@article{shu_ke_fei_huang_wang_gong_jiang_wang_li_lei_et al._2020, title={Photoflexoelectric effect in halide perovskites}, volume={19}, ISSN={["1476-4660"]}, DOI={10.1038/s41563-020-0659-y}, abstractNote={Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials1–3, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs. Flexoelectricity is the ability of materials to generate electricity upon bending. Here it is demonstrated that adding light to mechanical oscillation enhances effective flexoelectric coefficients by orders of magnitude, with the halide perovskites showing the largest coefficients.}, number={6}, journal={NATURE MATERIALS}, author={Shu, Longlong and Ke, Shanming and Fei, Linfeng and Huang, Wenbin and Wang, Zhiguo and Gong, Jinhui and Jiang, Xiaoning and Wang, Li and Li, Fei and Lei, Shuijin and et al.}, year={2020}, month={Jun}, pages={605-+} }
 @article{kim_kim_chang_huang_jiang_dayton_2019, title={Candle-Soot Carbon Nanoparticles in Photoacoustics Advantages and challenges for laser ultrasound transmitters}, volume={13}, ISSN={["1942-7808"]}, DOI={10.1109/MNANO.2019.2904773}, abstractNote={This article provides a review of candle-soot nanoparticle (CSNP) composite laser ultrasound transmitters (LUTs) and compares and contrasts this technology with other carbon-composite designs. Among many carbon-based composite LUTs, a CSNP composite has demonstrated its advantages of maximum energy conversion and fabrication simplicity for developing highly efficient ultrasound transmitters. We focus on the advantages and challenges of the CSNP-composite transmitter in the areas of nanostructure design, fabrication procedure, and promising applications.}, number={3}, journal={IEEE NANOTECHNOLOGY MAGAZINE}, author={Kim, Jinwook and Kim, Howuk and Chang, Wei-Yi and Huang, Wenbin and Jiang, Xiaoning and Dayton, Paul A.}, year={2019}, month={Jun}, pages={13–28} }
 @article{chang_zhang_kim_huang_bagal_chang_fang_wu_jiang_2018, title={Evaluation of Photoacoustic Transduction Efficiency of Candle Soot Nanocomposite Transmitters}, volume={17}, ISSN={["1941-0085"]}, url={https://doi.org/10.1109/TNANO.2018.2845703}, DOI={10.1109/TNANO.2018.2845703}, abstractNote={Candle soot nanoparticles (CSNP) and polydimethyl-siloxane (PDMS) composite has shown the highly efficient photoacoustic transduction owing to their high light absorption coefficient and low interfacial thermal resistance. In this study, we report the effect of candle soot structure and thickness on the photoacoustic transduction efficiency. Optical properties of the CSNP/PDMS nanocomposites were characterized through both experimental measurements and finite difference time domain analysis in the visible wavelength range, indicating that the carbon volume fraction and thickness of CS/PDMS composite are highly relevant with light absorption. With a low laser energy input ( <inline-formula><tex-math notation="LaTeX">$< {\text{1 mJ/pulse}}$</tex-math></inline-formula>), the CS/PDMS composite with 2.15 <italic>μ</italic>m thickness exerts an output pressure of 3.78 MPa and a conversion efficiency of <inline-formula><tex-math notation="LaTeX">${\text{9.69}}\,\times \,{\text{10}}^{- 3}$</tex-math> </inline-formula>, which is two orders of magnitude higher than previously reported results.}, number={5}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Chang, Wei-Yi and Zhang, Xu A. and Kim, Jinwook and Huang, Wenbin and Bagal, Abhijeet and Chang, Chih-Hao and Fang, Tiegang and Wu, Hanchang Felix and Jiang, Xiaoning}, year={2018}, month={Sep}, pages={985–993} }
 @inproceedings{li_huang_chang_jiang_2016, title={40-MHz micromachined PMN-PT composite ultrasound array for medical imaging}, DOI={10.1115/imece2015-52540}, abstractNote={Ultrasonography is well known as a relatively low cost and non-invasive modality for real-time imaging. In recent years, various high frequency array transducers have been developed and used for ophthalmology, dermatology, and small animal studies. This paper reports the development of a 48-element 40-MHz ultrasonic array using micromachined lead magnesium niobate-lead titanate (PMN-PT) single crystal 1–3 composite material. Array elements with a pitch of 100-micron were interconnected via a customized flexible circuit. Pulse-echo test showed an average center frequency of 40 MHz and a −6 dB fractional bandwidth of 52%. The −20 dB pulse length was evaluated as 120 ns. The electrical and acoustical separation showed the crosstalk less than - 24 dB. An image of a steel wire target phantom was acquired by stacking multiple A-lines. The results demonstrate resolutions exceeding 70 μm axially and 800 μm laterally. Those results imply the great potential of the developed array transducer for the high frequency medical imaging.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2015, vol 3}, author={Li, S. B. and Huang, W. B. and Chang, W. Y. and Jiang, X. N.}, year={2016} }
 @article{kwon_huang_zhang_yuan_jiang_2016, title={Study on a flexoelectric microphone using barium strontium titanate}, volume={26}, ISSN={["1361-6439"]}, DOI={10.1088/0960-1317/26/4/045001}, abstractNote={In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.}, number={4}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2016}, month={Apr} }
 @article{kim_huang_huang_jiang_2016, title={Thermal gradient induced flexoelectric effects in bulk Ba0.67Sr0.33TiO3}, volume={108}, ISSN={["1077-3118"]}, DOI={10.1063/1.4949358}, abstractNote={Flexoelectric effect, denoting electric field gradient induced mechanical strain or mechanical strain gradient induced electric polarization, is a universal phenomenon in all dielectrics. Although research on the topic of flexoelectricity under stress fields and electric fields has advanced significantly, information regarding the phenomenon under thermal fields is rather limited. In this letter, the flexoelectricity field of Ba0.67Sr0.33TiO3 (BST) was investigated by generating temperature gradients along the lengths of samples with symmetric geometry. An electric field gradient induced by a thermal gradient was analyzed based on the temperature-dependent dielectric property of BST. The strain was then experimentally verified due to the electric field gradient. Experimental results suggest converse flexoelectric effect of BST samples with symmetric geometry in a thermal field. This result was not only consistent with the theoretical prediction, but it also followed the scaling effect of flexoelectricity.}, number={19}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Taeyang and Huang, Wenbin and Huang, Shujin and Jiang, Xiaoning}, year={2016}, month={May} }
 @inproceedings{chang_kim_li_huang_jiang_2015, title={A novel laser ultrasound transducer using candle soot carbon nanoparticles}, DOI={10.1109/nano.2015.7388855}, abstractNote={Laser ultrasound provides a useful method to generate high frequency, broadband and high intensity acoustic waves. In this study, we demonstrated a novel optoacoustic transducer with high-energy conversion efficiency by using candle soot nanoparticles polydimethylsiloxane (CSPs-PDMS) composite. Carbon nanoparticles are used because of their excellent properties of light absorption and heat transfer. The mean diameter of collected candle soot carbon nanoparticles is about 40 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSPs-PDMS composite laser ultrasound transducer was excited by laser pulses, and the acoustic beam profile was measured and compared with Field II simulation results. Energy conversion coefficient and -6 dB frequency bandwidth of CSPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy and non-destructively testing applications.}, booktitle={2015 IEEE 15th International Conference on Nanotechnology (IEEE-NANO)}, author={Chang, W. Y. and Kim, J. and Li, S. B. and Huang, W. B. and Jiang, X. N.}, year={2015}, pages={1243–1246} }
 @article{chang_huang_kim_li_jiang_2015, title={Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers}, volume={107}, ISSN={["1077-3118"]}, DOI={10.1063/1.4934587}, abstractNote={Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and −6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10−3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.}, number={16}, journal={APPLIED PHYSICS LETTERS}, author={Chang, Wei-Yi and Huang, Wenbin and Kim, Jinwook and Li, Sibo and Jiang, Xiaoning}, year={2015}, month={Oct} }
 @article{huang_yang_zhang_yuan_jiang_2015, title={Direct Measurement of Opening Mode Stress Intensity Factors Using Flexoelectric Strain Gradient Sensors}, volume={55}, ISSN={["1741-2765"]}, DOI={10.1007/s11340-014-9914-y}, number={2}, journal={EXPERIMENTAL MECHANICS}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2015}, month={Feb}, pages={313–320} }
 @article{wang_huang_jiang_martin_dayton_2015, title={Dual-frequency IVUS array for contrast enhanced intravascular ultrasound imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0545}, abstractNote={Recent studies suggest that contrast enhanced intravascular ultrasound (CE-IVUS) may be used for identifying vulnerable plaques through molecular imaging or detecting neovascularizations within a growing atherosclerotic lesion. However, typical intravascular ultrasound (IVUS) transducers operate at a high frequency band (20-60 MHz) which makes them not ideal for imaging microbubble contrast agents due to the less effective microbubble excitation at high frequencies. In this paper, a prototyped dual-frequency array for CE-IVUS was developed and tested. The prototype flat transducer array consists of a receiving array (32 elements, 30 MHz) built on the top of a transmitting array (8 sub-elements, 2.25 MHz) to achieve real-time superharmonic contrast enhanced imaging. The size of the receiving aperture was varied, tested and resultant images were compared. Images of a contrast-filled microtube can be observed clearly with only 4 receiving elements at an excitation voltage of 55 V, which indicates feasibility of CE-IVUS imaging after circularly wrapping the array for catheter integration.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Huang, Wenbin and Jiang, Xiaoning and Martin, K. Heath and Dayton, Paul A.}, year={2015} }
 @article{jian_li_huang_cui_jiang_2015, title={Electromechanical response of micromachined 1-3 piezoelectric composites: Effect of etched piezo-pillar slope}, volume={26}, ISSN={["1530-8138"]}, DOI={10.1177/1045389x14546657}, abstractNote={ Micromachined single-crystal piezoelectric 1-3 composites are known for high electromechanical coupling coefficients, low acoustic impedance, high processing precision and uniformity, which are desired for high-frequency ultrasound transducers. In this article, based on Smith and Auld’s 1-3 composite thickness-mode oscillation model, the effect of etched side wall slope on the electromechanical characteristics of micromachined piezoelectric 1-3 composites was studied. In specific, strain constant, stiffness, dielectric constant, electromechanical coupling coefficient, acoustic impedance, longitudinal velocity, and frequency of micromachined 1-3 composites were deduced using the developed model. The analytical model was then verified by a COMSOL simulation and experimental measurements of a micromachined composite sample with pitch of 15.9 µm, thickness of 42.8 µm, and etched pillar slope angle of 83.8°. The measured center frequency was 49.05 MHz, electromechanical coupling coefficient was 0.66, dielectric constant was 1178, and strain constant was 26.90 C/m2, which all agreed well with the analytical calculations. These results will be helpful in design and fabrication of high-frequency micromachined ultrasound transducers. }, number={15}, journal={JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES}, author={Jian, Xiaohua and Li, Sibo and Huang, Wenbin and Cui, Yaoyao and Jiang, Xiaoning}, year={2015}, month={Oct}, pages={2011–2019} }
 @article{kwon_huang_zhang_yuan_jiang_2014, title={A new type of microphone using flexoelectric barium strontium titnate}, volume={9062}, ISSN={["1996-756X"]}, DOI={10.1117/12.2045072}, abstractNote={A flexoelectric bridge-structured microphone using bulk barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was investigated in this study. The flexoelectric microphone was installed in an anechoic box and exposed to the sound pressure emitted from a loud speaker. Charge sensitivity of the flexoelectric microphone was measured and calibrated using a reference microphone. The 1.5 mm×768 μm×50 μm micro-machined bridge-structured flexoelectric microphone has a sensitivity of 0.92 pC/Pa, while its resonance frequency was calculated to be 98.67 kHz. The analytical and experimental results show that the flexoelectric microphone has both high sensitivity and broad bandwidth, indicating that flexoelectric microphones are potential candidates for many applications.}, journal={SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS INTEGRATION 2014}, author={Kwon, Seol Ryung and Huang, Wenbin and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{huang_kwon_zhang_yuan_jiang_2014, title={A trapezoidal flexoelectric accelerometer}, volume={25}, ISSN={["1530-8138"]}, DOI={10.1177/1045389x13491021}, abstractNote={ In this article a new acceleration sensor using flexoelectric barium strontium titanate cantilever was designed, fabricated, and tested for vibration monitoring. The flexoelectric sensors were configured as a trapezoidal unimorph with a barium strontium titanate layer bonded onto a steel substrate. Seismic mass was attached to the unimorph tip to amplify the transverse flexoelectric response of the barium strontium titanate layer. The theoretical model was developed and validated by vibration tests using the prototyped flexoelectric unimorph. The prototyped accelerometer with thickness of 0.1 mm and length and width in millimeters showed a stable sensitivity of 0.84 pC/g over the frequency range of 100 Hz–1.6 kHz. The aging property of the flexoelectric material was demonstrated to be much better than that of the reported piezoelectric materials right after poling. Scaling effect analysis was also performed for flexoelectric unimorphs. The test results and initial scaling effect analysis indicate that micro/nano flexoelectric sensing holds promise for a broad range of applications. }, number={3}, journal={JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES}, author={Huang, Wenbin and Kwon, Seol-Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014}, month={Feb}, pages={271–277} }
 @article{shu_huang_kwon_wang_li_wei_zhang_lanagan_yao_jiang_2014, title={Converse flexoelectric coefficient f(1212) in bulk Ba0.67Sr0.33TiO3}, volume={104}, ISSN={["1077-3118"]}, DOI={10.1063/1.4882060}, abstractNote={The converse flexoelectric effect, referred as the electric field gradient induced strain, widely exists in dielectric materials, but its experimental studies have been reported by few research groups so far. In this Letter, we report our studies on the converse flexoelectric behavior of (Ba0.67Sr0.33)TiO3 ceramics and present the measured value of its flexoelectric coefficient f1212. In the experiments, the electric field gradient was generated by applying an electric field across the two lateral sides of trapezoid (Ba0.67Sr0.33)TiO3 samples. The shear displacement was measured using a laser vibrometer. The converse flexoelectric coefficient f1212 was found to be 124 ± 14 μC/m at room temperature. This result was in good agreement with the theoretical prediction of the flexoelectricity of the (Ba, Sr)TiO3 ceramics.}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={Shu, Longlong and Huang, Wenbin and Kwon, Seol Ryung and Wang, Zhao and Li, Fei and Wei, Xiaoyong and Zhang, Shujun and Lanagan, Michael and Yao, Xi and Jiang, Xiaoning}, year={2014}, month={Jun} }
 @article{huang_yang_zhang_yuan_jiang_2014, title={Cracks Monitoring and Characterization Using Ba0.64Sr0.36TiO3 Flexoelectric Strain Gradient Sensors}, volume={9061}, ISSN={["0277-786X"]}, DOI={10.1117/12.2045166}, abstractNote={This paper presents a new method for monitoring and characterizing cracks using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors. Firstly, strain gradient field around the mixed mode asymptotic crack tip was analyzed, followed by the derivation of induced flexoelectric polarization in the strain gradient sensors attached in the vicinity of a crack tip. It was found that the flexoelectric polarization of the sensor can be expressed as a function of the stress intensity factors of crack and relative coordinates between the sensor and crack. Given the information of the crack size, further analysis demonstrates that the location of the crack can be traced through the calculation based on flexoelectric outputs of the distributed sensors. A specimen with Mode-I crack was then prepared with two strain gradient sensors (4.7 mm × 0.9 mm × 0.3 mm) attached close to the crack tip to verify the analytical model for detection of cracks. The experimental results yield accurate location of the crack, confirming that flexoelectric strain gradient sensing can be a good avenue for monitoring cracks.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2014}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{huang_shu_kwon_zhang_yuan_jiang_2014, title={Fabrication and measurement of a flexoelectric micro-pyramid composite}, volume={4}, ISSN={["2158-3226"]}, DOI={10.1063/1.4904024}, abstractNote={A fabrication method by combining precision mechanical dicing and wet etching was developed to prepare micro-pyramid structures based on (Ba0.67Sr0.33)TiO3 ceramics. The effective piezoelectric properties of flexoelectric pyramid structures in ten micrometers scale were investigated and measured through converse flexoelectric effect. The scaling effect of the flexoelectric response was demonstrated as the structure size shrinks down. The results do suggest the great potential of flexoelectric micro pyramids as an alternative to lead-free piezoelectric material.}, number={12}, journal={AIP ADVANCES}, author={Huang, Wenbin and Shu, Longlong and Kwon, Seol Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014}, month={Dec} }
 @article{kwon_huang_shu_yuan_maria_jiang_2014, title={Flexoelectricity in barium strontium titanate thin film}, volume={105}, ISSN={["1077-3118"]}, DOI={10.1063/1.4898139}, abstractNote={Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba0.7Sr0.3TiO3 thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Kwon, Seol Ryung and Huang, Wenbin and Shu, Longlong and Yuan, Fuh-Gwo and Maria, Jon-Paul and Jiang, Xiaoning}, year={2014}, month={Oct} }
 @article{li_shu_huang_jiang_wang_2014, title={Giant flexoelectricity in Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite}, volume={105}, ISSN={["1077-3118"]}, DOI={10.1063/1.4899060}, abstractNote={Enhanced flexoelectricity in perovskite ceramics and single crystals has been reported before. In this letter, 3-3 ceramic-ceramic Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite with a colossal permittivity was employed in the conventional pure bending experiment in order to examine the transverse flexoelectric response. The measured flexoelectric coefficient at 30 Hz is 128 μC/m and varies to 16 μC/m with the frequency increasing from 30 Hz to 120 Hz, mainly due to the inverse correlation between the permittivity and the frequency. This result reveals the permittivity dependence of flexoelectric coefficient in the frequency dispersion materials, suggesting that the giant permittivity composites can be good flexoelectric materials.}, number={16}, journal={APPLIED PHYSICS LETTERS}, author={Li, Yong and Shu, Longlong and Huang, Wenbin and Jiang, Xiaoning and Wang, Hong}, year={2014}, month={Oct} }
 @article{shu_li_huang_wei_yao_jiang_2014, title={Relationship between direct and converse flexoelectric coefficients}, volume={116}, ISSN={["1089-7550"]}, DOI={10.1063/1.4897647}, abstractNote={Flexoelectric effect, as a universal electromechanical coupling, has drawn lots of interests in dielectric materials. However, due to the restrictions of present measurement techniques, only part of coefficients has been experimentally examined. In this study, we derived the coordinate-dependent Gibbs free energy density function in the inhomogeneous spatial field to investigate the relationship between the direct and converse flexoelectric coefficients. In crystalline mediums and systems, the direct and converse flexoelectric coefficients are proved to equivalent according to the Maxwell relation. These results will broaden the application of the Maxwell relation into non-linear spatial field, and provide the guideline for experimental measurement and prediction of flexoelectric coefficients.}, number={14}, journal={JOURNAL OF APPLIED PHYSICS}, author={Shu, Longlong and Li, Fei and Huang, Wenbin and Wei, Xiaoyong and Yao, Xi and Jiang, Xiaoning}, year={2014}, month={Oct} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={A sensor for the direct measurement of curvature based on flexoelectricity}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/8/085016}, abstractNote={A direct curvature sensing measurement based on the flexoelectricity of Ba0.64Sr0.36TiO3 (BST) material through electromechanical coupling is proposed and developed in this paper. The curvature sensing was demonstrated in four point bending tests of a beam with bonded BST curvature sensors under different applied loads with low time-harmonic frequencies from 0.5 to 3 Hz. A shear lag concept which describes the efficiency of the loading transfer from the epoxy bonding layer was taken into account in extracting the actual curvature from the sensor measurement. A finite element analysis has been performed to estimate the curvature transfer efficiency and the bonding layer thickness is found to be a critical parameter in determining the curvature transfer. Experimental results showed a good linearity of charge output dependence on curvature inputs in a limited frequency range and showed a curvature sensitivity of 30.78 pC m, in comparison with 32.48 pC m from theoretical predictions. Using the measured curvature, the bending stiffness of the beam was then obtained from the experimentally obtained moment–curvature curve. This work demonstrated that the flexoelectric BST sensor provides a direct curvature measurement instead of using a traditional strain gage sensor through interpolation, and thus offers an important avenue for on-line and in situ structural health monitoring.}, number={8}, journal={SMART MATERIALS AND STRUCTURES}, author={Yan, Xiang and Huang, Wenbin and Kwon, Seol Ryung and Yang, Shaorui and Jiang, Xiaoning and Yuan, Fuh-Gwo}, year={2013}, month={Aug} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={Design of a curvature sensor using a flexoelectric material}, volume={8692}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009941}, abstractNote={A curvature sensor based on flexoelectricity using Ba0.64Sr0.36TiO3 (BST) material is proposed and developed in this paper. The working principle of the sensor is based on the flexoelectricity, exhibiting coupling between mechanical strain gradient and electric polarization. A BST curvature sensor is lab prepared using a conventional solid state processing method. The curvature sensing is demonstrated in four point bending tests of the beam under harmonic loads. BST sensors are attached on both side surfaces of an aluminum beam, located symmetrically with respect to its neutral axis. Analyses have shown that the epoxy bonding layer plays a critical role for curvature transfer. Consequently a shear lag effect is taken into account for extracting actual curvature from the sensor measurement. Experimental results demonstrated good linearity from the charge outputs under the frequencies tests and showed a sensor sensitivity of 30.78pC•m in comparison with 32.48pC•m from theoretical prediction. The BST sensor provides a direct curvature measure instead of using traditional strain gage through interpolation and may offer an optional avenue for on-line and in-situ structural health monitoring.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2013}, author={Yan, X. and Huang, W. B. and Kwon, S. R. and Yang, S. R. and Jiang, X. N. and Yuan, F. G.}, year={2013} }
 @misc{jiang_huang_zhang_2013, title={Flexoelectric nano-generator: Materials, structures and devices}, volume={2}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2013.09.001}, abstractNote={Flexoelectricity, as a fundamental electromechanical coupling effect between electric polarization and mechanical strain gradient, or vice versa between electric polarization gradient and mechanical gradient, exists in various categories of materials including solid materials, liquid crystals, polymers, and biomembranes. Dependence of electric or mechanical gradients on geometry requires the adoption of specific structures for different flexoelectric mode applications. Scaling effect associated with gradient suggests that flexoelectric effect can be more significant in micro/nano systems, comparable to or even exceed piezoelectricity. In this review, flexoelectricity in those studied materials will be summarized and compared. Applications in sensors, actuators, capability of tuning the ferroelectric thin film properties, and roles in bio-system mechanosensitivity and mechanotranduction of flexoelectricity will be introduced respectively. Especially, flexoelectricity nano-generator enlightens a new technique for energy harvesting. Comparison with piezoelectric nano-generator suggests that flexoelectric counterpart can yield enhanced performance with specific nanostructures and provide a wider materials choice.}, number={6}, journal={NANO ENERGY}, author={Jiang, Xiaoning and Huang, Wenbin and Zhang, Shujun}, year={2013}, month={Nov}, pages={1079–1092} }
 @article{kwon_huang_zhang_yuan_jiang_2013, title={Flexoelectric sensing using a multilayered barium strontium titanate structure}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/11/115017}, abstractNote={The flexoelectric effect has been recently explored for its promise in electromechanical sensing. However, the relatively low flexoelectric coefficients of ferroelectrics inhibit the potential to develop flexoelectric sensing devices. In this paper, a multilayered structure using flexoelectric barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was fabricated in an attempt to enhance the effective flexoelectric coefficients using its inherent scale effect, and hence to improve the flexoelectric sensitivity. The performances of piezoelectric and flexoelectric cantilevers with the same dimensions and under the same conditions were compared. Owing to the flexoelectric scaling effect, under the same force input, the BST flexoelectric structure generated a higher charge output than its piezoelectric P(VDF-TrFE) and PMN-30PT counterparts when its thickness was less than 73.1 μm and 1.43 μm, respectively. Also, amplification of the charge output using the multilayered structure was then experimentally verified. The prototyped structure consisted of three layers of 350 μm-thick BST plates with a parallel electric connection. The charge output was approximately 287% of that obtained using a single-layer structure with the same total thickness of the multilayered structure under the same end deflection input, which suggests high sensitivity sensing can be achieved using multilayer flexoelectric structures.}, number={11}, journal={SMART MATERIALS AND STRUCTURES}, author={Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2013}, month={Nov} }
 @article{chang_huang_bagal_chang_tian_han_jiang_2013, title={Study on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O-3-0.3 PbTiO3 single crystal with nano-patterned composite electrode}, volume={114}, ISSN={["1089-7550"]}, DOI={10.1063/1.4821517}, abstractNote={Effect of nano-patterned composite electrode and backswitching poling technique on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 was studied in this paper. Composite electrode consists of Mn nano-patterns with pitch size of 200 nm, and a blanket layer of Ti/Au was fabricated using a nanolithography based lift-off process, heat treatment, and metal film sputtering. Composite electrode and backswitching poling resulted in 27% increase of d33 and 25% increase of dielectric constant, and we believe that this is attributed to regularly defined nano-domains and irreversible rhombohedral to monoclinic phase transition in crystal. The results indicate that nano-patterned composite electrode and backswitching poling has a great potential in domain engineering of relaxor single crystals for advanced devices.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Chang, Wei-Yi and Huang, Wenbin and Bagal, Abhijeet and Chang, Chih-Hao and Tian, Jian and Han, Pengdi and Jiang, Xiaoning}, year={2013}, month={Sep} }
 @inproceedings{huang_kim_zhang_yuan_jiang_2012, title={Flexoelectric materials and structures for M/NEMS}, DOI={10.1115/imece2011-64520}, abstractNote={Recent research progress on flexoelectricity suggests that dramatic enhancement of effective piezoelectric properties desirable for advanced M/NEMS, in principle, is attainable through flexoelectric (FE) effect and scale effect. In this paper, the transverse flexoelectric coefficient μ12 of barium strontium titanate (BST) microcantilevers with thicknesses ranging from 1.4 mm down to 30 μm was measured at room temperature. It was found that μ12 remains to be constant (8.5 μC/m) for all fabricated microcantilevers. Effective piezoelectric coefficients of these microcantilevers were also calculated, indicating that significantly increased effective piezoelectric coefficients can be obtained from microcantilevers with thickness of microns and nanometers, which is promising for micro/nano electromechanical systems (M/NEMS).}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2011, vol 11}, author={Huang, W. B. and Kim, K. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2012}, pages={761–766} }
 @article{huang_yan_kwon_zhang_yuan_jiang_2012, title={Flexoelectric strain gradient detection using Ba0.64Sr0.36TiO3 for sensing}, volume={101}, ISSN={["0003-6951"]}, DOI={10.1063/1.4772803}, abstractNote={Strain gradient sensing offers an alternative avenue for in-situ monitoring of onset and growth of cracks in structural health monitoring, where the strain gradient is the most sensitive measurand. In this study, flexoelectric strain gradient sensing structures using Ba0.64Sr0.36TiO3 (BST) were attached on the proximity of an open hole in an aluminum plate, to monitor strain gradient variations of the specimen under a uniaxial dynamic load. Charge outputs of the BST micro-bars showed good linearity with the average strain gradients, with a sensitivity of 88 pC m, which is in good agreement with the theoretical estimation by assuming a 30 μm bonding thickness.}, number={25}, journal={APPLIED PHYSICS LETTERS}, author={Huang, Wenbin and Yan, Xiang and Kwon, Seol Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2012}, month={Dec} }
 @article{huang_kim_zhang_yuan_jiang_2011, title={Scaling effect of flexoelectric (Ba,Sr)TiO3 microcantilevers}, volume={5}, ISSN={["1862-6254"]}, DOI={10.1002/pssr.201105326}, abstractNote={Abstract}, number={9}, journal={PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS}, author={Huang, Wenbin and Kim, Kyungrim and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2011}, month={Sep}, pages={350–352} }
 @article{kim_zhang_huang_yu_jiang_2011, title={YCa4O(BO3)(3) (YCOB) high temperature vibration sensor}, volume={109}, ISSN={["1089-7550"]}, DOI={10.1063/1.3598115}, abstractNote={A shear-mode piezoelectric accelerometer using YCa4O(BO3)3 (YCOB) single crystal was designed, fabricated and successfully tested for high temperature vibration sensing applications. The prototyped sensor was tested at temperatures ranging from room temperature to 1000 °C and at frequencies ranging from 80 Hz to 1 kHz. The sensitivity of the sensor was found to be 5.7 pC/g throughout the tested frequency and temperature range. In addition, YCOB piezoelectric accelerometers remained the same sensitivity at 1000 °C for a dwell time of four hours, exhibiting high stability and reliability.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Kim, Kyungrim and Zhang, Shujun and Huang, Wenbin and Yu, Fapeng and Jiang, Xiaoning}, year={2011}, month={Jun} }
 @inproceedings{li_huang_jiang_jian_cui, title={A dual-layer micromachined PMN-PT 1-3 composite transducer for broadband ultrasound imaging}, booktitle={2013 ieee international ultrasonics symposium (ius)}, author={Li, S. B. and Huang, W. B. and Jiang, X. N. and Jian, X. H. and Cui, Y. Y.}, pages={773–776} }