THE FINITE-ELEMENT METHOD FOR MICROSENSORS

The flexibility and usefulness of the finite-element method for microsensor design is demonstrated by this initial study. Effects of design changes can be studied computationally, rather thanby trial and error fabrication in silicon, because of the relative ease with which changes can be made in the model's geometry, material properties, boundary conditions, and forcing functions. For the region chosen, the finite-element calculation gives as much as a 40% difference in temperature differences between points in the model, as compared to a simple discrete model based on simple one- and two-dimensional approximations. The thermal resistance of the modeled membrane region is calculated to be 1020 K/W, without the micromachined holes, and 1290 K/W, with the holes, corresponding to a 21% decrease in power consumption for the same sensing element temperature.