Flexible pressure sensor with ordered three-level pyramid microstructures for high-sensitivity and wide-range human...

Flexible piezoresistive sensors are extensively applied in human physiological monitoring and dexterous hand motion detection. However, they often suffer from a trade-off between high sensitivity and wide sensing range, as well as limited linearity induced by the intrinsic microstructural drawbacks. In this study, we propose a flexible piezoresistive sensor featuring a well-ordered and three-level pyramidal microstructure (OTPm) fabricated by laser direct writing and wet etching to overcome such limitations. Benefiting from stress concentration at pyramid tips and stepwise interfacial contact, the OTPm sensor achieves progressive conduction behavior, which effectively enhances sensitivity and suppresses pressure saturation. Notably, the OTPm sensor exhibits three linear sensitivity stages of 77.80, 39.84, and 19.20 kPa^-1, a broad detection range up to 800 kPa, a low limit of detection of 98 Pa, and a response time of 91.2 ms, coupled with stable sensing performance over 10,000 cycling tests. These sensing features enable the sensor to effectively detect various physiological signals and dynamic human motion changes. Furthermore, the developed 3×3 sensor array realizes three-dimensional(3D) pressure distribution imaging and validates reliable mechanical sensing capability during grasping motions. With the balanced sensing performance, the proposed sensor presents great application potential for medical rehabilitation, robotic control, and human-machine interaction.