Valveless Micropump with Saw-Tooth Microchannel

Abstract

The micropump is the executive component in a microfluidic chip which impels the sample to flow. Its performance directly affects the precision and reliability of Micro Total Analysis Systems (μTAS), and it also plays a key role in the targeting transport of trace substances. The single and double chamber valveless micropumps with saw-tooth microchannel were designed. The saw-tooth diffuser/nozzle pipe was fabricated on chrome glass substrate using MEMS technology and the pump diaphragm was manufactured by PMMA material. The piezoelectric bimorph with cantilever beam was adopted as driving pump actuator and PDMS material as pump diaphragm. The valveless micropumps for both single and double chambers were formed with different saw-tooth structure parameters. The flow rate increased about 25% when the sidewall of microchannel changed from smooth to saw-tooth, and with the driving voltage increasing, the positive and negative flow difference of saw-tooth diffuser/nozzle pipe increased significantly, so does the micro pump flow rate. The best diffused angle θ was determined by the microchannel length L of saw-tooth diffuser/nozzle pipe, and the micro pump operated with its maximum flow rate only when the length-width ratio A reached the best value. The flow rate of a saw-tooth diffuser/nozzle valveless micropump with parallel double chambers increased approximately 30% than that of a single chamber.

An Efficiency improved diffuser with extended sidewall for application in valveless micropump

“…Asymmetric obstacles have also been implemented by Lee et al [16] to gradually narrow the channel to mimic the diffuser thereby creating the flow-directing effect in micropumps. Xu et al [17] implemented a saw-tooth diffuser/nozzle pair to increase the friction and thus enhancing the pump performance. More recently, Chandrasekaran and Packirisamy [18] reported on a geometrical tuning method for diffuser/ nozzle design and claimed that it could enhance the pump performance by using a concave or convex diffuser shape.…”

“…Clearly, some of these novel diffusers have little practical meaning [16,18] while others might be complicated to be microfabricated [15,17]. The present study focuses on a development based on the theory of re-entrant inlets, hereafter referred to as the extended sidewall (or 'lip') at the large end of a diffuser/nozzle element.…”