A NbOI2-based flexible piezoelectric sensor for acoustic signal acquisition and gesture-controlled human-machine interaction systems.

Driven by the demand for low-power sensing in wearable electronics and intelligent human-machine interaction, two-dimensional piezoelectric materials, which combine self-powered capability, mechanical flexibility, and integration compatibility, provide a promising material platform for high-performance flexible sensors. In this work, a flexible piezoelectric sensor based on two-dimensional NbOI2 was constructed on a polyimide substrate. The device exhibits stable and repeatable piezoelectric responses over bending angles from 30° to 75° and operating frequencies from 0.47 to 2.10 Hz. At a bending angle of 75°, the peak output current reaches 167.01 pA. Under the conditions of a bending angle of 45° and a bending frequency of 1.31 Hz, after more than 1000 bending cycles, the device retains approximately 95.0% of its initial output performance, demonstrating excellent electromechanical conversion capability and mechanical durability. Furthermore, the device enables acoustic signal acquisition, mechanical motion recognition, and gesture-triggered control and was successfully integrated into a human-machine interaction system for smart-home control and robotic-hand manipulation. This work highlights the potential of NbOI2-based flexible piezoelectric sensors in self-powered sensing, acoustic acquisition, and intelligent interaction, providing a practical reference for the integration of two-dimensional piezoelectric materials into flexible electronic systems.