Breathable Electrophysiological Sensors Based on Fiber-to-Continuous Network Transformation of Polydimethylsiloxane/Polyacrylonitrile Janus Films.

With the rapid development of flexible sensors in healthcare monitoring and human-machine interactions, traditional materials face challenges such as poor breathability and sweat accumulation, resulting in signal distortion and wearing discomfort. Developing breathable sensors is the main solution to address these issues. Here, breathable porous polydimethylsiloxane (pPDMS)/polyacrylonitrile (PAN) films with a Janus structure were fabricated through electrospinning and selective dissolution. The films possessed asymmetric wettability with hydrophilic PAN fiber layers and hydrophobic pPDMS layers, which had a unique rough-surface continuous network structure. These Janus films exhibited excellent breathability and directional water transport, enabling "breathability" for the fabricated sensors. Unprecedentedly, the fiber-to-continuous network transformation in pPDMS layers enhanced the surface metal adhesion after gold deposition and significantly improved their conductivity, stability, electrical stretchability, and durability as flexible sensors. When collecting physiological signals, these sensors demonstrated effective sweat-draining and breathability with improved signal stability. This work provides a solution for fabricating porous, breathable PDMS-based films and sensors, expanding material choices for next-generation smart textiles.