Adhesive-free PDMS/PUA bilayer using selective photopolymerization for transparent, attachable, and wearable triboelectric nanogenerator

Polydimethylsiloxane (PDMS) is a widely used elastomer substrate in various fields, including wearable devices, because of its diverse advantages. However, PDMS has low stretchability and lack of adhesion, thus requires additive adhesives, such as conventional tapes, which have potential to cause skin trauma. Meanwhile, polyurethane acrylate (PUA) is also a broadly used elastomer given its various advantages, such as biocompatibility and mechanical properties. This study introduces, for the first time, a novel laser process method to form an adhesive-free PDMS/PUA bilayer film. By adjusting UV laser scanning parameters, the interfacial bonding between the PDMS and PUA can be improved without additional additives. The fabricated PDMS/PUA bilayer showed high transparency, improved mechanical properties, and adhesiveness properties. Combining with PUA (as a backbone and adhesive layer) and PDMS (as a triboelectric layer), the PDMS/PUA bilayer was further used to fabricate a transparent, attachable, and stretchable PDMS/PUA-based triboelectric nanogenerator (PP-TENG) device. The transparent attachable PP-TENG successfully detected minute human motions and functioned as a virtual piano keyboard and a virtual computer keyboard when attached to an arbitrary paper.