Capacitance Probes

Capacitance Probes

High resolution, low cost sensors to measure gap and displacement in industries such as semiconductor, electronics, R&D applications and many more.

For grounded targets MTI offers standard capacitance probes.  For ungrounded or poorly grounded targets MTI offers push/pull dual sensor probes.  Both types of probes are available in stainless steel construction or flat and flexible polyimide construction.  Polyimide flat probes are perfect for gap applications or confined spaces.

Standard Capacitance Probes
Capacitance Probes
Capacitance flat probe sensor

How Probe Sensors Work

Standard capacitive sensors require the target to be electrically grounded (for position, gap and vibration measurement applications). Current flows from the probe face to the target and back to the amplifier to complete the circuit. The capacitance between probe and target is proportional to the distance and converted to a 0 – 10V output from the amplifier. The measurement of electrically grounded targets can be, however, affected by changes in the electrical conductivity or ground path of the target.

Capacitance displacement for grounded target

Push/Pull Capacitance Probes for Ungrounded Targets or Poorly Grounded Targets

To eliminate the effects of these variations, MTII developed a unique version of the Accumeasure sensor called the push-pull. In this design each probe consists of two capacitance sensors, built into one probe body. Each sensor is driven at the same voltage, however, there is a 180 degree phase shift between signals. This shift allows the current path to travel across the target surface rather than through the target to ground, eliminating any inaccuracies created by poorly grounded targets. Additionally, highly resistive targets can be measured with this technology allowing capacitance sensors to be used on semi-insulating and semi-conducting targets (for position, gap and vibration measurement applications).

for ungrounded targets


  • Cable and Probe Temperature Rating: -130°C (-202°F) to 200°C (392°F) Cryogenic and higher temperature probes are available up to 1200°C consult MTI Factory. A BNC to SMA adapter is required
  • Connector Temperature Rating: -65°C (-85°F) to 85°C(185°F)
  • Accuracy1: ±0.01% FSR or better, of range when probe and amplifier are calibrated to a known standard at x1 Range extension.
  • Probe and Cable Interchangeability: Accurate to within ± 0.2% at x1 range extension without recalibration
  • Pressure Rating Standard: 1400kPa (200 psig)
  • Material: Stainless steel construction, no active internal electronics
  • Highly flexible Cable for ILR/ILA/PSR Probes: 1m (3.28′) length – see options for extension cables. Connector type probes require selection of cable assembly upon ordering

Industries & Applications For This Product

Industry Measurement Type Applications
Consumer Electronics Positioning Height Gap of inkjet printers
Consumer Electronics Thickness Glass Thickness
Automotive Surface Brake Rotors

Recommended Accessories


P/N Image Model Product Description
8000-6890 SMA-female to BNC-male connector SMA-Female to BNC-Male For connecting Digital Series probes to MTI analog Amplifiers
8000-6891-410 SMA-female-to-SMA-male SMA-Female to SMA-Male Extension Cables, 1 meter
8000-6891-420 SMA-female-to-SMA-male SMA-Female to SMA-Male Extension Cables, 2 meters
8000-6891-440 SMA-female-to-SMA-male SMA-Female to SMA-Male Extension Cables, 4 meters
8000-6952 KD-CH4D precision fixture KD-CH4D Precision fixture that secures capacitance probes sensor and accurately varies the position of a target relative to the sensor. It provides an excellent means of obtaining calibration data at the user’s facility.