A Bioinspired Hierarchical Microstructure for Iontronic Pressure Sensors with an Ultrawide Range for Gesture Recognition

Abstract

Flexible pressure sensors are inherently limited by a fundamental trade-off between the sensitivity and detection range. Although iontronic pressure sensors (IPSs) exhibit superior sensitivity, they often encounter signal saturation under high-pressure conditions, thereby limiting their operational scope. In this study, we propose a bioinspired IPS that overcomes this limitation by incorporating a hierarchical microstructure inspired by a strawberry. The design features stiff achene-like protrusions integrated onto a compliant, mountain ridge-like architecture, which facilitates a sequential deformation mechanism. As a result, the sensor achieves both an exceptionally wide detection range (0-3.57 MPa) and high sensitivity across multiple linear response intervals (445.2 kPa^-1 at 0-250 and 188.4 kPa^-1 at 250-3570 kPa). Additionally, the device demonstrates excellent durability (>6000 cycles) at 976.1 kPa and a fast response time. Its functional applicability is demonstrated through a sensor-integrated glove, which, when integrated with a network, achieves 94% accuracy in recognizing 26 distinct sign language gestures. This work establishes a design framework for the development of high-performance flexible electronic systems capable of effectively responding to a wide range of mechanical stimuli, from subtle tactile inputs to intense mechanical impacts.