Nahideh Salehifar, a doctoral candidate in electrical engineering, will defend their dissertation titled “Metal Organic Thin Film Coated on Optical Fiber Gas Sensor.” Their advisor, Dr. Jie Huang, is an associate professor in the electrical and computer engineering department. The dissertation abstract is provided below.

This dissertation explores the development of metal-organic framework (MOF)-based optical fiber sensors for detecting volatile organic compounds (VOCs) at low concentrations (parts-per-billion to parts-per-million). In the first part of the study, theoretical calculations were performed using effective medium approximation (EMA) models, including Lorentz–Lorentz, Maxwell–Garnett, and Bruggeman equations, to predict the refractive index changes of MOFs upon gas adsorption. These models were applied to MOFs such as ZIF-7, ZIF-8, ZIF-90, MIL-101(Cr), and HKUST-1 to evaluate their potential for gas sensing.

In the second part of the dissertation, experimental work was conducted to validate the theoretical predictions. MOF-coated optical fibers were fabricated and tested for their ability to detect ethanol under varying concentrations. The experimental results showed significant refractive index shifts consistent with the calculated values, confirming the reliability of the EMA models. Enhancement factors were also determined to assess the selectivity and storage capacities of the MOFs based on guest-host interactions. The alignment between the theoretical calculations and experimental findings demonstrates the effectiveness of MOF-based sensors for real-time and highly sensitive gas detection. This work lays the foundation for further research on expanding the range of detectable gases and improving sensor stability for practical applications.