Research

Inertial MEMS Devices
Accelerometers are popular of the MEMS devices , with millions bought each year by the automotive industry. Devices with integral electronics offer readout electronics and self-test capability, and cost far less than accelerometers of decades ago. The physical mechanisms underlying MEMS accelerometers include capacitive, piezoresistive, electromagnetic, piezoelectric, ferroelectric, optical, and tunneling. The most successful types are based on capacitive transduction; the reasons are the simplicity of the sensor element itself, no requirement for exotic materials, low power consumption, and good stability over temperature. Although many capacitive transducers have a nonlinear capacitance vs. displacement characteristic, feedback is commonly used to convert the signal to a linear output. The output can be analog, digital, ratiometric to the supply voltage, or any of various types of pulse modulation. Sensors with digital output are convenient when the data must be transmitted without further noise degradation.In our laboratory, we focus on 3-D capacitive low-g accelerometers for IMU applications.

Beside the accelerometers, we’re developing new model of tuning fork gyroscope. Tuning fork gyros contain a pair of masses that are driven to oscillate with equal amplitude but in opposite directions. When rotated, the Coriolis force creates an orthogonal vibration that can be sensed by a variety of mechanisms.In our research, we’re using comb structure to detect the displacement of the sensing proofmass. Base on the result we can have the sensivity of the sensors. MEMS inertial sensing is an established industry, with performance-to-cost rapidly improving each year. Gyroscopes and angular accelerometers are entering the marketplace and will soon make many non-MEMS components obsolete. They should also open up new applications due to their small size and weight, modest power consumption and cost, and high reliability.

PiezoMEMS
Ferroelectric thin-films: Lead zirconate titanate Pb(Zr,Ti)O3; Barium strontium titanate Ba(Sr,Ti)O3.
Multiferroics thin-films: Bismuth ferrite BiFeO3.
Heterolayered structure and doping thin films.
Thin-films fabrication: Pulsed laser deposition and Sol-gel spin coating.
Piezoelectric devices: micro-diaphragms and micro-cantilevers for micro-fluidic pumps and micro-biosensors applications; High-resonance frequency resonator for sonar applications.

Optical MEMS
Update soon.