@article{bhuyan_wei_sin_yu_nah_jeong_dickey_park_2021, title={Soft and Stretchable Liquid Metal Composites with Shape Memory and Healable Conductivity}, volume={13}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.1c06786}, DOI={10.1021/acsami.1c06786}, abstractNote={Shape memory composites are fascinating materials with the ability to preserve deformed shapes that recover when triggered by certain external stimuli. Although elastomers are not inherently shape memory materials, the inclusion of phase-change materials within the elastomer can impart shape memory properties. When this filler changes the phase from liquid to solid, the effective modulus of the polymer increases significantly, enabling stiffness tuning. Using gallium, a metal with a low melting point (29.8 °C), it is possible to create elastomeric materials with metallic conductivity and shape memory properties. This concept has been used previously in core-shell (gallium-elastomer) fibers and foams, but here, we show that it can also be implemented in elastomeric films containing microchannels. Such microchannels are appealing because it is possible to control the geometry of the filler and create metallically conductive circuits. Stretching the solidified metal fractures the fillers; however, they can heal by body heat to restore conductivity. Such conductive, shape memory sheets with healable conductivity may find applications in stretchable electronics and soft robotics.}, number={24}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Bhuyan, Priyanuj and Wei, Yuwen and Sin, Dongho and Yu, Jaesang and Nah, Changwoon and Jeong, Kwang-Un and Dickey, Michael D. and Park, Sungjune}, year={2021}, month={Jun}, pages={28916–28924} }
 @article{park_shintake_piskarev_wei_joshipura_frey_neumann_floreano_dickey_2021, title={Stretchable and Soft Electroadhesion Using Liquid-Metal Subsurface Microelectrodes}, volume={6}, ISSN={["2365-709X"]}, DOI={10.1002/admt.202100263}, abstractNote={AbstractElectroadhesion is an attractive mechanism to electrically modulate adhesion to surfaces. Electroadhesion arises from the interaction of electric fields with conductive or dielectric materials. Electroadhesion devices consist of in‐plane, interdigitated electrodes that generate out‐of‐plane electric fields, which increase adhesion with target surfaces. To date, these electrodes have predominantly been composed of carbonaceous materials. Here, liquid metal is utilized to create the electrodes in silicone substrates. Liquid metal can be patterned in a variety of unique ways, including microfluidic injection, spray deposition, or printing. These electrodes have nearly unlimited deformation in soft and stretchable substrates while maintaining metallic conductivity. The experimental results show that stretching improves electroadhesion performance due to the changes in geometry of the electrodes and insulation layer, whose behaviors are theoretically predictable. The use of liquid‐filled, sub‐surface microchannels can help to maintain contact between the elastomer and substrate during peeling due to the surface stresses caused by the capillary pressure. This approach to electroadhesion can be implemented in ultra‐stretchable and soft substrates, including those used in soft robotics, due to the inherently compliant and deformable electrical conductivity of the liquid metal electrodes.}, journal={ADVANCED MATERIALS TECHNOLOGIES}, author={Park, Sungjune and Shintake, Jun and Piskarev, Egor and Wei, Yuwen and Joshipura, Ishan and Frey, Ethan and Neumann, Taylor and Floreano, Dario and Dickey, Michael D.}, year={2021}, month={Jun} }
 @article{sen_xiong_zhang_park_you_ade_kudenov_brendan t. o'connor_2018, title={Shear-Enhanced Transfer Printing of Conducting Polymer Thin Films}, volume={10}, ISSN={["1944-8244"]}, DOI={10.1021/acsami.8b09968}, abstractNote={Polymer conductors that are solution-processable provide an opportunity to realize low-cost organic electronics. However, coating sequential layers can be hindered by poor surface wetting or dissolution of underlying layers. This has led to the use of transfer printing where solid film inks are transferred from a donor substrate to partially fabricated devices using a stamp. This approach typically requires favorable adhesion differences between the stamp, ink, and receiving substrate. Here, we present a shear-assisted organic printing (SHARP) technique that employs a shear load on a post-less polydimethylsiloxane (PDMS) elastomer stamp to print large-area polymer films that can overcome large unfavorable adhesion differences between the stamp and receiving substrate. We explore the limits of this process by transfer printing poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) films with varied formulation that tune the adhesive fracture energy. Using this platform, we show that the SHARP process is able to overcome a 10-fold unfavorable adhesion differential without the use of a patterned PDMS stamp, enabling large-area printing. The SHARP approach is then used to print PEDOT:PSS films in the fabrication of high-performance semitransparent organic solar cells.}, number={37}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Sen, Pratik and Xiong, Yuan and Zhang, Qanqian and Park, Sungjune and You, Wei and Ade, Harald and Kudenov, Michael W. and Brendan T. O'Connor}, year={2018}, month={Sep}, pages={31560–31567} }
 @article{park_tsarkova_2017, title={Surface roughness-mediated ordering in block copolymer films toward spatially controlled patterns}, volume={50}, number={17}, journal={Macromolecules}, author={Park, S. and Tsarkova, L. A.}, year={2017}, pages={6840–6848} }