Download the full-sized PDF of Utilization of Semiconductors Piezoresistive Properties in Mechanical Strain Measurements under Varying Temperature Conditions for Structural Health Monitoring ApplicationsDownload the full-sized PDF



Permanent link (DOI):


Export to: EndNote  |  Zotero  |  Mendeley


This file is in the following communities:

Graduate Studies and Research, Faculty of


This file is in the following collections:

Theses and Dissertations

Utilization of Semiconductors Piezoresistive Properties in Mechanical Strain Measurements under Varying Temperature Conditions for Structural Health Monitoring Applications Open Access


Other title
Structural Health Monitoring
Mechanical Strain
Type of item
Degree grantor
University of Alberta
Author or creator
Mohammed, Ahmed Ahmed Shehata
Supervisor and department
Dr. Larry Kostiuk (Department of Mechanical Engineering - University of Alberta)
Dr. Martin Jun (Department of Mechanical Engineering - University of Victoria)
Examining committee member and department
Dr.Leszek Sudak (Mechanical Engineering Department - University of Calgary)
Dr.Stephane Evoy (Department of Electrical and Computer Engineering - University of Alberta)
Dr.Larry Kostiuk (Department of Mechanical Engineering - University of Alberta)
Dr.Martin Jun (Department of Mechanical Engineering - University of Victoria)
Dr.Michael Lipsett (Department of Mechanical Engineering - University of Alberta)
Department of Mechanical Engineering

Date accepted
Graduation date
Doctor of Philosophy
Degree level
Strain gauges have been powerful tools in experimental stress analysis. This importance is expected to continue, even though other means of strain measurement are continually introduced to the market. The strain gauge is a simple device that can be easily installed to measure mechanical strain. By far, the one-dimensional single-filament has been the most common strain gauge. Conventional strain gauges are typically made from thin-foil metal; thus the resistivity change under stress is insignificant. On the other hand, semiconductor material demonstrated considerable resistivity change as a result of the applied mechanical strain or stress. In this work, the piezoresistive characteristics of silicon crystal are investigated to realize a robust Micro Electro Mechanical (MEMS) strain sensor. This sensor has been developed to withstand harsh environmental conditions, such as those in Structural Health Monitoring (SHM) applications. Silicon strain gauges have demonstrated higher gauge factor, sensitivity, and accuracy compared to conventional thin-foil strain gauges. Unfortunately, silicon strain gauges suffer from large temperature effect, which influences their performance dramatically. This temperature effect puts various challenges on the development and application of semiconductor sensors. On top of these challenges are the temperature compensation of the output signal, packaging, and fabrication. In addition, transferring strain through different structural layers causes substantial loss in the sensed strain values. Piezoresistivity theory is presented and applied to develop a new MEMS strain sensor. Taking into account all geometric and material characteristics, various tools and techniques, such as indicial equations, Finite Element Modeling (FEM) (ANSYS10.0®), and experimental evaluation, were employed to go through the development cycle of the piezoresistive strain sensor. In addition, alignment errors during microfabrication have been investigated. The proper microfabrication parameters and piezoresistors configuration were selected by investigating the silicon crystal material properties based on the crystallographic directions. A microfabrication process flow has been developed exploring a group of fabrication processes available at the University of Alberta micromachining and nanofabrication facility (NanoFab). In order to minimize the loss in the transferred strain, geometric features were created in the silicon substrate. These geometric features have resulted in stress discontinuity in their vicinity, which introduced the concept of geometrical gauge factor. The geometrical gauge factor is a new concept that can ‘virtually’ improve the performance of any piezoresistive sensor by utilizing the silicon carrier to increase the differential stress around the piezoresistive sensing elements. The main limitation to use this concept is whether or not material properties will accommodate the resulted stress concentration without failing the sensor. The developed sensor was evaluated, tested, and characterized at the University of Alberta and Syncrude Canada Edmonton Development Research Center. Uniaxial tension was utilized to calibrate a number of chip designs. The temperature coefficient of resistance (TCR) was also evaluated. Preliminary packaging procedure was proposed and applied. Comparing the performance characteristics of the developed MEMS strain sensor to a 350Ω thin-foil strain gauge showed that the piezoresistive MEMS strain sensor had better performance characteristics: sensitivity and resolution, with room for significant improvements. In addition, the MEMS strain sensor can be successfully applied under varying temperature conditions. The solution of the above challenges and the small size of MEMS sensors have resulted in a novel MEMS-based strain sensor with low power consumption, compared to conventional strain gauges. This low power consumption promotes this sensor in wireless SHM systems as the sensing unit, which can extend such technology to wider range of applications. The MEMS strain sensor has potential to provide a valuable tool to improve the current SHM systems as well as allowing higher number of sensors to be economically deployed. As a result, the reliability of both the SHM system and equipment will be enhanced, which will reflect positively on the economic performance of the equipment.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
A. A. S. Mohammed, W. A. Moussa, and E. Lou, "High Sensitivity MEMS Strain Sensor: Design and Simulation," Journal of Sensors, vol. 8, pp. 2642-2661, 2008.A. A. S. Mohammed, W. A. Moussa, and E. Lou, "Optimization of Geometric Characteristics to Improve Sensing Performance of MEMS Piezoresistive Strain Sensors," Journal of Micromechanics and Microengineering, vol. 20, pp. 015015, 2010.A. A. S. Mohammed, W. A. Moussa, and E. Lou, "High-Performance Piezoresistive MEMS Strain Sensor with Low Thermal Sensitivity," Journal of Sensors, vol. 11, pp. 1819-1846, 2011.A. A. S. Mohammed, W. A. Moussa, and E. Lou, "Development and Experimental Evaluation of a Novel Piezoresistive MEMS Strain Sensor," Journal of Sensors IEEE, vol. 11, pp. 2220 - 2232, 2011.

File Details

Date Uploaded
Date Modified
Audit Status
Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 3605851
Last modified: 2016:10:24 16:03:19-06:00
Filename: Mohammed_Ahmed_Spring 2013.pdf
Original checksum: 1c0d70edb29e84d370caee86bbceca3b
Well formed: true
Valid: true
File title: 9802456
File author: Ahmed A. Shehata Mohammed
Page count: 249
File language: en-CA
Activity of users you follow
User Activity Date