A novel approach to the sensing of liquid density using a plastic optical fibre cantileverbeam

Abstract

This article reports for the first time the use of a plastic optical fibre (POF)cantilever beam to measure the density of a liquid. The sensor is based on theArchimedes buoyancy principle. The sensor consists of a POF bonded on the surface ofa metal beam in the form of a cantilever configuration, and at the free end ofthe beam a displacer is attached. Due to the apparent loss of the true weight ofthe displacer there is a deflection in the cantilever beam, which causes macrobending in the POF. The loss of intensity due to macro bending of the POF is ameasure of the density of the liquid under test. The variation of weight loss withthe density of different liquids showed that the weight loss is proportional todensity. This sensor is capable of detecting the weight loss with respect to theirdensities even for liquids having close values of density like distilled water, tapwater, and milk of various brands. The resolution of the sensor is observed to be1.1 mg cm−3.