Design and FEM simulation study of a microflow sensor based on piezoresistive PDMS composite for microfluidic systems

An electrical response of a microflow sensor would open a wide horizon of uses and should intensify the integration of MEMS (Micro-Electro-Mechanical-System) microfluidic-based LOC (Lab-On-Chip). This paper presents an original microflow sensor which will be able to measure a low fluid flow rate. The sensor is designed and optimized using a multiphysics modelling and FEM (Finite Element Method) simulations implemented on Comsol Multiphysics software. The sensing element made of CPDMS (Conductive PolyDiMethylSiloxane) consists in microbridge suspended into PDMS microchannel. The microbridge acts as a transducer. It converts the mechanical bending due to a fluid flow to an electrical signal using the piezoresistive property of the CPDMS. The numerical simulation results show that under specific geometrical parameters, the sensor has a sensitivity of 0.12 % ml⁻¹ min for low flow rates. Furthermore, the simulation results also show that the laminar aspect of the flow is maintained and to avoid the strangling effect, a good equilibrium must be achieved between the microchannel height and the desired range of the microbridge dimensions. This work opens a horizon for microfluidic devices to measure a low flow rate using a piezoresistive effect giving access to an electrical response.