Virtual Valve for Microfluidics

Lab-on-a-Chip technology now becomes increasingly attractive due to advantages such as reduced sample size, reduced reagent consumption, shortened analysis time, potential for high throughput and automation and reduced costs, leading to the potential for manufacturing of disposable devices. On such microchip system, the ability to handling microfluid is important. Extensive microfluidic handling componets including microflow regulator, microfluidic sensor, microvalve and micropump have been reported. Although these microfluid handling methods are successful, for the polymer based microfluidic device, a simple design, easy fabrication and the ability to integrate into the microsystem lacks report. In this paper, we presented such microvalve by utilizing the hydrophobicity of the PDMS material, a popular biocompatible material widely used in microfluidic system. The valve utilized air trapped on the side wall of microchannel by a special microconcave structure design. Controlled by an external coil heater, the trapped air will be enlarged to reduce channel width and so reduce the fluid flow in the microchannel. The valve can work in on/off mode or on flow regulating mode depending on specific flow control requirement.