This EAGER project uses newly developed micro-ultrasonic and micro-electro-discharge machining methods to develop rapid prototyping of a new generation of nano-enabled sensors. If successful, the work will both dramatically expand available options for lithography-compatible, batch-mode microfabrication of ceramic and metal microstructures and provide new technology allowing the development of new, more sensitive, and more robust environmental sensors for aquatic environments. Recently developed lithography-compatible micromachining techniques will be explored, with the goal of decreasing the thickness and increasing the sensitivity and spatial resolution of protonic ceramic membranes, such as yttrium-stabilized zirconia (YST), a ceramic used in pH and redox sensor electrodes that are used to make measurements in high temperature (400 degree C) corrosive environments (seawater).
Broader impacts of the work include the collaboration of researchers from three fields that do not commonly interact (nan-manufacturing, geoscience, and biology), development of new infrastructure for science engineering, and the potential for dramatically improving aquatic sensor sensitivity and longevity even in harsh environmental conditions like those found in seafloor hydrothermal vents. Student training in novel, state-of-the-art manufacturing techniques and nanotechnology is also involved.
A major challenge to ocean and earth science research involves acquisition of chemical and physical data on a time and spatial scale that permits a better understanding of a natural process without affecting the process itself. Processes such as earthquake activity, climate change, and environmental remediation all serve as good examples of natural and human induced events that could benefit from monitoring of chemical and physical variables. Our research connected with this NSF funded project involved collaborative efforts with colleagues at the Center for Wireless Integrated Micro-Sensing and Systems (WIMS2), University of Michigan, to design and build chemical sensors for measuring pH (acidity) and dissolved gases (hydrogen and hydrogen sulfide). These chemical components are particularly relevant to the chemical evolution of seafloor hydrothermal (hot water) systems where unusual biologic communities exist in association with warm fluids escaping from recently erupted volcanic rocks. High pressures at the seafloor and small size of the cracks from which the fluids vent, present severe science and engineering challenges to sensor construction using conventional technology. Thus, the chemical sensor system conceived of at the University of Minnesota and fabricated at the University of Michigan takes full advantage of recent advances in micro-machining technology, electrochemistry, and signal processing. A prototype instrument with a small and sensitive integrated package of sensors has been built at the University of Michigan, while sensor components are undergoing tests in the high pressure facilities at Minnesota. The entire sensor system will be tested again early next year at seafloor vent sites. Although the chemical sensor system was designed specifically for monitoring the chemistry of seafloor vent fluids, with earth and ocean science questions in mind, we believe broader applications are possible with clear and important societal benefits.
