Characterization of Constant Flow-Driven Microfluidic Oscillator

Abstract

Development of microfluidic circuits that are analogous to electronic circuits is useful because of their potential to drastically reduce dynamic off-chip controllers. In microfluidic circuits, a microfluidic oscillator that converts constant input to pulsatile output is the key component. Here, we apply a constant inflow to our previous constant pressure-driven oscillator and demonstrate its distinct behavior. The outflow of the oscillator has a pulse-duration period ( $T_{\textrm {D}}$ ) and a pulse-rest period ( $T_{\textrm {R}}$ ) at a low inflow rate of 20– $120~\mu \text{L}$ /min. In this range of inflow rates, the pulse number of $T_{\textrm {D}}$ increased, and $T_{\textrm {R}}$ decreased. In each $T_{\textrm {D}}$ , the maximum value of each pulse sequentially decreased. On the other hand, at a high inflow rate of 140– $260~\mu \text{L}$ /min, the oscillator produced a continuous sawtooth pulsatile flow without $T_{\textrm {R}}$ . Our theoretical model reveals that average increase and decrease rates of the inlet pressure are critical parameters for determining the output pulse behaviors. Our study is useful and provides a foundation for developing microfluidic circuits using the electrofluidic analogy. [2019-0193]