Mathematical Modeling and Characterization of Thin Film, Narrow Gap Sensor Array Units (SAU)

Design, modeling, testing and analysis multi-gap PbPc sensor array units for the purpose of gas detection are carried out. The tested devices showed reduction in conductance as a function of increasing gap width and reducing film thickness and an increase as a function of temperature up to 160°C. An observed morphological change in the sublimed film is realized at 190°C as the conductance of the sensor array started to drop. Analytical modeling using semi-infinite coplanar electrode arrangement supported the obtained testing results. Problem statement: Stability in gas detection and subsequent discrimination is closely related to sensor design and test parameter and its response to an applied set of chemicals. Approach: To enhance sensor performance and improve sensor designs, a suggested design with mathematical analysis and gas response analysis is carried out. Results: A solid analytical mathematical model is established with both electric field and conductance equations. Effect of deposited sensor film thickness and inter-electrode separation on its response is also established and proved through practical test data. Conclusion: The obtained experimental results agree with the derived mathematical solutions.