Fiber optic Fabry–Perot interferometer based on HA/PVA composite film for humidity sensing

A fiber optic humidity sensor based on Fabry-Perot (F-P) interferometer with the composite film of hyaluronic acid (HA) and polyvinyl alcohol (PVA) is proposed. The humidity characteristics of the sensors with different mixture ratios of HA/PVA composite are investigated for the first time. The experimental results show that the addition of HA to pure PVA contributes to the improvement of the humidity sensitive properties of the material. Furthermore, the sensor with the ratio of 1:2 HA/PVA composite film has the best performance for relative humidity (RH) sensing, whose humidity sensitivity is −233 pm/%RH. And the stability and response time of the sensor were tested. The sensor has the advantages of high sensitivity, low temperature cross sensitivity, fast response time and good stability.