Agarose Coated Silica Microfiber and Plastic Optical Fiber for Relative Humidity Detection

The effect of agarose gel coating on tapered fiber ability to detect relative humidity changes was studied here. Agarose gel is a hydrophilic material commonly used for relative humidity sensing. Tapered fiber makes a good choice for sensing structure due to evanescent mode interaction with the external surroundings. Two different types of tapered fiber were studied, plastic and silica, each type was used to construct a separate sensing structure. In the relative humidity range of 50-80%RH, agarose coated silica tapered fiber showed a sensitivity of 0.1054dB/%RH compared to the 0.0106 dB/RH% sensitivity of the uncoated silica fiber. On the other hand, tapered plastic fiber coated with agarose showed a sensitivity of 0.0228mV/%RH compared to the uncoated plastic fiber sensitivity of 0.0028mV/RH%. This shows agarose’s potential as a coating for fiber optics relative humidity sensors.