Smart Driving Hardware Augmentation by Flexible Piezoresistive Sensor Matrices with Grafted-on Anticreep Composites

Signal drift and hysteresis of flexible piezoresistive sensors pose significant challenges against the widespread applications in emerging fields such as electronic skin, wearable equipment for metaverse and human-AI (artificial intelligence) interfaces. To address the creep and relaxation issues associated with pressure-sensitive materials, a highly stable piezoresistive composite is proposed, using polyamide-imide (PAI) fibers as the matrix and in situ grafted-polymerized polyaniline (PANI) as the semi-conducting layer. The PAI with large rigid fluorenylidene groups exhibits a high glass transition temperature of 372 °C (PAI 5-5), which results in an extremely long relaxation time at room temperature and consequently offers outstanding anti-creep/relaxation performances. The enhancement of PAI-PANI interfacial bonding through in situ grafting improves the sensor reliably. The sensor presents high linear sensitivity of 35.3 kPa^-1 over a pressure range of 0.2-20 kPa, outstanding repeatability, and excellent dynamic stability with only a 3.8% signal deviation through ≈10 000 cycles. Real-time visualization of pressure distribution is realized by sensor matrices, which demonstrate the capability of tactile gesture recognition on both flat and curved surfaces. The recognition of sitting postures is achieved by two 12 × 12 matrices facilitated by machine learning, which prompts the potential for the augmentation of smart driving.