AVS 50th International Symposium
    Homeland Security Topical Conference Wednesday Sessions
       Session HS+MM-WeA

Paper HS+MM-WeA3
Fabrication, Packaging and Testing of Micronozzles for Gas Sensing Applications

Wednesday, November 5, 2003, 2:40 pm, Room 309

Session: Detection of Explosives and Other Chemicals for Homeland Security
Presenter: S. Li, University of Maryland, College Park
Authors: S. Li, University of Maryland, College Park
C.B. Freidhoff, Northrop Grumman Electronic Systems Inc.
R.M. Young, Northrop Grumman Electronic Systems Inc.
R. Ghodssi, University of Maryland, College Park
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There has been recent, rapid development of MEMS-based gaseous microfluidic devices (GMDs) working under standard atmospheric conditions. One of the applications considered for the GMD is for a frontend of a miniature chemical sensor to improve its sensitivity. We report a fabrication technology for developing linear converging-diverging micronozzles using low temperature wafer-level adhesive bonding with SU-8. The process is quick, repeatable and relatively insensitive to presence of particles on the wafers to be bonded. A selection of wafer bonding tests with SU-8 as the intermediate bonding material has been performed to investigate the influence of different parameters on the bonding of structured wafers. A crack-opening method is used to evaluate the surface energy of bonded wafers to be in the range of 0.42-0.56 J/m@super 2@. Based on the results of wafer bonding test with SU-8, sealed micronozzles with throat widths as small as 3.6 µm are fabricated successfully. For the purpose of comparison, micronozzles of same geometries and dimensions are also fabricated using deep reactive ion etching (DRIE) and silicon-glass anodic bonding techniques. The micronozzles are packaged to interface with a gas flow test setup using capillary needles, O-rings and flexible tubing. Gas flow rates and pressure distributions in the micronozzles are measured and compared with those predicted from the one-dimensional isentropic flow model, which demonstrate that these developed techniques may extend the flexibility of fabricating and packaging microfluidic devices for gas sensing applications. The detailed fabrication process and testing results will be presented.