Sheet resistance and resistivity measurements of conductive materials using the four-point probe technique. The Jandel RM3 applies a known current through the outer two probes and measures the voltage drop across the inner two, eliminating contact resistance from the measurement.
| Category | Details |
|---|---|
| Instrument | Jandel RM3-AR Four-Point Probe Test Unit |
| Technique | Four-point probe (Kelvin sensing) |
| Measurement | Sheet resistance (Ω/□) and resistivity (Ω·cm) |
| Correction | Geometric correction factors applied to V/I ratio |
A background measurement was taken first to verify probe contact. Each sample was placed on the measurement stage, the four-point probe head lowered onto the surface, and current applied through the outer probes while voltage was measured across the inner two. Sheet resistance was calculated from the V/I ratio with geometric correction factors. Multiple points were measured per sample.
| # | Category | Samples |
|---|---|---|
| 1 | Coins | quarter, penny (unpolished / semi-polished / fully polished) |
| 2 | Household metals | stainless steel spoon, aluminum foil, metal washer, house key |
| 3 | Biological | leaf |
| 4 | Other | DVD, paper cardboard |
Conductive samples (coins, household metals) produced measurable sheet resistance readings. Non-conductive samples (leaf, DVD, paper cardboard) returned Contact Limit or Out of Range at all current settings. The penny was sanded into three bands — untouched copper, lightly polished, and fully sanded to exposed zinc — to compare surface condition effects. Each sample was measured multiple times in both forward and reverse current directions.
Raw measurement data available on GitHub.
Analysis in progress.