Patent ID: 8174276

Claim:
A coaxial four-point probe measuring configuration comprising: a sample device; a coaxial four-point probe comprising an upper coaxial probe set contacting a top surface of the sample device and an lower coaxial probe set contacting a bottom surface of the sample device, wherein the upper and lower coaxial probe sets have a common center across the sample device and wherein each coaxial probe set comprising: an outer conductive sheath comprising a hollow conductive tip portion at one end; wherein the hollow conductive tip portion comprises a flat surface having a surface area; a flexible inner conductor positioned coaxially within the outer conductive sheath having an insulating material positioned there-between, the inner conductor comprising an exposed inner conductive portion at one end, the exposed inner conductive portion having a tip protruding through and further outside the hollow conductive tip portion of the outer conductive sheath; and a mechanical spring surrounding at least a portion of the inner conductor to allow for an axial movement of the protruding tip relative to the hollow conductive tip portion of the outer conductive sheath and to enable a simultaneous contact of the protruding tip and the hollow conductive tip portion with a sample material; a set of mechanical supports comprising: a lower brass plate surrounding the lower coaxial probe set to support the lower coaxial probe set; an upper insulating plate surrounding the upper coaxial probe set, wherein the upper insulating plate comprises a plastic and is loosely attached and spring loaded against the lower brass plate; and a lower insulating collar configured to guide the lower probe set to maintain the common center with the upper probe set.