Patent ID: 7068054

Claim:
A solute sensor probe for measuring a solute concentration profiles in a conductive material by sequestering and sampling a plurality of defined subsurface volume elements, said sensor probe comprising: at least one first electrode for contacting a first portion of an external surface of said material, said first electrode defining a first boundary surface of each of said sampled volume elements; at least one second opposing electrode for contacting a second portion of said external surface, said second electrode in coaxial alignment with said first electrode, said second electrode defining a second boundary surface of each of said sampled volume elements; said first and second electrodes being adapted for receiving an alternating current source, said current source configured for providing a plurality of alternating current frequencies to said electrodes; said first and second electrodes being adapted for measurement of a plurality of voltage potentials established between said electrodes by application of said alternating current at said plurality of said frequencies; a plurality of third boundary surfaces of each of said sampled volume elements, each one of said third boundary surfaces positioned at a unique, frequency-dependent depth δ i below said external surface where δ = 1 μ ⁢ ⁢ σ ⁢ ⁢ π ⁢ ⁢ f , μ is the material magnetic permeability, σ is the material conductivity and f i is one of said alternating current frequencies, each one of said sampled volume elements being bounded by a region enclosed by said first and second boundary surfaces, one of said frequency-dependent third boundary surfaces and the external surface of said material; and a solute concentration correlation means for determining the solute concentration of each of said sampled volume elements from a measured resistivity of each sampled volume element, said resistivity of each volume element being derived from said applied current and said measured voltage at one of said plurality of frequencies.