Skin-Tailored Adhesive Bio-Electrode with Tunable Poisson's Ratio for Stable Electrophysiological Communication.

Stretchable electrodes are crucial healthcare device components for electrophysiology signal sensing. Compared to conventional rigid gel electrodes, stretchable electrodes are advantageous for long-term monitoring with superior skin conformality. However, current devices often show limited compliance and adhesive reliability, especially during human motion. Here, a skin-tailored adhesive bio-electrode (STABL) is fabricated using a substrate designed to comply with the deformation behavior of wrist skin. The substrate patch possesses a negative Poisson's ratio (PR) through an auxetic structured glass fabric reinforcement embedded in a soft, adhesive elastomer film. Based on the direct measurement of wrist skin deformation behavior, the chemical composition and geometry of the substrate patch are optimized to match the negative PR of the skin. Using this tailored substrate, STABL is fabricated with EGaIn liquid metal conductors and exhibits superior stability in electrophysiology communication during repetitive wrist motion compared to conventional pristine PDMS substrates. This result highlights the potential of skin-tailored auxetic substrates and liquid metal electrodes for reliable, long-term wearable bioelectronics applications.