Sensor

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"Sensors" redirects here. For other uses, see Sensors (disambiguation).
"Detector" redirects here. For detector circuits in radio and other signal-related electronics, see Detector (radio).
Not to be confused with Censor, Censure, Censer, or Senser.
light sensors

A sensor is a device that produces an output signal for the purpose of detecting a physical phenomenon.

In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor.

Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure and flow measurement,[1] for example into MARG sensors.

Analog sensors such as potentiometers and force-sensing resistors are still widely used. Their applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robotics and many other aspects of our day-to-day life. There is a wide range of other sensors that measure chemical and physical properties of materials, including optical sensors for refractive index measurement, vibrational sensors for fluid viscosity measurement, and electro-chemical sensors for monitoring pH of fluids.

A sensor's sensitivity indicates how much its output changes when the input quantity it measures changes. For instance, if the mercury in a thermometer moves 1  cm when the temperature changes by 1 °C, its sensitivity is 1 cm/°C (it is basically the slope dy/dx assuming a linear characteristic). Some sensors can also affect what they measure; for instance, a room temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer. Sensors are usually designed to have a small effect on what is measured; making the sensor smaller often improves this and may introduce other advantages.[2]

Technological progress allows more and more sensors to be manufactured on a

macroscopic approaches.[2][3] Due to the increasing demand for rapid, affordable and reliable information in today's world, disposable sensors—low-cost and easy‐to‐use devices for short‐term monitoring or single‐shot measurements—have recently gained growing importance. Using this class of sensors, critical analytical information can be obtained by anyone, anywhere and at any time, without the need for recalibration and worrying about contamination.[4]

Classification of measurement errors

infrared sensor

A good sensor obeys the following rules:[4]

  • it is sensitive to the measured property
  • it is insensitive to any other property likely to be encountered in its application, and
  • it does not influence the measured property.

Most sensors have a linear transfer function. The sensitivity is then defined as the ratio between the output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is constant with the units [V/K]. The sensitivity is the slope of the transfer function. Converting the sensor's electrical output (for example V) to the measured units (for example K) requires dividing the electrical output by the slope (or multiplying by its reciprocal). In addition, an offset is frequently added or subtracted. For example, −40 must be added to the output if 0 V output corresponds to −40 C input.

For an analog sensor signal to be processed or used in digital equipment, it needs to be converted to a digital signal, using an analog-to-digital converter.

Sensor deviations

Since sensors cannot replicate an ideal transfer function, several types of deviations can occur which limit sensor accuracy:

All these deviations can be classified as

random errors. Systematic errors can sometimes be compensated for by means of some kind of calibration strategy. Noise is a random error that can be reduced by signal processing
, such as filtering, usually at the expense of the dynamic behavior of the sensor.

Resolution

The sensor resolution or measurement resolution is the smallest change that can be detected in the quantity that is being measured. The resolution of a sensor with a digital output is usually the

numerical resolution of the digital output. The resolution is related to the precision
with which the measurement is made, but they are not the same thing. A sensor's accuracy may be considerably worse than its resolution.

Chemical sensor

A chemical sensor is a self-contained analytical device that can provide information about the chemical composition of its environment, that is, a

gas phase.[5][6] The information is provided in the form of a measurable physical signal that is correlated with the concentration of a certain chemical species (termed as analyte). Two main steps are involved in the functioning of a chemical sensor, namely, recognition and transduction. In the recognition step, analyte molecules interact selectively with receptor molecules or sites included in the structure of the recognition element of the sensor. Consequently, a characteristic physical parameter varies and this variation is reported by means of an integrated transducer
that generates the output signal. A chemical sensor based on recognition material of biological nature is a
biomimetic materials are going to substitute to some extent recognition biomaterials, a sharp distinction between a biosensor and a standard chemical sensor is superfluous. Typical biomimetic materials used in sensor development are molecularly imprinted polymers and aptamers.[7]

Chemical sensor array

This section is an excerpt from Chemical sensor array.[edit]
A chemical sensor array is a sensor architecture with multiple sensor components that create a pattern for analyte detection from the additive responses of individual sensor components. There exist several types of chemical sensor arrays including electronic, optical, acoustic wave, and potentiometric devices. These chemical sensor arrays can employ multiple sensor types that are cross-reactive or tuned to sense specific analytes.[8][9][10][11]

Biosensor

Main article: Biosensor

In

biomimetic polymers, are called biosensors
. Whereas a non-biological sensor, even organic (carbon chemistry), for biological analytes is referred to as sensor or
in-vitro
and in vivo applications. The encapsulation of the biological component in biosensors, presents a slightly different problem that ordinary sensors; this can either be done by means of a semipermeable barrier, such as a dialysis membrane or a hydrogel, or a 3D polymer matrix, which either physically constrains the sensing macromolecule or chemically constrains the macromolecule by bounding it to the scaffold.

Neuromorphic sensors

Neuromorphic sensors are sensors that physically mimic structures and functions of biological neural entities.[12] One example of this is the event camera
.

MOS sensors

environmental parameters.[14]

Biochemical sensors

A number of MOSFET sensors have been developed, for measuring

genetic technology.[16]

By the mid-1980s, numerous other MOSFET sensors had been developed, including the

gene-modified FET (GenFET) and cell-potential BioFET (CPFET) had been developed.[16]

Image sensors

Main articles: Image sensor, Charge-coupled device, and Active-pixel sensor

MOS technology is the basis for modern

television broadcasting.[18]

The MOS active-pixel sensor (APS) was developed by Tsutomu Nakamura at Olympus in 1985.[19] The CMOS active-pixel sensor was later developed by Eric Fossum and his team in the early 1990s.[20]

MOS image sensors are widely used in

5 µm NMOS sensor chip.[21][22] Since the first commercial optical mouse, the IntelliMouse introduced in 1999, most optical mouse devices use CMOS sensors.[23]

Monitoring sensors

LIDAR sensor (bottom, center), as part of the camera system on an iPad Pro.[24]

MOS monitoring sensors are used for

health, security and lighting.[25] MOS gas detector sensors are used to detect carbon monoxide, sulfur dioxide, hydrogen sulfide, ammonia, and other gas substances.[26] Other MOS sensors include intelligent sensors[27] and wireless sensor network (WSN) technology.[28]

See also

References

  1. ISBN 978-0-86341-280-6The source states "controls" rather than "sensors", so its applicability is assumed. Many units are derived from the basic measurements to which it refers, such as a liquid's level measured by a differential pressure sensor.{{cite book}}: CS1 maint: postscript (link
    )
  2. ^
    ISBN 9781118638729
    .
  3. ISBN 978-81-7482-180-5
    .
  4. ^
    PMID 31094032
    .
  5. S2CID 211012680
    .
  6. ISBN 978-1-118-35423-0
    .
  7. S2CID 219902328
    .
  8. PMID 11749297
    .
  9. PMID 26132346
    .
  10. S2CID 206542436
    .
  11. PMID 24091381
    .
  12. PMID 27065784
    .
  13. ^ "1960: Metal Oxide Semiconductor (MOS) Transistor Demonstrated". The Silicon Engine: A Timeline of Semiconductors in Computers. Computer History Museum. Retrieved August 31, 2019.
  14. ^
    ISSN 0250-6874
    .
  15. ^ Chris Toumazou; Pantelis Georgiou (December 2011). "40 years of ISFET technology: From neuronal sensing to DNA sequencing". Electronics Letters. Retrieved 13 May 2016.
  16. ^
    PMID 12375833
    .
  17. ^
    ISBN 9783319490885
    .
  18. doi:10.1002/j.1538-7305.1970.tb01790.x
    .
  19. S2CID 108450116
    .
  20. ^ Eric R. Fossum (1993), "Active Pixel Sensors: Are CCD's Dinosaurs?" Proc. SPIE Vol. 1900, p. 2–14, Charge-Coupled Devices and Solid State Optical Sensors III, Morley M. Blouke; Ed.
  21. ISBN 9783319093871
    .
  22. ISBN 978-3-642-68404-3
    .
  23. ^ Brain, Marshall; Carmack, Carmen (24 April 2000). "How Computer Mice Work". HowStuffWorks. Retrieved 9 October 2019.
  24. ^ "LiDAR vs. 3D ToF Sensors — How Apple Is Making AR Better for Smartphones". Retrieved 2020-04-03.
  25. ISBN 9781119107354
    .
  26. PMID 30424341
    .
  27. ISBN 978-1-4613-1639-8
    .
  28. ISBN 9781461416708
    .

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