Bioinspired ionic capacitive pressure sensor based on multilevel rigid-soft coupled architecture for foot-type classification and human-machine interaction

High-performance flexible pressure sensors have found extensive applications in critical areas such as flexible robotics, brain-machine interfaces, wearable electronics, and human-machine interaction systems. These applications necessitate not only a broad detection range for mechanical signals but also sustained high sensitivity throughout the entire pressure range. Nevertheless, flexible materials typically suffer from limited compressibility and structural saturation under high loads, resulting in a precipitous decline in sensing sensitivity across a wide pressure range and impeding their practical deployment. Drawing inspiration from the structural and material attributes of the human fingertip, a flexible ionic capacitive pressure sensor based on multilevel rigid-soft coupled architecture has been designed. The proposed design substantially augments the sensor’s load-bearing capacity and extends its pressure detection range. Meanwhile, the electric double-layer (EDL) effect formed at the surface of the ionic dielectric polymer film triggers significant capacitance variations under small applied pressures, thereby further enhancing the sensing sensitivity. The results demonstrate that the sensor attains an exceptionally high sensitivity of up to 2190.0 kPa -1 in the low-pressure regime (<8 kPa), while preserving an outstanding sensitivity of 155.4 kPa -1 under high pressure (800 kPa). Additionally, the sensor exhibits a rapid response time of 18 ms. To substantiate its performance, the sensor was deployed in several practical scenarios, encompassing human motion detection, foot-type classification based on plantar pressure distribution, and human-machine interaction control systems. This work is anticipated to offer a crucial reference for fostering the synergistic development of pressure sensors towards achieving both high sensitivity and wide pressure range detection. • A fingertip-inspired multilevel rigid-soft coupled architecture enables high sensitivity and broad pressure adaptability. • The BMCPS achieved 2109.0 kPa -1 sensitivity under 8 kPa and remains 155.4 kPa -1 sensitivity even at 800 kPa. • The BMCPS was used for human motion detection, foot-type classification based on plantar pressure distribution, and human-machine interaction control systems.