Grantee Research Project Results

Measuring individual exposure in real-time can revolutionize air quality monitoring in communities everywhere. Such information would allow citizens to take preventive measures to reduce their exposures to air toxics, which would impact their health and quality of life tremendously. Mobile devices such as smart-phones and tablets represent a powerful infrastructure that could be leveraged to develop personal air monitors. However, traditional sensor technologies (e.g., electrochemical and photo-ionization detectors) commonly used for industrial safety monitoring, are big, power-hungry, and have limited sensitivity and lifetime.

 

N5 Sensors, Inc. will demonstrate highly-selective sensor architecture, utilizing nanoengineered gallium nitride (GaN) photoconductors functionalized with multicomponent nanoclusters of metal-oxides and metals. Innovation in photoenabled sensing enables these sensors to operate at room-temperature, resulting in a significant reduction in operating power. The strength of N5 Sensors’ technology is that it uses all standard microfabrication techniques, which promises economical, multianalyte, single-chip sensor solution. Due to the use of inert wide-bandgap semiconductor, metal-oxides and noble metals, the environmental impact of the sensors during their life cycles is minimal.

 

By combining the “designer'” adsorption properties of multicomponent nanoclusters together with sensitive transduction capability of nanostructured GaN backbones, N5 Sensors will demonstrate sensors for benzene, toluene, ethylbenzene, xylene—commonly referred to as BTEX. Feasibility of this approach will be demonstrated by designing sensors and testing their sensitivity to such chemicals with detection range from 500 ppt to 1 percent, with minimal cross-sensitivity to various components of environmental matrix, namely particulate matter, reactive gases and non-target gases. Sub-micron structures will be formed on GaN epitaxial thin-films on sapphire using lithography and plasma etching. Such structures will be functionalized with multicomponent nanoclusters of metal­oxides and metals using reactive-sputter deposition. The Phase 1 effort will demonstrate BTEX sensors, consuming < 1 mW of power and through detailed testing establish their operation reliability, measurement accuracy and calibration needs. Innovative sensor designs and measurement protocols will be evaluated for increased reliability and accuracy. Completion of Phase 2 will result in an array of nanoengineered sensors on a single chip, each tailored to sense specific air toxics: BTEX, O_x, SO_x, CO₂, and O₃.

 

Future prospects of such low-power, small form-factor sensors include embedded-chip or plug-in module with multi­analyte sensor arrays for the smart phones for citizens and soldiers for acquiring real-time environmental information. An opportunity for commercialization is in low-cost, mobile devices-based trace air toxic monitors for rapid alert in indoor and outdoor environments.