Highly sensitive sensor for detecting refractive index change of liquids using single microfiber

We demonstrate a novel sensor capable of detecting small refractive index change of liquids using single microfiber. The sensor is based on the principle of differential frequency technique and is used to measure the variation of refractive index with concentration of glucose in distilled water. Our experimental results show that the device exhibits the capability of measuring an index variation of 10^-5. The sensor reported here is featured with high sensitivity, easy fabrication, compact size, and easy integration with electronic devices, which make it suitable for bio/chemical analyses, pharmaceutical and process control.