Events Calendar

AME Department

Speaker: Yen Lin Han, Assistant Professor in Residence, University of Connecticut

Talk Title: Applications of Molecular Gas Dynamics to MEMS Devices

Abstract: Assistant Professor-in-Residence
Department of Mechanical Engineering
University of Connecticut

ABSTRACT:

Continuing advances in MEMS fabrication capabilities have facilitated significant progress in miniature devices. This can be achieved by utilizing molecular gas dynamics phenomena such as mass separation, thermal edge, and thermal creep flows. Besides the better-known Knudsen Compressor, other examples, including a continuous trace gas preconcentrator, and a thermal bimorph micropump will be discussed.

A trace gas preconcentrator is commonly included in gas detection systems to increase the ultra low, yet dangerous trace gas concentration, to the level at which a detection unit can accurately determine the presence of the trace gas. The widely-used adsorption/desorption preconcentrators interrupt gas flows for significant periods, in order to accumulate sufficient number of trace gas molecules, before they are released to the detection unit. The continuous Trace Gas Preconcentrator provides a unique approach, utilizing molecular gas dynamics theory to provide mass separation. In the continuous trace gas preconcentrator, the gas flow is not stopped and the time required to reach the proper concentration is significantly shorter than the adsorption/desorption method.

Using the rarefied gas dynamic phenomenon of thermal edge flow, a micropump with a built-in thermal bimorph microvalve is studied. This micropump contains an isolated heating element, made of thermal bimorph materials, that is serve as a heating element to initiate the flows, and to thermally activated bimorph valve. DSMC (Direct Simulation Monte Carlo) simulation results indicate the flow characteristics, including the maximum pressure ratio and mas flow rate vary with the bimorph valve lengths and the flow channel sizes. Finite element analysis of selected thermal bimorph structures has also demonstrated proper deflections of the thermal bimorph valve. Combining the flow and structural studies, the characteristics of the thermal bimorph micropump can be realized for future fabrication and experimental investigations.


Host: Professor Phil Muntz

More Info: http://ae-www.usc.edu/seminars/9-21-11-han.shtml

Location: Seaver Science Library (SSL) - Room 150

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ae-www.usc.edu/seminars/9-21-11-han.shtml