Author ORCID Identifier

https://orcid.org/0009-0005-7651-853X

Semester

Summer

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Edward Sabolsky

Committee Co-Chair

Konstantinos Sierros

Committee Member

Konstantinos Sierros

Committee Member

Terence Musho

Abstract

The demand for high temperature sensing technologies in industrial applications has been steadily increasing, driven by the need for precise monitoring and control in extreme environments. This thesis presents an investigation into the development and optimization of passive wireless sensors for high temperature sensing applications. The research focuses on overcoming the challenges associated with traditional sensing methods by leveraging passive wireless sensor technology, offering advantages such as reduced complexity, improved reliability, and enhanced flexibility.

A passive wireless high temperature sensor for far-field applications was developed for stable temperature sensing up to 1000 °C. The goal is to leverage the properties of electroceramic materials, including adequate electrical conductivity, high temperature resilience, and chemical stability in harsh environments. Initial sensors were fabricated using Ag for operation up to 600 °C to achieve a baseline understanding of temperature sensing principles using patch antenna designs. Fabrication then followed with higher temperature sensors made from (In, Sn) O2 (ITO) for evaluation up to 1000 °C. A patch antenna was modeled in ANSYS HFSS to operate in a high-frequency region (2.5–3.5 GHz) within a 50 × 50 mm2 confined geometric area using characteristic material properties. The sensor was fabricated on Al2O3 using screen printing methods and then sintered at 700 °C for Ag and 1200 °C for ITO in an ambient atmosphere. Sensors were evaluated at 600 °C for Ag and 1000 °C for ITO and analyzed at set interrogating distances up to 0.75 m using ultra-wideband slot antennas to collect scattering parameters. The sensitivity (average change in resonant frequency with respect to temperature) from 50 to 1000 °C was between 22 and 62 kHz/°C which decreased as interrogating distances reached 0.75 m.

Further experimentation was conducted with a modified system aimed at increasing the interrogation distance. The modified system incorporated a power amplifier to the transmitting signal to increase the amount of power being reflected by the sensor. The modified system demonstrated improvements in interrogation distance, enabling more extensive monitoring capabilities in high temperature environments. The experimental results demonstrate the feasibility of passive wireless sensors for high temperature sensing applications, with promising performance observed in terms of measurement accuracy, reliability, and operational range. However, challenges such as signal attenuation and interrogation distance limitations are identified, highlighting areas for further research and optimization.

In conclusion, this thesis contributes to the advancement of high temperature sensing technology by presenting a comprehensive investigation into the development and optimization of passive wireless sensors. The findings provide valuable insights into the potential applications of passive wireless sensor technology in industrial settings, paving the way for improved monitoring and control in high temperature environments.

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