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. E

    Event generator and detector simulation softwares

    I'm looking for some event generator and detector simulation software. While I was searching, I found a lot of event generator software like PYTHIA, HERWIG, etc. But I was having difficulties in finding a software that will create a detector simulation. If you could tell me which event generator...
  2. J

    How does the Crystal Barrel detector (at ELSA) work?

    Simple explanation for non-physicist, please!
  3. B

    Engineering Sequence detector, finite state machine circuit

    Homework Statement Please see the attached photo. (The one with the green highlighter), I haven't written it out to avoid mistakes. Homework Equations None. The Attempt at a Solution I have constructed a moore state diagram, a state transition table and come up with boolean...
  4. A

    Linear movement detector using magnetic, wire coil and transistors

    Hello, I have cool idea for a device and one hardest part of it is to detect the movement of the object. I think I can use a wire coil, and a small magnet attached to the moving object. When the object passes the wire coil (up or down), there will be small voltage inside the wire coil. It...
  5. F

    Is a slit automatically also a detector?

    Suppose you're shooting electrons one at a time through a double-slit experiment. If we don't detect which slit an electron enters, you get a fringe pattern on the screen beyond the slits. If you detect which slit the electrons go through, then the fringe pattern is lost. However, wouldn't...
  6. R

    Proposed dark matter detector - how does it work?

    A few weeks ago I stumbled upon an MIT Technology Review article about a DNA-based dark matter detector. As a biologist I thought the idea was strange, since I didn't see how DNA would interact with dark matter in a way that a more easily manufacturable material such as silicon wouldn't. I put...
  7. X

    Mealy FSM Edge Detector Code Problems

    Homework Statement Create a Mealy Edge Detector, then measure the pulse width of 75 micro seconds by 50 MHz clock; here is the timing diagram: I am basically trying to emulate this diagram in my test fixture code (using Xilinx 14.1 in Verilog) and am having errors. Also, the tick is...
  8. T

    What is the acceptance of the detector?

    dear all is there anybody familiar with the definition of the acceptance of detector, especially used in high energy physics? please explain it for me. Thanks in advance!
  9. X

    Can I make a motion detector with my limited circuit experience?

    I am fairly new to circuits, (I am an applied physics major, I have one year left until I get my bachelors) and I thought it would be really cool to make something that shines a light or something if someone crosses past a sensor. For example, if I wanted to know if someone walks into my shed...
  10. A

    Affordable Water Detector for Plastic Tanks - Expert Tips

    I'm new to the forum, and will much appreciate your advice. Looking to build a cheap water detector, that will not change the chemistry of the water. It should simply indicate if water is touching it (if water reach a certain level in a tank made of plastic). Many thanks Al
  11. V

    Radiation Diode Detector Doping question.

    I'm reading up on semiconductors and there seems to be a few fundamentals I cannot find answers for if anyone can help? I understand that n-type substrate is doped with a donor and p-type substrate is doped with an acceptor creating excess electrons and holes. When you put the p-type and...
  12. D

    Link to description of detector type for double-slit experiment

    Can someone supply me with a link to a good article or book, or anything, that gives details on the type of detector that determines "which way" in experiments where the double-slit interference pattern is cancelled? DC
  13. H

    Cherenkov detector on a venus orbiter (Venera 9)

    questions about the Soviet's Venus missions I was reading about the Soviet Union's Venus missions and they equipped Venera 9 orbiter with cherenkov detector. So it detects particles traveling faster than the speed of light in a given medium What was this Cherenkov detector used for? It...
  14. F

    Quadrature sampling detector circuit

    Hi. I'm trying to build a quadrature sampling detector, or Tayloe detector based on the design at http://garage-shoppe.com/wordpress/?p=371 . I intend to feed the I and Q signals into a ADC that uses a 1.65V reference. One thing I'm confused about is the purpose of the 2.5 VDC offset fed into...
  15. T

    What is the unruh-dewitt detector?

    Dear everybody, this is my first post :biggrin:, I need help here can anyone tell me what exactly is the unruh-dewitt detector? I really interest on this effect (unruh), so lately I read many paper about it, but I really struck in what exactly Unruh dewitt detector. Thx for helping me.
  16. N

    Understanding a Homemade Lie Detector

    Hey guys, I'm new to this forum, and I want to start off by asking about some help to understand the composition of this circuit. The circuit is made by Kip Kedersha, and is found http://www.howcast.com/videos/1499-How-To-Make-a-Homemade-Lie-Detector. This is the circuit: I'd like to...
  17. D

    Question about scintilation detector

    Hi guys, I have some questions about this detector. So i have a project about this detector, i made some experiments, made some graphs, answering to some questions, but one questions is struggling me. How can we avoid to calculate the solid angle, i mean in what situations? In my lab documents...
  18. D

    How Does the Doppler Effect Relate Detector Speed to Sound Speed?

    Homework Statement A detector initially moves at a constant velocity directly toward a stationary sound source and then (after passing it) directly from it. The emitted frequency is f. During the approach the detected frequency is f'app and during the recession it is f'rec. If the...
  19. B

    Relativistic particles travelling at near light speed, past a detector

    Homework Statement Part a - A set of particles are traveling at a constant speed close to the speed of light, past a detector. From the detector's point of view, it takes a set period of time (t seconds) for the entire set of particles to pass by a set point on the detector. Write an...
  20. S

    Bell's Theorem and the detector

    Edgardo thanks for posting the links to Bell's Theorem. I read the first one and it was a clear description of Bell's experiment. I have a question (or an alternative explanation for the difference in probabilities between mathematical calculations and experimental results in the Bell's...
  21. E

    Chip detector for neurostimulator RNS

    hello, We work on a topic concerning the RNS neurostimulator against epileptic seizures: http://latavernedes3i.free.fr/files/...20Valerian.pdf (RNS consists of a computerized device implanted into the skull with electrodes implanted in presumed epileptic foci in the brain. Brain electrodes...
  22. M

    Abnormal behavior from [working] voltage detector

    It is a GREENLEE "GT-11 Voltage Detector" "50-1000V AC CAT IV" It has a little plastic encased metal nib on the end and it looks like a fat marker. You just stick it in an outlet and it lights up and beeps to indicate a current. There is no read-out, it just detects. Anyway, an outlet of...
  23. B

    How can tuning a coil with a capacitor help detect multiple metal objects?

    Good Day All, I would like to know if anyone can help with the following; I am running it a few problems and I am not able to find the formulas that will allow me to prove my idea. I have a loop of 20 Gauge magnet wire; it's 24 inches by 2 inches. I'm using this as a detector, but i want to...
  24. E

    Photon detector used in Young's Double Slit experiment?

    I am trying to recreate Young's double slit experiment and I can't figure out what he used to detect the photons. In some things I read it says he used a photographic plate. However, these are outdated and no longer available. Any ideas?
  25. C

    Directional photon detector to detect which path?

    I know this is not possible but I want to know why. Why cannot a directional photon (or electron) detector placed on the screen of a 2 slit experiment detect which slit an individual photon comes from without destroying the fringes? Fire the photons one at a time. They can be detected...
  26. N

    Range of alpha particles in a silicon detector

    Hi, I'm trying to find the range of α-particles in silicon; I can work out the stopping power, \frac{dE}{dx}, but the reference I'm using then states that I need to integrate it as follows: R=\int_T^0 (-\frac{dE}{dx} ) ^{-1} dE The thing is, I'm not sure as to how to even start this...
  27. M

    Understanding the Spatial Accuracy of Track Detectors

    Hi please forgive me if you find that this is not the correct place, but since my work is of experimental nuclear physics and I didn't find a sub.forum in math neither engineering I decide to post here. Here is the question: in any track detector, the spatial accuracy of the detector is...
  28. N

    Calculating the number of alpha particles incident on a detector

    Hi, firstly I'm not sure if I'm posting in the correct forum, if not could I request that the moderators move it to the right one. Ok, so my problem is pretty much as I stated in the title. The background to this is that I have been asked to roughly calculate the number of alpha...
  29. E

    Why is my AM detector output distorted and only at 110mV peak instead of 700mV?

    Im working in Pspice, I have an RF amp with a modulated input signal coming in on ~600kHz carrier wave and an amplified signal coming out, here is what the output looks like 1Megaohm load after a blocking capacitor to isolate AC: http://i.imgur.com/56NSI.png I am trying to use a simple...
  30. F

    Can a Red Plastic Cover Improve an IR Sensor Performance?

    IR Detector Question... If someone take an IR sensor and puts a red covered piece of plastic over the sensor...is that really going to significantly affect the performance? A friend of mine has a laser detector for road use and it appears to have a red plastic cover over the IR sensor...
  31. D

    Engineering Window Detector Circuit Design: LED Activation for Voltage Thresholds

    Homework Statement I think I know how to do this but wanted to make sure before I actually make the circuit. Here's a general diagram: [PLAIN]http://forum.allaboutcircuits.com/image_cache/httphome.cogeco.ca~rpaisley4ComparatorWindow.GIF So as you can see I'm trying to make a window...
  32. V

    Building a simple cosmic ray detector

    During a visit to CERN (more precisely:ATLAS) I got the idea of building a cosmic ray detector from the guide (who was a full time researcher there). The detector would look like a small rectangle with colored stripes going trough it about once a few seconds to signal the path of the muons...
  33. F

    Cosmic Ray Detector Problems

    I am building a cosmic ray detector and I am following these designs: http://www.lbl.gov/abc/cosmic/documentation/CosmicDetector2-0.pdf I have a few questions for those who may be familiar with this. a) In the parts page (http://www.lbl.gov/abc/cosmic/parts.html) I see that the price for the...
  34. chris2112

    Double-Slit Detector: How Physicists Detect Particles

    How exactly do physicists detect if a particle goes through one slit or the other in the double-slit experiment? Every book and article I read seems to elude this part.
  35. J

    What is inside the detector in a particle accelerator?

    What is inside the detector in a particle accelerator?? We need E and B fields to steer and focus beams in a particle accelerator, but all the calculations we do in QFT assume (apart from the colliding particles) that we are in the vacuum state. Does this mean there are no fields at the point...
  36. L

    Non line of sight position sensor/ detector

    Hi, I am looking for a sensor/ detector (A) which could perform the following: constrain: transmitter/ receiver (B) size must be small so that it can be inserted in human bone to be detected later, diameter 3mm X 6mm length is preferred, however, a bigger size can be consider as well...
  37. I

    What can I use as a detector to collapse the wave function?

    Hi! I have a plan to build my own version of young's experiment using various household items, a laser, and my physics textbook. My question is about what I could use as a "detector" to observe and collapse the wave function? I had the idea of making a tiny inductor to go around one of the...
  38. J

    What are the conditions inside the LHC Atlas detector?

    If I could be inside the LHC Atlas detector during a proton bean collision what would I see? Would there be a huge flash of light? Would I be killed, if yes how fast? Or would there be nothing to see?
  39. J

    Maxwell-boltzmann distribution on detector

    Hi, here's something seemingly rather simple that has puzzled me a bit. If i have a collection of thermal neutrons. They will follow the Maxwell-Boltzmann distribution. I guess this is a pretty good approximation for the energy spread of thermalized neutrons in water if one ignores absorption...
  40. J

    Resistance Temperature Detector (RTD) response time

    How would u work this problem? Q-If a RTD has a time constant of 10.0secs, approximately how long will the sensor take to get with 5% of the final value? I am thinking two ways to approach this problem. S1- It is known that the RTD takes 5 time constants to reach its final value, hence...
  41. E

    Finding Resolution for PIPS Detector Using Am-241 Source

    Homework Statement Determining the resolution for a new PIPS (Passivated Implanted Planar Silicon) detector. I've done this earlier for a Ge detector, but that was easy because the two peaks of the Co-60 are far apart. For this measurement we use the normal Am-241 source which has two...
  42. J

    Can Ultra Sound Detectors Conflict with Other Components on a Mobile Robot?

    Hi, I'm currently designing a mobile robot which is capable of detecting its surroundings and also any obstacles. I'm currently deciding to use IR to detect the range of objects. However I am using an ultra sound component for a different purpose on the robot, to analyse ground surface. My...
  43. F

    Understanding the Role of the Red Wire in Wiring Smoke Detectors

    wiring in smoke detector...?... Hello Forum, simple question about wiring in a house smoke detector. It operates at 120 V. Two wires, the black (hot) and white (neutral) are enough. There is a 3rd wire, red, to interconnect multiple alarms: if one rings all the others ring too... The...
  44. A

    Relation between position of detector and basis of angular momentum

    Hi, I'm trying to understand if where I put my detector affects the basis in which I'm measuring. For example if I have a photon with spin | 1,1 \rangle _z (i.e. spin 1 in the z basis) emitted in the +z direction and I put a detector in the z direction I expect to see a circularly polarized...
  45. D

    Which way detector (hardware) information

    I am still searching the net for information on the actual hardware used for the which way detector(s) in the double slit experiment(s), and descriptions of the experiments as really performed in the real world. I am NOT referring to the "screen" at the pathway termination used to detect the...
  46. W

    Ohmic junction in Cat's-whisker detector

    Hello, I have read (wiki and physicsforums besides other sources) about how preparing an ohmic junction is hard on wafers in the clean room and that usually one gets a Schottky barrier instead, if one is not careful enough. This makes me wonder, how come that people used to get an ohmic...
  47. C

    Blackbody energy detector, from Liboff's QM

    Homework Statement Problem 2.11 of Liboff's Introductory Quantum Mechanics, 1st edition Suppose that you are inside a blackbody radiation cavity which is at temperature T. Your job is to measure the energy in the radiation field in the frequency interval 10^{14} to 89 \times 10^{14}...
  48. A

    Sodium Iodide Detector (NaI) FWHM and applied Voltage

    Hi! I have a question regarding the applied voltage on NaI(Tl) detectors, how does the voltage effect the FWHM ( energy resolution)? For example, in a HPGe detector, the higher the applied voltage ( to some extent because of the leakage current) the more electron and holes are collected...
  49. F

    How does a metal detector work ?

    Hey there, I have problems trying to understand how a metal detector works. I don't understand why the inductance of a coil changes when a metal is approaching. Can someone explain that to me ? :redface: Thanks a lot for your help
  50. Janus

    Smoke detector sets itself off.

    Okay, I'm at work and I get a phone call from my daughter. Our smoke detector had gone off for no apparent reason. Unfortunately, it is the type that runs off of house current and the only way to turn it off is to turn the breaker off. However, that breaker also supplies power to the whole...
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