Comparison of wall attachment and jet deflection microfluidic amplifiers

Two types of microfluidic amplifiers (unvented wall attachment and jet deflection) were examined using dry nitrogen as the test fluid. The devices were fabricated in silicon using standard micromachining methods and anodic sealing with a glass cap. Flow control and flow gain were demonstrated with supply pressures ranging up to 630 kPa. An asymmetric output flow was observed from the two output ports at sufficiently high supply pressures in both devices, suggesting possible shock wave formation. The jet deflection microfluidic amplifier presents a more symmetric behavior and provides higher flow variation than the wall attachment device. The ratio of the maximum and minimum output flows, as measured for the jet deflection device for various control and supply pressures, reveals a performance degradation at the onset of choked supply flow.