Different to the traditionally defined valved piezoelectric (PZT) pump and valveless PZT pump, two groups of PZT pumps with built-in compliant structures—with distances between the free ends of 0.2 mm (Group A) and 0 mm (Group B)—were designed, fabricated, and experimentally tested. This type of pump mainly contains a chamber 12 mm in diameter and 1.1 mm in height, a PZT vibrator, and two pairs of compliant structures arranged on the flowing channel. The flow-resistance differences between these two groups of PZT pumps were theoretically and experimentally verified. The relationships between the amplitude, applied voltage and frequency of the PZT vibrators were obtained experimentally, with results illustrating that the amplitude linearly and positively correlates with the voltage, while nonlinearly and negatively correlating to the frequency. The flow rate performance of these two groups was experimentally tested from 110–160 Vpp and 10–130 Hz. Results showed that the flow rate positively correlates to the voltage, and the optimum flow rate frequency centers around 90 Hz for Group A and 80 Hz for Group B, respectively. The flow rate performances of Group B were further measured from 60–100 Hz and 170–210 Vpp, and obtained optimal flow rates of 3.6 mL/min at 210 Vpp and 80 Hz when ignoring the siphon-caused backward flow rate. As the compliant structures are not prominently limited by the channel’s size, and the pump can be minimized by Micro-electromechanical Systems (MEMS) processing methods, it is a suitable candidate for microfluidic applications like closed-loop cooling systems and drug delivery systems.

In this paper, a streamlined flow tube valveless piezoelectric pump (SLFT PZT pump) is proposed to modify the single flow trend and improve the fluid flow stability. Firstly, the structural and working principle of the streamlined flow tube, which accounts for changing the flow trend and improving the flow stability, were analyzed. The flow resistance and flow rate equations were established. Secondly, the pressure and velocity fields of the tube were simulated. These simulated results were consistent with the theoretical results. Thirdly, the flow resistance of the flow tube was tested with pressure differences of 1000 Pa, 1200 Pa, 1400 Pa and 1600 Pa respectively. The trend of the result curves was consistent with the simulated results. The amplitude-frequency relationship and the flow-rate-frequency relationship were also tested, both result curves highly corelate. The maximum amplitude was 0.228 mm (10 Hz, 120 V), and the maximum flow rate was 17.01 mL/min (10 Hz, 100 V). Finally, the theoretical flow rate of the SLFT PZT pump was calculated at 100 V and 120 V. These results roughly fitted with the experimental results. The streamlined flow tube could change the internal flow trend that remarkably improved the flow stability. Therefore, it promoted the application of the valveless PZT pump in living cells, biomedical and polymer delivery.

In order to promote the application of raindrop-shaped flow tube valveless piezoelectric pump (RSFTV PZT pump), basing on the existing research, the RSFTV PZT pump was simulated by computer. Firstly, the existence of the flow resistance of the flow tube was proved by simulation of FLUENT. Then, the dynamic mesh analysis of the pump was carried out to simulate the pumping flow rate at different driving frequencies. Lastly, the simulated results were compared with the experimental results, which shows that the flow rate tendency and value obtained by simulation are basically consistent with that by experiment. The simulation of the RSFTV PZT pump would be helpful to further accelerate related researches and promote the application of RSFTV PZT pump in MEMS and other fields.

No abstract

No abstract