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.

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

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

Photomultipliers FYS 4250 Fysisk institutt Rikshospitalet

Membrane potential Nernst equation for potassium K (Nor - Kalium): across a cell membrane with active channels pumping K ions into the cell.

Dipoles in the axon

Neural velocity

The heart

Atrioventricularblock

Ectopic beat

Tachycardia flutter= increased regular frequency

flimmer (norsk) = fibrillation (eng) = = uregelmessig rytme

Ischemia

Metal / electrolyte = electron / ion transitions

Ag / Ag. Cl Non-polarizable electrode

Electrode polarization + skin + deeper layer

Stimulation electrodes

Einthoven triangle

Wilson central terminal

Augmented leads

”Driven right leg”

Biopotentail amplifiers

The circulatory system

Typical blood pressures

Invasive blood pressure measurement

Harmonic analysis, Fourier

Heart sounds

Stethoscopes, spektrogram

Non-invasive blood pressure

Ultrasound measurement

Bloodpressure, oscillometric

Non-contact tonometry

Indicator-dilution method

Elektromagnetic flowmeter

Electromagnetic flowmeter waveforms

Quadrature-suppression flowm.

Plethysmography

Plethysmography curve

Figure 1 Airways with larynx, trachea, bronchi and alveoles

Figure 2 Lung volume parameters Equation 1 Compliance C = ΔV / ΔP [L/Pa, L/cm. H 2 O]

Equation 2 Poiseuille [Pa/m 3/s = pressure / flow rate]

Figure 6 Laplace cylinder model P=T/r

Figure 10 Rebreathing circle with one-directional valves 1 and 2

Figure 13 IR absorption spectra for some anaesthetic agent vapours. Datex Ohmeda Division, Instrumentarium Corporation

Figure 14 Multigas spectrophotometric gas analyzer with rotating filter wheel

p. H-measurement

p. CO 2 (Severinghaus) electrode

p. O 2 (Clark) electrode

Fluorescent dye sensor

p. H-sensitive dyes

Pulsoxymetry light absorption