Download - A Project Report Submitted
STUDY AND DESIGN OF LOW COST PRESSURE SENSORS FOR PREVENTING THEFT OF VEHICLE
A Project Report Submitted in Partial Fulfillment of the Requirements
for the Degree ofBachelor of Technology
inMechanical Engineering
byGROUP M17
MECHANICAL ENGINEERINGMOTILAL NEHRU NATIONAL INSTITUTE OF TECHNOLOGY
ALLAHABAD, INDIADecember, 2011
CERTIFICATE
Certified that the work contained in this titled “STUDY AND DESIGN OF LOW COST PRESSURE SENSORS FOR PREVENTING THEFT OF VEHICLE”, has been carried out under my supervision and that this work has not been submitted elsewhere for a degree.
Asst. Prof. S.B. MISHRAMechanical EngineeringMNNIT
Contents
INTRODUCTION
MEMS
APPLICATION OF MEMS
ADVANTAGES OF MEMS
MEMES BASED PRESSURE SENSOR DESIGN
VARIOUS RESPONSE OF PIEZORESISITIVE SENSOR
MECHANICAL DESIGN
]
Chapter 1
Introduction
Mems, micro electro mechanical systems, are the integration of electronic and mechanical components on micro level. These consists of sensor to obtain signals from the environment, electronic system provides logic and manipulation of signal obtained and finally actuators produce desired output.
This technology is targeted at devices that range in size from millimeters down to microns, and involve precision mechanical components that can be manufactured using semiconductor manufacturing technologies.A diverse range of application areas has been proposed, and applications developed for these devices include a wide range of sensor, fluid mechanics, optics, RF, storage, and biotechnology applications.
1.1 APPLICATION OF MEMS
MEMS are most popular in the automotive industry as accelerometers
for airbag systems. MEMS have many other uses besides airbag
systems, and not only for the automotive market. They also have
applications in industrial, military, and consumer markets.
Automotive Market: Airbag Systems
Vehicle Security Systems
Intertial Brake Lights
Headlight Leveling
Rollover Detection
Automatic Door Locks
Active SuspensionConsumer Market: Appliances
Sports Training Devices
Computer Peripherals
Car and Personal Navigation Devices
Active SubwoofersIndustrial Market: Earthquake Detection and Gas Shutoff
Machine Health
Shock and Tilt SensingMilitary: Tanks
Planes
Equipment for Soldiers
1.2 ADVANTAGES OF MEMS
They have proven to be a key enabling technology of developments in
areas such as transportation, telecommunications and health care, but the
range of MEMS applications covers nearly every field. The most
significant advantage of MEMS is their ability to communicate easily with
electrical elements in semiconductor chips. Other advantages include small
size, lower power consumption, lower cost, increased reliability and higher
precision.
(1) IC Technology used: Integrated multiple and more complex
functions on a chip, to form a monolithic system(sensors+processing+
actuators), Miniaturization with no loss of functionality, Improved
Performanc.
(2) Batch Fabrication: Reduced Manufacturing Cost & Time.
(3) Microcomponents make the system faster, more reliable, more
portable, cheaper, low power consumption, easily & massively employed,
easily maintained & replaced.
(4) Easy to integrate into systems or modify.
(5) Little harm to environment and capable of incorporating.
(6) Exploitation of new physics domains.
Chapter 2
MEMS BASED PRESSURE SENSEOR DESIGN
The pressure microsensors often use a thin square-shaped diaphragm as
their main sensor element. This is because of its compatibility with bulk
and surface silicon micromachining processes. A pressure applied on the
diaphragm generates an increase in its deflection until the elastic force is
balanced by the pressure. The pressure range that can be measured by the
diaphragm depends on its dimensions (surface area and thickness),
geometry, edge conditions, and material .
The diffused resistors on the silicon substrate are used to measure the
strain of the diaphragm of the pressure microsensors. This piezoresistive
microsensor generally has four piezoresistors in a Wheatstone bridge
configuration to measure the stresses in a silicon diaphragm under normal
Pressure.
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The deformation response of piezoresistive sensor to a pressure of 2*10^6 Pa
The stress response of piezoresistive sensor to a pressure of 2*10^6 Pa
• Data Used
• pi(t)= 71.8*10^-11 / Pa• pi(l)= - 66.3*10^-11 / Pa• E=169.8 GPa• Nu= .066
MECHANICAL DESIGN
The del(v)/v vs pressure response of piezoresistor