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micron resolution capacitive proximity sensor

Question asked by Viking65 on May 21, 2016
Latest reply on May 18, 2017 by Viking65


Is it possible to use a capacitive sensor, like AD714x or AD715x, for high-precision proximity sensing ?

The scenario is a calm water surface for reference, with a vertically movable, and vertically mounted (downwards) capacitance sensor above it.

This is for measuring the vertical straightness of a horizontal CNC axis, so the absolute water-to-sensor distance is irrelevant.

I only need relative measurements (height), with the sensor moved across the water surface.

The CNC Z-axis will provide the measurement values (relative vertical distance), with the sensor moved to yield a fixed capacitance reading for each measurement (chosen on a steep section on the position-to-capacitance curve for best precision).

For practical reasons, the absolute distance must be >1mm (so the sensor doesn't get wet ).

I'm looking for about 10 microns of repeatability/precision - is this possible ?