, title={Flexible polydimethylsiloxane/multi-walled carbon nanotubes membranous metacomposites with negative permittivity}, volume={125}, ISSN={0032-3861}, url={http://dx.doi.org/10.1016/j.polymer.2017.07.083}, DOI={10.1016/j.polymer.2017.07.083}, abstractNote={Metacomposites with negative electromagnetic parameters can be promising substitute for periodic metamaterials. In this paper, we devoted to fabricating flexible metacomposite films, which have great potential applications in the field of wearable cloaks, sensing, perfect absorption and stretchable electronic devices. The conductivity and the complex permittivity were investigated in flexible polydimethylsiloxane (PDMS)/multi-walled carbon nanotubes (MWCNTs) membranous nanocomposites, which were fabricated via in-situ polymerization process. With the increase of conductive one-dimension carbon nanotubes concentration, there was a percolation transition observed in conduction due to the formation of continuous networks. The dielectric dispersion behavior was also analyzed in the spectra of complex permittivity. It is indicated that the conduction and polarization make a combined effect on the dielectric loss in flexible PDMS/MWCNTs composites. The negative permittivity with a dielectric resonance was obtained, and was attributed to the induced electric dipoles.}, journal={Polymer}, publisher={Elsevier BV}, author={Sun, Kai and Xie, Peitao and Wang, Zhongyang and Su, Tongming and Shao, Qian and Ryu, JongEun and Zhang, Xihua and Guo, Jiang and Shankar, Akash and Li, Jianfeng and et al.}, year={2017}, month={Sep}, pages={50–57} }
@article{truongvo_kennedy_chen_chen_berndt_agarwal_zhu_nakshatri_wallace_na_et al._2017, title={Microfluidic channel for characterizing normal and breast cancer cells}, volume={27}, number={3}, journal={Journal of Micromechanics and Microengineering}, publisher={IOP Publishing}, author={TruongVo, TN and Kennedy, RM and Chen, H and Chen, A and Berndt, A and Agarwal, M and Zhu, L and Nakshatri, H and Wallace, J and Na, S and et al.}, year={2017}, pages={035017} }
@article{cao_huang_peng_cao_galaska_qiu_liu_khan_young_ryu_et al._2017, title={Poly(vinylidene fluoride) derived fluorine-doped magnetic carbon nanoadsorbents for enhanced chromium removal}, volume={115}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/j.carbon.2017.01.033}, DOI={10.1016/j.carbon.2017.01.033}, abstractNote={Newly designed fluorine-doped magnetic carbon (F-MC) was synthesized in situ though a facile one-step pyrolysis-carbonization method. Poly(vinylidene fluoride) (PVDF) served as the precursor for both carbon and fluorine. 2.5% F content with core-shell structure was obtained over F-MC, which was used as a adsorbent for the Cr(VI) removal. To our best knowledge, this is the first time to report that the fluorine doped material was applied for the Cr(VI) removal, demonstrating very high removal capacity (1423.4 mg g−1), higher than most reported adsorbents. The unexpected performance of F-MC can be attributed to the configuration of F dopants on the surface. The observed pseudo-second-order kinetic study indicated the dominance of chemical adsorption for this process. High stability of F-MC after 5 recycling test for the Cr(VI) removal was also observed, indicating that F-MC could be used as an excellent adsorbent for the toxic heavy metal removal from the wastewater.}, journal={Carbon}, publisher={Elsevier BV}, author={Cao, Yonghai and Huang, Jiangnan and Peng, Xiangfang and Cao, Dapeng and Galaska, Alexandra and Qiu, Song and Liu, Jiurong and Khan, Mojammel A. and Young, David P. and Ryu, Jong Eun and et al.}, year={2017}, month={May}, pages={503–514} }
@article{shankar_salcedo_berndt_choi_ryu_2017, title={Pulsed light sintering of silver nanoparticles for large deformation of printed stretchable electronics}, volume={1}, ISSN={2522-0128 2522-0136}, url={http://dx.doi.org/10.1007/s42114-017-0012-3}, DOI={10.1007/s42114-017-0012-3}, number={1}, journal={Advanced Composites and Hybrid Materials}, publisher={Springer Science and Business Media LLC}, author={Shankar, Akash and Salcedo, Eduardo and Berndt, Aaron and Choi, Daniel and Ryu, Jong Eun}, year={2017}, month={Nov}, pages={193–198} }
@article{hopkins_gill_kringel_wang_hass_acharya_park_jeon_an_lee_et al._2017, title={Radio frequency-mediated local thermotherapy for destruction of pancreatic tumors using Ni–Au core–shell nanowires}, volume={28}, DOI={10.1088/1361-6528/28/3/03LT01}, abstractNote={We present a novel method of radio frequency (RF)-mediated thermotherapy in tumors by remotely heating nickel (Ni)–gold (Au) core–shell nanowires (CSNWs). Ectopic pancreatic tumors were developed in nude mice to evaluate the thermotherapeutic effects on tumor progression. Tumor ablation was produced by RF-mediated thermotherapy via activation of the paramagnetic properties of the Ni–Au CSNWs. Histopathology demonstrated that heat generated by RF irradiation caused significant cellular death with pyknotic nuclei and nuclear fragmentation dispersed throughout the tumors. These preliminary results suggest that thermotherapy ablation induced via RF activation of nanowires provides a potential alternative therapy for cancer treatment.}, number={3}, journal={Nanotechnology}, author={Hopkins, X. and Gill, W. and Kringel, R. and Wang, G. and Hass, J. and Acharya, S. and Park, J. and Jeon, I.-T. and An, B.H. and Lee, J. and et al.}, year={2017}, month={Jan}, pages={03LT01} }
@article{chen_wang_li_sherman_ryu_hamamura_liu_nakshatri_yokota_2017, title={Reduction in Migratory Phenotype in a Metastasized Breast Cancer Cell Line via Downregulation of S100A4 and GRM3}, volume={7}, ISSN={2045-2322}, url={http://dx.doi.org/10.1038/s41598-017-03811-9}, DOI={10.1038/s41598-017-03811-9}, abstractNote={Abstract}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Chen, Andy and Wang, Luqi and Li, Bai-Yan and Sherman, Jesse and Ryu, Jong E. and Hamamura, Kazunori and Liu, Yunlong and Nakshatri, Harikrishna and Yokota, Hiroki}, year={2017}, month={Jun}, pages={3459–3460} }
@article{cheng_fan_wang_shao_guo_xie_yin_zhang_an_lei_et al._2017, title={Tunable and weakly negative permittivity in carbon/silicon nitride composites with different carbonizing temperatures}, volume={125}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/j.carbon.2017.09.037}, DOI={10.1016/j.carbon.2017.09.037}, abstractNote={Despite the exotic electromagnetic properties have been demonstrated in metamaterials to date, how to effectively adjust negative electromagnetic parameters remains a challenge. Tunable negative permittivity is essential for the metamaterials to satisfy a variety of practical applications, such as capacitor, microwave absorbing and shielding. Here, we fabricated a random metamaterial, carbon/silicon nitride (C/Si3N4) composite, using a feasible impregnation-pyrolysis method. The microstructure and dielectric property of the composites with different heat treatment temperatures (HTTs) and carbon contents were investigated. The amorphous carbon membrane adhered on the rod-like Si3N4 grains. The negative permittivity behavior combined with inductive character was obtained in the composites, which was attributed to the low frequency plasmonic state generated from the formative conducting carbon networks. The magnitude of negative permittivity is demonstrated to be successfully adjusted by controlling the HTT and carbon content. The result is in good agreement with the analysis of Drude model. Interestingly, a weakly negative permittivity behavior was observed in the measured frequency, showing small negative values of permittivity between −50 and −10, which was ascribed to a moderate carrier concentration provided by the carbon networks. This work provides an effective way to achieve the tunable and weakly negative permittivity in random metamaterials.}, journal={Carbon}, publisher={Elsevier BV}, author={Cheng, Chuanbing and Fan, Runhua and Wang, Zhongyang and Shao, Qian and Guo, Xingkui and Xie, Peitao and Yin, Yansheng and Zhang, Yuliang and An, Liqiong and Lei, Yanhua and et al.}, year={2017}, month={Dec}, pages={103–112} }
@article{mosey_gaire_kim_ryu_cheng_2017, title={Tunable cobalt nanoparticle synthesis by intense pulse flash annealing}, volume={7}, ISSN={2158-3226}, url={http://dx.doi.org/10.1063/1.4975044}, DOI={10.1063/1.4975044}, abstractNote={Magnetically susceptible materials can serve as a basis for the directed assembly of nanoscale network devices which can be used to extract energy from phase change materials. So far, matrix production cost has been a prohibitive factor in the realization of real world applications. Here we report a cost-effective method to synthesize magnetic nanoparticles. Samples were fabricated by sputtering magnetic thin films on carbon nanotube substrates followed by xenon intense pulsed light flash annealing. The results indicate that spatially ordered magnetic spheres can be tuned by various parameters such as initial thin film thickness, xenon lamp exposure excitation energy, local surface geometries, and the presence of an external magnetic field during annealing.}, number={5}, journal={AIP Advances}, publisher={AIP Publishing}, author={Mosey, Aaron and Gaire, Babu and Kim, Jeongwhan and Ryu, Jong Eun and Cheng, Ruihua}, year={2017}, month={Jan}, pages={056308} }
@article{gill_ali_choi_park_ryu_kim_2016, title={3 Dimensional-Printed Micro-Container with Graphene Current Collector and Manganese Oxide Thin-Film as Cathodes of Li-Batteries}, volume={8}, ISSN={1941-4900 1941-4919}, url={http://dx.doi.org/10.1166/nnl.2016.2273}, DOI={10.1166/nnl.2016.2273}, number={12}, journal={Nanoscience and Nanotechnology Letters}, publisher={American Scientific Publishers}, author={Gill, Waqas A. and Ali, Dima and Choi, Daniel S. and Park, Jung-Rae and Ryu, Jong Eun and Kim, Young Keun}, year={2016}, month={Dec}, pages={1095–1098} }
@article{choi_an_mansouri_ali_khalil_xu_nwoke_park_shankar_ryu_2016, title={Micro-capacitor with vertically grown silver nanowires and bismuth ferric oxide composite structures on silicon substrates}, volume={51}, ISSN={0021-9983 1530-793X}, url={http://dx.doi.org/10.1177/0021998316656767}, DOI={10.1177/0021998316656767}, abstractNote={ We have designed and demonstrated a complementary metal-oxide-semiconductor compatible process for fabricating high capacitance micro-capacitors based on vertically grown silver nanowires on silicon substrates. Array of silver nanowires with high-aspect ratio were electrochemically grown in the pores of anodized aluminum oxide film, which was pre-formed through anodization of aluminum thin film deposited on titanium/silicon oxide/silicon substrates. High dielectric bismuth ferric oxide layer was electrodeposited to fill the gap between silver nanowires after anodized aluminum oxide film was removed. It was found that the micro-capacitor based on the silver nanowires/bismuth ferric oxide composite film possessed higher capacitance by approximately one order of magnitude from the COMSOL simulation results from the flat Ag thin-film capacitor and the silver nanowire capacitor. }, number={7}, journal={Journal of Composite Materials}, publisher={SAGE Publications}, author={Choi, Daniel and An, Boo Hyun and Mansouri, Mariam and Ali, Dima and Khalil, Malathe and Xu, Ke and Nwoke, Dominic and Park, Jung-Rae and Shankar, Akash and Ryu, Jong Eun}, year={2016}, month={Jul}, pages={965–969} }
@article{kim_shankar_zhu_choi_guo_ryu_2016, title={Reinforcement of Cu nanoink sintered film with extended carbon nanofibers for large deformation of printed electronics}, volume={51}, ISSN={0021-9983 1530-793X}, url={http://dx.doi.org/10.1177/0021998316656394}, DOI={10.1177/0021998316656394}, abstractNote={ Metallic nanoparticle inks (nanoinks) have attracted great interest in the manufacturing of printed flexible electronics. However, sintering pure nanoinks in ambient conditions results in micro-cracks and pores within the sintered film, which deteriorate the mechanical and electrical characteristics of the sintered nanoinks. To alleviate these problems, we demonstrate the use of very long carbon nanofiber (average length 200 µm) to reinforce the sintered nanoink films. In this study, different weight fractions of carbon nanofiber are dispersed into the Cu nanoink to improve the mechanical bending characteristics. Scanning electron micrographs show improved dispersion of oxidized carbon nanofiber in the nanoink compared to the as-received carbon nanofiber. The composite nanoinks are stencil printed on polyethylene terephthalate film and sintered by intense pulsed light using Xe-flash. The electrical measurements show 90%, 65%, and 66% improved electrical conductivity in the composite nanoink film (0.7% of oxidized carbon nanofiber) compared to the pure Cu nanoink under the 7.5 cm, 5.0 cm, and 2.5 cm of bending radii, respectively. }, number={7}, journal={Journal of Composite Materials}, publisher={SAGE Publications}, author={Kim, Jeonghwan and Shankar, Akash and Zhu, Jiahua and Choi, Daniel S and Guo, Zhanhu and Ryu, Jong E}, year={2016}, month={Jul}, pages={997–1003} }
@article{espich_salcedo_kulkarni_sung choi_ryu_2016, title={Scalable nanoparticle assembly on carbon nanotubes using flash-induced dewetting}, volume={51}, ISSN={0021-9983 1530-793X}, url={http://dx.doi.org/10.1177/0021998316682310}, DOI={10.1177/0021998316682310}, abstractNote={ Nanoparticle assembly through a novel photothermal dewetting was demonstrated on a macro-scale carbon nanotube (CNT) film. Intense pulsed Xe-light (IPL) was applied to transform a gold (Au) thin-film on CNT into nanoparticles (NPs). Au films measuring 3, 6, and 9 nm were completely dewetted by 10, 20, and 35 J/cm2 of IPL intensities, respectively. The means of NP diameters after dewetting were 7.25 nm (standard deviation, σ = 2.23 nm), 13.07 nm ( σ = 2.38 nm), and 21.02 nm ( σ = 5.86 nm) for the 3, 6, and 9 nm of Au films, respectively. On the other hand, the means of Au NPs formed by furnace annealing were 13.16 nm ( σ = 1.78 nm) and 20.98 nm ( σ = 15.60 nm) for 6 and 9 nm of Au films, respectively. The 6 and 9 nm of Au films on CNTs were annealed in a furnace at 300 and 400℃, respectively. The distributions of NPs induced by IPL were not significantly different from the result of conventional furnace annealing ( p values = 0.45 and 0.96 for 6 and 9 nm Au films, respectively). Finally, thermodynamic stability of IPL dewetted NPs was evaluated by comparing the samples treated with multiple IPL up to five times and with extended thermal annealing up to 10 h. }, number={9}, journal={Journal of Composite Materials}, publisher={SAGE Publications}, author={Espich, Taylor and Salcedo, Eduardo and Kulkarni, Ameya and Sung Choi, Daniel and Ryu, Jong Eun}, year={2016}, month={Dec}, pages={1299–1305} }
@article{ota_wang_ryu_wang_chen_zhang_2013, title={Intracellular delivery of top-down fabricated tunable nano-plasmonic resonators}, volume={5}, ISSN={2040-3364 2040-3372}, url={http://dx.doi.org/10.1039/c3nr02910g}, DOI={10.1039/c3nr02910g}, abstractNote={Engineered plasmonic structures fabricated using top-down technologies have demonstrated huge enhancements in the optical response of molecules, including Raman scattering. However, providing a sufficient number of such top-down fabricated nanostructures in solution has been a nontrivial task which has limited their potential in intracellular applications. Here we report the development of a protocol for the intracellular delivery of tunable nanoplasmonic resonators fabricated via scalable top-down techniques. This offers excellent possibilities towards the real-time parallel optical detection of intracellular molecular events.}, number={21}, journal={Nanoscale}, publisher={Royal Society of Chemistry (RSC)}, author={Ota, Sadao and Wang, Sheng and Ryu, Jongeun and Wang, Yuan and Chen, Yong and Zhang, Xiang}, year={2013}, pages={10179} }
@article{zhu_zhang_haldolaarachchige_wang_luo_ryu_young_wei_guo_2012, title={Polypyrrole Metacomposites with Different Nanostructures}, volume={22}, DOI={10.1039/c2jm14020a}, abstractNote={Polypyrrole (PPy) nanocomposites incorporating different carbon nanostructures (CNS), including graphenes of different sizes, carbon nanofibers (CNFs) and carbon nanotubes (CNTs), have been successfully synthesized using a surface initiated polymerization (SIP) method. The effects of graphene size, loading level and surface functionality on the electrical conductivity and dielectric permittivity of their corresponding nanocomposites have been systematically studied. The electron transportation mechanism has been investigated, which follows a quasi 3-d variable range hopping (VRH) behavior in the nanocomposites. Meanwhile, CNFs and CNTs with the same loading as graphene are also comparatively studied. Scanning electron microscopy and transmission electron microscopy results indicate that the PPy coating on one-dimensional carbon nanostructures, such as CNFs and CNTs, is more smooth and uniform than that on the two-dimensional graphenes. PPy/CNTs nanocomposites exhibit the lowest resistivity, followed by the composites incorporating the smaller sized graphene without surfactant. More interestingly, a negative permittivity is found in each composite system, which can be easily controlled by adjusting the nanofiller loading, morphology and surface functionality. TGA results indicate that the thermal stability of the polymer nanocomposites (PNCs) is affected by the graphene loading rather than the different nanostructures.}, number={11}, journal={Journal of Materials Chemistry}, author={Zhu, J. and Zhang, X. and Haldolaarachchige, N. and Wang, Q. and Luo, Z. and Ryu, J. and Young, D.P. and Wei, S. and Guo, Z.}, year={2012}, pages={4996–5005} }
@article{zhang_zhu_haldolaarachchige_ryu_young_wei_guo_2012, title={Synthetic process engineered polyaniline nanostructures with tunable morphology and physical properties}, volume={53}, ISSN={0032-3861}, url={http://dx.doi.org/10.1016/j.polymer.2012.02.042}, DOI={10.1016/j.polymer.2012.02.042}, abstractNote={Polyaniline (PANI) nanofibers (NFs) obtained by the interfacial polymerization method are studied and compared with PANI nanostructures prepared by the ultrasonication method and the polymer acid doping method. In the case of PANI NFs, the effects of the reaction time, the size of the interfacial area, scale ratio, and concentration of reactant on the crystalline structure, thermal stability, morphology, electrical conductivity and dielectric permittivity are systematically studied. Meanwhile, huge difference in morphology is observed and related to the nanofiber growth condition. Unusual morphology and peaks on X-ray diffraction curve of PANI doped with polymer acid (poly(2-acrylamido-2-methyl-1-propanesulfonic acid)) (PAMPSA) are observed and associated with high molecular weight of the doped polymer acid. The change of the conductivity is attributed to a combination of crystallinity and crystal size. Temperature dependent conductivity reveals a 3-d variable range hopping (VRH) electron transport mechanism. The electrical conductivity and dielectric permittivity are investigated and mainly depend on the morphology and crystalline structure. The resistivity of the PANI NFs is observed to be the lowest one compared with the other two at room temperature. Both PANI nanostructures (NFs and NPs) exhibit negative real permittivity in the whole frequency range. Meanwhile, positive magnetoresistance (MR) is observed in all the three kinds of PANI nanostructures and is analyzed theoretically from the currently available wave-function shrinkage model.}, number={10}, journal={Polymer}, publisher={Elsevier BV}, author={Zhang, Xi and Zhu, Jiahua and Haldolaarachchige, Neel and Ryu, Jongeun and Young, David P. and Wei, Suying and Guo, Zhanhu}, year={2012}, month={Apr}, pages={2109–2120} }
@article{zhu_wei_zhang_mao_ryu_haldolaarachchige_young_guo_2011, title={Electrical and dielectric properties of polyaniline–Al2O3 nanocomposites derived from various Al2O3 nanostructures}, volume={21}, ISSN={0959-9428 1364-5501}, url={http://dx.doi.org/10.1039/c0jm03908j}, DOI={10.1039/c0jm03908j}, abstractNote={Four Al2O3 nanostructures (i.e. nanofiber, nanoplatelet, nanorod and nanoflake) have been successfully synthesized via hydrothermal procedures followed by a dehydration process. Subsequently, polyaniline (PANI) nanocomposites incorporating these four Al2O3 nanostructures have been fabricated using a surface initialized polymerization (SIP) method. Both TEM and SEM are used to characterize the morphologies of the Al2O3 nanostructures and PANI/Al2O3 nanocomposites. X-Ray diffraction results reveal that the morphology of the nanofiller has a significant effect on the crystallization behavior of the PANI during polymerization. The electrical conductivity and dielectric permittivity of these nanocomposites are strongly related to both the morphology of the filler and the dispersion quality. Temperature-dependent-conductivity measurements from 50–290 K show that the electron transportation of the nanocomposites follows a quasi 3-d variable range hopping (VRH) conduction mechanism. The extent of charge carrier delocalization calculated from VRH is well correlated to the dielectric response of these nanocomposites. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results reveal an enhanced thermal stability of the PANI/Al2O3 nanocomposites as compared to that of pure PANI due to the strong interaction between the nanofillers and polymer matrix. The mechanism of the SIP method is also elaborated in this work.}, number={11}, journal={Journal of Materials Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Zhu, Jiahua and Wei, Suying and Zhang, Lei and Mao, Yuanbing and Ryu, Jongeun and Haldolaarachchige, Neel and Young, David P. and Guo, Zhanhu}, year={2011}, pages={3952} }
@article{li_zhu_wei_ryu_sun_guo_2011, title={Poly(propylene)/Graphene Nanoplatelet Nanocomposites: Melt Rheological Behavior and Thermal, Electrical, and Electronic Properties}, volume={212}, ISSN={1022-1352}, url={http://dx.doi.org/10.1002/macp.201100263}, DOI={10.1002/macp.201100263}, abstractNote={Poly(propylene) polymer nanocomposites containing graphene nanoplatelets (GnPs) with different loadings are fabricated via a facile ex-situ solution approach. Improved thermal stability and higher crystallinity are observed in the PNCs. Both electrical conductivity and real permittivity increase with increasing GnP loading. Electrical conductivity percolation is observed at 12.0 wt% GnP. The rheological behavior of the PNC melts are also investigated. It is found that the modulus and viscosity are reduced at small GnP loadings and increased above a critical loading.}, number={18}, journal={Macromolecular Chemistry and Physics}, publisher={Wiley}, author={Li, Yunfeng and Zhu, Jiahua and Wei, Suying and Ryu, Jongeun and Sun, Luyi and Guo, Zhanhu}, year={2011}, month={Jul}, pages={1951–1959} }
@article{zhu_wei_zhang_mao_ryu_karki_young_guo_2011, title={Polyaniline-tungsten oxide metacomposites with tunable electronic properties}, volume={21}, ISSN={0959-9428 1364-5501}, url={http://dx.doi.org/10.1039/c0jm02090g}, DOI={10.1039/c0jm02090g}, abstractNote={Polyaniline (PANI) nanocomposites reinforced with tungsten oxide (WO3) nanoparticles (NPs) and nanorods (NRs) are fabricated via a facile surface-initiated-polymerization (SIP) method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations reveal the uniform coating of polymer on the filler surface and a good dispersion of the nanofillers within the polymer matrix. Unique negative permittivity is observed in pure PANI and its nanocomposites. The switching frequency (frequency where real permittivity switches from negative to positive) can be easily tuned by changing the particle loading and filler morphology. Conductivity measurements are performed from 50∼290 K, and results show that the electron transportation in the nanocomposites follows a quasi 3-d variable range hopping (VRH) conduction mechanism. The extent of charge carrier delocalization calculated from VRH well explains the dielectric response of the metacomposites. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) reveal an enhanced thermal stability of the nanocomposites with the addition of nanofillers as compared to that of pure PANI.}, number={2}, journal={J. Mater. Chem.}, publisher={Royal Society of Chemistry (RSC)}, author={Zhu, Jiahua and Wei, Suying and Zhang, Lei and Mao, Yuanbing and Ryu, Jongeun and Karki, Amar B. and Young, David P. and Guo, Zhanhu}, year={2011}, pages={342–348} }
@article{ryu_kim_hahn_2011, title={Reactive Sintering of Copper Nanoparticles Using Intense Pulsed Light for Printed Electronics}, volume={40}, ISSN={0361-5235 1543-186X}, url={http://dx.doi.org/10.1007/s11664-010-1384-0}, DOI={10.1007/s11664-010-1384-0}, number={1}, journal={Journal of Electronic Materials}, publisher={Springer Science and Business Media LLC}, author={Ryu, Jongeun and Kim, Hak-Sung and Hahn, H. Thomas}, year={2011}, pages={42–50} }
@article{kang_ryu_kim_hahn_2011, title={Sintering of Inkjet-Printed Silver Nanoparticles at Room Temperature Using Intense Pulsed Light}, volume={40}, ISSN={0361-5235 1543-186X}, url={http://dx.doi.org/10.1007/s11664-011-1711-0}, DOI={10.1007/s11664-011-1711-0}, number={11}, journal={Journal of Electronic Materials}, publisher={Springer Science and Business Media LLC}, author={Kang, J. S. and Ryu, J. and Kim, H. S. and Hahn, H. T.}, year={2011}, month={Aug}, pages={2268–2277} }
@article{zhu_wei_ryu_guo_2011, title={Strain-Sensing Elastomer/Carbon Nanofiber “Metacomposites”}, volume={115}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp202999c}, DOI={10.1021/jp202999c}, abstractNote={Electrically conductive elastomer nanocomposites reinforced with 1, 2, 3, and 5 wt % carbon nanofibers (CNFs) have been fabricated from two slightly different elastomers (VM1, VM2). The electrical and dielectric percolation threshold of 1 wt % in VM2 nanocomposites is much lower than 3 wt % in the VM1 nanocomposites. Unique negative permittivity is observed in the composites with the CNF concentration correlating well with the percolation thresholds. About 40% unrecoverable strain loss and a permanently increased resistivity by about 2 orders of magnitude are observed due to the formation and opening/closing of the cracks during the first cyclic loading. In the subsequent stretching cycles, the reversible resistivity at 120% strain is about 2–3 orders of magnitude higher than that at 40% strain. Higher fraction of ethylene is found to reduce the thermal stability of the propylene portion in the elastomer. An enhanced thermal stability of the elastomers is observed in both nanocomposite systems; however, t...}, number={27}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Zhu, Jiahua and Wei, Suying and Ryu, Jongeun and Guo, Zhanhu}, year={2011}, month={Jun}, pages={13215–13222} }
@article{wang_ota_guo_ryu_rhodes_xiong_kalim_zeng_chen_teitell_et al._2011, title={Subcellular Resolution Mapping of Endogenous Cytokine Secretion by Nano-Plasmonic-Resonator Sensor Array}, volume={11}, ISSN={1530-6984 1530-6992}, url={http://dx.doi.org/10.1021/nl2018838}, DOI={10.1021/nl2018838}, abstractNote={Local extracellular signaling is central for cellular interactions and organizations. We report a novel sensing technique to interrogate extracellular signaling at the subcellular level. We developed an in situ immunoassay based on giant optical enhancement of a tunable nano-plasmonic-resonator array fabricated by nanoimprint lithography. Our nanoplasmonic device significantly increases the signal-to-noise ratio to enable the first time submicrometer resolution quantitative mapping of endogenous cytokine secretion. Our study shows a markedly high local interleukin-2 (IL-2) concentration within the immediate vicinity of the cell which finally validates a decades-old hypothesis on autocrine physiological concentration and spatial range. This general sensing technique can be applied for a broad range of cellular communication studies to improve our understanding of subcellular signaling and function.}, number={8}, journal={Nano Letters}, publisher={American Chemical Society (ACS)}, author={Wang, Sheng and Ota, Sadao and Guo, Bin and Ryu, Jongeun and Rhodes, Christopher and Xiong, Yi and Kalim, Sheraz and Zeng, Li and Chen, Yong and Teitell, Michael A. and et al.}, year={2011}, month={Aug}, pages={3431–3434} }
@article{ryu_kim_lee_hahn_lashmore_2010, title={Carbon Nanotube Mat as Mediator-Less Glucose Sensor Electrode}, volume={10}, ISSN={1533-4880}, url={http://dx.doi.org/10.1166/jnn.2010.1892}, DOI={10.1166/jnn.2010.1892}, abstractNote={In this paper, the direct electron transfer of glucose oxidase (GOx) on carbon nanotube (CNT) mat electrode is demonstrated. Because of the electrical conductivity and mechanical strength of CNT mat, it can be used as an electrode as well as a catalyst support. Therefore, the preparation process for the CNT mat based sensor electrode is simpler than that of the conventional CNT dispersed sensor electrodes. GOx was covalently immobilized on the oxidized CNT mat, which is connected to a wire by using silver paste and epoxy glue. Attenuated Total Reflectance Fourier Transform-Infrared (ATR-FTIR) result shows transmittance peaks at 1637 cm(-1) and 1525 cm(-1) which are corresponding to the band I and II of amide. Cyclic voltammetric shows a pair of well-defined redox peaks with the average formal potential of -0.425 V (vs. Ag/AgCl reference electrode) in the phosphate buffered saline solution (1 x PBS, pH 7.4). Calculated electron transfer rate constant and the surface density of GOx were 1.71 s(-1) and (3.27 +/- 0.20) x 10(-13) mol/cm2, respectively. Cyclic voltammograms of GOx-CNT mat in glucose solution show that the immobilized GOx retains its catalytic activity to glucose. The amperometric sensor response showed a linear dependence on the glucose concentration in the range of 0.2 mM to 2.18 mM with a detection sensitivity of 4.05 microA mM(-1) cm(-2). The Michaelis-Menten constant of the immobilized GOx was calculated to be 2.18 mM.}, number={2}, journal={Journal of Nanoscience and Nanotechnology}, publisher={American Scientific Publishers}, author={Ryu, Jongeun and Kim, Hansang and Lee, Sangeui and Hahn, H. Thomas and Lashmore, David}, year={2010}, month={Feb}, pages={941–947} }
@article{ryu_kim_hahn_lashmore_2010, title={Carbon nanotubes with platinum nano-islands as glucose biofuel cell electrodes}, volume={25}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2009.11.019}, DOI={10.1016/j.bios.2009.11.019}, abstractNote={A novel method using intense pulsed light (IPL) for the metal nano-island formation on carbon nanotube (CNT) was introduced. The IPL-induced photothermal dewetting process improved platinum (Pt) catalyst utilization by transforming nano-islands from Pt film on CNT and increasing the surface area for the subsequent sputtering. The irradiation of high intensity of light on the Pt film causes surface-energy-driven diffusion of Pt atoms and forms the array of nano-islands on CNT. The thickness of Pt film can change the size of nano-islands. Cyclic voltammetry showed a dramatically improved glucose oxidation at the IPL morphology modified Pt-CNT electrode compared to the Pt sputtered CNT electrode without IPL irradiation. The power densities of glucose/air biofuel cell based on the morphology modified Pt-CNT electrode and the as-sputtered Pt-CNT electrode were 0.768 microW/cm(2) and 0.178 microW/cm(2), respectively. The biofuel cell based on morphology modified Pt-CNT electrode showed highly stable output in long-term performance. The power density dropped 14.1% in 30 days. Efforts are underway to improve the interface transfer to achieve higher potential and current output.}, number={7}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Ryu, Jongeun and Kim, Hak-Sung and Hahn, H. Thomas and Lashmore, David}, year={2010}, month={Mar}, pages={1603–1608} }
@article{zhu_wei_zhang_mao_ryu_mavinakuli_karki_young_guo_2010, title={Conductive Polypyrrole/Tungsten Oxide Metacomposites with Negative Permittivity}, volume={114}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp1062463}, DOI={10.1021/jp1062463}, abstractNote={Polypyrrole (PPy) nanocomposites reinforced with tungsten oxide (WO3) nanoparticles (NPs) and nanorods (NRs) are fabricated by a surface-initiated polymerization method. The electrical conductivity is observed to depend strongly on the particle loadings, molar ratio of oxidant to pyrrole monomer, and the filler morphology. The electron transportation in the nanocomposites follows a quasi-three-dimensional variable range hopping (VRH) conduction mechanism as evidenced by the temperature-dependent conductivity function. Unique negative permittivity is observed in both pure PPy and its nanocomposites, and the switching frequency (frequency where the real permittivity switches from negative to positive) can be tuned by changing the particle loading, ratio of oxidant to pyrrole monomer, and the filler morphology. The extent of charge carrier localization calculated from the VRH mechanism is well-correlated to the dielectric properties of the nanocomposites. WO3 NRs are observed to be more efficient in improvin...}, number={39}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Zhu, Jiahua and Wei, Suying and Zhang, Lei and Mao, Yuanbing and Ryu, Jongeun and Mavinakuli, Pallavi and Karki, Amar B. and Young, David P. and Guo, Zhanhu}, year={2010}, month={Sep}, pages={16335–16342} }
@article{zhu_wei_ryu_budhathoki_liang_guo_2010, title={In situ stabilized carbon nanofiber (CNF) reinforced epoxy nanocomposites}, volume={20}, ISSN={0959-9428 1364-5501}, url={http://dx.doi.org/10.1039/c0jm00063a}, DOI={10.1039/c0jm00063a}, abstractNote={Carbon nanofibers (CNFs) suspended epoxy resin nanocomposites and the corresponding polymer nanocomposites are fabricated. The surface of CNFs is introduced a functional amine terminated groups via silanization, which in situ react with epoxy monomers. This in situ reaction favors the CNFs dispersion and improves the interfacial interaction between CNFs and monomers. Effects of particle loading, surface treatment and operating temperatures of rheological tests on the complex viscosity, storage modulus and loss modulus are systematically studied. Unique rheological phenomena “a decreased viscosity with a better dispersion” are observed and explained in terms of the improved filler dispersion quality. Meanwhile, significant increase in the tensile property and storage modulus is observed and related to the better dispersion and the introduced strong interfacial interaction as revealed by SEM imaging. Finally, electrical conductivity is investigated and an unusual deficiency of surface treatment to improve the electrical conductivity is explained by an insulating coating layer.}, number={23}, journal={Journal of Materials Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Zhu, Jiahua and Wei, Suying and Ryu, Jongeun and Budhathoki, Mahesh and Liang, Gang and Guo, Zhanhu}, year={2010}, pages={4937–4948} }
@article{kang_kim_ryu_hahn_jang_joung_2010, title={Inkjet printed electronics using copper nanoparticle ink}, volume={21}, ISSN={0957-4522 1573-482X}, url={http://dx.doi.org/10.1007/s10854-009-0049-3}, DOI={10.1007/s10854-009-0049-3}, abstractNote={Inkjet printing of electrode using copper nanoparticle ink is presented. Electrode was printed on a flexible glass epoxy composite substrate using drop on demand piezoelectric dispenser and was sintered at 200 °C of low temperature in N2 gas condition. The printed electrodes were made with various widths and thickness. In order to control the thickness of the printed electrode, number of printing was varied. Resistivity of printed electrode was calculated from the cross-sectional area measured by a profilometer and resistance measured by a digital multimeter. Surface morphology of electrode was analyzed using scanning electron microscope (SEM) and atomic force microscope (AFM). From the study, it was found that 10 times printed electrode has the most stable grain structure and low resistivity of 36.7 nΩ m.}, number={11}, journal={Journal of Materials Science: Materials in Electronics}, publisher={Springer Science and Business Media LLC}, author={Kang, Jin Sung and Kim, Hak Sung and Ryu, Jongeun and Hahn, H. Thomas and Jang, Seonhee and Joung, Jae Woo}, year={2010}, month={Jan}, pages={1213–1220} }
@article{ryu_kim_kim_hahn_lashmore_2010, title={Intense pulsed light induced platinum–gold alloy formation on carbon nanotubes for non-enzymatic glucose detection}, volume={26}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2010.07.021}, DOI={10.1016/j.bios.2010.07.021}, abstractNote={We demonstrated a novel method for the formation of alloy nano-islands on carbon nanotube (CNT). The two metal layers (Pt, Au) were sputtered on CNTs and the intense pulsed light (IPL) was irradiated on the metal layers. The absorbed light provides enough energy for the diffusion mixing between Pt and Au, forming Pt-Au alloy phase. While the alloy is being formed by the IPL irradiation, the metal layers are broken into nano-islands on CNT due to the surface energy minimization between the metal layers and CNT. The surface characterizations of the Pt-Au/CNT were performed with X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopy. Different compositions of alloy nanoparticles were obtained by adjusting the deposition thicknesses of Pt and Au on CNT. Pt50Au50/CNT electrode showed the highest glucose oxidation current peak among Pt, Pt70Au30, Pt50Au50, Pt30Au70, and Au/CNT electrodes while the electroactive surface areas of them are kept to be similar (average surface area=7.00 cm2, coefficient of variation=0.06). The amperometric response of Pt50Au50/CNT electrode to the glucose concentrations showed a wide linear range up to 24.44 mM with a high detection sensitivity of 10.71 μA mM(-1) cm(-2). Reproducibility and long-term stability of the Pt-Au/CNT electrode were also proven in the experiments.}, number={2}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Ryu, Jongeun and Kim, Kyunghyun and Kim, Hak-Sung and Hahn, H. Thomas and Lashmore, David}, year={2010}, month={Oct}, pages={602–607} }
@article{kim_huh_ryu_2010, title={Investigation of moisture-induced delamination failure in a semiconductor package via multi-scale mechanics}, volume={44}, ISSN={0022-3727 1361-6463}, url={http://dx.doi.org/10.1088/0022-3727/44/3/034007}, DOI={10.1088/0022-3727/44/3/034007}, abstractNote={In this work, moisture-induced interfacial delamination in a semiconductor package was investigated by experiment and multi-scale numerical analysis. The interfacial adhesion strength between a silicon wafer and an epoxy adhesive layer was characterized by a die-shear test with respect to moisture concentration and temperature. Molecular dynamics simulation was performed to study the effect of moisture and temperature on the interfacial adhesion energy and strength at the Si/epoxy adhesive interface. Based on the molecular dynamics predicted interfacial adhesion strength, a numerical stress analysis was performed considering hygro-swelling stress and the thermo-mechanical stress during a solder reflow process to predict the moisture-induced delamination failure of the semiconductor package. The multi-scale simulation result was compared with the actual reliability test result. From this study, it was concluded that the proposed multi-scale simulation technique can be used successfully for the prediction of moisture-induced package failure.}, number={3}, journal={Journal of Physics D: Applied Physics}, publisher={IOP Publishing}, author={Kim, Hak-Sung and Huh, Jeehyang and Ryu, Jongeun}, year={2010}, month={Dec}, pages={034007} }
@article{zhu_wei_ryu_sun_luo_guo_2010, title={Magnetic Epoxy Resin Nanocomposites Reinforced with Core−Shell Structured Fe@FeO Nanoparticles: Fabrication and Property Analysis}, volume={2}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/am100361h}, DOI={10.1021/am100361h}, abstractNote={Epoxy resin nanocomposites reinforced with various loadings of core−shell structured nanoparticles (Fe@FeO) are prepared using a surface wetting method. Nanoparticle loading effect on the viscosity of epoxy monomers is well-correlated to Cross’ rheological model. Dynamic mechanical analysis (DMA) results reveal that the glass transition temperature is increased by 10 °C with the addition of nanoparticles, which is surprisingly independent of the particle loadings. The saturation magnetization (Ms) of the 20 wt % Fe@FeO/epoxy nanocomposites is 17.03 emu/g, which is about 15.8% of that of the pure nanoparticles. Meanwhile, the coercivity increases from 62.33 to 202.13 Oe after the nanoparticles are dispersed in the epoxy matrix. The electrical conductivity percolation is found to be around 5−10 wt %, where the resistance of the nanocomposites sharply decreases by 6 orders of magnitude. Thermal stability and tensile properties of the pristine epoxy and nanocomposites are also investigated in this work.}, number={7}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Zhu, Jiahua and Wei, Suying and Ryu, Jongeun and Sun, Luyi and Luo, Zhiping and Guo, Zhanhu}, year={2010}, month={Jul}, pages={2100–2107} }
@article{ryu_dehlinger_heller_hahn_2009, title={Electrophoretic Layer-by-Layer Assembly of Biotin/Avidin Functionalized Nanoparticles}, volume={26}, ISSN={0934-0866}, url={http://dx.doi.org/10.1002/ppsc.200900090}, DOI={10.1002/ppsc.200900090}, abstractNote={Abstract}, number={5-6}, journal={Particle & Particle Systems Characterization}, publisher={Wiley}, author={Ryu, Jongeun and Dehlinger, Dietrich and Heller, Michael and Hahn, Thomas}, year={2009}, month={Dec}, pages={275–282} }