Differential mobility spectrometers with tuneable separation voltage - Theoretical models and experimental findings

Differential mobility spectrometry (DMS) is a method for identification of ions based on the nonlinear dependence of ion velocity on electric field intensity. The most important parameters characterising sensitivity and selectivity of DMS detectors are signal intensity, position of the peak in the DMS spectrum and the width of the peak. These parameters depend on the detector construction and on its control method. The shape and amplitude of the supplying (separation) voltage waveform are also very important. In this work, four different models of a DMS detector are studied. The models are based on simple algebra, partial differential equations, finite elements method and a statistical approach. All considered models give an opportunity for determining the key DMS parameters. Theoretical data are compared with the results of measurements performed with a detector of a simple structure for which tuning the parameters of separation voltage is possible.