Programmable thermally actuated wax valve for low-cost nonwoven-based microfluidic systems

Nonwoven-based microfluidics is an emerging field in low-cost microfluidics as another alternative to paper-based microfluidics. Comparing with the conventional paper material that has been widely used in low-cost microfluidics, the cost of nonwoven fabric material is the same range, but with the advantages of higher mechanical strength and a wider choice of chemical/physical properties. In this study, we proposed a novel method for defining a programmable and single-use wax valve on nonwoven-based microfluidic devices. The nonwoven-based microfluidic devices were fabricated using wax-printing and thermal reflow approach to define the basic microchannels for fluid penetration. Then, another layer of wax material contain valve structures were deposited on the surface of the microchannels, each wax valve structure has a corresponding heater resistor that can trigger the wax penetration to block (close) the microchannel. With the controlled thermal actuator operation, the fluid penetration inside the porous media of nonwoven fabric microchannel can be programmed with the control of wax valves. A chemical method for reopening the microchannels was also introduced in this study. The proposed programmable wax valve on nonwoven-based microfluidics is easily accessible with low-cost for point-of-care applications in biological and medical fields.