I have very low conducting epoxy composite sample, conductivity in the range of 10^-6 to 10^-10 S/cm. I want to know what would be difference in the result if conductivity is measured using four point probe and two point probe. In two point probe the probes are places across the thickness (i.e. one probe is on one surface and the second probe is on another surface).
For really low conductivity materials (with 10 ad-14 - 10 ad-16 ohm-1 cm-1) the four probes test is not necessary, only a guard ring and a picaommeter, using kV stabulized voltage. The conductivites you mention are not exteremely low, it belongs to the antistatic - static dissipative range. In the four probe method only the values measured between the two central electrodes are used for calculating the conductivity which eliminates several errors. In your case I woudl suggest using the four probe method.
Hi
This is a matter of impedance: that of the sample, the contact of the wire and the setup.Look at the keithley very good "Low Level Measurements Handbook". You will getall
the answers you need, and more !
Best wishes.
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