Fabrication, packaging, and testing of a wafer-bonded microvalve

The authors report the complete fabrication and packaging process which yields functional pressure-balanced microvalves and report the results on the fluidic behavior of the valve using pneumatic actuation. The process to implement the valve uses three silicon wafer bonding steps to form the structure. The valve is packaged by anodically bonding a machined glass part having the appropriately sized inlet and outlet ports to the top surface of the microvalve. A chrome/platinum layer on the glass side prevents the valve plunger from bonding to the glass so that the valve can be successfully actuated. Flow rates of up to 120 ml/min were measured when the differential pressure across the valve was 35 psi and the pneumatic actuation pressure was 5 psi absolute. The on-off ratio has been estimated to be over 300. The pressure-balancing concept has been shown to be successful.<>