PDMS and tubing-based peristaltic micropumps with direct actuation

This work presents the design and characterization of novel PDMS and tubing-based micropumps based on ‘direct actuation.’ A simple PDMS microchip consisting of a microchannel formed around a circular hole in the center of the microchip was pumped peristaltically. The center hole housed a miniature-motor driven, roller-type actuator, analogous to that used in bench-top peristaltic pumps. The roller-type actuator compressed the channel walls together as it rotated, thereby invoking peristalsis. A miniaturized tubing-based micropump was designed to utilize the same actuator by employing a polycarbonate housing fabricated to hold commercial peristaltic pump tubing.Channel/tubing dimensions, actuation frequency (RPM), percent compression of the PDMS microchip, and roller diameter can be varied to provide a large range of flow rates. Additionally, when stopped, the pumps also provide normally closed valve functionality. A linear flow rate range spanning 0.5–27 μL/min was obtained for the PDMS micropump by simply varying RPM and channel cross-section while one size of commercial tubing provided a range from 0.65 to 41 μL/min. The PDMS micropump valved up to 2 psi, while the tubing-based pump exhibited no leakage up to 50 psi. The two micropumps have similar dimensions with the fluid/actuator portions being ∼2 cm × 2 cm × 1 cm and the mini-motor/gearbox having dimensions of 2.1 cm × 1.0 cm × 1.2 cm with a 0.25-cm diameter, 0.8-cm long shaft.The micropumps performed comparably to a much larger commercial peristaltic pump, while consuming much less space and power. When pump driver size is included, the complete package is miniaturized enough to be portable. The tubing-based pump provides an inexpensive, modular micropump while the PDMS microchannel pump design facilitates pump integration into a microfluidic substrate.