Micromachined high-resolution accelerometers

In this paper, we review the high-resolution, micromachined accelerometers by enunciating the development of their mechanical components, the electronic circuitry and the microfabrication processes. A survey of the literature suggests that the research in this area is mostly focused on improving microfabrication and electronic circuitry. The resolution of the accelerometers is dependent on the sensitivity of the mechanical components as well as the ability of the electronic circuitry in suppressing the noise. The noise comes from mechanical components as well as electronic circuitry and plays a detrimental role in achieving high resolution. This is reviewed in this paper after explaining the working principles of selected high-resolution micromachined accelerometers. Sensing acceleration by measuring the change in capacitance is widely used but it has many complications. These are discussed in detail by presenting various techniques for sensing capacitance. The microfabrication processes that dictate the design are reviewed by tracking the evolution of high-resolution accelerometers found in the literature and comparing their sensitivities and resolutions. This paper gives an account of the significant accomplishments, some challenges for the future, and a few novel concepts in achieving high resolution of the order of a millionth of g, the acceleration due to gravity.