Pressure distributions and TMAC measurements in near unity aspect ratio, anodically bonded microchannels

We present pressure distributions as well as mass flow measurements of air flows in near unity aspect ratio, anodically bonded microchannels using Deep RIE and anodic bonding. Using the first order slip formulas and experimental data, we also extracted Tangential Momentum Accommodation Coefficient (TMAC) of 0.204 for the case of air flowing through a microchannel of Pyrex glass and silicon at atmospheric conditions. Increased mass flow over the incompressible flow case is due to both compressibility and rarefaction. Deviations from the linear incompressible distributions get larger with the inlet to outlet pressure ratio. The dimensionless streamwise location of the maximum deviations is slightly less than 0.6, which is skewed slightly downstream of the middle of the channel. It is notable that these experimental data are much closer to the simulation results of 0.55 than those of Pong et al.(2002), 0.4 , which have been the most frequently cited experimental data for the pressure distribution in uniform and straight micro channels.