Date of Award

Fall 2013

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

First Advisor

Dimitrios Peroulis

Committee Chair

Dimitrios Peroulis

Committee Member 1

Babaz Ziaie

Committee Member 2

Farshid Sadeghi

Committee Member 3

Jason V. Clark


Condition monitoring of machines is advantageous in predicting failure and estimating machine component lifetime. Continuous monitoring of parameters such as temperature, vibration, and strain using sensors and consequent data analysis can help in reducing machine downtime by taking corrective actions before failure. Various wireless and wired sensors may be attached to critical components such as bearings, gears, mechanical seals, shafts etc. for measurements. These sensors however are often inadequate solutions as wired sensors are dicult to mount on rotating components, especially in millimeter-size spaces that may exist in some of these components. Wireless sensors provide a viable solution for measurements in rotating components but their range and performance are often limited due to power-supply constraints. The majority of these components are enclosed in metal housings (ex.pumps and motors). In such scenarios, wireless communication is nearly impossible due to severe signal attenuation. This research provides a unique solution to the above issues by implementing sensors based on temperature-induced magnetic field change of permanent neodymium magnets. Hall Effect sensors are employed to detect these changes. The static magnetic The field can pass through non-magnetic, metals such as estimates steels, copper, aluminum etc. thus allowing temperature sensing through complete metal enclosures. In this thesis, we present wireless sensors for bearing inner race and mechanical seal remote temperature measurement. A permanent neodymium ring-shaped magnet is attached to the inner race of the bearing, while temperature is read remotely using a Hall Effect sensor. The sensor is characterized on a hot plate for calibration equation and noise analysis. These calibration equations are later used for dynamic testing on bearing test rig. For mechanical seals, the sensor is implemented using a 2.2- mm diameter semi-cylindrical magnet with Hall Effect sensor mounted in a hole on steel flange. Temperature sensing is achieved through a metallic flange holding the seal in place. The temperature measurement concept is further extended to measure temperature and vibration simultaneously using permanent magnet and Hall Effect sensor. Furthermore, we also present various magnet lifetime tests and results with a detailed discussion about magnet lifetime. High temperature effects on magnet's magnetic field are also discussed.