Introduction to Biomedical Instrumentation

• Bio-medical engineering is aimed at keeping people healthy and helping to cure them when they are ill. 
• In general, the term bio-medical is used for the field. The term, bio-medical instrumentation is used for the methods of measurement within the field.
• The electrocardiograph first used by Einthoven at the end of the nineteenth century.
• Physiological parameters are not measured in the same way as physical parameters. 
• The branch of science that includes the measurements of physiological variables and parameters is known as bio-metrics. Bio-medical instrumentation provides the tools by which these measurements can be achieved.
• Function: Bio-medical Instrumentation is to aid the medical clinician and researcher in devising ways of obtaining reliable and meaningful measurements from living human being.
• Man Instrument System: The overall system, which includes both the human organism and the instrumentation required for the measurement of a human.
• Component of Man Instrument System: Subject, Stimulus, Transducer, Signal Conditioning equipment, Display Equipment, 'Recording, Data Processing and Transmission Equipment' and Control Devices.
• Objective and Goal: Information gathering, Diagnosis, Evaluation, Monitoring, Control. The Goal is to make possible the measurement of information communicated by the various elements of the human body.

Types

1. Clinical - It is devoted to the diagnosis, care and treatment of patients.
2. Research - It is used primarily in the search for new knowledge pertaining to the various systems that compose the human organism.

Types of Measurements

1. Vivo - It is made on or within the living organism itself. For Example - A device inserted into the blood stream to measure the pH of the blood directly.
2. Vitro - It is performed outside the body, even though it relates to the functions of the body. For Example - pH of a sample of blood.

Major Physiological Systems of the body

1. The Bio-chemical System - Chemical Systems that produce energy for the activity of the body, messenger agents for communication, materials for body repair and growth and substances required to carry out the various body functions.
2. The Cardiovascular System - A complex, closed hydraulic system with a four chamber pump i.e. the Heart, connected to flexible and sometimes elastic tubing i.e. blood vessels.
3. The Respiratory System - The pneumatic system of the body. 
4. The Nervous System - Communication network for the body. If a certain section is damaged, other section can adapt and eventually take over the function of the damaged section.

Problems encountered in measuring a living system 

1. Inaccessibility of variables to measurements.
2. Variability of the data. 
3. Lack of knowledge about interrelationships.
4. Interaction among physiological systems.
5. Effect of the transducer on the measurement.
6. Energy limitations.
7. Safety considerations.

Author:

Paramjeet Singh Jamwal, M.Tech Scholar, Sant Longowal Institute of Engineering and Technology (SLIET), Longowal, Punjab, INDIA.

Reference: 

Leslie Cromwell, Fred J. Weibell, Erich A. Pfeiffer, "Biomedical Instrumentation and Measurements", Pearson Education.