Micromachined diffuser/nozzle elements for valve-less pumps

We present an investigation of the flow directing properties of several micromachined diffuser elements with different lengths and opening angles for valve-less micropumps. The lengths of the diffusers are from 1.45 to 3.95 mm and the half-elliptic cross-sections about 30/spl times/100 /spl mu/m. Analytical results are compared to experimental results on individual diffuser chips and diffusers in a pump chip. The diffuser elements were fabricated in silicon and glass using isotropic and anisotropic etching and anodic bonding.