Flexible Array Cushion Based on Short-Cut Carbon Fiber Reinforced CNT/TPU Aerogel Sensor for Sitting-Posture Recognition.

The sitting-posture monitoring strategies based on visual capture or inertial measurement units cannot be widely adopted because of light occlusion, privacy concerns, and wearing discomfort. In this work, a flexible piezoresistive sensor array based on the short-cut carbon fiber-reinforced carbon nanotube (CNT)/thermoplastic polyurethane (TPU) aerogel sensor (SCT) for sitting posture recognition was proposed. The results show that the compressive modulus of SCT3 can be increased to 0.623MPa compared with pure TPU aerogel (0.053MPa), showing a low density (0.159 g/cm3) as well as high porosity (90.1%) due to the enhancement and supporting effect of short-cut carbon fiber (SF) in the matrix. The pressure sensing range of SCT3 reaches 382 kPa, and good sensitivity (3.01kPa-1) as well as durability (3500 cycles) can meet the real-time monitoring requirements of high pressure on hips. Additionally, an anti-crosstalk 8 × 8 array acquisition circuit was proposed to adapt the flexible array cushion, and a simple convolutional neural network was used to recognize five sitting postures, including proper posture, kyphosis, leaning forward, left-leaning, and right-leaning. This work proposes a sitting posture recognition strategy in a piezoresistive sensor array, which provides a promising approach to monitor sitting postures for adolescents.