Cactus-inspired dual-sided micro-cilia arrays with swelling-induced CNT networks for high-performance wearable pressure sensing

Flexible and wearable pressure sensors have garnered significant attention due to their transformative potential in healthcare, human-machine interfaces, and robotics. Here, we report a cactus-inspired dual-sided micro-cilia array (DMCA) sensor incorporating swelling-induced CNT networks for enhanced wearable pressure sensing. The device leverages magnetically-assisted self-assembly through combined spray and spin coating processes, creating a bilayer architecture with distinct mechanical characteristics. Spray-coated, elongated cilia provide exceptional sensitivity under low-pressure conditions, while spin-coated, robust cilia ensure structural stability and a broad dynamic range. Post-fabrication infiltration of CNT networks into an elastomeric matrix via solvent-induced swelling imparts electrical conductivity without compromising the mechanical flexibility. Systematic morphological optimization identified ideal processing parameters balancing the sensitivity (up to 379 kPa^-1 in the 0-60 kPa range) and extended linear response (up to 200 kPa with a sensitivity of 85 kPa^-1). Demonstrations highlight the sensor's capabilities in accurately monitoring physiological signals and enabling sophisticated human-machine interfaces, thereby offering a scalable and versatile platform for next-generation wearable electronics.