The development of a silicon micromachined concentrator that can be used with sensors and in micro gas chromatography (GC) was discussed. It was found that the use of microconcentrator could enhance the sensitivity by two or three order of magnitude and makes feasible analysis of very low concentrations. The devices were fabricated on 6-inch silicon substrate using standard photolithographic processes and the channels were lined with a conductive layer through which an electric current could pass causing Ohmic heating. The results show that the preconcentration effect enhanced sensitivity and it was possible to use it as an injector for GC. The microconcentrator response was stable and it exhibited good precision.