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Development of a piezoelectric pump with unfixed valve

Piezoelectric pump, driven by piezoelectric actuator, is one of the most promising micropumps in compact system. However, the application of piezoelectric pump is limited by the check valve, which is not efficient enough and needs careful fixation. This work presents a novel design with unfixed check valve, which greatly simplifies the assembly of valve-based piezoelectric pump and improves the output performance. The valve is unfixed with a small gap to obtain variable stiffness at different working stages, making it open more quickly. The piezoelectric pumps with three different valve gaps were designed, fabricated, and tested. The pump with the unfixed valve shows a 25.6% flow rate improvement compared with the fixed check valve without reducing the output pressure. To reveal the mechanism of the flow rate improvement, we investigated the flow resistance and the volumetric efficiency of the piezoelectric pump. The results show that the unfixed valve increases the volumetric efficiency of the piezoelectric pump, which improves the flow rate. The prototype pump achieved the maximum output performance of 162 ml min−1 and 33 kPa. The power consumption was less than 100 mW, reaching a pump efficiency of 21.7%.