Researchers at the University of South Florida have developed a low power single-use valve for microfluidic applications.
Advances in microfluidics technology are revolutionizing molecular biology procedures for enzymatic analysis, DNA analysis, proteomics and other biochemical system analyses. Common fluids used in microfluidic devices include whole blood samples, bacterial cell suspensions, protein or antibody solutions and various buffers. Only small volumes of these fluids, usually several nanoliters are required, which suggests that the amount of reagents and analytes used is also quite small. Therefore, valves form an integral component for automated and controlled delivery of such fluids. In addition, applications involving remote or unattended sensing have lower power and short operational time constant requirements to achieve longer operational life and fast actuation.
To address these requirements, our researchers have developed a thermally induced single-use valve chip. The valve consists of a metallic thin ohmic resistor patterned on a thin silicon nitride membrane which constitutes the flow barrier. Heating of the micro-patterned resistor via an electric pulse causes thermal stresses in the resistive membrane thus causing the valve to open.
Well characterized processing steps are employed to achieve high yield. Different sized membranes with various silicon nitride thicknesses are developed and tested, which offer them high versatility. The fabricated valves are operated at different voltage requirements, which facilitate the interfacing with electronics that operate other subsystems.
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