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EGGN 3610 Bioinstrumentation

EGGN 3610 Bioinstrumentation. Dr. Tuinstra 2.1.11. Example Clinical Instruments. Blood Pressure. EKG. Thermometer. Major Manufacturers of Bioinstruments. Basic System. Patient. Clinical Instrument. Analog Processing. Sensor. Analog to Digital. Storage. DSP. Control & Feedback.

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EGGN 3610 Bioinstrumentation

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  1. EGGN 3610Bioinstrumentation Dr. Tuinstra 2.1.11

  2. Example Clinical Instruments Blood Pressure EKG Thermometer

  3. Major Manufacturers of Bioinstruments

  4. Basic System Patient Clinical Instrument Analog Processing Sensor Analog to Digital Storage DSP Control & Feedback Display Transmit

  5. Analog Processing: Important Circuits in Bioinstrumentation Most circuits used in bioinstrumentation circuits involve the use of operational amplifiers

  6. Important Op-amp circuits Inverting Amplifiers

  7. Important Op-amp circuits Differential Amplfier

  8. The key question is: What are the quantities that we will measure?

  9. Biopotential Electrolyte + + Metal Electrolyte - - - - + + - - Electrolyte + + + Electrolyte Half Cell Potential: Voltage arising from the distribution of charge around a metal in an electrolyte

  10. Measuring Biopotential • non-invasive • invasive Electrode 1 Diff Amp Electrode 2

  11. BioSensors-ECG Adhesive Disk ECG: Electrocardiogram, Measures the electrical impulses that are associated with a beating heart. ECG = EKG Snap Connector

  12. Human Heart Anatomy Right side of heart pumps deoxygenated blood to the lungs. Left side of heart pumps oxygenated blood to the rest of the body. Heart beat consists of contraction (systole) and relaxation (diastole).

  13. The Heart Beat The Virtual Heart: http://thevirtualheart.org/anatomyindex.html • Key Terms: • Depolarization: Occurs when interior of heart cells goes from being more negative with respect to the extracellular fluid to more positive. Travels as a wave in the heart. Causes Contraction (systole) • Repolarization: Normal voltage potential balance is regained. Also travels as a wave in the heart (diastole).

  14. ECG (EKG) Signals P-wave: Atrial Depolarization…Left and right atria contract QRS Complex: Ventricular Depolarization…Left and right ventricles contract T-wave: Repolarization of the ventricles

  15. BioSensors-EMG EMG: Electromyography - measures the electrical potential of muscles during contraction and rest. EMG Electrodes

  16. BioSensors-EEG EEG: Electroencephalography Used to monitor brain activity

  17. Physical Measurements • Measurement of Temperature • May be measured electronically using a thermistor • Thermistors present a resistance that changes with temperature

  18. Measuring Motion • Linear Variable Differential Transformer (LVDT)

  19. Other ways to measure linear motion • Strain Gauges • Used in measuring blood pressure (inside the blood pressure cuff)

  20. Measuring Airflow Differential Pressure Screen Fleish Pneumotachometer

  21. Measuring Airflow • Common Airflow Measurements: • Forced Vital Capacity (FVC) • How much air can you exhale in one breath? (litres) • Peak Expiratory Flow (PEF) • What is the maximum rate of exhaling? (litres per second)

  22. Measuring Gases in Blood • What we typically measure: • Oxygen (O2) • Carbon Dioxide (CO2) • pH • These measurements usually made during surgery or while patient is in the ICU.

  23. Measuring Oxygen • Oxygen carried in two places in blood: • Dissolved in plasma (2%) • Attached to hemoglobin (oxyhemoglobin)

  24. Measuring Oxygen - + V A Silver/Silver chloride Gold Electrolyte OH- Cathode Anode O2

  25. Measuring Oxygen • It is possible to measure the oxygen content of blood optically • This follows from the observation that arteries appear red and veins appear blue.

  26. Measuring Oxygen λ1 λ2

  27. Measuring Oxygen

  28. Transmission-type Pulse Oximeter Finger Probe • Measure Red/Infrared Ratio • Digital Signal Processing is used to do the “math”

  29. Microbial Biosensors • Primary Uses: • Detection of pollutants in the atmosphere • Detection of chemical warfare agents • Detection of biological warfare agents • With this technology the biology is in the sensor

  30. Microbial Bio-Sensors Bacteria Biproducts Chemical Agents Electrode

  31. Optical BioSensors • We transmit light into a medium to be tested and measure characteristics about the returned light

  32. Optical BioSensors Computer Detector Optical Fiber Transceiver Material to be tested

  33. BioSignal Processing Patient Analog Processing Sensor Analog to Digital Storage DSP Display Transmit

  34. Where do biosignals come from? • Bioelectric • Biomagnetic • Biochemical • Biomechanical • Bioacoustic

  35. Dr. T’s BioSignal Tree BioSignals Continuous Discrete Random Deterministic Random Deterministic Periodic Aperiodic Periodic Aperiodic

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