Study of self-actuated time-controlled tower microvalves

Abstract Time-controlled microvalves are vital components of microfluidic systems, primarily used to regulate the sequential or precise introduction of reagents. However, existing time-controlled microvalves face certain limitations. For instance, those driven by magneto-thermal mechanisms require additional control elements, and fabricating some 3D time-controlled microvalves can be complex. To address these challenges, a self-driven time-controlled tower microvalve was designed and fabricated. This study investigates how structural parameters of the time-delay unit affect bubble generation and the time-delay effect. Experimental testing confirmed that the delay time of the time-controlled microvalve increases and then decreases with variations in the trapezoidal aspect ratio ( a ) and the upper and lower width ratios ( b ). Additionally, the delay time of a single unit extends as the width of the delay unit increases. The optimal parameters for the time-controlled microvalve were determined as follows: W 1 =1, 000 μm, W 2 =500 μm, and H =800 μm, achieving an overall delay time of 16.7±0.8 s.