1. Bioinstrumentation (1)
Mohamed Bingabr, Ph.D. Associate Professor Department of Engineering and Physics University of Central Oklahoma

2. Outlines BME in medical instrumentation
Common components of a measurement system
System with feedback
Biological system with feedback
Medical devices with feedback

3. BME Task
Invent, design, build, and test devices for use in medicine.

4. BME Task
Oversee maintenance of medical instruments and adapting instruments to serve patients and doctors

5. BME Task
Do research and take measurements in research laboratories. (Third eye)

6. Measurement Systems
Sensor: convert an input variable into measurable quantity
Processor: amplification, filtering, comparison, and other mathematical operations.
Receiver: presents readable results

7. Systems With Feedback

8. Feedback – Blood Pressure

9. Feedback – Glucose Production
Normal blood glucose levels: mg/dL
by beta cells
by alpha cells

10. Feedback – ATP Production
ATP: Adenosine Triphosphate
ADP: Adenosine Diphosphate

11. Feedback – Muscle Reflex

12. Systems With Feedback Gain without feedback = H-
x(t)
y(t) H F +
v(t)
Case 1 without feedback
G = H = 10 ± 10%
Case 2 with feedback
H = 100 ± 10%
F= 0.09
G = 10 ± ??%

13. Systems Without Feedback
Example:
The system has a gain of 10 and due to noise the gain may increase or decrease by 10%. In an ideal case the output will be 20 volt if the input is 2 volt. Find the maximum and minimum outputs if the system gain fluctuates by 10%.
x(t)
y(t) H

14. Systems With Feedback Example:
The system with the feedback has a gain of 10. The forward gain H is 100 and the reverse gain F is Due to noise the forward gain H may increase or decrease by 10%. In an ideal case the output will be 20 volt if the input is 2 volt. Find the maximum and minimum outputs if the forward gain fluctuates by 10%. -
x(t)
y(t) H F +
v(t)

15. Cardiac Pacemakers Cardiac Pacemaker:
An electric device that regulate the heart’s beat by producing periodic electric pulses to stimulate the heart’s muscle.

16. Cardiac Pacemakers
Timing Circuit: pulse rate is 70 to 90 pulse per minute
Output Circuit: Constant-Voltage Amplitude pulses: 5.0 to 5.5 V with duration of 0.5 to 0.6 msec.
What is the problem with fixed heart rate?

17. Cardiac Pacemakers with Feedback
Physiological Variable Sensor Right-ventricle blood temperature Thermistor Venous blood oxygen saturation Optical Oximeter

18. Homework 3 (due February 24)
Search for a biological system that uses feedback mechanism and write a paper describing the following points:
What does the feedback regulate.
The mechanism and type of feedback (positive, negative, or both)
What are the measured parameter (proteins, light, heat, pressure, etc..) to determine the states of the body.
How does the feedback maintain the homeostasis of the body.
What are the consequences of the absence of the feedback.
Examples biological feedback:
Controlling the opening and closing of the iris in the Eye
Controlling the stiffness of the outer hair cells in the cochlea of the ear
Controlling the movement of the stapes in the middle ear.
Production of white blood cells
Production of proteins
Muscles and movement