a laboratory activity in bioelectrical impedance analysis elliot mylott ([email protected]) sabrina...
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![Page 1: A LABORATORY ACTIVITY IN BIOELECTRICAL IMPEDANCE ANALYSIS Elliot Mylott (emylott@pdx.edu) Sabrina Hoffman Ralf Widenhorn (ralfw@pdx.edu) Physics Department](https://reader036.vdocument.in/reader036/viewer/2022083008/56649ec55503460f94bd030d/html5/thumbnails/1.jpg)
A LABORATORY ACTIVITY IN BIOELECTRICAL IMPEDANCE ANALYSIS
Elliot Mylott ([email protected])Sabrina HoffmanRalf Widenhorn ([email protected])
Physics Department
Portland State University, Portland, OR
European Journal of Clinical Nutrition 63, 619-626 (May 2009)
OMRON Body Fat Analyzer (healthgoods.com)
![Page 2: A LABORATORY ACTIVITY IN BIOELECTRICAL IMPEDANCE ANALYSIS Elliot Mylott (emylott@pdx.edu) Sabrina Hoffman Ralf Widenhorn (ralfw@pdx.edu) Physics Department](https://reader036.vdocument.in/reader036/viewer/2022083008/56649ec55503460f94bd030d/html5/thumbnails/2.jpg)
Bioelectrical Impedance Analysis
OMRON Body Fat Analyzer (healthgoods.com)
RJL Bioelectric Impedance Analyzer (rjlsystems.com\products)
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The Body as an RC Circuit
(Liedtke, Principles of Bioelectrical Impedance Analysis 1997)
•Reactive components due to cellular walls•Resistive components due to both intra- and extracellular fluid•Current flows primarily through Fat Free Mass
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Series Equivalent Circuit
•Body impedance frequency dependant
•Single Frequency BIA uses 50kHz
•More complex body models approximated with series circuit
Single Frequency Series Equivalent
Bio-Impedance Analysis BIAEvaluation of Nutrition and Hydration Status Using Vectorgram and BiaGram,(rjlsystems.com)
![Page 5: A LABORATORY ACTIVITY IN BIOELECTRICAL IMPEDANCE ANALYSIS Elliot Mylott (emylott@pdx.edu) Sabrina Hoffman Ralf Widenhorn (ralfw@pdx.edu) Physics Department](https://reader036.vdocument.in/reader036/viewer/2022083008/56649ec55503460f94bd030d/html5/thumbnails/5.jpg)
Circuit Analysis
22cXRZ
RcXtan tanRcX
2tan1
2
ZR
• Measured Impedance and Phase Leads to Reactance and Resistance
• Comparison of voltage across a known resistor gives gain and phase
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•Current
•Impedance
•Phase
Measurement I – NI ELVIS and LabView
Tto 1360 DAQ must have a high sampling rate.
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Measurement II – Apparatus Competition
Main Components:• Function Generator• Differential Amplifier• Gain / Phase Detector
• Outputs DC Voltage proportional to Z and
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Mass Calculation
Estimate mass of a resistor
Wikipedia, Electrical resistivity and conductivity
In human testing • Cylinder model• Measure of Fat Free Mass• Length Height• Density approximately equal
to that of water• Coefficients and fitting factors
empirically derived
http://nutrition.uvm.edu/bodycomp/bia/lesson4.html
• Example equation to determine total body water (TBW)
Lukaski and Bolonchuk, Aviation Space and Environmental Medicine 59 1163-1169, 1988)
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Multi-frequency BIA
American Journal of Clinical Nutrition 1996; 64: 388S-96S
Students can explore
• Series and Parallel impedance combinations
• More accurate models for human electrical characteristics
• Relationship between frequency and impedance
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Summary
Introductory Physics Level Laboratory Exercise Exploring:
• Resistance, reactance
• Parallel and Series Impedance
• Phasor diagrams and phase shifts
• Waveform measurement
• Resistivity, density and mass
• RC Circuits
• Electrical Characteristics of the body