Nanowire-Nanocluster Hybrid Sensor Technology for Environmental, Industrial, and Security Monitoring

A. Motayed
University of Maryland, College Park, US

Keywords: gas sensors, nanoscale photocatalytic sensors, nanowire-nanocluster sensors

Summary:

Next-generation of environmental monitors suitable for integration with smart-phone and other mobile platforms require single-chip, ultra low-power sensor technology capable of recognizing multiple threats. Traditional sensor technologies, such as electrochemical, catalytic, and photoionization based detectors all have significant limitations in terms of physical size, power requirement, sensitivity, selectivity, range, and operating life. We have developed a novel chemical sensor architecture by combining the sensitive transduction capability of gallium nitride (GaN) nanowires together with the enhanced catalytic efficiency of metal and metal-oxides nanoclusters. Using multicomponent nanocluster design, we can produce sensors with high selectivity to any small set of chemicals, currently not possible with any other technology. We have shown that GaN nanowires decorated with nanoclusters of titanium dioxide can be used to detect volatile organic compounds, such as benzene, toluene, ethylbenzene, and xylene – commonly referred to as BTEX at concentration levels as low as 50 ppb. The photocatalytic metal-oxide nanoclusters allowed room-temperature sensor operation using only UV excitation. These sensors also detected nitroaromatic explosive compounds such as trinitrotoluene at levels of 500 ppt in air. By adding platinum to the titanium dioxide nanoclusters, the same sensors can be “retuned” to respond to hydrogen, methanol, and ethanol.