Date of Award

8-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering (Holcomb Dept. of)

Committee Member

Dr. Hai Xiao, Committee Chair

Committee Member

Dr. Harlan Russell

Committee Member

Dr. Hongxin Hu

Abstract

Semiconductor gas sensors detect gases by a chemical reaction that takes place when the gas is in contact with the sensor and sensitivity is affected by operating temperature and humidity. The accurate control of gas sensor’s operating temperature is a fundamental aspect that determines the sensitivity and selectivity of gas sensors. A variety of gas sensors are developed so far, and each has different working temperature requirement ranging from 200°C - 400°C for functioning at the finest. This research mainly focuses on the package design criteria of semiconductor gas sensor substrate being developed by Arizona State University. To maximize the sensor’s sensitivity, stability, and accuracy; the package design needs to regulate the gas sensing material at a preset temperature of 200°C using automated temperature control system. To achieve these requirements, we developed a system that contains a microcontroller, micro-heater, and temperature control circuit with temperature sensors(thermocouples) to control the temperature measurement and read the resistance change of the gas sensor using Proportional Integral Derivative (PID) Controller algorithms. This paper proposes an invention of smart package design for gas sensor technology. It uses the Arduino microcontroller for processing and controlling the circuit operation and PID controller algorithm to automatically control the temperature by using PWM control of the metal ceramic heater and temperature sensor. This technology utilizes the principle of Wheatstone bridge to read the resistance change of the gas sensor and used an instrumentational amplifier (INA125P) to amplify the voltage reading from the circuit. In addition to the sensor’s performance, the designed package considers low-cost fabrication, portability, energy consumption and regulation of low voltage for operation.

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