fys4250fysisk institutt - rikshospitalet. image: grimnes, høgetveit. biomedical engineering...
TRANSCRIPT
FYS4250 Fysisk institutt - Rikshospitalet
QuickTime™ og en-dekomprimerer
kreves for å se dette bildet.
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?
QuickTime™ og en-dekomprimerer
kreves for å se dette bildet.
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....
FYS4250 Fysisk institutt - Rikshospitalet
Transducer - sensor (føler) - probe Position
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”
QuickTime™ og en-dekomprimerer
kreves for å se dette bildet.
Image: www.conservationphysics.org
Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.
QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressor
are needed to see this picture.
FYS4250 Fysisk institutt - Rikshospitalet
Pressure-transducer
Strain gauge:
R= L/A
FYS4250 Fysisk institutt - Rikshospitalet
Pressure-transducer
Strain gauge:
R= L/A
Pressure transducerand Wheatstone bridge
QuickTime™ and a decompressor
are needed to see this picture.
QuickTime™ and a decompressor
are needed to see this picture.
Image: Grimnes-Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.
FYS4250 Fysisk institutt - Rikshospitalet
Force measurements
FYS4250 Fysisk institutt - Rikshospitalet
Force pressure
Semiconductor transducer Piezoresistive
FYS4250 Fysisk institutt - Rikshospitalet
Plethysmograph = volummåler
FYS4250 Fysisk institutt - Rikshospitalet
Inductive displacement sensors
L = n2Gμ
FYS4250 Fysisk institutt - Rikshospitalet
Linear VariableDifferential
Trafo (LVDT)
sign problem
FYS4250 Fysisk institutt - Rikshospitalet
Position detection, capacitive sensor
FYS4250 Fysisk institutt - Rikshospitalet
Piezoelectric
transducer
C=εA/x
FYS4250 Fysisk institutt - Rikshospitalet
Step response
FYS4250 Fysisk institutt - Rikshospitalet
2.ordersystem
FYS4250 Fysisk institutt - Rikshospitalet
Temperature measurements, termocouple
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
QuickTime™ og en-dekomprimerer
kreves for å se dette bildet.
Image: Grimnes-Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.
FYS4250 Fysisk institutt - Rikshospitalet
Temperature measurement, termistor
]/)([0
00 TTTTt eRR −= β
FYS4250 Fysisk institutt - Rikshospitalet
Radiation thermometry
Black body radiation
Wiens law:λm=2898/T [μm]
Stefan-Boltzmann:Wt=εσT4 [W/cm2]
FYS4250 Fysisk institutt - Rikshospitalet
Radiation thermometer
Infrared ear thermometer
QuickTime™ og en-dekomprimerer
kreves for å se dette bildet.
Image: Harsanyi, 2000, p 102
FYS4250 Fysisk institutt - Rikshospitalet
Fiberoptical thermometer, non-metallic
FYS4250 Fysisk institutt - Rikshospitalet
Optical instrument
FYS4250 Fysisk institutt - Rikshospitalet
Radiation sources
FYS4250 Fysisk institutt - Rikshospitalet
Light emitting diode (LED)
FYS4250 Fysisk institutt - Rikshospitalet
FiberopticsSnells lov: n2 sinθ2 = n1 sinθ1
FYS4250 Fysisk institutt - Rikshospitalet
Photomultipliers
FYS4250 Fysisk institutt - Rikshospitalet
Diode as a light detector