Single element differentiation of chemical vapors using an array
We present a heterosensor array that exploits the collective recognition ability of a set of different gas sensors to identify individual chemical vapors. In contrast to the conventional sensing approach based on the "lock-and-key" design, the heterosensor array rely on the response patterns produced over the collection of different sensors. Diverse sensors with different operating principles are employed to provide as much chemical diversity as possible. We demonstrate that this platform provides a highly discriminative tool with single element precision.
Detection of hazardous gases and vapors: pattern recognition analysis of data from an electrochemical sensor array
A portable device is being developed by Argonne National Laboratory to detect, identify, and warn US Coast Guard emergency response personnel of the presence of hazardous gases and vapors. The device operates in the situation of a spill or ship cargo hold where a puddle of the contaminant may be present. The prototype device uses an array of four different electrochemical sensors, which can be operated in four different modes. Thus, the array yields 16 channels of data for each chemical species detected. Pattern recognition is one way of determining the uniqueness of the information obtained and the capacity of each of the channels for classification. The matrices generated by detecting 22 gases and vapors with a prototype instrument are being examined by use of pattern recognition methods. Results to date indicate that approximately half of the channels provide unique information. 11 references, 9 figures, 3 tables.
Monitoring of electrochemically inactive compounds by amperometric gas sensors
Abstract Electrochemical sensors have many useful applications in air and toxic gas monitoring, but they are extremely limited in the gaseous species that they can detect. To extend the applicability of amperometric gas-sensing instruments to electrochemically inactive compounds, gas samples were exposed to a heated platinum or gold filament before being introduced into the sample chambers of several different amperometric sensors. The sensors were of the three-electrode type, having platinum-black reference and counter electrodes and sensing electrodes made of platinum black, powdered gold or vapor-deposited platinum or gold on porous tetrafluoroethylene membranes. All three electrodes were in contact with a 25 – 30 wy.% sulfuric acid solution. The responses of four different sensors to various compounds at 20°C were measured at sensing electrode potentials ranging from 0.9 V to 1.4 V versus RHE (reversible hydrogen electrode in the same electrolyte), with and without a heated platinum filament at the sample inlet. Of 10 compounds tested, only two elicited significant responses without the filament. With the filament heated to about 700 °C, each of the tested compounds elicited a significant response under certain conditions. Moreover, the particular sensors and electrode potentials corresponding to the strongest responses were different for each compound. Qualitatively similar, but quantitatively more pronounced, responses were obtained with the same filament heated to 800 °C or 1050 ± 50 °C, or with a gold filament heated to 950 ± 50 °C. The responses were proportional to concentration in the 0 – 50 ppm range, and usually proportional in the 0 – 200 ppm range.