Patent ID: 8384378

Claim:
A conductivity sensor, comprising: an oscillator configured to provide an input signal; a reactive circuit operatively connected to the oscillator; the reactive circuit comprising an induction coil, a capacitive element, and a resistive element connected in parallel, the induction coil configured to be placed adjacent to a specimen, the induction coil comprising a first conductive element that spirals outward to an external perimeter from a first terminal located inward of the external perimeter, and a second conductive element operably connected to the first conductive element, the second conductive element spiraling inward from the external perimeter staggered relative to the first conductive element to a second terminal located inward of the external perimeter; and a control circuit for driving the reactive circuit to resonance when the induction coil is placed adjacent to the specimen; wherein the reactive circuit provides an output signal, the output signal comprising a parameter indicative of the conductivity of the specimen when the reactive circuit is at resonance.