Date of Graduation

2012

Document Type

Thesis

Abstract

There is a large need for microsensors that have a quick response, can be implemented cheaply and operate at low power. These sensors must also be sensitive to specific chemistries and have little to no cross-sensitivity to other stimuli in the environment. Previous researchers have shown that the incorporation of nanomaterials as the selective material resulted in very high sensitivity. Unfortunately, these nanomaterials are unstable at high temperatures due to sintering and coarsening. Therefore, within this work, new hydrogen selective nanomaterials will be investigated for these micro sensors that will be highly selective to hydrogen and be stable within the proposed harsh environment. In addition these nanomaterials where incorporated into chemi-resistive microsensors architectures. In order to fabricate these microsensors, the sensor requires the deposition of the active materials onto metal interconnects. This process is usually completed by physical vapor deposition processes, but results in unstable nanomaterials with low crystalinity. Current work focuses on the deposition of refractory nanomaterials through a lost-mold method patterned by lithography. It will also detail methods for stabilizing the microstructure of nano-composite H2 selective materials for high-temperature sensing applications using refractory, perovskite- and pyrochlore-zirconate electrolyte nanoparticles. This work investigated the effects of colloidal stabilization, suspension characteristics, photoresist composition, photoresist-suspension interactions, micro-mold geometry, and thermal processing. The differences between sensing mechanisms in material systems ranging from traditional semiconductors to mixed electronic conductors will also be explored. The macro and micro configurations of the H2 sensors are tested and compared for sensitivity, response time, stability, and recovery time. The impact of this work will foster the inexpensive implementation of sensor arrays to a host of industrial applications where efficient gas sensing is required.

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