Synthesis of a Photo-Crosslinkable Elastomer for Stretchable Electronics and Its Use in Strain-Insensitive Pressure Sensors

A stretchable electronic substrate with strategically positioned rigid and soft islands offers a significant platform to overcome the limitations of current stretchable substrates. This design facilitates the integration of conventional rigid electroactive materials into high-performance stretchable electronics. This study introduces a photo-crosslinkable, transparent elastomer substrate based on acrylates. When exposed to UV irradiation, it undergoes selective crosslinking (with crosslinking density and modulus depending on the number of crosslinkers); it can achieve a modulus increase of up to 38 000%. Rigid regions of specific shapes and sizes can be created using a photomask, while soft regions remain intact for expansion during stretching. The substrate is used to produce a capacitive strain/strain-insensitive pressure (SIP) sensor in which rigid islands act as the dielectric layer of the capacitor; sensitivity to external stimuli is modulated by the modulus of the rigid islands. In addition, a high-efficiency SIP sensor (SIPS) employing an electrospun dielectric layer, which amplifies the pressure sensitivity by 780-fold, is developed, ensuring a constant low strain sensitivity. A stretchable substrate, utilizing a photo-crosslinkable acrylate elastomer, is developed. The "rigid-island" strategy is seamlessly integrated using this system. High-resolution rigid regions are created, while soft regions are preserved for stretching. This innovative substrate is employed in capacitive strain sensors and SIP sensors, with the rigid islands serving as the dielectric layer of the capacitor.image