Modeling and simulation of a MEMS-based mass measurement sensor in viscous environments

Microelectromechanical Systems (MEMS) are devices manufactured using existing integrated circuit (IC) technologies. By using IC based technologies, designers can create micron scale mechanical devices with new capabilities as well extending the utility of integrated circuits by allowing integration of sensors, electronics and actuators on the same die. MEMS technology is now established in some industries, especially the automotive industry where pressure sensors and accelerometers have been used for more than a decade. Recently, there has been a surge of interest in biomedical applications of MEMS, also known as Bio-MEMS.; In this work, a MEMS-based precise mass sensor for biomedical applications is proposed. The mass sensor, with proper surface treatment, can be used to detect the presence of bioparticles of interest such as bacteria or viruses. The sensor is based on a micron scale cantilever beam operating in a dynamic mode. The natural frequency of the cantilever depends on its mass and therefore when the beam is loaded, the frequency shift can be used to determine how much mass was added. Electrostatic actuation is used to oscillate the cantilever to ensure that the displacement of the beam is above the thermal noise floor.; Extensive modeling and simulation of the damping phenomenon, electrostatic actuation, modal analysis and reduced order modeling are performed. It is shown that the second mode of vibration is better in terms of reduced damping and sensitivity to precise location of the mass on the beam. Finite element simulations for the different domains carried out using ANSYS and extracted reduced order model code in VHDL-AMS was generated. Parameters from the VHDL-AMS code were used in a system simulator Simulink to demonstrate the advantage of using feedback to control damping.