All-fiber temperature and humidity sensor based on photopolymer and polydimethylsiloxane with low-crosstalk and high-sensitivity

Abstract

The ability to monitor temperature and humidity simultaneously is critical for biomedical and industrial production. We demonstrate a novel temperature and humidity optical fiber sensor based on a photopolymer and polydimethylsiloxane for dealing with temperature cross-sensitivity problem. The low-frequency signal and the high-frequency signal in the interference spectrum were obtained by filtering. Due to structural and material properties, the low-frequency signal is only temperature dependent, while the high-frequency signal is affected by temperature and humidity. Temperature and humidity signals rely on different interferometric mechanisms for measurement to achieve negligible crosstalk. The sensor exhibits a high temperature sensitivity of 1.88 nm/°C by measuring the shift of an interference dip wavelength in the low-frequency signal. The humidity sensitivity is up to 0.282 nm/%RH due to the excellent water absorption capacity of the photopolymer. High accuracy, good repeatability, and stability enable the sensor to measure ambient temperature and humidity. We believe the sensor has excellent potential in environmental monitoring, biomedicine, and human–machine interface.