Optimising Performance of a Cantilever-type Micro Accelerometer Sensor

A technique for optimising performance of cantilever-type micro acceleration sensor has been developed. Performance of a sensor is judged mainly by its sensitivity and bandwidth. Maximising product of these two important parameters of inertial sensors helps to optimise the sensor performance. It is observed that placement of a lumped mass (add-mass) on the sensor's proof-mass helps to control both sensitivity and the first resonant frequency of the cantilever structure to the designer's choice. Simulation and modelling of various dimensions of rectangular structures for acceleration sensor with this novel add-mass technique are discussed. Coventorware MEMSCAD has been used to model, simulate, and carry out FEM analysis. A simple analytical model is discussed to elaborate the mechanics of cantilever-type micro accelerometer. The comparison of the results obtained from analytical model and the finite element simulations reveal these to be in good agreement. The advantages of this technique for choosing the two most important sensor parameters (i.e., sensitivity and bandwidth) of an inertial sensor are brought out.

C

Distance from fixed-end at which force F is acting

Modulus of elasticity

Ratio of distance of CG of structure from fixed-end to beam length

Force

Moment of inertia of about Z-axis flexure

Proportionality constant

Flexure stiffness constant

Length of flexure beam

Bending moment for a force acting at any location X from the fixed-end

Mass of proof-mass

Sensitivity

Thickness of the flexure

Deflection

Location from the fixed-end

Resonant frequency