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 ?