Design And Simulation Of A Mems-based Photoelectric Tilt Sensor

MEMS (Micro-Electro-Mechanical Systems) are chips that are made in semiconductor fabs that combine electronic functions and mechanical actions. MEMS-based tilt sensors are used to detect angular orientation of an object with respect to a reference, usually supplied by gravity. Remarkable advancements in MEMS device are increasingly accomplished through low cost, accuracy, integration and hybrid structure.With a comprehensive design and simulation, this paper presents a novel microfluidic photoelectric tilt sensor for obtaining tilt angle and direction in a two-dimensional plane. The hybrid MEMS/CMOS device consists of a monochromatic collimated light source, a MEMS-based microfluidic sloshing tank, and a photoelectric array. Light projects in sloshing tank and throws a shadow onto surface of an array composed of PIN photodiode and operational amplifier. Tilt angle and direction are obtained by combining photoelectric output and converting into digital signal. Some discussions can be listed as follows:1. The microfluidic sloshing tank is built up by COMSOL Multiphysics (V.2.3). Mathematic model is analyzed. Simulation results, geometry and liquid choice are reported.2. The principles of photodetection and characteristic of Si-PIN photodiode are explained. After discussing about layout and fabrication process, a design of signal detection and analysis of amplifier gain influence are developed.3. A single-ended folded cascade amplifier and an improved AB-push-pull output buffer amplifier are designed by Cadence Spectre (V.5.1.0). Parameter calculation, simulation results, and circuit layout are presented.According to the simulation, the complete sensor occupies a volume of 0.314 mm3, with height of 400μm and bottom diameter of 1000μm. The total power dissipation of the amplifier is 1.188 mW and the measurement range is 180°. The bottom part can cover 260-unit electro array. Excellent resolution, accuracy, low cost and small structure can be obtained.