MSM 99
MSM 99
Technical Proceedings of the 1999 International Conference on Modeling and Simulation of Microsystems

Applications: Micropumps, Heaters, Coolers Chapter 18

Finite Element Modeling of a Microhotplate for Microfluidic Applications

Authors: R.P. Manginell, D.A. Rosato, D.A. Benson and G.C. Frye-Mason

Affilation: Sandia National Laboratory, United States

Pages: 663 - 666

Keywords: microhotplate, preconcentrator, IR microscope, chemical analysis, TAS

Abstract:
A hand-held chemical laboratory (mChemLab) is being developed that utilizes a silicon- nitride-supported microhotplate in the front-end, gas sampling and preconcentration stage. Device constraints include low-power (<200mW at 5V), rapid heating (<20msec), and a relatively uniform temperature distribution throughout the heated area (~3mm2). To optimize for these criteria, the electro-thermal behavior of the microhotplate was modeled using Thermal Analysis System (TAS). Predicted steady-state and transient behavior agree well with infrared (IR) microscope data and measured transient response for a low-stress silicon nitride thermal conductivity of kn = 6.4?10-2 W?(cm??C)-1 and a convection coefficient of hcv = 3.5?10-3 W?(cm2??C)-1. The magnitude of hcv is framed in the context of vacuum measurements and empirical data. Details and limitations of the IR measurement are discussed. Finally, the efficacy of methods for reducing thermal gradients in the microhotplateís active area is presented.

Finite Element Modeling of a Microhotplate for Microfluidic Applications

ISBN: 0-9666135-4-6
Pages: 697