Abstract:         

Humidity sensing is crucial in many applications, for instance, food processing, chemical industry, and civil engineering work, to name a few. The conventional electronic humidity sensors are prone to electromagnetic interference and are less sensitive due to their inherent single-pass nature. However, fiber optic humidity sensors using the cavity attenuated phase shift spectroscopy (CAPS) technique are immune to electromagnetic interferences and provide high sensing sensitivity and accurateness. In this work, we propose such a robust and inexpensive fiber optic sensor for humidity sensing applications. Moreover, we are developing a novel optical fiber sensing head by micromachining SMF-28 fiber using a carbon dioxide laser. By the micromachining procedure, we are able to reduce the fiber core diameter to 50 m, and further reduction is possible after we install a few more optimization procedures in the overall micromachining setup. In addition, to mimic the humidity sensing, at this point, we have used an electrical loss element in our CAPS experimental setup, and the setup tends to give very accurate loss measurements. The future steps include developing a compatible gas cell for the setup and conducting the humidity measurements. We anticipate that the current work will lead to a viable humidity sensor for various agriculture and food security applications.

Evaluation Committee 

• Supervisor:     Dr. Imran Cheema
• Co-Supervisor: Dr. Sabieh Anwar
• Evaluator:       Dr. Tayyab Imran