Development of optical sensing based mems fabry- perot pressure sensors

Abstract

Optical metrology offers significant advantages in remote sensing and has been recently developed as an alternative to conventional piezoresistive and capacitive sensing techniques used for sensing applications capable of operating in harsh environments. Recent advancement in silicon micromachining techniques makes optical sensing devices more feasible for commercialization by reducing sizes and improving performance and manufacturability. Unfortunately, some common issues, such as signal-averaging effect induced by the non-planar pressurized deflection, crosssensitivity to temperature and measurement errors arising from the process-induced variations, are major stumbling blocks facing the successful realization of this type of pressure sensors. In this study, a high-performance single deeply corrugated diaphragm (SDCD) was developed to enable optical sensing technology to be better realized with MEMS technology. The key novelty marking the proposed SDCD is that it consists of a flat bottom-region that behaves as a normal flat diaphragm, and suspending sidewalls that serve as stress concentrator and buffer, thereby enhancing flatness of the diaphra,m under pressurized deflection while reducing temperature dependence by releasing the thermally induced stress. The non-planar deflection behavior of different types of sensing diaphragm was studied using FE analysis and the resultant signal averaging effects of different Fabry-Perot pressure sensors were modeled and simulated. Substantial reduction in signal averaging effect of Fabry-Perot pressure sensor using SDCD has been demonstrated. Based on the