Micro-structured Polydimethylsiloxane Films Research Articles

Piezoresistive Electronic-Skin Sensors Produced With Self-Channeling Laser Microstructured Silicon Molds

Highly sensitive and cost-effective flexible piezoresistive sensors are pursued as essential components of electronic skin (e-skin) for a variety of applications such as soft robotics and body prosthesis. A common strategy for achieving high sensitivity of these sensors is to fabricate their electrode material with complex 3-D microstructures, but manufacturing cost-effective micro-structured sensors with high reliability and reproducibility is a challenge. Herein, a robust approach for producing high-reproductive microstructured polydimethylsiloxane (PDMS) films composing the sensors is proposed, based on silicon molds with a honeycomb-like architecture fabricated rapidly and cost-effectively at a standoff distance by femtosecond laser pulses in the self-channeling regime. Single-walled carbon nanotubes (SWNTs) are embedded in the micro-structured PDMS films composing sandwich-structural flexible piezoresistive sensors. The sensing devices exhibit good performance with high sensitivity, fast response time, and excellent stability and are used with success for the detection of hand motion pressure and blood pressure at the wrist, thus showing a great potential as components of e-skin for detection of various human motions.

A sandpaper assisted micro-structured polydimethylsiloxane fabrication for human skin based triboelectric energy harvesting application

This paper reports a sandpaper based inexpensive and simple fabrication process of functional micro-structured PDMS (Polydimethylsiloxane) film to be used as a triboelectric layer. The micro-structured PDMS film was replicated directly from the low surface energy sandpaper template without the use of any surfactant coating, high vacuum or high-pressure equipment. A human skin and PDMS interaction based triboelectric generator (TEG) is demonstrated using as-fabricated micro-structured PDMS film. In our proposed TEG harvester, electrical energy is produced by continual contact-separation processes between PDMS and human skin. Four different micro-structures were compared with flat film and the influences of surface structures on the electrical output of the harvester are systematically studied. Results show that the existence of micro-structures on the PDMS films effectively enlarges the contact area and provides more surfaces for charge storage and hence improve the output performance of TEG. The as-fabricated prototype can produce peak-peak open-circuit voltage up to 103V and 4.8mW/m2 of peak power density, which is exceptionally attractive for the fabrication of self-powered and portable devices. This stable PDMS film with functional micro-structures, which is fabricated using reusable sandpaper template facilitates robust and large-scale fabrication, and has potential for future applications in triboelectric energy harvesting devices.