Electromagnetically-actuated reciprocating pump for high-flow-rate microfluidic applications

Abstract

This study presents an electromagnetically-actuated reciprocating pump for high-flow-rate microfluidic applications. The pump comprises four major components, namely a lower glass plate containing a copper microcoil, a middle PMMA plate incorporating a PDMS diaphragm with a surface-mounted magnet, upper PMMA channel plates, and a ball-type check valve located at the channel inlet. When an AC current is passed through the microcoil, an alternating electromagnetic force is established between the coil and the magnet. The resulting bi-directional deflection of the PDMS diaphragm causes the check-valve to open and close; thereby creating a pumping effect. The experimental results show that a coil input current of 0.4 A generates an electromagnetic force of 47 mN and a diaphragm deflection of 108 μm. Given an actuating voltage of 3 V and a driving frequency of 15 Hz, the flow rate is found to be 13.2 mL/min under zero head pressure conditions.

Figure 1.

Operating principle of reciprocating pump.

Figure 2.

Major steps in pump fabrication process: (a) microcoil patterning and deposition, (b) PDMS diaphragm attachment to PMMA middle plate, and (c) pump assembly.

Figure 3.

Photographs of: (a) microcoil surface, (b) microcoil on lower glass plate, and (c) completed pump.

Figure 4.

Measurement instrument set-ups of (a) flux density, (b) electromagnetic force and (c) membrane displacement.

Figure 4.

Measurement instrument set-ups of (a) flux density, (b) electromagnetic force and (c) membrane displacement.

Figure 5.

Variation of magnetic flux density produced by single-layer microcoil stack with vertical distance from microcoil surface given input currents of 0∼0.5 A.

Figure 6.

Variation of magnetic flux density produced at center of single-, double- and four-layer microcoil stacks given input currents of 0∼0.5 A.

Figure 7.

Variation of electromagnetic force with input current (0∼0.4 A) at various vertical distances from microcoil surface (Note that results correspond to single-layer microcoil stack).

Figure 8.

Variation of electromagnetic force with input current (0∼0.4 A) at vertical distance of 1.5 mm from surface of single-, double- and four-layer microcoil stacks.

Figure 9.

Variation of maximum diaphragm deflection with excitation frequency (15∼30 Hz) given actuating voltages ranging from 1.0∼3.0 V. (Note that results correspond to four-layer microcoil stack.)

Figure 10.

Variation of head pressure given: (a) applied voltage ranging from 1∼3.5 V and excitation frequency of 15 Hz, and (b) excitation frequency ranging from 15∼30 Hz and applied voltage of 3.0 V.

Figure 11.

Variation of flow rate with actuation frequency (15∼30 Hz) given: (a) applied voltage ranging from 1.0∼3.0 V, and (b) head pressure ranging from 0∼68 Pa.