Wireless Human Motion Detection with a Highly Sensitive Wearable Pressure Sensing Technology

Abstract Wireless flexible sensing devices using inductive‐capacitive (LC) resonator‐enabled transmission technologies are attractive in the areas of human motion detection, health inspection, and implantable medical devices. However, challenges remain in LC‐based wireless sensing devices, including low device sensitivity/resolution and slow signal readout speed based on sweeping excitation frequencies. Herein, an LC resonator‐based wireless pressure sensing technology (LC‐WPS) is proposed for flexible contact pressure measurements in a real‐time manner. It includes a fully flexible passive LC pressure sensor and a signal‐reading circuit for wireless communication with the sensor and real‐time data processing. The passive sensor detects external pressure by the changes in resonant frequency. Importantly, by optimizing the design of the LC resonator in the sensor, the LC‐WPS converts the pressure‐dependent resonant frequency into circuit output voltage to a great extent, achieving a high sensitivity (1.23 × 10 −2 kPa −1 ) and resolution (54 Pa) within a pressure range of 0–15 kPa. In addition, the LC‐WPS utilizes a single operating frequency (i.e., 13.56 MHz) instead of sweeping the operating frequencies to identify the sensor resonant frequency, featuring fast and real‐time data analysis and processing. Real‐time monitoring of human motions, such as laryngeal movement, neck bending and wrist rotation, is demonstrated, verifying the applicability of the LC‐WPS in the fields of wearable medical care and sports biomechanics.