An epidermal-codeformed adhesive film for flexible PCB-based sensors towards full-body motion capture system

Flexible printed circuit boards (FPCBs) play crucial roles in wearable electronics. FPCB-based sensors can be easily integrated into motion capture systems to detect and digitize human movements. However, non-conformity between sensors and human skin leads to signal distortion and motion artifacts. Herein, a polydimethylsiloxane-(Z)-sorbitan mono-9-octadecenote (PDMS-Span 80) adhesive film is developed to connect and co-deform the FPCB-based bending sensor with human skin. The PDMS-Span 80 adhesive film demonstrates a high adhesive (a higher adhesion force of 38.0 kPa), reusability (over 300 cycles), long-term stability (over 20 d), and robustness (high tolerance to washing and high temperatures). Meanwhile, the adhesive film can be stripped by a low peeling strength without skin damage and shows relatively better biocompatibility with skin. Specifically, combining the high adhesive, larger stretchability, and elasticity, and skin-like elasticity modulus, the adhesive film can co-deform with human skin. With the assistance of the PDMS-Span 80 adhesive film, the FPCB-based bending sensor not only possesses exceptional responsiveness, reliability, and durability but also eliminates the overshoot phenomenon when responding to the deformation of the skin. Successful application in a full-body motion capture for the digital twin of Chinese Kungfu demonstrated the great application promise of PDMS-Span 80 adhesive film.