FYS 4250 Fysisk institutt Rikshospitalet What is a

FYS 4250 Fysisk institutt Rikshospitalet

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

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 halfsensor 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.

Transducer - sensor (føler) - probe Position FYS 4250 Fysisk institutt Rikshospitalet

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

Pressuretransducer Strain gauge: R= L/A FYS 4250 Fysisk institutt Rikshospitalet

Pressuretransducer Strain gauge: R= L/A FYS 4250 Fysisk institutt Rikshospitalet

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

Force measurements FYS 4250 Fysisk institutt Rikshospitalet

Semiconductor transducer Piezoresistive Force pressure FYS 4250 Fysisk institutt Rikshospitalet

Plethysmograph = volummåler FYS 4250 Fysisk institutt Rikshospitalet

Inductive displacement sensors L = n 2 Gμ FYS 4250 Fysisk institutt Rikshospitalet

Linear Variable Differential Trafo (LVDT) sign problem FYS 4250 Fysisk institutt Rikshospitalet

Position detection, capacitive sensor FYS 4250 Fysisk institutt Rikshospitalet

Piezoelectric transducer C=εA/x FYS 4250 Fysisk institutt Rikshospitalet

Step response FYS 4250 Fysisk institutt Rikshospitalet

2. order system FYS 4250 Fysisk institutt Rikshospitalet

Temperature measurements, termocouple FYS 4250 Fysisk institutt Rikshospitalet

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.

Temperature measurement, termistor FYS 4250 Fysisk institutt Rikshospitalet

Radiation thermometry Black body radiation Wiens law: λm=2898/T [μm] Stefan-Boltzmann: Wt=εσT 4 [W/cm 2] FYS 4250 Fysisk institutt Rikshospitalet

Radiation thermometer FYS 4250 Fysisk institutt Rikshospitalet

Infrared ear thermometer Image: Harsanyi, 2000, p 102

Fiberoptical thermometer, non-metallic FYS 4250 Fysisk institutt Rikshospitalet

Optical instrument FYS 4250 Fysisk institutt Rikshospitalet

Radiation sources FYS 4250 Fysisk institutt Rikshospitalet

Light emitting diode (LED) FYS 4250 Fysisk institutt Rikshospitalet

Snells lov: n 2 sinθ 2 = n 1 sinθ 1 FYS 4250 Fysisk institutt Rikshospitalet Fiberoptics

Photomultipliers FYS 4250 Fysisk institutt Rikshospitalet

Diode as a light detector FYS 4250 Fysisk institutt Rikshospitalet