DESIGN, FABRICATION, AND IMPLEMENTATION OF A NANO-ENABLED CHEMICAL VAPOR SENSOR Open Access
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The work described in this dissertation involves the fabrication of an Interdigitated Capacitor (IDC) chemical vapor sensor requiring only a small number of fabrication steps. This was achieved by growing monoclinic gallium oxide (-Ga2O3) nanowires over platinum interdigitated electrodes. Nanowires were fabricated using a Vapor-Liquid-Solid method of nanowire growth over platinum interdigitated electrodes, and were grown directly in-place forming a chemically-sensitive dielectric mesh.A computerized analyte vaporization apparatus and an automated flow control system were used to deliver controlled pulses of an analyte to the sensor devices. This controlled vapor flow is directed into a sample chamber for detection by the chemical sensor. As a suitable analyte passes over the nanowire mesh, the vapor adsorbs onto oxygen defect sites at the nanowire surface. The presence of a detectable analyte is sensed by a change in the capacitance of the sensor devices. Measurement of the capacitance of the vapor sensor was obtained by a balanced ac-bridge circuit.Sensor device response is a strong function of the analyte of interest. The sensors are capable of detecting acetone, methanol, and other hydrocarbons at room temperature. The sensor devices responded within a few seconds when the analyte/carrier was applied, and the devices recovered just as quickly after the analyte/carrier was removed. Fast recovery of the sensing devices without the use of an external heat source allows these devices to operate at low power. Capacitance is seen to increase following a Freundlich Isotherm in response to increasing concentrations of analyte vapors.