Study on the characteristics of microfluidic oscillator based on a new type of normally closed valve structure

This article introduced a new type of normally closed micro-valve (NCV) equipped with curved channels and trapezia-shaped valve seat, which could solve the issues of large area of dead zone, high threshold pressure and slow response speed of NCV in the current microfluidic oscillators. The new type of NCV has a three-layered structure with a top controlling layer, medium membrane layer and the bottom feedback layer. The membrane channel in the feedback layer is specifically deigned as curved to decrease the dead zone area. The valve seat is designed as a trapezoid to reduce the adhesion between the membrane and the valve seat and the threshold pressure of the NCV , and to improve the response speed of the system .The results of simulation study on COMSOL shows that this micro-valve structure reduces the NCV threshold pressure by 45% and the oscillation period of the micro-oscillator by 36%. This article conducted further simulation studies on the factors that influence the oscillation period of micro-oscillator. When enlarging inlet flow rate of micro-oscillator, lowering NCV threshold pressure and decreasing valve seat angle, the oscillation period would be reduced. Otherwise, the oscillation period will be increased.