Microgradient: effects of contact resistance, material properties and geometry for polymer-based sensor applications

Microgradient has become an important parameter in the description of the electrical output signal as a function of displacement for potentiometric position sensors. These sensors are employed in increasingly sensitive control circuits which require linear outputs for resolution of very small incremental mechanical displacements. Contact resistance and variations in material resistivity were thought to create significant errors in output signal. This paper uses experimental data to explore the effects of material properties and geometry on the electrical output signal of a polymer-based material utilized as a potentiometric sensor. The output signal is described in terms of both microgradient and linearity. The relative contributions of contact resistance, material homogeneity, surface roughness, and contactor geometry are explored and discussed.