Date of Award

1-1-2022

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Electrical and Computer Engineering

Keywords

Chemicapacitor, Chemiresistor, Electrochemical Impedance Spectroscopy, Electronic nose (eNose) Systems, Fringing field capacitance, Gas sensors

Supervisor

A. Ahmadi

Supervisor

A. Emadi

Rights

info:eu-repo/semantics/embargoedAccess

Abstract

The agriculture industry in its current form is under considerable threat due to rapidly changing climate conditions and severe weather brought upon by global warming. This global food production crisis has prompted a growing affluence towards greenhouse farming which is reported to increase the per acre yield by up to 15 times when compared to traditional open-air farming. The increase in crop production capacity is attributed in part to the controlled environmental conditions which is made possible through the implementation of gas sensing technologies. All gas sensing technologies implement a sensing material which acts as the chemical interface between the surrounding environment and the sensor. However, a single sensing material will often interact with multiple target parameters therefore requiring arrays of gas sensors coated with different sensing materials to monitor the concentration of a single target gas. These arrays of gas sensors coupled with the required driving and readout circuitries are often referred to as electronic Nose (eNose) systems, where selectivity is dependent on the number of sensors in the array. In this work, impedance-based gas sensors are designed and developed as a promising candidate technology in reducing the number of sensors required in an eNose system employed in complex environments. Fringing field utilization is identified as a critical design parameter and two unique sensor designs are proposed which utilize a greater volume of fringing fields when compared to the three most commonly used sensor designs. The performance of these proposed designs is compared against the conventional sensor designs through simulation and controlled environmental experimentation. The proposed designs exhibit a capacitive response more than 100 times greater and an impedance sensitivity 20 times greater than the highest performing conventional benchmark.

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