Influence of scaling effects on designing for power efficiency of a micropreconcentrator

Abstract

Rapid and reliable assessment of volatile and semivolatile organic compounds in the environment using gas chromatography (GC) is often limited by cost of analysis, and time delays between sampling and analysis. Many environmental monitors incorporating GC systems are too large for portability, and lack sufficient sensitivity and/or selectivity to serve as practical environmental monitors. Frequently, a complete system redesign, due to nonlinear power scaling relative to component size, is required to reduce the mass and volume of power supplies, especially for the micro-systems of present interest. Here, we examined four strategies in reducing power demand by the largest consumer of power in a model micro GC, the preconcentrator. Our simulations included alterations in heater pad placement/size, reduction of thermal mass in the device, vacuum sealing, and incorporation of a gas dwell time during preconcentrator heating. Our numerical results were in general agreement with experimental findings in simpler systems, in terms of the benefits of vacuum sealing. The greatest reductions in power demand were achieved with vacuum sealing (51%) and reductions in thermal mass (15%). Future work will address structural and materials issues involved in reduction of thermal mass, and also optimization of power supplies required to meet the multilevel power demands of these complex microelectromechanical systems.