Piezoelectret Thin‐Film Acoustic Sensor with High Flexibility and Sensitivity for Noise‐Immune Human‐Robot Interaction

Acoustic detection and recognition are crucial for information exchange in diverse fields, yet traditional acoustic sensors face limitations in bulk, sensitivity, and flexibility. The existing flexible acoustic sensors still struggle with performance degradation under bending. Therefore, this study introduces a piezoelectret thin‐film acoustic sensor (PETAS) that includes a vibrating membrane, a spacer layer, and an electret layer made of fluorinated ethylene propylene (FEP). The air gaps within the electret layer are fully charged after corona poling, and charge redistribution occurs when the device undergoes deformation. By decoupling the diaphragm and the electret layer, the diaphragm can specifically respond to acoustic pressure variations and affect charge distribution so that bandwidth and sensitivity are significantly enhanced while flexibility is maintained. The fabricated sensor demonstrates a stable output across 0∼830 Hz frequency range, high sensitivity (2.744 pC/Pa at 500 Hz), and excellent durability (>105 continuous operational and 1,000 bending cycles without performance loss). The exceptional performance ensures an over 96% accuracy in the command recognition and strong ability of environmental noise rejection in the human‐robot interaction. As demonstrated in experiments, neck‐mounted PETAS significantly outperformed commercial microphones. These demonstrations illustrate that PETAS offers a versatile solution for next‐generation wearable electronics and HRI systems.