Transcript Slide 1

A Persistent Surveillance Technique for the Detection of Explosive Precursors
O.J. Gregory, Y. Chu, K. Waterman, C. Hurley, M. Platek, University of Rhode Island
Purpose/Relevance: To develop an inexpensive metal-oxide gas sensor that is capable of
detecting trace levels of target gases. Explosives and explosive precursors can be detected in
air, under ambient conditions, using transition metal oxides as catalysts. Very low concentrations
of specific target molecules can be detected using our gas sensors, which rely on a
thermodynamic response, rather than a conductometric or other type of transducer response.
These thermodynamic responses occur at a specific temperature for a given target molecule
and catalyst, as the sensor is thermally scanned, similar to protocols used in microcalorimetry.
Innovation: A TATP gas detection platform was developed using nickel microheaters coated with
different metal oxide catalysts. Since TATP contains neither metallic elements nor nitro groups,
does not fluoresce and has no significant absorption in the ultraviolet region, a non-spectroscopic
approach for the detection of TATP has considerable merit. Novel catalysts were developed for
the TATP sensors using combinatorial chemistry techniques in conjunction with co-sputtering
from multiple oxide targets. Rapid screening protocols were facilitated by “printing” large arrays
of sensor elements, so that a wide range of catalyst chemistries could be explored.
This Year outcome: An inexpensive, robust gas sensor, capable of detecting TATP at levels less
than 1 part per million, was developed using nickel microheaters coated with various metal oxide
catalysts including tungsten oxide, vanadium oxide, copper oxide, zinc oxide and tin oxide.
Long-range impact: Arrays of microheater sensors containing
individual “catalyst pixels”, each optimized for a particular target
gas, are envisioned. These sensors will be integrated onto a chip
such that an unknown gas sample could be analyzed for a large
number of potential threat molecules in real time. A detection
capability that persists in the presence of high concentrations of
background gases, or interferants, is also highly desirable.
A Persistent Surveillance Technique for the Detection of Explosive Precursors O.J.
Gregory, Y. Chu, K. Waterman, C. Hurley, M. Platek, University of Rhode Island
Education Students Present & Graduate: Yun Chu- PhD student in Chemical Engineering,
Kellie Waterman and Caitlin Hurley -Undergraduate students in Chemical Engineering, Matin
Amani-Undergraduate student in Electrical Engineering and Chemical Engineering, Mary
Stoukides- chemistry teacher from Mount St. Charles High School.
Papers/Patents/Presentations: 219th Electrochemical Society Meeting 2011, Montreal, Canada,
“Detection of TATP Using Thermodynamic Based Gas Sensors with Metal Oxide Catalysts”, Y.
Chu, K. Waterman, C. Hurley, M. Amani and O.J. Gregory.
Microscopy and Microanalysis 2010, Portland , OR, “Characterization of Pipe Bomb Fragments
using Optical Microscopy and Scanning Electron Microscopy”, M.J. Platek, O. J. Gregory, T.
Duarte, H. Ghonem, J. Oxley, J. Smith, E. Bernier.
Y. Chu, K. Waterman, C. Hurley, M. Amani, O.J. Gregory, “Detection of TATP Using a
Thermodynamic Based Gas Sensor”, submitted to Sensors Letters
“Thermodynamic Based Gas Sensors Using Metal Oxide Catalysts”, O.J. Gregory, M. Platek and
A. Cote, URI Patent Disclosure filed Feb. 2011
Transition to Industry or Collaboration with Industry: We have collaborated with SensorTech,
Inc. (Savannah, GA) over the past few years on gas detection protocols for the US Army and
DARPA. Raytheon, Smiths and Draper Labs have expressed a keen interest in our technology
and key personnel from both organizations are updated on a regular basis.
Next Year: Partnering with engineers from the Navy (NUWC) in Middletown RI, we are designing
and developing a MEMS based sensor platform that incorporates free standing diaphragms with
embedded microheaters in a silicon architecture to improve the response time and sensitivity of
the sensor. The mixed-mode MEMS catalytic gas detector will initially use TATP as the target gas
to demonstrate the improvement in performance metrics using this approach with other target
gases of interest pursued as time permits.