Contact Study of MEMS High g Impact Sensor

Abstract

In this paper, we report the contact behavior of a MEMS high g impact sensor. These devices are designed to measure high g shock loads with precision and latch in response to a threshold input. The contact mechanics of latching and impact need to be modelled in detail to design to a high degree of precision. The COMSOL Multiphysics tools and analytical solutions were used to analyze the contact behavior for impact sensors. The design validation using contact mechanics simulation of an acceleration sensor and an impact mass is reported. The electrical contact resistance of the latching switch is modelled using Hertzian contact mechanics theory. Diffusion transport resistance is seen to be the dominant mechanism and was determined to be $0.45\ \mathrm{m}\Omega$ for $0.19\ \mu\mathrm{m}^{2}$ contact area. The maximum temperature at the contact area was analyzed using the finite element method was quite close to the analytical solution.