Piezoelectric PDMS films with micro plasma discharge for electromechanical sensors

We have successfully demonstrated the fabrication of piezoelectric polydimethylsiloxane (PDMS) films utilizing multilayer casting, stacking, surface coating and micro plasma discharge processes. The PDMS films have micrometer-sized voids inside, which are connected and each has a size of 50×50× 50 μm³. First, all voids were surface coated with PTFE thin films, and sputtered elastic gold films as flexible electrodes on the top and bottom of PDMS films. Then all voids were implanted with bipolar charges on the opposite surfaces. During the micro plasma discharge process, an AC electric field up to 38 MV/m was applied at 0.5 Hz for 15 minutes. Whenever the required breakdown field was reached, a self-extinguishing micro discharge was ignited inside the voids, accompanied by the emission of short light pulses and by the transfer of charges across the voids. After charge implantation, the cellular PDMS films showed strong piezoelectricity, with an effective piezoelectric coefficient (d₃₃) as high as 1000 pC/N. Furthermore, the piezoelectricity of the PDMS films could be tailored by adjusting the sizes of the cellular structures. Therefore, the demonstrated piezoelectric PDMS films could potentially serve as sensitive electromechanical materials, and fulfill the desire of various sensing and actuation applications.