A thin PDMS nozzle/diffuser micropump for biomedical applications

Micropumps are finding more applications in biomedical fields. One application that holds great potential for micropumps is the treatment of glaucoma. Shunts are currently used in the treatment glaucoma. They lower intraocular pressure by passively increasing the outflow of aqueous humour from the anterior chamber in the eye. Nozzle/diffuser micropumps are an attractive alternative to shunts. They would provide both passive outflow and variable active outflow of aqueous humour as necessary. They would be able to overcome increases in flow resistance caused by biofouling and scar tissue growth. This study presents a proof of concept of a 1-mm-thick electromagnetic PDMS nozzle/diffuser micropump for biomedical applications. The pump is composed of a cast PDMS body, a spin coated PDMS membrane, and commercial silicone tubing, all bonded together with PDMS. Micromachining a pump cast enables multiple pumps to be produced quickly and reliably. An in-plane design is used to attach the inlet and outlet tubes. The pump produces a peak flow rate of 135 μL/min and a maximum backpressure of 25 mmH2O at an actuation frequency of 12 Hz and a duty cycle of 25%. The membrane thickness, actuator type, and duty cycle were shown to have a significant impact on the performance of the pump.