Textile-Based Wireless Pressure Sensor Array for Human-Interactive Sensing

A textile-based wireless pressure sensor array (WiPSA) is proposed for flexible remote tactile sensing applications. The WiPSA device is composed of a fabric spacer sandwiched by two separate layers of passive antennas and ferrite film units. Under the external pressure, the mechanical compression of the flexible fabric spacer leads to an inductance change, which can further be transduced to a detectable shift of the resonant frequency. Importantly, WiPSA integrates the ferrite film featuring an ultrahigh permeability, which effectively improves the device sensitivity and avoids the interference of conductive materials simultaneously. The device performance with a high quality factor (>35) and sensitivity (-0.19 MHz kPa(-1)) within a pressure range of 0-20 kPa is demonstrated. In addition, WiPSA achieves excellent reproducibility under periodical pressures (>20 000 cycles), temperature fluctuations (15-103 degrees C), and humidity variations (40-99%). As a proof of concept for human-interactive sensing, WiPSA is successfully 1) integrated with a flexible wrist band for fingertip pressure-guided direction choices, 2) developed into a smart wireless insole to map the plantar stress distributions, and 3) embedded into a waist-supporting belt to resolve the contact pressure between the belt and human abdomen in a remote transmitting scheme.