If you insert an insulator with a dielectric constant of ɛr between the electrodes, the capacitance will be ɛr times that of the empty one.

If an object with a thickness of t is inserted while keeping the distance between the electrodes d, the capacitance will change depending on the thickness.

This is a graph of the capacitance change when the distance d between two electrodes with a detection area of φ20 is set to 11 mm and an acrylic plate of 1 to 10 mm is inserted there.
You can measure 0.05μm when the electrode spacing d is 1mm with our product, which has high sensitivity of 10-3pF/.
If the thickness of the object is uneven you can compensate by adjusting.