Carbon and TiO2 based electrodes with metal alloy electrode for self-powered detection of water

Abstract

Self-powered devices are an emerging research field that could be leveraged into many devices that ordinarily are cost-prohibitive or otherwise high maintenance to utilize. The emergence of self-powered devices that do not rely on transient sources of power such as solar or wind further expands the possibilities of such devices. Currently, while many such devices are theoretically possible, the actual implementation and useable self-generated sources are experimental at best using proof-of-concept ideas rather than any functioning and reliable prototyping data. One of these ideas is the concept of using low-cost Metal alloy and carbon-based electrodes to form a power generating device when exposed to water. This thesis takes this idea and expands upon it by thoroughly characterizing and optimizing the different possible electrode material combinations such that it could be used in a functional device. A carbon-based material, graphite, was chosen based on preliminary experiments for one of the electrodes. The metal alloy determined to be optimal for characterization was Magnesium Alloy MgAZ31. The goal to characterize the chosen material in a power-generating device by measuring its voltage-current curve was achieved to a level required for informed optimization of a workable device. From the characteristic curves, optimal global or local power maximums were found when subjected to changes in electrode dimensions or ambient conditions. These characteristic curves can be useful in future development of an integrated water detection sensor system. Additionally, the optimized sensor material was further tested in proof-of-concept level experiments to detect water-borne additives such as NaCl and phosphate salts as well as water pH level. This could further broaden the potential capabilities of the material and allow future development of a water leak sensor to be multi-functional. This work was achieved by developing a standardized methodology for production of a fixed dimension sensor as well as creating cross-comparable testing systems for obtaining the characteristic curves of the sensor. It was found that the graphite when force-pressed serves as the most cost-effective and most efficient sensor material for producing the voltages and power requirements needed for the bluetooth low energy (BLE) technology currently. Recommendations for the diameter, thickness, densities and operating conditions of the sensor were found using similar testing methodologies and used as a baseline for manufacturing of a BLE water iv sensor. When measured at the most optimal dimensions and ambient conditions, the base graphite sensor was shown to be the most consistent for high power generation at an output voltage of ≈1.6V. It was also discovered that the graphite sensor could also be used to sense other differences such as pH level without discerning acidity or alkalinity as well as some salts such as phosphate and NaCl. The thesis also indicates the characteristic curves of the same graphite sensor under varying dimensions, conditions and timespans which can prove useful for further exploration of other variables associated with the device.