Bio-geochemically inspired capacitive sensors for heavy metals pollution monitoring

A novel sensor for environmental pollution monitoring is presented in this paper. A capacitive measuring system, together with suitable signal conditioning electronics, has been developed for performing real-time estimations of heavy metals concentration in air particulate. The proposed measuring system is biologically inspired from the observation of lichens that are widely used as bio-monitors for the environmental pollution. A synthetic replica of such bio-chemical elements has been developed regarding their behavior in the trapping of atmospheric particulate. A capacitive probe is then applied to this substrate in order to perform conversion of trace element concentration to an electric signal. The proposed prototype has been characterized through a large set of measurements performed in laboratory conditions with several pollutants as found in the real environment: features such as element selectivity and sensitivity to pollutant concentration have been highlighted. A procedure for performing both the pollutant classification and the estimation of its concentration has also been developed.