Principal Investigator: Craig Grimes
Institution: Pennsylvania State Univ University Park
Analysis (rationale for decision):
Hydrogen sensors based upon highly ordered titania nanotube arrays, made by anodizing a starting piece of titanium foil in an acidic solution, exhibit a resistance variation of over 108 (10,000,000,000%) in the presence of 1000 ppm hydrogen at 23C. This dynamic change in electrical resistance is the largest known response of any material, to any gas, at any temperature. The sensors demonstrate complete reversibility, response times of a few seconds, and no measurement drift. The nanoscale architecture of the nanotubes, in particular the wall thickness and points of tube-to-tube contact, is believed responsible for the outstanding gas sensitivity. To achieve such a material-gas response is a remarkable scientific result, and of great significance to the sensor community. The nanotube-array architecture provides a roadmap by which other gas sensors of exquisite sensitivity can be fabricated. Since no heating element is required to improve sensitivity, as is common with metal oxide gas sensors, the nanotube arrays have a tremendous potential for use in low-power sensor network monitoring applications. Furthermore, the nanotube-array geometry gives rise to remarkable photoconversion efficiencies, generally about 12%, hence upon exposure to light the sensors are able to self-clean from contamination enabling long term monitoring capabilities.
While the proposed research has broad utility in the sensing field, specific broader impacts include: {1} The highly-ordered nanotube-array material architecture provides a roadmap by which a variety of gas sensors of exquisite sensitivity can be realized. Consequently, the research will have significant scientific impact in the development of high performance, low power chemical sensors. {2} The research will have a significant impact in the development of a new generation of high performance hydrogen sensors, with beneficial results to applications ranging from energy, industrial production, to improved health care. {3} The research will provide high quality, interdisciplinary graduate student education. {4} The research will provide outreach-oriented laboratory internships for undergraduates.
