Flexible Piezoresistive Sensor Based on PDMS @ PU Composite Foam Modified by Multicomponent Carbon Materials

Flexible piezoresistive sensors hold promising prospects in health monitoring and wearable electronics. Lightweight polyurethane (PU) foam is an ideal flexible substrate, while traditional PU‐based sensors suffer from inhomogeneous conductive networks and poor cycling stability. This study adopts a stepwise composite construction strategy to fabricate RCCB/PDMS@PU composite foam sensors. Polydimethylsiloxane (PDMS) is used for in situ coating onto the PU pore skeleton to fabricate PDMS@PU composite foams. Carbon nanofibers (CNF) and carbon black (CB) are incorporated into the PDMS@PU frameworks via impregnation and curing to form preliminary conductive pathways. Subsequently, reduced graphene oxide (rGO) is introduced through hydrothermal reduction to further construct three‐dimensional conductive networks. PDMS improves the deformation consistency between the substrates and fillers. The conductive network of multicomponent carbon materials generates more contact points under compression and improves piezoresistive performance. The RCCB/PDMS@PU‐3 composite foam sensor exhibits a sensitivity of 0.14 kPa −1 in the low‐pressure range of 0–3 kPa and maintains a measurable resistance response over a broader detectable pressure range of 3–43 kPa. The optimized sensor also shows a conductivity of 2.33 × 10 −4 S m −1 , rapid response, and stable cycling performance. Furthermore, it precisely captures physiological and joint motion signals, exhibiting great potential for wearable health monitoring.