A Micromachined Field Asymmetric-Ion Mobility Spectrometer for Detecting Volatile Organic Chemicals in Ambient Air

Drift tubes barely the size of a quarter coin have been created and shown to provide analytical performance for detecting volatile organic compounds (VOCs) in air with sensitivity and selectivity comparable to larger analyzers in ion mobility spectrometry (IMS). These new micro-scale drift tubes have been operated under high field radio frequency (RF) regimes so that ion shutters and aperture grids could be removed from the drift tube. This advance also allowed the prototype units to be made with a planar design using manufacturing methods suitable for mass production and low cost. Ion characterization and separation with an RF-IMS drift tube are based upon differential mobilities, of gas phase ions, between high field and low field limits. Analytical measurement performance for a VOCs in air are shown and discussed.