UBC Theses and Dissertations

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UBC Theses and Dissertations

Planar microwave resonator sensor technology for real-time and contactless monitoring of microbial growth on solid media Chhajer Jain, Mandeep


This thesis presents an innovative approach using microwave technology for contactless monitoring of microbial growth on solid growth matrices. Microwave sensors are widely employed in various biomedical applications owing to their portable, ease of fabrication, low cost, label-free, and contactless sensing capabilities. The unique ability of the microwave sensor to detect variations in the conductivity in the surrounding medium related to microbial growth makes it a promising candidate for microbial growth monitoring and related applications. This thesis presents an in-depth analysis of the design, fabrication, and testing of one-port planar microwave sensors. The designed sensors allow microbial growth monitoring capabilities in both temperature-controlled and uncontrolled environments. Microbial growth largely depends on environmental factors that include growth temperature, nutrient availability, spatial position, and presence of growth-inhibiting compounds such as antibiotics. Through this research, the potential of designed microwave sensors to investigate the influence of these factors was explored. The first study utilized a microwave sensor to detect microbial growth on a solid matrix provided with different glucose concentrations (0- 10 % w/v). Experimental results demonstrated a positive correlation between microbial growth at different nutrient concentrations with the microwave sensor’s response. In the second study, the microwave sensor successfully monitored the subsurface growth of microorganisms, confined between two layers of solid growth matrices. In the third study, the potential of the designed microwave sensor was investigated and was successfully demonstrated in monitoring the effect of antibiotics on microbial growth. The data from all these experiments and supporting data from microbial growth imaging demonstrates the high efficiency of microwave sensors in fast and contactless monitoring of microbial growth and its effectiveness in biomedical applications. Through this work, the ability of microwave resonator sensor to rapidly detect bacterial growth before any visual indicators was demonstrated. These initial studies lay the foundation and prove the microwave sensor as a prospective tool to detect and monitor microbial growth in food and pharmaceutical industries. The sensor resolution and sensitivity can be further improved by utilizing active resonators. Moreover, the sensor design can be modified and enhanced to operate wirelessly for long-range measurement systems.

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Attribution-NonCommercial-NoDerivatives 4.0 International