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R2-B.1: Orthogonal Sensors for the Trace Detection of Explosives
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 2014 |
| Abstract | An orthogonal sensor has been developed using thin fi lm microheaters and electrodes, printed onto alumina substrates and coated with various metal oxide catalysts. Experimental results to date indicate that this orthogonal sensor, consisting of thermodynamic and conductometric platforms, is very effective in detecting explosives in the vapor phase at the ppm level or better. The additional conductometric sensor signature provides a certain redundancy, which helps mitigate false positives and negatives, while the core thermodynamic sensor is effective in detecting both nitrogen and non-nitrogen based explosives. In parallel with our ongoing sensor and catalyst development efforts to enhance sensitivity and selectivity, is the development of small footprint MEMS based sensor, the latest version of which is shown in Figure 1. This technology has the potential to produce large arrays of microheater sensors, each coated with different catalysts specifi cally tuned to specifi c threat molecules. Given the specifi c nature of the elements in each area and the thermal signature created by the target analytes, identifi cation of the specifi c explosive molecule will be possible. This is a passive detection system capable of continuously monitoring threat molecules where the detector is simply not waiting for the explosive to approach. Rather, it has an active collection system in the sense that the analyte is drawn over the active sensor elements. Progress made this year includes improved detection limits for TATP, DADP, 2,6-DNT and ammonium nitrate using new testing protocols employing active dynamic control to eliminate unwanted background signals and pre-concentration steps. Active dynamic control is achieved by adding a second microheater without a catalyst coating, and measuring the difference in signals due to catalytic activity which not only improves the sharpness of the characteristic signature but improves the magnitude of the response by a factor of 3-4. Finally, to lower the detection limit for threat molecules of interest beyond current levels, a polystyrene preconcentrator was incorporated into our detection system. Based on preliminary experiments utilizing our pre-concentration approach, a 20% increase in sensor response was achieved, which could ultimately translate into a ppb detection limit. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.northeastern.edu/alert/assets/R2-B.1_2014.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
