@article{lee_hossain_jamalzadegan_liu_wang_saville_shymanovich_paul_rotenberg_whitfield_et al._2023, title={Abaxial leaf surface-mounted multimodal wearable sensor for continuous plant physiology monitoring}, volume={9}, ISSN={["2375-2548"]}, DOI={10.1126/sciadv.ade2232}, abstractNote={Wearable plant sensors hold tremendous potential for smart agriculture. We report a lower leaf surface-attached multimodal wearable sensor for continuous monitoring of plant physiology by tracking both biochemical and biophysical signals of the plant and its microenvironment. Sensors for detecting volatile organic compounds (VOCs), temperature, and humidity are integrated into a single platform. The abaxial leaf attachment position is selected on the basis of the stomata density to improve the sensor signal strength. This versatile platform enables various stress monitoring applications, ranging from tracking plant water loss to early detection of plant pathogens. A machine learning model was also developed to analyze multichannel sensor data for quantitative detection of tomato spotted wilt virus as early as 4 days after inoculation. The model also evaluates different sensor combinations for early disease detection and predicts that minimally three sensors are required including the VOC sensors.}, number={15}, journal={SCIENCE ADVANCES}, author={Lee, Giwon and Hossain, Oindrila and Jamalzadegan, Sina and Liu, Yuxuan and Wang, Hongyu and Saville, Amanda C. and Shymanovich, Tatsiana and Paul, Rajesh and Rotenberg, Dorith and Whitfield, Anna E. and et al.}, year={2023}, month={Apr} }
 @article{yang_liu_yu_husain_2023, title={Sequence Prediction for SiC MOSFET Active Gate Driving With a Recurrent Neural Network}, volume={4}, ISSN={["2644-1241"]}, DOI={10.1109/OJIA.2023.3291637}, abstractNote={This article develops a recurrent neural network (RNN) with an encoder–decoder structure to predict the driving sequence of SiC MOSFET active gate drivers (AGDs). With a set of switching targets as the input, the predictor generates an optimal active gate driving sequence to improve the switching transient. The development is based on a hybrid platform across MATLAB, PyTorch, and LTspice. A high-fidelity switching model is implemented in MATLAB to obtain reliable training data. The sequence predictor is trained with PyTorch. The predicted sequence is verified on an example Buck circuit in LTspice. In contrast to the state-of-the-art approach, the proposed method avoids exhaustive search in a large solution space; the sequence length is dynamically predicted per the driving strength at each step. The AGD sequences generated by the predictor effectively and precisely improve the switching transients, making the proposed sequence predictor an integral and valuable component for active gate driving.}, journal={IEEE OPEN JOURNAL OF INDUSTRY APPLICATIONS}, author={Yang, Li and Liu, Yuxuan and Yu, Wensong and Husain, Iqbal}, year={2023}, pages={227–237} }
 @article{shukla_liu_zhu_2022, title={Eco-friendly screen printing of silver nanowires for flexible and stretchable electronics}, ISSN={["2040-3372"]}, DOI={10.1039/d2nr05840e}, abstractNote={This paper reports an eco-friendly method for screen printing of silver nanowires on a diverse range of substrates with high resolution and high electric conductivity. A low annealing temperature makes the method compatible with plastic substrates.}, journal={NANOSCALE}, author={Shukla, Darpan and Liu, Yuxuan and Zhu, Yong}, year={2022}, month={Dec} }
 @article{booth_schrickx_hanby_liu_qin_ade_zhu_brendan t. o'connor_2022, title={Silver Nanowire Composite Electrode Enabling Highly Flexible, Robust Organic Photovoltaics}, volume={6}, ISSN={["2367-198X"]}, DOI={10.1002/solr.202200264}, abstractNote={Using Ag nanowires (NWs) is a promising approach to make flexible and transparent conducting electrodes for organic photovoltaics (OPVs). However, the roughness of the NWs can decrease device performance. Herein, a Ag NW electrode embedded in a UV‐curable epoxy that uses a simple mechanical lift‐off process resulting in highly planar electrodes is demonstrated. A bimodal blend of Ag NWs with varying aspect ratios is used to optimize the transparency and conductivity of the electrode. In addition, a ZnO layer is coated on the Ag NWs prior to the embedding process to ensure low contact resistance in the OPV cells. The resulting resin‐embedded ZnO‐encapsulated silver nanowire (REZEN) electrode is found to have excellent mechanical stability. REZEN electrode‐based OPV cells exhibit comparable performance with reference devices, achieving maximum power conversion efficiency (PCE) of 13.5% and 13.6% respectively. The REZEN‐based OPV cells are also mechanically robust, retaining 97% of their PCE after 5000 cycles at R = 1.2 mm and 94% PCE after 1000 cycles at R = 0.55 mm. This flexibility is among the highest reported for freestanding devices. Thus, the REZEN electrode is a promising and simple strategy to achieve mechanically robust ITO‐free flexible OPV cells.}, journal={SOLAR RRL}, author={Booth, Ronald E. and Schrickx, Harry M. and Hanby, Georgia and Liu, Yuxuan and Qin, Yunpeng and Ade, Harald and Zhu, Yong and Brendan T. O'Connor}, year={2022}, month={Jun} }
 @misc{liu_shukla_newman_zhu_2022, title={Soft wearable sensors for monitoring symptoms of COVID-19 and other respiratory diseases: a review}, volume={4}, ISSN={["2516-1091"]}, DOI={10.1088/2516-1091/ac2eae}, abstractNote={The COVID-19 pandemic has put extraordinary stress on medical systems and global society more broadly. The condition of infected patients may deteriorate rapidly due to overburdened hospital systems. This raises an urgent need for real-time and remote monitoring of physiological parameters to address the challenges associated with the COVID-19 pandemic. This review will present recent progress on soft wearable sensors that can potentially be used for monitoring respiratory diseases such as COVID-19. First, emerging monitoring devices and systems that can monitor key physiological parameters as suggested by the Centers for Disease Control and Prevention (e.g. body temperature, respiration rate, heart rate, oxygen saturation and body movement) are reviewed. Then, multimodal sensor systems consisting of two or more correlative sensors are presented. This review will conclude with challenges and future directions for wearable sensors for the diagnosis and therapy of respiratory diseases. While this review focuses on COVID-19, the sensing technologies reviewed can be applicable to other respiratory diseases such as H1N1 influenza.}, number={1}, journal={PROGRESS IN BIOMEDICAL ENGINEERING}, author={Liu, Yuxuan and Shukla, Darpan and Newman, Holly and Zhu, Yong}, year={2022}, month={Jan} }
 @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{ren_liu_song_o'connor_dong_zhu_2021, title={Achieving High-Resolution Electrohydrodynamic Printing of Nanowires on Elastomeric Substrates through Surface Modification}, volume={3}, ISSN={["2637-6113"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85099220488&partnerID=MN8TOARS}, DOI={10.1021/acsaelm.0c00747}, abstractNote={Stretchable electronics based on nanomaterials has received much interest recently. However, it is challenging to print 1D nanomaterials (e.g., nanowires) with high resolution on stretchable elasto...}, number={1}, journal={ACS APPLIED ELECTRONIC MATERIALS}, publisher={American Chemical Society (ACS)}, author={Ren, Ping and Liu, Yuxuan and Song, Runqiao and O'Connor, Brendan and Dong, Jingyan and Zhu, Yong}, year={2021}, month={Jan}, pages={192–202} }
 @article{li_liu_bhuiyan_zhu_yao_2021, title={Printed Strain Sensors for On-Skin Electronics}, ISSN={["2688-4062"]}, DOI={10.1002/sstr.202100131}, abstractNote={On‐skin electronics have drawn extensive attention as they revolutionize many aspects of healthcare, motion tracking, rehabilitation, robotics, human–machine interaction, among others. Flexible and stretchable strain sensors represent one of the most explored devices for on‐skin electronics. Many printing techniques have recently emerged showing great promises for manufacturing strain sensors. Herein, it is aimed to provide a timely survey of recent advancements in printed strain sensors for on‐skin electronics. This review starts with an overview of sensing mechanisms for printed strain sensors, followed by a review of various printing techniques employed in fabricating these sensors. The materials, structures, and printing processes of representative strain sensors are discussed in detail for each printing method. Finally, potential applications of printed flexible and stretchable strain sensors are presented focusing on three areas: healthcare, sports performance monitoring, and human–machine interfaces. The review concludes with a discussion of challenges and opportunities for future research.}, journal={SMALL STRUCTURES}, author={Li, Yizong and Liu, Yuxuan and Bhuiyan, Shah Rifat Alam and Zhu, Yong and Yao, Shanshan}, year={2021}, month={Nov} }
 @article{li_liu_hossain_paul_yao_wu_ristaino_zhu_wei_2021, title={Real-time monitoring of plant stresses via chemiresistive profiling of leaf volatiles by a wearable sensor}, volume={4}, ISSN={["2590-2385"]}, DOI={10.1016/j.matt.2021.06.009}, abstractNote={Determination of plant stresses such as infections by plant pathogens is currently dependent on time-consuming and complicated analytical technologies. Here, we report a leaf-attachable chemiresistive sensor array for real-time fingerprinting of volatile organic compounds (VOCs) that permits noninvasive and early diagnosis of plant diseases, such as late blight caused by Phytophthora infestans. The imperceptible sensor patch integrates an array of graphene-based sensing materials and flexible silver nanowire electrodes on a kirigami-inspired stretchable substrate, which can minimize strain interference. The sensor patch has been mounted on live tomato plants to profile key plant volatiles at low-ppm concentrations with fast response (<20 s). The multiplexed sensor array allows for accurate detection and classification of 13 individual plant volatiles with >97% classification accuracy. The wearable sensor patch was used to diagnose tomato late blight as early as 4 days post inoculation and abiotic stresses such as mechanical damage within 1 h.}, number={7}, journal={MATTER}, author={Li, Zheng and Liu, Yuxuan and Hossain, Oindrila and Paul, Rajesh and Yao, Shanshan and Wu, Shuang and Ristaino, Jean B. and Zhu, Yong and Wei, Qingshan}, year={2021}, month={Jul}, pages={2553–2570} }
 @article{liu_wang_zhu_2021, title={Recycling of Nanowire Percolation Network for Sustainable Soft Electronics}, ISSN={["2199-160X"]}, DOI={10.1002/aelm.202100588}, abstractNote={Abstract}, journal={ADVANCED ELECTRONIC MATERIALS}, author={Liu, Yuxuan and Wang, Hongyu and Zhu, Yong}, year={2021}, month={Jul} }
 @article{liu_bai_yang_ma_sun_2021, title={Self-supported electrode of NiCo-LDH/NiCo2S4/CC with enhanced performance for oxygen evolution reaction and hydrogen evolution reaction}, volume={367}, ISSN={["1873-3859"]}, DOI={10.1016/j.electacta.2020.137534}, abstractNote={The exploitation of bifunctional electrocatalysts for stable and efficient water splitting is of great significant for the development of clean energy industry. Herein, a hierarchical NiCo-LDH/NiCo2S4/CC electrode is prepared on carbon cloth by coupling NiCo-LDH nanosheets with NiCo2S4 nanoneedles through a simple process. This NiCo-LDH/NiCo2S4/CC electrode serves as an efficient bifunctional electrocatalyst for overall water splitting with excellent activity and stability in alkaline media. The enhanced electrocatalytic performance is ascribed to the hierarchical structure, the synergistic effect of NiCo-LDH and NiCo2S4 as well as the phase transformation of NiCo2S4 in alkaline condition. The NiCo-LDH/NiCo2S4/CC electrode requires overpotentials of 254 and 219 mV to deliver the current density of 50 mA cm-2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M KOH aqueous solution, respectively. The Tafel results further reveal favorable reaction kinetics during electrolysis. When used as the bifunctional electrode for overall water splitting, the NiCo-LDH/NiCo2S4/CC performs superior activity with a voltage of 1.64 V at the current density of 50 mA cm-2. This work offers a new approach for the exploitation of high-performance and cost-efficient bifunctional catalysts for water splitting.}, journal={ELECTROCHIMICA ACTA}, author={Liu, Yuxuan and Bai, Yu and Yang, Weiwei and Ma, Jiahuan and Sun, Kening}, year={2021}, month={Jan} }
 @article{wu_yao_liu_hu_huang_zhu_2020, title={Buckle-Delamination-Enabled Stretchable Silver Nanowire Conductors}, volume={12}, ISSN={["1944-8252"]}, url={http://dx.doi.org/10.1021/acsami.0c09775}, DOI={10.1021/acsami.0c09775}, abstractNote={Controlled buckling and delamination of thin films on a compliant substrate has attracted much attention for applications ranging from micro/nanofabrication to flexible and stretchable electronics to bioengineering. Here a highly conductive and stretchable conductor is fabricated by attaching a polymer composite film (with a thin layer of silver nanowires embedded below the surface of the polymer matrix) on top of a pre-stretched elastomer substrate followed with releasing the prestrain. A partially delaminated wavy geometry of the polymer film is created. During the evolution of the buckle delamination, the blisters pop up randomly but self-adjust into a uniform distribution, which effectively reduces the local strain in the silver nanowires. The resistance change of the conductor is less than 3% with the applied strain up to 100%. A theoretical model on the buckle-delamination structure is developed to predict the geometrical evolution, which agrees well with experimental observation. Finally, an integrated silver nanowire/elastomer sensing module and a stretchable thermochromic device are developed to demonstrate the utility of the stretchable conductor. This work highlights the important relevance of mechanics-based design in nanomaterial-enabled stretchable devices.}, number={37}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Wu, Shuang and Yao, Shanshan and Liu, Yuxuan and Hu, Xiaogang and Huang, He Helen and Zhu, Yong}, year={2020}, month={Sep}, pages={41696–41703} }
 @article{song_yao_liu_wang_dong_zhu_brendan t. o'connor_2020, title={Facile Approach to Fabricating Stretchable Organic Transistors with Laser-Patterned Ag Nanowire Electrodes}, volume={12}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.0c15339}, DOI={10.1021/acsami.0c15339}, abstractNote={Stretchable electronics are poised to revolutionize personal healthcare and robotics, where they enable distributed and conformal sensors. Transistors are fundamental building blocks of electronics, and there is a need to produce stretchable transistors using low-cost and scalable fabrication techniques. Here, we introduce a facile fabrication approach using laser patterning and transfer printing to achieve high-performance, solution-processed intrinsically stretchable organic thin-film transistors (OTFTs). The device consists of Ag nanowire (NW) electrodes, where the source and drain electrodes are patterned using laser ablation. The Ag NWs are then partially embedded in a poly(dimethylsiloxane) (PDMS) matrix. The electrodes are combined with a PDMS dielectric and polymer semiconductor, where the layers are individually transfer printed to complete the OTFT. Two polymer semiconductors, DPP-DTT and DPP-4T, are considered and show stable operation under the cyclic strain of 20 and 40%, respectively. The OTFTs maintain electrical performance by adopting a buckled structure after the first stretch-release cycle. The conformability and stretchability of the OTFT is also demonstrated by operating the transistor while adhered to a finger being flexed. The ability to pattern highly conductive Ag NW networks using laser ablation to pattern electrodes as well as interconnects provides a simple strategy to produce complex stretchable OTFT-based circuits.}, number={45}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Song, Runqiao and Yao, Shanshan and Liu, Yuxuan and Wang, Hongyu and Dong, Jingyan and Zhu, Yong and Brendan T. O'Connor}, year={2020}, month={Nov}, pages={50675–50683} }
 @article{poblete_cui_liu_zhu_2020, title={Stretching nanowires on a stretchable substrate: A method towards facile fracture testing and elastic strain engineering}, volume={41}, ISSN={["2352-4316"]}, DOI={10.1016/j.eml.2020.101035}, abstractNote={Nanomaterials are building blocks for a wide range of applications. They typically exhibit ultrahigh strength, which make them also promising candidates for elastic strain engineering. Here we demonstrate a potentially facile method to measure fracture strain and strain distribution of nanomaterials, with Ag nanowires as an example. Nanowires are placed on top of or embedded in a stretchable substrate (i.e., elastomer), either as-prepared (van der Waals interactions) or treated with UV ozone (chemical bonding), which is subjected to uniaxial tensile loading. Nonlinear and bilinear cohesive shear-lag models can well capture the interfacial shear stress transfer characteristics associated with the two types of interactions, respectively. For each type, interfacial parameters such as stiffness, shear strength, and/or fracture toughness are identified by fitting the measured average strains of the nanowires. The nanowires embedded in as-prepared and on top of treated substrate are found to fracture under large substrate strain. The fracture strain and strain distribution along the nanowires are predicted using the shear-lag models. This method can be readily applied to investigate fracture and elastic strain engineering of 1D nanomaterials (regardless of aligned or inclined with respect to the stretching direction) and 2D nanomaterials.}, journal={EXTREME MECHANICS LETTERS}, author={Poblete, Felipe R. and Cui, Zheng and Liu, Yuxuan and Zhu, Yong}, year={2020}, month={Nov} }