Modelling of non-stationary processes in optomechanical thermal microsensors

An analytical method is developed to determine the frequency response of optomechanical thermal microsensors. The three types of the microsensors are considered: microsensor with the two supporting beams in adjacent corners of the plate; microsensor with the two supporting beams in opposite corners of the plate; microsensor with the four supporting beams. Taking into account the features of each type of the microsensors, in they structures, the domains of modelling are marked out. The domains are divided into the regions with homogeneous parameters. For each region the non-steady-state heat conduction equation is obtained that is solved by means of the time Fourier transform. The heat flux densities between the regions are determined using adjoint boundary conditions in the frequency domain. The analytical expression for the frequency responses of the microsensors is obtained. This method is applied to find the frequency responses, cutoff frequencies and time constants for the three types of optomechanical thermal microsensors. The dependencies of the sensitivity and the time constant on the length of the bi-material section of the beams for the microsensor with the two supporting beams in adjacent corners are obtained.