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FYS4250Fysisk institutt - Rikshospitalet. Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary.

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Presentation on theme: "FYS4250Fysisk institutt - Rikshospitalet. Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary."— Presentation transcript:

1 FYS4250Fysisk institutt - Rikshospitalet

2 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 What is a sensor?

3 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. More definitions....

4 FYS4250Fysisk 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: Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

6 FYS4250Fysisk institutt - Rikshospitalet Pressure- transducer Strain gauge: R=  L/A

7 FYS4250Fysisk institutt - Rikshospitalet Pressure- transducer Strain gauge: R=  L/A

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

9 FYS4250Fysisk institutt - Rikshospitalet Force measurements

10 FYS4250Fysisk institutt - Rikshospitalet Force pressure Semiconductor transducer Piezoresistive

11 FYS4250Fysisk institutt - Rikshospitalet Plethysmograph = volummåler

12 FYS4250Fysisk institutt - Rikshospitalet Inductive displacement sensors L = n 2 Gμ

13 FYS4250Fysisk institutt - Rikshospitalet Linear Variable Differential Trafo (LVDT) sign problem

14 FYS4250Fysisk institutt - Rikshospitalet Position detection, capacitive sensor

15 FYS4250Fysisk institutt - Rikshospitalet Piezoelectric transducer C=εA/x

16 FYS4250Fysisk institutt - Rikshospitalet Step response

17 FYS4250Fysisk institutt - Rikshospitalet 2.order system

18 FYS4250Fysisk 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 FYS4250Fysisk institutt - Rikshospitalet Temperature measurement, termistor

21 FYS4250Fysisk institutt - Rikshospitalet Radiation thermometry Black body radiation Wiens law: λ m =2898/T [μm] Stefan-Boltzmann: W t =εσT 4 [W/cm 2 ]

22 FYS4250Fysisk institutt - Rikshospitalet Radiation thermometer

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

24 FYS4250Fysisk institutt - Rikshospitalet Fiberoptical thermometer, non-metallic

25 FYS4250Fysisk institutt - Rikshospitalet Optical instrument

26 FYS4250Fysisk institutt - Rikshospitalet Radiation sources

27 FYS4250Fysisk institutt - Rikshospitalet Light emitting diode (LED)

28 FYS4250Fysisk institutt - Rikshospitalet Fiberoptics Snells lov: n 2 sinθ 2 = n 1 sinθ 1

29 FYS4250Fysisk institutt - Rikshospitalet Photomultipliers

30 FYS4250Fysisk institutt - Rikshospitalet Diode as a light detector


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