Sponge-Hosting Polyaniline Array Microstructures for Piezoresistive Sensors with a Wide Detection Range and High Sensitivity

The development of highly elastic spongy conductors is attractive for use in piezoresistive sensors due to their low cost, easy fabrication, and wide sensing range. However, the combination of high sensitivity and broad sensing range in a single piezoresistive sensor, though highly demanded, is challenging because they are contradictory in principle. Herein, a highly elastic spongy conductor with sponge-hosting polyaniline (PANI) fluff-like array microstructures is fabricated through cryopolymerization. The as-obtained sponge-hosting conductors exhibited an excellent elasticity under high compression strain and stress of up to 80% and 101 kPa, respectively, covering typical deformation ranges for detecting complex human activities. Benefiting from the presence of the sponge-hosting fluff-like PANI arrays, the as-prepared sponge-hosting conductors for piezoresistive sensors possessed a high sensitivity of 0.54 kPa-1 in a broad pressure range of 0.1-101 kPa, ascribing to the formation of the sponge-hosting fluff arrays with graded conductive network structures of array contacts and sponge-skeleton contacts at low and high compressions, respectively. As a result, the as-assembled piezoresistive sensors were demonstrated for tactile sensing and human-motion monitoring. This work reveals new approaches for tailored fabrication of sponge-hosting conducting polymers with tunable fluff-like microstructures for highly sensitive and wide-range wearable piezoresistive sensors.