PETA Polymer/Graphene Composite Film-Enabled Optical Microcavity Relative Humidity Sensor for Respiratory Monitoring

A relative humidity (RH) sensor based on pentaerythritol tetraacrylate polymer and graphene oxide (PETA/GO) composite film with an optical microcavity is presented. The PETA/GO composite film serves as both an internal reflective surface and a moisture-sensitive film for the optical microcavity, which effectively enhances the interaction between light and ambient humidity changes and improves the sensitivity and response speed of the sensor. The composite film-enabled sensor can be used for high-performance human respiratory monitoring. Experimental results show that the sensor has a humidity sensitivity of −288.2 pm/%RH over an RH range of 14.5%–59.4%, with the response time and recovery time of 1.84 and 1.85 s, respectively. The sensor has the advantages of a compact structure, high sensitivity, good repeatability and stability, and fast response time. Therefore, it has potential applications in the medical, biological, and industrial fields related to RH measurement and monitoring.