Modeling and simulation of tapered fiber-optic oil concentration sensor using negative dielectrophoresis

This work presented the model of dieletrophoresis (DEP) and tapered fiber technology. The aim was to improve the sensitivity of oil concentration measurement in the separation of oil-water mixture process. Simulations via COMSOL v4.3b Multiphysics software were implemented to calculate and study the distribution of electric field, which was generated from both sides of tapered fiber with two metal-coated silver electrodes using direct current (DC) electric fields. The emulsified oil particles with radius of 0.09 μm could be repelled from the strong electric field region so as to change the refractive index around the tapered fiber region. Then, the evanescent wave field would induce to change the transmission intensity of the optical fiber. The finite element method (FEM) was used to solve optical wave field coupled convection-diffusion-migration (CDM) equation. The results indicated that the oil concentration measurement sensitivity of the proposed sensor was increased to be 25% higher than that of an identical tapered fiber sensor without negative DEP.