An ion-focusing aspiration condenser as an ion mobility spectrometer

Ion mobility spectrometry is a well-known method for detecting hazardous compounds in air. Detection limits in the low ppb range and fast response times make this technique more and more popular. Typical applications are the detection of chemical warfare agents, toxic industrial compounds, explosives and drugs. This paper describes the concept and preliminary results of a simple planar ion-focusing aspiration condenser as an ion mobility spectrometer (IMS). Compared to other aspiration condenser IMS with identical ion carrier gas and drift gas, our design has separate gas flows. This allows fluidic focusing of the ion carrier gas by means of geometric constrains. Thus, ions are focused before separation, which results in improved separation power. Furthermore, humidity in the ion carrier gas does not effect peak position in the ion mobility spectrum when using dry drift gas. In addition, the system is easy to fabricate at low-cost, has small dimensions and low power consumption. First measurements of 1-Octanol in air demonstrate the potential of this novel concept.