1. Bioinstrumentation 1
Course Overview

2. Course Synopsis
This course provides an intensive coverage to medical electronics and bioinstrumentation. It will cover sensors and instrumentation for medical applications, as well as measurement of biosignals, such as electrocardiogram (ECG), electroencephalography (EEG), blood pressure and respiratory system.
At the end of the course, the students are expected to provide clear understanding in various medical instrumentation principles and demonstrate the ability to apply, evaluate and integrate basic sensors and design basic electronic circuits for medical applications.

3. Course Outcomes (COs) CO1
Ability to identify, apply and distinguish sensors and transducers for measurement of biological parameters in medical instrumentation system.
CO2
Ability to discuss, explain and analyse design requirements and constraints for specific medical devices
CO3
Ability to design, assemble, analyse, and evaluate basic circuits in medical instrumentation.

4. Course Evaluation 30 Final Examination : 60% Mid Term Exam : 10%
Laboratory :
Assignments/Quiz :
Total Mark :
100% 30

5. List of References
Webster, J.G. (2009). Medical Instrumentation: Application and Design. 4th Ed., Wiley.
Khandpur, RS (2003). Handbook of Biomedical Instrumentation. 2nd Ed. Tata McGraw-Hill
Carr, J.J. (2000). Introduction to Biomedical Equipment Technology. 4th Ed. Prentice Hall.

6. Academic Staff Members
Lecturers
Dr. Shuhaida Yahud
Dr. Hanafi Mat Som

7. Academic Staff Members
Teaching Engineer (PLV)
En. Fauzi Mahmood

8. Teaching Plan Week Course Content 1
Principles of medical instrumentation - SY
2-3
Medical sensors and transducers - SY
4-5
Origin of biopotential signals - SY
6-7
Amplifiers and filters - HMS 9
Electrocardiogram (ECG) - HMS
Mid Term Exam 10
Electroencephalogram (EEG) - HMS 11
Other Biomedical Recorders - HMS
12-13
Measurement of Blood Pressure - HMS
14-15
Measurement of Blood Volume and Flow - SY

9. Laboratory Week Title 2 Lab 1: Measurement Circuit 6
Lab 2: Pre-Amplifier

10. TIME TABLE LECTURE & LAB
Lab (MN4BO)
TUTORIAL
WILL BE INFORM

12. Basic Concepts of Medical Instrumentation
Bioinstrumentation I
Basic Concepts of Medical Instrumentation

13. Contents Principles of Medical Instrumentation
Generalized Medical System
Sources of Biomedical Signals
Classification of Medical Devices
System Static & Dynamic Characteristics
General Design Criteria & Process
General & Additional Design Constraints

14. Medical Instrumentation
The primary purpose of medical instrumentation system is to measure or determine the presence of some physical quantity. (is that all?)
Aimed to aid medical personnel in making:
Diagnosis
Treatment
The majority of the instruments are electrical or electronic systems, although mechanical systems are also employed.
Give two (2) examples of mechanical-based medical instrument.

15. Diagnostic Equipments
Stethoscope
Ultrasound Machine

16. Diagnostic Equipments
Mobile C-Arm
ECG Machine

17. Therapeutic Devices
Defibrillator Monitor
Volumetric Infusion Pump

18. Therapeutic Devices Ventilator
Transcutaneous Electrical Nerve Stimulator (TENS)

19. Generalized Medical System
MEASURAND
SENSORS
OUTPUT DISPLAY
SIGNAL CONDITIONING
Radiation, electric current, or other applied energy
Calibration signal
Data storage
Data transmission
Control and feedback
Power source
Perceptible output
Generalized block diagram of a medical system

20. Generalized Medical System
The primary flow of information is from the measurand to the output display.
Elements and connections shown by dashed lines are optional for some applications.
Compare an advanced ECG instrumentation system with a simple mercury thermometer.
The major difference between the medical and conventional instrumentation systems:
Source from living tissue
Energy applied to living tissues

21. System Components Measurand
The physical quantity, property, or condition that the system measures.
The accessibility of the measurand is important because it may be:
Internal (eg. blood pressure)
On the body surface (eg. electrocardiogram potential)
Emanate from the body (eg. infrared radiation)
Derived from a tissue sample (eg. blood or biopsy)
The medically important measurands will be discussed later under the topic of ‘Sources of Biomedical Signals’.

22. System Components Sensors
Generally, transducer is defined as a device that converts one form of energy to another.
A sensor converts the physical measurand to an electrical output.
It should be selective (only respond to the energy in the measurand, to the exclusion of all others).
Should interface with the living system is a way that minimizes the energy extracted, while being minimally invasive.

23. System Components Signal Conditioning Output Display
Simple signal conditioner amplifies, filter or merely match the impedance of the sensor to the display.
Often, sensor outputs are converted to digital form and processed by specialized digital circuits or a microcomputer.
Output Display
The results must be displayed in a form that a human operator can perceive (eg. numerical or graphical).
Although most display rely on visual senses, some may best be perceived by other senses (eg. auditory sense).

24. System Components Auxiliary Component
A calibration signal with properties of the measurand should be applied to the sensor input or as early in the signal-processing chain as possible.
Many forms of control and feedback may be required to elicit the measurand, to adjust the sensor and signal conditioner, and to direct the flow of output for display, storage or transmission. May be automatic or manual.

25. System Components Auxiliary Component
Data may be stored briefly to meet requirements of signal conditioning or to enable operator to examine the data that precede alarm conditions. Or data may be stored before signal conditioning, so that different processing schemes can be utilized.
Conventional principles of communication can often be used to transmit data to remote displays at nurses’ stations, medical centers, or medical data-processing facilities.

26. Device Operational Modes
Direct Mode
Indirect Mode
Direct measurement of accessible measurands
Indirect measurement of inaccessible measurands
Sampling Mode
Continuous Mode
Infrequent monitoring of slow changing measurands
Frequent monitoring of vital measurands
Generating Sensors
Modulating Sensors
Produce signal output from energy taken directly from the measurand
The measurand alters the energy flow from the external source

27. Device Operational Modes
Analogue Mode
Digital Mode
Continuous signal able to take any value within a dynamic range
Discrete signal only able to take on a finite number of values
Real-Time Mode
Delayed-Time Mode
The sensors measure and the results are displayed almost immediately
The results are delayed due to considerable signal processing

28. Sources of Biomedical Signals

29. Sources of Biomedical Signals
Bioelectrical
Membrane potentials generated by nerve and muscle cells.
Eg. electrocardiogram, electromyogram signals etc.

30. Sources of Biomedical Signals
Bioacoustics
Acoustic signals created by biomedical phenomena.
Eg. sound from heart valves, air flow in the lung etc.

31. Sources of Biomedical Signals
Biomechanical
Originate from mechanical functions of biological system.
Eg. displacement, pressure and flow signals.

32. Sources of Biomedical Signals
Biochemicals
Resultant of chemical measurement from living tissues or samples.
Eg. Concentration of various ions in the blood.

33. Sources of Biomedical Signals
Biomagnetics
Weak magnetic signals produced by various organs.
Eg. MEG signals from the brain.

34. Sources of Biomedical Signals
Bio-Opticals
Generated as a result of optical functions from the biological system.
Eg. Modified IR absorption due to blood oxygenation.

35. Sources of Biomedical Signals
Bioimpedance
Tissue impedance that gives information regarding its composition, blood volume etc.
Eg. Galvanic skin resistance, respiratory rate etc.

36. Classification of Medical Devices
(Viewpoints)
Quantity Sensed
(eg. temperature, flow, pressure etc)
Principles of Transduction
(eg. resistive, capacitive, inductive, ultrasonic etc)
Clinical Medicine Specialties
(eg. pediatrics, obstetrics, cardiology, radiology etc)
Organ System
(eg. cardiovascular, pulmonary, nervous etc)

37. Instrument Characteristics
Characteristics of instrument performance are usually subdivided into static and dynamic characteristics which are based on the frequency of the input signals.
This provides a quantitative criteria for the performance of instruments that are needed.
These criteria must clearly specify how well an instrument measures the desired input and how much output depends on interfering and modifying inputs.

38. Static Characteristics
Describes the performance of instruments for dc or very low frequency inputs.
The properties of the output for a wide range of constant inputs demonstrate the quality of the measurement, including non-linear and statistical effects.
Some sensors and instruments, such as piezoelectric device, responds only to time-varying inputs and have no static characteristics.

39. Static Characteristics
Accuracy & Precision (Which is which?)

40. Static Characteristics
Accuracy & Precision
Accuracy refers to the degree of conformity between the measurand and the standard.
Precision refers to the degree of refinement of measurement.
Resolution is the smallest incremental quantity that can be measured with certainty.
Repeatability is the ability of the instrument to give the same output for equal inputs applied over some period of time.

41. Static Characteristics
Statistical control ensures that random variations in measured quantities that result from all factors that influence the measurement process is tolerable.
Static sensitivity is the ratio of the incremental output quantity to the incremental input quantity.
Zero drift occurs when all the output values increase or decrease by the same absolute amount.
Sensitivity drift causes error that is proportional to the magnitude of input.

42. Static Characteristics
Static sensitivity

43. Static Characteristics
Static sensitivity

44. Static Characteristics
Linearity
If y1=x1 and y2=x2, y1+y2=x1+x2 and Ky1=Kx1.
Input ranges
Normal linear operating range specifies the maximal inputs that give linear output.
Input impedance
Ratio of the phasor equivalent of a steady-state effort input to flow input variable.

45. Dynamic Characteristics
Dynamic characteristics require the use of differential or integral equations to describe the quality of the measurements.
Transfer functions are used to predict the output of a system.
Zero-order instruments
A derivative where the output is proportional to the input for all frequencies.
Eg. Linear potentiometer.
First-order instruments
Devices that have a single energy storage element.
Eg. Low-pass RC filter.

46. Dynamic Characteristics
Second-order instruments
Instruments that need a second-order differential equation to describe its dynamic response.
Eg. Force-measuring spring scale.
Time delay
Instruments that produce exactly the same output as input, however with delayed time.
Eg. Equipments that require significant signal processing schemes.

47. General Design Criteria
Signal considerations
Type of sensor, sensitivity range, input impedance, frequency response, accuracy, linearity, reliability, differential or absolute input.
Environmental considerations
Signal-to-noise ratio, stability with regards to temperature, pressure, humidity, acceleration, shock, vibration, radiation etc.

48. General Design Criteria
Medical factors
Invasive or non-invasive technique, patient discomfort, radiation and heat dissipation, electrical safety, material toxicity etc.
Economic factors
Initial cost, cost and availability of consumables and compatibility with existing equipment.

49. General Design Process
Initial instrument design
Prototype tests
Final instrument design
FDA BMD approval
Production
Measurand
Economic factors
Medical factors
Environmental considerations
Signal considerations

50. General Design Constraints
Measurement range
Most physiological parameters are in the range of microvolts (µV).
Frequency range
The medical signals are in the range of audio-frequencies and lower. Contains dc and low frequency components.

51. Additional Design Constraints
Inaccessibility of the signal source
Variability of physiological parameters
Transducer interface problems
High possibility of artifacts
Safe levels of applied energy
Patient safety considerations
Reliability aspects
Human factor considerations
Government regulations

52. Further Reading…
Webster, J.G. (2009). Medical Instrumentation: Application and Design. 4th Ed., Wiley.
Chapter 1
Khandpur, RS (2003). Handbook of Biomedical Instrumentation. 2nd Ed. Tata McGraw-Hill
Carr, J.J. (2000). Introduction to Biomedical Equipment Technology. 4th Ed. Prentice Hall.
Chapter 1 & 4