Pressure drop measurement in microfluidics channel by the Fabry-Perot diaphragm-based flow sensor

The measurement and control of pressure is an important parameter in optimizing flow rates in microfluidic channels. In this paper, we present simulation and experimental results of measuring pressure drop in a rectangular microfluidics channel by two Fabry-Perot (FP) flow sensors. Sensors include two circular diaphragms made of PDMS (Polydimethylsiloxane) with 50 μm thickness and 200 μm radius, located 2 cm apart which the surface of them create FP cavity with end surface of the fiber optic. Fabry-Pérot interferometers above two diaphragms measure the different deflections of the diaphragms caused by pressure changes in the micro channel. The fluid-structure interaction method is used to solve three-dimensional (3D) Navier-Stokes and continuity equations for selecting appropriate diaphragm thickness and validating experimental results. The experimental and theoretical results are in good agreement and according to the experimental results, these sensors have sensitivities of 30 (nm. (μL/min)^-1) and 10 (nm. (μL/min)^-1) without hysteresis and the resolution of the sensor is 33 nL/min.