Ultra‐Broadband Flexible Thin‐Film Sensor for Sound Monitoring and Ultrasonic Diagnosis

Abstract Small‐scale and flexible acoustic probes are more desirable for exquisite objects like human bodies and complex‐shaped components than conventional rigid ones. Herein, a thin‐film flexible acoustic sensor (FA‐TES) that can detect ultra‐broadband acoustic signals in multiple applications is proposed. The device consists of two thin copper‐coated polyvinyl chloride films, which are stimulated by acoustic waves and contact each other to generate the triboelectric signal. Interlocking nanocolumn arrays fabricated on the friction surfaces are regarded as a highly adaptive spacer enabling this device to respond to ultra‐broadband acoustic signals (100 Hz–4 MHz) and enhance sensor sensitivity for film weak vibration. Benefiting from the characteristics of high shape adaptability and ultrawide response range, the FA‐TES can precisely sense human physiological sounds and voice (≤10 kHz) for laryngeal health monitoring and interaction in real‐time. Moreover, the FA‐TES flexibly arranged on a 3D‐printed vertebra model can effectively and accurately diagnose the inner defect by ultrasonic testing (≥1 MHz). It envisions that this work can provide new ideas for flexible acoustic sensor designs and optimize real‐time acoustic detections of human bodies and complex components.