A dynamic microindentation device with electrical contact detection.

We developed a microindentation instrument that allows direct measurement of the point of contact for reasonably conductive samples. This is achieved in the absence of a contact load using a simple electrical circuit. Force is measured using an optical interrupter to measure the deflection of a cantilever beam. Displacement is achieved using a piezoelectric motor and is measured using an independent optical interrupter. Force and displacement measurements are accomplished in real time, allowing the specification of arbitrary waveforms. The instrument was rigorously validated by comparing mechanical property measurements from the indenter with results from traditional dynamic mechanical analysis. Details of the construction and feedback control schemes are given explicitly.