Sensors

thumb|Different types of light sensors A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal.

A thermistor is a semiconductor type of resistor in which the resistance is strongly dependent on temperature. The word thermistor is a portmanteau of thermal and resistor. The varying resistance with temperature allows these devices to be used as temperature sensors, or to control current as a function of temperature. Some thermistors have decreasing resistance with temperature, while other types have increasing resistance with temperature. This allows them to be used for limiting current to cold circuits, e.g. for inrush current protection, or for limiting current to hot circuits, e.g. to pr

thumb|A hair tension dial hygrometer with a nonlinear scale.

thumb|right|Thermocouple connected to a multimeter displaying room temperature in °C

Lidar (, an acronym of light detection and ranging or laser imaging, detection, and ranging, often stylized LiDAR) is a method for determining ranges by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. Lidar may operate in a fixed direction (e.g., vertical) or it may scan directions, in a special combination of 3D scanning and laser scanning.

thumb |right |Helium vector magnetometer (HVM) of the Pioneer 10 and 11 spacecraft

A photoresistor (also known as a light-dependent resistor, LDR, or photo-conductive cell) is a passive component that decreases in resistance as a result of increasing illuminance (light) on its sensitive surface, in other words, it exhibits photoconductivity. A photoresistor can be used in light-sensitive detector circuits and light-activated and dark-activated switching circuits acting as a semiconductor resistance. In the dark, a photoresistor can have a resistance as high as several megaohms (MΩ), while in the light, it can have a resistance as low as a few hundred ohms. If incident light

thumb|alt=Image of spiderweb bolometer for measurements of the cosmic microwave background radiation.|Spiderweb bolometer for measurements of the cosmic microwave background radiation. Image credit: NASA/JPL-Caltech.

device used in electrical engineering

quantum physical phenomenon

electronic component

type of temperature sensor (thermometer)

Device that detects movement of people or objects

Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related areas of metrology, automation, and control theory. The term has its origins in the art and science of scientific instrument-making.

proximity sensor

electric switch operated by the movement of a machine part or the presence of an object

thumb|Two different types of phototubes A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photoemissive cell' to distinguish it from photovoltaic or photoconductive cells. Phototubes were previously more widely used but are now replaced in many applications by solid state photodetectors. The photomultiplier tube is one of the most sensitive light detectors, and is still widely used in physics research.

type of force transducer

measurement device, transducer activated by pressure changes

electronic sensor that measures infrared light

Type of sensor

Smartdust is a system of many tiny microelectromechanical systems (MEMS) such as sensors, robots, or other devices, that can detect, for example, light, temperature, vibration, magnetism, or chemicals. They are usually operated on a computer network wirelessly and are distributed over some area to perform tasks, usually sensing through radio-frequency identification. Without an antenna of much greater size the range of tiny smart dust communication devices is measured in a few millimeters and they may be vulnerable to electromagnetic disablement and destruction by microwave exposure.

An ion-sensitive field-effect transistor (ISFET) is a field-effect transistor used for measuring ion concentrations in solution; when the ion concentration (such as H+, see pH scale) changes, the current through the transistor will change accordingly. Here, the solution is used as the gate electrode. A voltage between substrate and oxide surfaces arises due to an ion sheath. It is a special type of MOSFET (metal–oxide–semiconductor field-effect transistor), and shares the same basic structure, but with the metal gate replaced by an ion-sensitive membrane, electrolyte solution and reference ele

switching device activated by rainfall

sensor which measures heat transfer

public company

equipment used to discover the distance, absence, or presence of an object by using a light transmitter and a photoelectric receiver

Level sensor

acoustic sensor

measurement device using quantum mechanical effects such as entanglement

sensor to detect the level of substances that flow

type of sensor

combining of sensor data from disparate sources

Type of rotary electrical transformer

sensor that uses optical fiber either as the sensing element or as a means of relaying signals

electronic sensors that convert light into electrical signals

a sensor that takes some predefined action when it senses the appropriate input

field-effect transistor used as a sensor for measuring chemical concentrations in solution.

system that detects and conveys the location of gunfire or other weapon fire

electromechanical transducer used in the playback of records

software where several measurements are processed together

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resistor whose resistance changes when pressure is applied

type of optical instrument

Chemotronics is an intersection field of chemistry (especially electrochemistry) and electronics dealing with the design of electrochemical and optical chemical sensors. One of pioneers of this field was Alexander Frumkin.

GCaMP is a genetically encoded calcium indicator (GECI) initially developed in 2001 by Junichi Nakai. It is a synthetic fusion of green fluorescent protein (GFP), calmodulin (CaM), and M13, a peptide sequence from myosin light-chain kinase. When bound to Ca2+, GCaMP fluoresces green with a peak excitation wavelength of 480 nm and a peak emission wavelength of 510 nm. It is used in biological research to measure intracellular Ca2+ levels both in vitro and in vivo using virally transfected or transgenic cell and animal lines. The genetic sequence encoding GCaMP can be inserted under th

wireless network sensor node

optoelectronic temperature sensing device

measurement of electric current

group of sensors, usually deployed in a geometric pattern, used to increase gain or dimensionality over a single sensor

thumb|An entomologist demonstrates the attraction of female yellow fever mosquitoes to his hand in an olfactometer An olfactometer is an instrument used to detect and measure odor dilution. Olfactometers are used in conjunction with human subjects in laboratory settings, most often in market research, to quantify and qualify human olfaction. Olfactometers are used to gauge the odor detection threshold of substances. To measure intensity, olfactometers introduce an odorous gas as a baseline against which other odors are compared.

type of cryogenic energy sensor or cryogenic particle detector

device which produces a voltage by a chemical reaction with oxygen proportional to partial pressure

An EOSFET or electrolyte–oxide–semiconductor field-effect transistor is a FET, like a MOSFET, but with an electrolyte solution replacing the metal for the detection of neuronal activity. Many EOSFETs are integrated in a neurochip.

academic discipline

An optode or optrode is an optical sensor device that optically measures a specific substance usually with the aid of a chemical transducer.

scientific equipment used for enforcement of safety standards

type of journalism