Abstract:
Advances in micromachining have led to the development of microelectromechanical systems
(MEMS) devices with suspended structures used in a variety of sensors. Of note for this work are sensor types
where two elements exist on the suspended membrane, including examples like air flow and differential pressure
detectors, gas detection, and differential scanning calorimetry sensors. Intuitively one would argue that some
thermal loss exists between the two elements. However, surprisingly little is documented about this electrothermal
interaction. The work presented here addresses this shortcoming by defining a new parameter set, a matrix
of thermal coupling coefficients. They are used within our novel two-port electrothermal model based on the heat
flow equation adapted as a linear system of equations. However, the model is only effective with knowledge of
these coefficients.We introduce an approach to extract the coefficients using finite-element method (FEM)-based
multiphysics simulation tools and revisit and extend our previous method of non-ideal power coupling, this time
to extract the coefficient matrix from measured data. Both specialist simulation tools and device manufacturing
are very expensive. However, they are the only choices in the absence of an analytic model. A major contribution
of this work is the derivation of a model to predict the coefficients by analytic means from the device dimensions
and material properties. The research contribution and paper culminate in a comparison of analytic, simulated,
and experimentally extracted values of two different devices to verify and demonstrate the effectiveness of the
proposed models. The values compare well and show that the best results achieved are approximately 90% and
70% thermal linkage respectively for vacuum and atmospheric pressure conditions.
