On-chip automation of sequential flow switching with serially connectable fluidic monostable multivibrator

Abstract

We propose a fluidic monostable multivibrator (fMMV) circuit, which is a new flow-switching mechanism in microfluidic chips. Flow control using parallel fMMV circuits does not require an external controller; this is a distinct advantage over various conventional micro-flow control methods. The fMMV circuit mainly consists of an inverter and an RC circuit. Each of the parts uses a microchannel as a resistor, a membrane chamber as a capacitor and a membrane valve as a transistor. The inverter acts as a trigger which opens the membrane valve and the RC circuit delays the closing of the valve, so that flow switching can occur over a time interval. A serial fMMV circuit can switch flows in multiple channels and regulate flowrates with pre-defined durations. By modifying the resistances in fMMV circuits, the flow rates and duration of each phase could be adjusted. For a proof of concept demonstration, we performed experiments using 3 parallel fMMV and 4 parallel fMMV circuit systems and these experiments show the applicability of fMMV circuit to various biochemical processes.