Design and Simulation of Bulk Micromachined Accelerometer for Avionics Application - VLSI Design and Test - page 94

Design and Simulation of Bulk Micromachined
Accelerometer for Avionics Application

Amit Sharma 1 , Ravindra Mukhiya 2 , S. Santosh Kumar 2 , and B.D. Pant 2

1 Arya College of Engineering & IT, Jaipur, India
[e-mail]
2 CSIR-Central Electronics Engineering Research Institute (CEERI),
Pilani-333 031, India
{rmukhiya,santoshkumar,bdpant}@ceeri.ernet.in

Abstract. In the present paper, the design and simulation of a MEMS
polysilicon piezoresistive based bulk micromachined accelerometer for avionics
application i.e. ± 10g has been presented. The maximum acceleration this
design can bear is ± 50g. The accelerometer design presented in this paper
consists of a trapezoidal shaped proof-mass suspended by four flexures. The
piezoresistors are placed at the maximum stress locations on the beams, worked
out through simulation tool COMSOL TM Multiphysics. The optimum size of the
sensor structure, stress, displacement of proof-mass and output voltage are
analytically calculated. For 10g acceleration the relative resistance change is
3.66 × 10 -3 and output voltage is 18.29 mV. Sensitivity of this accelerometer is
0.366 mV/V/g. A comparison of the analytical and simulation results is also
presented.

Keywords: MEMS, Bulk micromachining, Accelerometer.

1 Introduction

Accelerometer is a mechanical device which measures the linear acceleration of a
moving object. A large number of different types of accelerometers have been
developed until now. The conventional accelerometers are found to be bulky and large,
and consume high power. They also need careful maintenance and large operational
cost. With the evolution of Micro-Electro-Mechanical Systems (MEMS) technology a
new class of micro mechanical sensors has been developed, including accelerometers.
MEMS accelerometer is one of the most desired miniature sensors for a wide
variety of mechanical measurement applications. Although, several types of MEMS
accelerometers are now available in commercial market, yet there is always a demand
of devices for customised applications with superior characteristics and lower cost.
In MEMS technology it is possible to batch fabricate and to scale down the size of
accelerometers leading to low power consumption and economy. These remarkable
properties of new generation accelerometers open up new application segments in
industrial as well as in consumer electronics. In micro scale regime, most commonly
available accelerometers are based on piezoresistive and capacitive transduction
mechanism [1]. Each type of accelerometer has its own advantages and limitations.