1. 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 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.

2. 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: 219 th 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.