Design and Modeling of a Mems-Based Valveless Pump Driven by an Electromagnetic Force

A novel valveless micro impedance pump is proposed and analyzed in this study. The pump is constructed of a upper glass plate, two glass tubes, a PDMS (polydimethylsilxane) diaphragm with an electromagnetic actuating mechanism and a glass substrate. The actuating mechanism comprises an electroplated permanent magnet mounted on a flexible PDMS diaphragm and electroplated Cu coils located on a glass substrate. The upper glass plate, PDMS diaphragm and the glass substrate were aligned and assembled to form a micro channel with a compressible section surrounded by a rigid section, creating an acoustic mismatch in the channel. The electromagnetic force between the magnet and the Cu coils causes the diaphragm to deflect and then creates the accumulative effects of wave propagation and reflection at the junction of the compressible and rigid sections. The resulting pressure gradient in the fluid drives the flow from the inlet to the outlet of the micropump. The constituent parts of the electromagnetic actuator, namely the diaphragm, the microcoils, and the magnet are modeled and analyzed in order to optimize the actuator design. The design models are verified both theoretically and numerically and the relationships between the magnetic force, diaphragm displacement, and diaphragm strength are established. The magnitude of the magnetic force acting on the flexible diaphragm are calculated using Ansoft/Maxwell3D FEA software and the resulting diaphragm deflection simulated by ANSYS FEA software are found to agree with the theoretical predictions. Different diaphragm shapes are investigated and their relative strength and flexibility are compared. It is found that a circular PDMS diaphragm represents the most appropriate choice for the actuating mechanism in the micropump. The desired diaphragm deflection of 15 m  is obtained using a compression force of 16 N  , generated by a coil input current of 0.9A. The diaphragm deflection can be regulated by varying the current passed through the microcoil and hence the flow rate can be controlled. The valveless micro impedance pump proposed in this study is easily fabricated and can be readily integrated with existing biomedical chips. The results of the present study provide a valuable contribution to the ongoing development of Lab-on-aChip systems.