Patent attributes
A sensor is provided for detecting small concentrations of volatile organic compounds in ambient air. The sensor has a lamp assembly and a gas sampling chamber assembly which are operatively associated. The gas sampling chamber assembly has an ionization chamber and an electrode assembly. The electrode assembly has sensing, counter and auxiliary electrodes and circuitry. The electrodes are positioned within the ionization chamber and are separated from one another. The circuitry is configured to apply a voltage difference to the sensing and counter electrodes, control an electrical potential of the auxiliary electrode to be substantially equal to an electrical potential of the counter electrode, measure/estimate a current at the sensing electrode and at the auxiliary electrode, determine a difference between the current at the sensing electrode and the current at the auxiliary electrode, and correct the current at the sensing electrode by using the difference.
