Carbon Nanocoils and Polyvinyl Alcohol Composite Films for Fiber-Optic Fabry–Perot Acoustic Sensors

Carbon nanocoils (CNCs) are widely used in functional devices due to their helical morphology, which can be utilized in the fabrication of functional materials with unique properties. In this study, CNCs/polyvinyl alcohol (PVA) composite films were prepared using an electrostatic spinning method and used to form a diaphragm for Fabry–Perot acoustic sensors. With the addition of CNCs, the fabricated composite film showed enhanced mechanical performance responding to acoustic wave pressure. Considering the optical and mechanical response, the content of CNCs was set as 0.14 wt.%; the highest acoustic wave pressure response of the sensor was 1.89 V/Pa at 16.2 kHz, which was relatively higher than that of devices with pure polymer films. Additionally, the sensor had a broadband frequency response from 2 to 10 kHz. The results indicate that the proposed composite film acoustic sensor is suitable for low-frequency acoustic sensing, which lays the foundation for the extended application of functional sensors based on CNCs.