Highly Sensitive Humidity Sensor With Low-Temperature Cross-Sensitivity Based on a Polyvinyl Alcohol Coating Tapered Fiber

A highly sensitive humidity sensor with low-temperature sensitivity is proposed and demonstrated using a polyvinyl alcohol (PVA) coating tapered fiber. The taper fiber is highly sensitive to the environmental medium due to its microscale diameter. Thus, a humidity sensor can be prepared by plating a PVA moisture-sensitive film in a tapered region. The experimental results show that the sensor has a high humidity sensitivity of 0.1194 nm/%RH but with a relatively low-temperature sensitivity of 0.029 nm/°C. Thus, the sensor can eliminate temperature interference and achieve accurate measurement of environmental humidity. At the same time, the sensor has excellent reversibility, stability, and advantages common to optical fiber sensors, such as small size, antielectromagnetic interference, and remote measurement.