Capacitive displacement sensors are non-contact type displacement sensor devices capable of high-resolution measurement of the position and/or change of position of any conductive target. Capacitive displacement sensors can be used to measure the thickness or density of non-conductive materials. Capacitive displacement sensors are used in a wide variety of applications including semiconductor processing, assembly of precision equipment such as disk drives, precision thickness measurements, machine tool metrology and assembly line testing. These types of sensors can be found in machining and manufacturing facilities around the world.

Capacitive gauges (capacitance sensors) are the nanometrology system of choice for the most demanding precision positioning, scanning and measurement applications. Capacitive sensors ensure highest resolution, linearity and longterm stability. These absolute-measuring, non-contact devices detect motion at sub-nanometer levels directly (direct metrology). They provide accuracy, linearity, resolution, stability and bandwidth superior to conventional sensors such as LVDTs, strain gauge type sensors (piezo resistive sensors), and incremental encoders (glass scale type encoders).

Applications of Capacitive Displacement Sensors

  • Precision Positioning – One of the more common applications of capacitive sensors is for precision positioning. Capacitive displacement sensors can be used to measure the position of objects down to the nanometer level. This type of precise positioning is used in the semiconductor industry where silicon wafers need to be positioned for exposure. Capacitive sensors are also used to pre-focus the electron microscopes used in testing and examining the wafers.
  • Disc Drive Industry – In the disc drive industry, capacitive displacement sensors are used to measure the runout (a measure of how much the axis of rotation deviates from an ideal fixed line) of disc drive spindles.
  • Precision Thickness Measurements – Capacitive displacement sensors can be used to make very precise thickness measurements. Capacitive displacement sensors operate by measuring changes in position. If the position of a reference part of known thickness is measured, other parts can be subsequently measured and the differences in position can be used to determine the thickness of these parts.
  • Non-Conductive Targets – While capacitive displacement sensors are most often used to sense changes in position of conductive targets, they can also be used to sense the thickness and/or density of non-conductive targets as well.
  • Machine Tool Metrology – Capacitive displacement sensors are often used in metrology applications. In many cases, sensors are used to measure shape errors in the part being produced. But they also can measure the errors arising in the equipment used to manufacture the part, a practice known as machine tool metrology.
  • Assembly Line Testing – Capacitive displacement sensors are often used in assembly line testing. Sometimes they are used to test assembled parts for uniformity, thickness or other design features. At other times, they are used to simply look for the presence or absence of a certain component, such as glue.