Description
In this research , we report on the heat transfer characteristics of a MEMS chemoresistive chemical sensor using Finite Element Analysis. These tiny sensors rely on accurate temperature control in order to enhance the performance of their sensing material. This temperature control is typically achieved using Joule heating in a microhotplate upon which the sensing material is situated. The purpose of this research was to further understand the heat loss experienced by the MEMS device in the forms of conductive and convective losses. This was accomplished using the simulation software COMSOL Multiphysics 4. The use of this technology allowed for rapid, detailed calculation of the behavior of the device during steady state operation to be conducted in three dimensions. This resulted in numerical data as well as visual representations that allowed for better understanding of the device's heat transfer characteristics. In the end, this study demonstrated that for this particular sensor, which features a hotplate suspended over a membrane by way of four supporting arms, the heat lost to the surrounding air was far greater than that lost via conduction to the supporting arms. Further investigation into optimizing certain geometric traits of the device were also undertaken. This demonstrated the benefits of smaller supporting arms and the benefits and drawbacks of larger microhotplate heating elements. This information should be of use to future designers of MEMS sensors employing the use of microheater technology.
