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Full-Text Articles in Physics
Hydrogel Microphones For Stealthy Underwater Listening, Yang Gao, Jingfeng Song, Shumin Li, Christian Elowsky, You Zhou, Stephen Ducharme, Yong Mei Chen, Qin Zhou, Li Tan
Hydrogel Microphones For Stealthy Underwater Listening, Yang Gao, Jingfeng Song, Shumin Li, Christian Elowsky, You Zhou, Stephen Ducharme, Yong Mei Chen, Qin Zhou, Li Tan
Stephen Ducharme Publications
Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or …
Charge Collection Kinetics On Ferroelectric Polymer Surface Using Charge Gradient Microscopy, Yoon-Young Choi, Sheng Tong, Stephen Ducharme, Andreas Roelofs, Seungbum Hong
Charge Collection Kinetics On Ferroelectric Polymer Surface Using Charge Gradient Microscopy, Yoon-Young Choi, Sheng Tong, Stephen Ducharme, Andreas Roelofs, Seungbum Hong
Stephen Ducharme Publications
A charge gradient microscopy (CGM) probe was used to collect surface screening charges on poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] thin films. These charges are naturally formed on unscreened ferroelectric domains in ambient condition. The CGM data were used to map the local electric current originating from the collected surface charges on the poled ferroelectric domains in the P(VDF-TrFE) thin films. Both the direction and amount of the collected current were controlled by changing the polarity and area of the poled domains. The endurance of charge collection by rubbing the CGM tip on the polymer film was limited to 20 scan cycles, after …
Finite-Size Scaling Of Flexoelectricity In Langmuir-Blodgett Polymer Thin Films, Shashi Poddar, Keith Foreman, Shireen Adenwalla, Stephen Ducharme
Finite-Size Scaling Of Flexoelectricity In Langmuir-Blodgett Polymer Thin Films, Shashi Poddar, Keith Foreman, Shireen Adenwalla, Stephen Ducharme
Stephen Ducharme Publications
The flexoelectric effect, which is a linear coupling between a strain gradient and electrical polarization, is a fundamental electromechanical property of all materials with potential for use in nanoscale devices, where strain gradients can be quite large. We report a study of the dependence of the flexoelectric response on thickness in ultrathin films of polar and non-polar polymers. The measurements of the flexoelectric response in non-polar polyethylene and the polar relaxor polymer polyvinylidene-co-trifluoroethylene-co-chlorofluoroethylene were made using a bent cantilever method and corrected for the contribution from the electrode oxide. The results show that the value of …
Ferroelectric Polymer Nanopillar Arrays On Flexible Substrates By Reverse Nanoimprint Lithography, Jingfeng Song, Haidong Lu, Keith Foreman, Shumin Li, Li Tan, Shireen Adenwalla, Alexei Gruverman, Stephen Ducharme
Ferroelectric Polymer Nanopillar Arrays On Flexible Substrates By Reverse Nanoimprint Lithography, Jingfeng Song, Haidong Lu, Keith Foreman, Shumin Li, Li Tan, Shireen Adenwalla, Alexei Gruverman, Stephen Ducharme
Stephen Ducharme Publications
With the increasing interest in deploying ferroelectric polymer in flexible electronics and electromechanics, high-throughput and low-cost fabrication of 3D ferroelectric polymer nanostructures on flexible substrates can be a significant basis for future research and applications. Here, we report that large arrays of ferroelectric polymer nanopillars can be prepared directly on soft, flexible substrates by using low-cost polydimethylsiloxane (PDMS) soft-mold reverse nanoimprint lithography at 135 °C and at pressures as low as 3 bar. The nanopillar arrays were highly uniform over large areas of at least 200 × 200 μm and had good crystallinity with nearly optimum (110) orientation. Furthermore, the …
2d Cocrystallization From H‑Bonded Organic Ferroelectrics, Donna A. Kunkel, James Hooper, Benjamin Bradley, Lisa Schlueter, Tom Rasmussen, Paulo Costa, Sunit Beniwal, Stephen Ducharme, Eva Zurek, Axel Enders
2d Cocrystallization From H‑Bonded Organic Ferroelectrics, Donna A. Kunkel, James Hooper, Benjamin Bradley, Lisa Schlueter, Tom Rasmussen, Paulo Costa, Sunit Beniwal, Stephen Ducharme, Eva Zurek, Axel Enders
Stephen Ducharme Publications
The synthesis of 2D H-bonded cocrystals from the room-temperature ferroelectric organics croconic acid (CA) and 3-hydroxyphenalenone (3-HPLN) is demonstrated through self-assembly on a substrate under ultrahigh vacuum. 2D cocrystal polymorphs of varied stoichiometry were identified with scanning tunneling microscopy, and one of the observed structural building blocks consists of two CA and two 3-HPLN molecules. Computational analysis with density functional theory confirmed that the experimental (CA)2(3-HPLN)2 tetramers are lower in energy than single-component structures due to the ability of the tetramers to pack efficiently in two dimensions, the promotion of favorable electrostatic interactions between tetramers, and the …
Fabrication Of Diisopropylammonium Bromide Aligned Microcrystals With In-Plane Uniaxial Polarization, Shashi Poddar, Haidong Lu, Jingfeng Song, Om Goit, Shah Valloppilly, Alexei Gruverman, Stephen Ducharme
Fabrication Of Diisopropylammonium Bromide Aligned Microcrystals With In-Plane Uniaxial Polarization, Shashi Poddar, Haidong Lu, Jingfeng Song, Om Goit, Shah Valloppilly, Alexei Gruverman, Stephen Ducharme
Stephen Ducharme Publications
Textured arrays of ferroelectric microcrystals of diisopropylammonium bromide were grown from solution at room temperature onto silicon substrates and studied by means of x-ray diffraction, atomic force microscopy, electron microscopy, and piezoresponse force microscopy. The needle-shaped crystals had dimensions of approximately 50 μm × 5 μm in the plane and were approximately 200 nm thick, where the dimensions and arrangement were influenced by growth conditions. The observations suggest an Ostwald ripening mechanism of the microcrystal growth. The crystals had the structure of the ferroelectric phase, where the polarization axis was in-plane and parallel to the long axis of …