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Since capacitance level sensors are electronic devices, phase modulation and the use of higher frequencies makes the sensor suitable for applications in which dielectric constants are similar. The sensor contains no moving parts, is rugged, simple to use, and easy to clean, and can be designed for high temperature and pressure applications.
Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be accurately tracked at the same time. [13] Self-capacitance sensors can have the same X-Y grid as mutual capacitance sensors, but the columns and rows operate independently. With self-capacitance, current senses the capacitive load of a finger on each ...
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.
Capacitance sensors (or Dielectric sensors) use capacitance to measure the dielectric permittivity of a surrounding medium. The configuration is like the neutron probe where an access tube made of PVC is installed in the soil ; probes can also be modular (comb-like) and connected to a logger.
The capacitance, , equals /, where is permeability, is the area of the sensor and is the distance between parallel plates. If the material is linearly elastic (so follows Hooks Law ), then the displacement, due to an applied force F {\displaystyle F} , is x = F / k {\displaystyle x=F/k} , where k {\displaystyle k} is the spring constant .
2009 Nobel Prize in Physics laureates George E. Smith and Willard Boyle, 2009, photographed on a Nikon D80, which uses a CCD sensor. The basis for the CCD is the metal–oxide–semiconductor (MOS) structure, [2] with MOS capacitors being the basic building blocks of a CCD, [1] [3] and a depleted MOS structure used as the photodetector in early CCD devices.
A float switch is a type of level sensor, a device used to detect the level of liquid within a tank. The switch may be used to control a pump, as an indicator, an alarm, or to control other devices. One type of float switch uses a mercury switch inside a hinged float.
The effects of varying the characteristics of the dielectric can also be used for sensing and measurement. Capacitors with an exposed and porous dielectric can be used to measure humidity in air. Capacitors are used to accurately measure the fuel level in airplanes; as the fuel covers more of a pair of plates, the circuit capacitance increases.