Optimal design of fluidic diode for valveless piezoelectric pump based on entropy production theory

In order to improve the outflow of valveless piezoelectric pump with fluidic diodes, the unidirectional cut-off performance of the fluidic diode needs to be improved. For this reason, this study used entropy production theory to calculate the flow field of two fluidic diodes (biconical tube and hyperbolic tube). The results of the calculations showed that the greatest entropy production occurs at the throat of the tube. On the basis of the results of the calculations, the vitosinski curved tube has been proposed after the improvement of the structure of the hyperbolic tube, and the flow field calculations were carried out. The results showed that the entropy production value of the tube between forward flow and reverse flow is higher than that of the biconical tube and the hyperbolic tube, which shows a good unidirectional cut-off performance. The prototype of the valveless piezoelectric pumps with biconical tubes, hyperbolic tubes and vitosinski curved tubes were manufactured and the output performance experiments were carried out. The experiment results showed that the maximum output flow rate of the valveless piezoelectric pump with vitosinski curved tubes is significantly better than that of valveless piezoelectric pump with biconical tubes or hyperbolic tubes. When the driving voltage is 100 V and the driving frequency is 42 Hz, the maximum flow rate of the valveless piezoelectric pump with vitosinski curved tubes is 137 mL/min, which verifies the effectiveness of the optimal design of the fluidic diode structure based on the entropy production theory. Thus, the results of the study can be used as a reference for the structural design and optimization of various types of valveless micropumps and microfluidic transfer devices.