A MEMS-based Impedance Pump Based on a Magnetic Diaphragm

In realizing Lab-on-a-Chip systems, micro pumps play an essential role in manipulating small, precise volumes of solution and driving them through the various components of the micro chip. The current study proposes a micro pump comprising four major components, namely a lower glass substrate containing a copper micro coil, a microchannel, an upper glass cover plate, and a PDMS-based magnetic diaphragm. A Co-Ni magnet is electroplated on the PDMS diaphragm with sufficient thickness to produce a magnetic force of the intensity required to achieve the required diaphragm deflection. When a current is passed through the micro coil, an electromagnetic force is established between the coil and the magnet on the diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which results in a net flow. The performance of the micro pump is characterized experimentally. A deflection of 30 μm is obtained by supplying the micro coil with an input current of 0.6A, and results in a flow rate of 1.5 μl/sec when the PDMS membrane is driven by an actuating frequency of 240 Hz.