Electrowetting on Dielectric (EWOD)-Based Thermo-Responsive Microvalve for Interfacing Droplet Flow With Continuous Flow

This paper reports on a hybrid electrowetting-thermal passive microvalve for a flow control mechanism to interface droplet flow with continuous flow. When heated, a thermo-responsive polymer, in the form of a dilute aqueous droplet, forms a gel, and upon cooling, it liquefies. The gel blocks and its subsequent liquefaction unblocks the pressurized flow. Electrowetting on dielectric (EWOD) actuation was used to control and position a polymer droplet at a desired valving location. The valve interfaced a pressurized flow to a planar EWOD-based droplet flow in a single device. It was fabricated using a standard planar microfluidic glass platform. It has a three-layer architecture bonded by oxygen plasma bonding. The valve demonstrated zero leakage and no cross-mixing across the interface.