Patent ID: 7307436

Claim:
An electrical feedback detection system for detecting electrical contact of a multi-point probe to a material test sample surface, comprising: electric generator means connected to a first multitude of electrodes of a multi-point probe; a second multitude of switched impedance detection elements connecting said first multitude of electrodes of said multi-point probe; and electrical detector means for detecting a measuring signal from the electrical signal across said second multitude of switched impedance detection elements; wherein the electric generator means is a differential voltage to current converter comprising: a precision amplifier providing two differential inputs, one output, and one reference input; a precision resistive element providing an internal and external port, said internal port connected to said output of said precision amplifier; and a voltage follower providing an input and an output, said input connected to said external port of said precision resistive element, and said output connected to said reference input of said precision amplifier.