Design, fabrication and experimental characterization of whole-thermoplastic microvalves and micropumps having micromilled liquid channels of rectangular and half-elliptical cross-sections

Various designs and fabrication methods have been recently developed for the fabrication of whole-thermoplastic microfluidic actuators. In view of fabrication methods, micromilling has attracted attentions for high-precision micromachining of complex microfluidic structures. This method is also employed for cost-effective rapid prototyping of microdevices. In this study, the impacts of micromilled structures on the performance of gas-actuated microvalves and micropumps were reported. The liquid channels of the actuators were fabricated in rectangular and half-elliptical cross-sections in Poly(methyl methacrylate) PMMA to explore the geometrical effects on valving and pumping functions. Unlike the microvalve with rectangular cross-section, that of half-elliptical cross-section presented a leakage-free operation. Regarding the experimental characterization of micropumps, the maximum flow rates of 350.23 +/- 6.13 and 382.50 +/- 5.38 mu l/min were obtained for the micropumps with rectangular and half-elliptical cross-sections, respectively. Compared to the rectangular cross-section, the half-elliptical one was more efficient in production of maximum flow rates at lower actuation gas pressures. However, fabricating rectangular micropump is more cost-effective in terms of required time and manpower. Thus, the appropriate channel design for micropump fabrication is determined by the final application of the pump, the operating conditions and the fabrication costs. Moreover, the robust performance of the actuators revealed that the presented method enables the production of microfluidic actuators for applications with long-term durability. (C) 2019 Elsevier B.V. All rights reserved.