Back scattering method based-plastic optical fiber coupler viscosity sensors

Abstract

Abstract Viscosity determination is necessary in variety of applications such as evaluation of environmental pollution, chemical analysis, and as a material quality assessment. Optical fiber-based viscosity sensors are interested since it has various advantages compared to conventional viscosity sensors such as free from electromagnetic interference, compact and could be applied in hazard environment. This study aims to study the performance of back scattering method based viscosity sensor using optical coupler. The sensor design consists of 2×2 plastic optical fiber coupler connected with un-cladded POF as sensor head (sensor A). Characterization was done by connecting 660 nm LED as light source to the one of the coupler branch and an Ocean Optic USB4000 spectrometer to the other branch as light detector. Meanwhile, the sensor head was immersed in glycerin solution. The glycerin solution concentration was varied for various concentration which are 40%, 50%, 60%, 70%, and 80%. Sensor head without the use of optical coupler was fabricated and characterized as comparison (sensor B). The results show that sensor A has a better performance compared to sensor B in terms of linear range. The sensitivity of sensor A is -0.88584 dB/mPa.s at working range of 8.765-57.265 mPa.s with a correlation coefficient of 95.72%.