Fabrication and flow rate characterization of a DRIE process based valveless piezoelectric micropump

Abstract

Micropumps have become one of the major research topics in the field of microfluidics. Different actuators have been used in active micropumps including piezoelectric ones, which convert electrical energy to mechanical energy. In this study, a piezoelectric disc was designed as an actuator and was integrated into a fabricated piezoelectric micropump. Unlike wet etching methods, which is generally used to etch layers of relatively high thickness in the silicon wafer, dry etching was used in this study. Aluminum was used as a mask material during the fabrications-steps, and the fabrication process was shortened with the use of the masking steps. The etching process of the slot, in which the piezoelectric disc was placed, and etching of the inlet/outlet channels were performed simultaneously. Thus, the processing time was significantly shortened. The fabrication of this silicon-based valveless micropump was accomplished by using the DRIE (Deep Reaction-Ion Etching) technique, which provided controlled etching. Experiments were conducted on the fabricated micropump with the use of the bulk micromachining technology to deliver the desired pumping action. The leakage and the air entrapment between the consecutive micropump structural layers were satisfactorily eliminated. This micropump is capable of delivering a promising flow rate of 52 [µL/min] for deionized water, which corresponds to a 150 [Hz] square wave type and a peak-to-peak voltage of 60 [V] Vp-p . No moving mechanical valves were included so that the risks of clogging, reduced performance, and reduced reliability due to wear and fatigue were minimized. Not only gases and liquids but also fluids containing particles could be used as the working fluid for this micropump. The piezoelectric micropump design was optimized to achieve a high time-averaged flow rate (>50 [µL/min]) with a relatively low excitation voltage (<100 [V] Vp-p ) as opposed to the use of a high excitation voltage.

Biomedical Applications of Microfluidic Devices: A Review

“…This approach has slower etching rates than wet etching. Both techniques have been utilized in fabricating microfluidic devices and biological detection systems [ 173 , 174 , 175 ].…”

Design and simulation of a MEMS-based piezoelectric micropump for bio-medical applications

“…Micropump is a device that has gained a great deal of attention in this field due to its ability to create flow in the range of milliliters to microliters. As of today, numerous applications for micropumps are in the process of investigation, including drug delivery (Gidde et al , 2019; Yang et al , 2022; Şimşek et al , 2022), biological detection (Andersson et al , 2001), clinical analysis in medicine (Mi et al , 2020) and cardiology systems (Díaz González et al , 2007). Reciprocating micropumps have been extensively studied, having flexible membranes propelling the flow and microvalves directing it.…”