Bryan M. Blackburn

Multifunctional Gas Sensor Array with Improved Selectivity Through Local Thermal Modification

This work involves the development of small, easily manufactured, potentiometric gas sensor arrays for continuous monitoring of pollutant (NOx, CO, HCs) concentrations. These low-power devices consist of coplanar sensing electrodes operating in the same gas environment without the need for an air-reference. The selectivity of a sensing electrode-pair is temperature dependent and may be enhanced with the use of integrated heating elements. Finite Element Modeling was used to predict thermal distributions and find the ideal locations of sensing electrodes and heating elements. General trends of baseline shift and sensitivity with changes in individual electrode temperatures are discussed. The results demonstrate that a gas sensor array with thermally modified sensing electrodes yields a device capable of selectively determining the concentrations of combustion byproducts.

Exploration of Electric-Field Effects in Solid State Ionic Devices

This work explored the effect of localized electric fields on the performance of solid-state ionic devices. This was accomplished through the use of field electrodes, which created an electric field without leaking charge to the electrochemical cell. This is a significant distinction from fields generated with a direct bias including electrochemically promoted or NEMCA (Non-Faradaic Electrochemically Modified Catalytic Activity) enhanced cells. To investigate these field effects, we utilized a potentiometric gas sensor as a model device. We found that indirectly generated fields can improve device performance. For example, we have seen more than a 20X increase in NO x sensitivity. In this work, we compare planar sensor results, core and valence level photoelectron spectroscopy measurements, and other past surface science evidence to explore the origin of these effects. Our method for actively controlling ionic device performance can potentially be applied to gas sensors, fuel cells, gas separation membranes, and chemical reactors.