1 / 30

Chapter 2 Basic sensors and principles

Chapter 2 Basic sensors and principles. What is a sensor?. Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

karenbarnes
Download Presentation

Chapter 2 Basic sensors and principles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fysisk institutt - Rikshospitalet Chapter 2 Basic sensors and principles

  2. What is a sensor? Image: Grimnes, Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts. ”A sensor is a mediator able to convert one or more measurands or physical variables into an equivalent signal variable of another type of quantity within a frame of a given unity” Pallàs-Areny, Webster, Sensors 2001

  3. More definitions.... Image: Grimnes-Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts. • Sensor system: ”comprises the total signal path from the measurand to the observer and includes all sensing, conditioning and real-time processing elements in the path” • Electrode: ” An electrode is an electrochemical cell converting charge carriers from ions to electrons or vice versa. An electrode is only a half-sensor in the way that two electrodes are necessary in order to apply a current or read a potential difference in living tissue” • Probe: A ”probe is a broader concept than a sensor. A probe is often comprising multiparameter sensors (e.g. temperature) and may be held by the operator and be equipped with switches and level adjustment facilities. Example: Ultrasound probe” Source: Grimnes-Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

  4. Fysisk institutt - Rikshospitalet Transducer - sensor (føler) - probe Position

  5. Strain gages • - Strain gages: ”are primarily displacement sensors based on variations in the electrical resistance of conductors or semiconductors as a function of mechanical stress” Image: Grimnes, Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts. Image: www.conservationphysics.org

  6. Fysisk institutt - Rikshospitalet Pressure-transducer Strain gauge: R= L/A

  7. Pressure-transducer Strain gauge: R= L/A FYS4250 Fysisk institutt - Rikshospitalet

  8. Pressure transducerand Wheatstone bridge Image: Grimnes-Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

  9. Fysisk institutt - Rikshospitalet Force measurements

  10. Fysisk institutt - Rikshospitalet Force pressure Semiconductor transducer Piezoresistive

  11. Fysisk institutt - Rikshospitalet Plethysmograph = volummåler

  12. Fysisk institutt - Rikshospitalet Inductive displacement sensors L = n2Gμ

  13. Fysisk institutt - Rikshospitalet Linear VariableDifferential Trafo (LVDT) sign problem

  14. Fysisk institutt - Rikshospitalet Position detection, capacitive sensor

  15. Fysisk institutt - Rikshospitalet Piezoelectric transducer C=εA/x

  16. Fysisk institutt - Rikshospitalet Step response

  17. Fysisk institutt - Rikshospitalet 2.ordersystem

  18. Fysisk institutt - Rikshospitalet Temperature measurements, termocouple

  19. Thermocouple • Junction between metal A and B (hot junction), and an isothermal block with an ice bath temperature in connection to a voltmeter • A change in temperature will result in a voltage change readable on the voltmeter Image: Grimnes-Høgetveit.Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

  20. Fysisk institutt - Rikshospitalet Temperature measurement, termistor

  21. Fysisk institutt - Rikshospitalet Radiation thermometry Black body radiation Wiens law: λm=2898/T [μm] Stefan-Boltzmann: Wt=εσT4[W/cm2]

  22. Fysisk institutt - Rikshospitalet Radiation thermometer

  23. Infrared ear thermometer Image: Harsanyi, 2000, p 102

  24. Fysisk institutt - Rikshospitalet Fiberoptical thermometer, non-metallic

  25. Fysisk institutt - Rikshospitalet Optical instrument

  26. Fysisk institutt - Rikshospitalet Radiation sources

  27. Fysisk institutt - Rikshospitalet Light emitting diode (LED)

  28. Fysisk institutt - Rikshospitalet Fiberoptics Snells lov: n2 sinθ2 = n1 sinθ1

  29. Fysisk institutt - Rikshospitalet Photomultipliers

  30. Fysisk institutt - Rikshospitalet Diode as a light detector

More Related