Elastomeric microfluidic valve with low, constant opening threshold pressure†
This paper presents the realization of low, constant opening threshold pressures of an elastomeric valve by appropriate design and surface coating of the valve in a self-oscillating microfluidic device. The valve has a V-shaped valve seat, which separates the valve's inlet and outlet, and a membrane-pressurization bottom chamber. We utilized the V-shaped valve seat design to manipulate the mechanical deformation of the valve's membrane due to differences in applied pressure. Furthermore, we used a simple biomolecular surface coating to remove the adhesion force between the valve seat and the membrane. As such, the opening threshold pressure of our valve reduced from 13.1 to 2.4 kPa (i.e., an 81.7% reduction) at a flow rate 8 μL min−1. More importantly, we achieved a nearly constant opening threshold pressure regardless of the change in the input flow rate (i.e., a 0.07 kPa min μL−1 pressure change rate), thereby achieving a linear oscillating frequency response of the microfluidic device. Such a valve having low, constant opening threshold pressures is envisioned to be broadly useful for sophisticated fluidic routing applications, where numerous integrated valves with low actuation pressures are necessary.