Device and method for identifying and quantifying layered substances

An apparatus for identifying and measuring substances overlying a surface, the apparatus comprising:

• a sensor head comprising a protective layer having a top surface, an electrode layer having a plurality of concentric electrodes imbedded therein, a backing layer having temperature means for generating a signal dependent on temperature and a ground plane layer, connector pins extending from said plurality of electrodes and said temperature means through the backing layer and insulated from the ground plane layer, a grounding pin for grounding one electrode to the ground plane layer, said layers integrally moulded together,
• an electrode control means connected to the plurality of electrodes for defining an electric field at the top surface, said electric field approximating a Bessel function which varies sinusoidally with respect to time and which has a fixed magnitude and phase,
• an amplitude and phase measurement means connected to the plurality of electrodes and to the electrode control means for measuring the a plurality of currents responsive to the electric field and converting the currents to a measurement set comprising at least seven dimensional regions defined by three complex measurements of impedance and temperature, and
• a first computer means having a memory for storing a map means comprising a partition of a vector space of predetermined characteristics of substances into regions of profiles corresponding to the substances which could be overlying the surface, said computer means having a processor for correlating the measurement set with the map means thereby identifying and quantifying the substances overlying the surface and for generating an output signal corresponding to the identity and quantity of substances overlying the surface, and
• display means responsive to the output signal for displaying the identity and quantity of substances overlying the surface.

A method for identifying and measuring substances overlying a surface using a plurality of concentric electrodes underlying a surface, an electrode control means connected to the plurality of electrodes for defining an electric field at the surface, an amplitude and phase measurement means connected to the plurality of electrodes and to the electrode control means for measuring a plurality of currents responsive to the electric field, computer means having a memory for storing a map means comprising a partition of a vector space of predetermined characteristics of substances into regions of profiles, and a display means responsive to an output signal for displaying the identify and quantity of substances overlying the surface, the method comprising the steps of:

• (a) applying an electric field at the surface,
• (b) measuring a plurality of currents responsive to the electric field,
• (c) converting the currents to a measurement set, and
• (d) correlating the measurement set with the map means thereby identifying and quantifying the substances overlying the surface, and
• (e) generating an output signal corresponding to the identity and quantity of substances overlying the surface.