Chemical detection

Environics is using multisensor technology for chemical detection. The two main technologies used in the Chempro-product family are

  • Aspiration Ion Mobility Spectrometry (AIMS)
  • Surface active microsensors

The detection of gases is based on proprietary neuro-fuzzy fusion of the sensor signals. AIMS sensor measures ions and creates fingerprint-type pattern which is characteristic to the measured analyte. The Aspiration Ion Mobility Sensor works with following principle:

  1. The sample gas is ionized. This is done with alpha particles from Am-241 sources which is similar than in smoke detectors.
  2. The original ions react with the analyte and form ions which are transported with flowing gas to the measurement area.
  3. The measurement area is narrow flat channel with electrodes on both sides of the channel. These electrodes are used to create electric field which is perpendicular to the flow.
  4. The ions are transported via the channel with the flow and  towards the electrodes by the forces caused by the electric field and ion’s charge. The movement depends on the characteristics of the ion: high mobility ions goes fast and drop to the first electrodes while low mobility ions travel long time with the flow and hits to the latter electrodes.. When the ion hits the electrode, the ion loses it’s charge. The charges hitting the electrodes are measured as current and the current is used as indication of the existence of certain type of ions.

The microsensors work with surface reaction principle. The sensor material is heated and it interacts with surrounding gas. The chemicals in the gas affect to the resistance of the sensor material. This effect depends on the material properties and the gas components.  The change depends on the concentration and the chemical type of chemical sensor is exposed. The sensor resistance varies between tens of ohms to hundreds of megaohms. This value can be measured and used for gas detection purposes.