What is Detector: Definition and 276 Discussions

In the broadest definition, a sensor is a device, module, machine, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. A sensor is always used with other electronics.
Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, besides 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 or flow measurement, for example into MARG sensors. Moreover, analog sensors such as potentiometers and force-sensing resistors are still widely used. Applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robotics and many other aspects of our day-to-day life. There are a wide range of other sensors, measuring chemical & physical properties of materials. A few examples include optical sensors for Refractive index measurement, vibrational sensors for fluid viscosity measurement and electro-chemical sensor for monitoring pH of fluids.
A sensor's sensitivity indicates how much the sensor's output changes when the input quantity being measured changes. For instance, if the mercury in a thermometer moves 1 cm when the temperature changes by 1 °C, the 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.Technological progress allows more and more sensors to be manufactured on a microscopic scale as microsensors using MEMS technology. In most cases, a microsensor reaches a significantly faster measurement time and higher sensitivity compared with macroscopic approaches. 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.

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  1. S

    Detector Coverage and Power of Electric Dipole: Calculation and Diagram

    Homework Statement A detector hjaving a radius 10 cm is placed 1 m away from an electric dipole. What fraction of total solid angle does the detector cover and what fraction of total dipole power does it detect (assuming 100% detection efficiency) 2. The attempt at a solution I drew the...
  2. L

    Infrared Emitter and Detector Question

    Hi nerdy geeky folks, I have two questions: 1. can a regular cadmium-sulfide detect infrared in a complete absence of light (but a beam of infrared)? if not, what can be used to detect infrared (for a beam break sensor)? 2. I just want to make sure that I am building the circuit right...
  3. D

    IR Phototransistor Emitter and Detector Questions

    I recently bought a phototransistor emitter and detector from radio shack: http://www.radioshack.com/sm-matched-infrared-emitter-and-phototransistor-detector--pi-2049723.html . It didn't come with much instruction but i thought i could simply put a voltage across the emitter and the detector...
  4. Bob Walance

    Dr. Robert Forward's curvature gradient detector

    In a response by Pervect to another topic, he mentioned a device called a Forward mass detector, named after its inventor Dr. Robert Forward. It's an intersting device with the claim that it can detect small gradients in the curvature of spacetime. I couldn't find any info regarding...
  5. Y

    Cosmic-Ray Detector May Be Shelved

    I thought you guys might find this interesting click http://www.nytimes.com/2007/04/03/science/space/03stat.html?_r=2&ref=science&oref=slogin&oref=slogin"This seems criminal to me.
  6. K

    Should we replace traditional grading methods with lie detector tests?

    <sarcasm>Since lie detector tests are very very accurate (like 99%), we should use them as an alternative for human grading. So what do you think? I believe it would obviously work due to the use of the lie detector test in law enforcement. It can save the teacher a lot of time because since...
  7. S

    Calculating EMF in Metal Detector Coils

    Can i get some help with this problem? This problem deals with the basic loop configuration you will use in the laboratory to construct a metal detector. Two concentric circular coils of wire lie in a plane. The larger coil has 49 turns and a radius of a = 7.90 cm. The smaller coil also has 49...
  8. R

    Sensitivity Model for a detector

    hello, I have to make a sensitivity model for a near infra red detector and I need help. I have so far done radiometric calculations taking into account noise, due to dark current, sky background, etc and calculated the minimum signal intensity i need. However, i have a few blocks: I need to...
  9. M

    Motion detector graphs, distance vs time

    hi! a ball is dropped from a height of 1 meter above the floor. Take the origin to be the point from which the ball is released. would the graph be like a curved graph rising to the right starting from the origin? how would the graph look like if a car is parked on a steep hill? thank you
  10. H

    Oil Leakage Detection: Gamma vs Beta Rays

    In industry, do you use gamma ray or beta ray to detect oil leakage?
  11. E

    How does a photo detector detect?

    Please guys I really need your help. How does a photo detector detect? Can you also tell me where you got the info from. thanks einstein2603
  12. L

    Mathematica Mathematica perfect square number detector oddity

    This may possibly be the wrong place for this, but I figure it's the closest area around since it's mostly software related I think. It may be a lame question, I'm not entirely at home in this area to say the least - this is a horizon streaching game more then anything on my part. For reasons...
  13. T

    Sources of non-linearity in detector

    Basic setup is a photo-detector coupeled with an amplifier. Questions is what are possible sources of non-linear behaviour ? Now, one possible source is obviously the amplification of background noise, but what other sources are there ? Alternatively could one give me a book or website to...
  14. S

    Geometric efficiency of a detector

    I'm not to sure how to do this question. Q. A 4MBq gamma source emitting 5 KeV photons is held at a distance of 5 cm from the end window of a detector. The diameter of the detector window is 3.5 cm, and the quantum detection efficiency of the detector is 15%. i)What is the geometric...
  15. M

    Building a Functional Lie Detector: Troubleshooting Tips and Breadboard Basics

    I'm trying to build this simple lie detector (picture below). I'm 90% sure that i have it built correct on my breadboard, but for some reason my LEDS are getting destroyed if i try applying the full 9V. It takes around 3V to make the LEDS to turn on about halfway. For some reason, there is a lot...
  16. S

    What frequency of light is recorded by a detector attached to the moving mirror

    A stationary light source S wit ha natural frequency Fo is viewed in a mirror M by a stationary observer O. The mirror moves away from the observer wit ha velocty of Vrel << c a) what frequency of light is recorded by a detector attached to the moving mirror because Vrel << c classical may...
  17. Y

    The proper article to use in the sentence A/An NaI detector

    The proper article to use in the sentence "A/An NaI detector" I'm not sure if this is the best forum to put this in, but I'm curious, what is the proper article to use in a sentence such as "A/An NaI detector"? The source I found this from uses "An," probably because "NaI" is read letter by...
  18. S

    Linear range- in detector of GC

    what does it mean with Linear range in detector of Gas Chromatography? thanks!
  19. H

    Accelerated Detector in Minkowski Vacuum: Effects & Quantification

    In a Minkowski vacuum virtual particles with electric charge (electrons, positrons,…) create and annihilate. If a detector is accelerated within the Minkowski spacetime, will it detect a radiation from the charged virtual particles? How to quantify this effect? Is this effect related to the...
  20. J

    Unmasking a Pseudoscience: The Tachyon Detector

    some time ago i found this information http://www.spots.ab.ca/~belfroy/tachyonDetector.html on internet about a supposed "tachyon detector " . I have to confess that i believe this junk until a more deep study of electronics and amplificators led me to conclude that this is only a...
  21. C

    Doppler Effect: Source vs Detector Motion

    If a source and detector are moving towards one another, for the general doppler equation, would this be considered the source moving or the detector moving?
  22. benzun_1999

    Can You Help Me Find a Heart Beat Detector Circuit with LED Display?

    can anyone sugest me a good heart beat detector circuit. note the circuit must detect the current from the heart and LED display in a column. -Benzun
  23. B

    Cosmic Ray Detector: Equipment & DIY Builds

    what kind of equipment do we need to detect cosmic rays? can i build something to detect fairly high energy cosmic rays in my basement?
  24. Monique

    Why Does My Smoke Detector Go Off When I Shower?

    ..we recently got a smoke detector installed by the city. It seems to have some kind of an identity crisis.. it goes off every time we take a shower Sure, at least we regularly get the confirmation its still working not really my idea of practicality though..
  25. A

    Detecting Neutrons: Simple Methods for Beginners

    Hello all I am new here, please pardon me if I have posted to the wrong board. My question should be fairly simple. I am building a fusor which I am hoping will generate neutrons from a D-D reaction. However, I have no way to detect them:frown: I was wondering if there are simple ways to...
  26. M

    Particle and three slits + one detector experiment

    What would happen if the slit experiment is done with three slits and at only one slit some sort of particle detecting or particle tagging device is placed and at the remaining slits no means of particle detecting is introduced. I know the results of two slits with and without two detectors...
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