title: A microfabricated microconcentrator for sensors and gas chromatography.
abstract: The key component in trace analysis is the concentration step where the analytes are accumulated before the analysis. This paper presents the development of a micromachined microconcentrator that can be used to enhance the sensitivity of microsensors. Another application demonstrated here is a concentrator-injector for a gas chromatograph. The microconcentrators were fabricated on a 6-in. silicon substrate using standard photolithographic techniques (1 in.= 2.54 cm). The channels were lined with a resistive layer, through which an electric current could be passed to cause ohmic heating. The preconcentration was done on a thin-film polymeric layer deposited above the heater in the channel. Rapid heating of the resistive layer caused the "desorption pulse" to be injected into the sensor, or onto a GC column. Due to their small size, the microconcentrators could be fabricated 20 to 50 (depending upon the size) at a time on a 6-in. silicon wafer. This paper presents the development and characterization of the microconcentrator. It was found that the microconcentrator performed well as a concentrator, and as an injector for GC. A 14-fold enrichment factor was achieved. The microconcentrator exhibited long-term stability in response, with typical relative standard deviation of between 3 and 5%.
authors.affiliation: Department of Chemistry and Environmental Science, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982, USA.
authors.forename: Minhee
authors.initials: M
authors.lastname: Kim
authors.forename: Somenath
authors.initials: S
authors.lastname: Mitra
mesh_terms: D002849:Chromatography, Gas / Q000295:instrumentation*; D003201:Computers; D004560:Electricity; D006358:Hot Temperature; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity; D012825:Silicon
chemical_list: D012825:Silicon