The electrical engineering handbook SN11

The electrical engineering handbook

Bronzino, J.D “Section XI – Biomedical Systems”

The Electrical Engineering Handbook

Ed Richard C Dorf

Boca Raton: CRC Press LLC, 2000

Essential tremor is the most common neurological movement disorder in the U.S The condition afflicts more than one million people, usually age 45 and older, in the U.S alone Thanks to Medtronic, Inc., the world’s leading medical technology company specializing in implantable and invasive therapies, help for this debilitating condition is in sight

The Activa Tremor Control System, shown above, uses an implanted device, similar to a cardiac pacemaker,

to deliver electrical stimulation to block or override brain signals that cause tremor The system allows the stimulation level to be adjusted to the needs of each patient

Patients in Canada, Europe, and Australia are already using the Activa Tremor Control System In the U.S

it has been recommended unanimously for marketing clearance by the Neurological Device Panel Advisory

Biomedical Systems

Neuroelectric Principles • Bioelectric Events • Application of Electrical and Magnetic Fields in Bone and Soft Tissue Repair

Physical Sensors • Chemical Sensors • Bioanalytical Sensors • Applications • Summary

W.M Smith

The Electroencephalogram • The Electrocardiograph • Pacemakers/Implantable Defibrillators

Tomography • Ultrasound • Semiconductor Detectors for Radiation Measurements

Clinical Information Systems • Hospital Information Systems

Joseph D Bronzino

Trinity College

ECHNOLOGICAL INNOVATION in the twentieth century has progressed at such an accelerated pace that it has permeated almost every facet of our lives This is especially true in the field of medicine and the delivery of health care services Although the art of medicine has a long history, the evolution of a health care system capable of providing a wide range of positive therapeutic treatments in the prevention and cure of illnesses is a decidedly new phenomenon Of particular importance in this evolutionary process has been the establishment of the modern hospital as the center of a technologically sophisticated health care system

In the process, the discipline of biomedical engineering has emerged as an integrating medium for two dynamic professions, medicine and engineering, assisting in the struggle against illness and diseases by providing materials, tools, and techniques (such as signal and image processing and artificial intelligence) that can be utilized for research, diagnosis, and treatment by health care professionals

Today, biomedical engineering is an interdisciplinary branch of engineering heavily based both in engineering and in the life sciences It ranges from theoretical, nonexperimental undertakings to state-of-the-art applica-tions It can encompass research, development, implementation, and operation Accordingly, like medical practice itself, it is unlikely that any single person can acquire expertise that encompasses the entire field As a result, there are now a great number of biomedical engineering specialists to cover this broad spectrum of activity Yet because of the interdisciplinary nature of this activity, there is considerable interplay and overlapping

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of interest and effort between them For example, biomedical engineers engaged in the development of bio-sensors may interact with those interested in prosthetic devices to develop a means to detect and use the same bioelectric signal to power a prosthetic device Those engaged in automating the clinical chemistry laboratory may collaborate with those developing expert systems to assist clinicians in making clinical decisions based upon specific laboratory data The possibilities are endless

There are seven major career areas in biomedical engineering: (1) application of engineering system analysis and modeling (computer simulation) to biological problems; (2) measurement or monitoring of physiological signals; (3) diagnostic interpretation via signal processing techniques of bioelectric data; (4) therapeutic and rehabilitation procedures and devices; (5) prosthetic devices for replacement or augmentation of bodily func-tions; (6) computer analysis of patient-related data; and (7) medical imaging, i.e., the graphic display of anatomical detail or physiological function Biomedical engineers, therefore, engage in the following pursuits:

• Design of instrumentation for human physiology research

• Monitoring astronauts and maintenance of life in space

• Research in new materials for implanted artificial organs

• Development of new diagnostic instruments for blood analysis

• Computer modeling of the function of the human heart

• Writing software for analysis of medical research data

• Analysis of medical device hazards for the U.S government

• Monitoring the physiological functions of animals

• Development of new diagnostic imaging systems

• Design of telemetry systems for patient monitoring

• Design of biomedical sensors for measurement of human physiological systems variables

• Research on artificial intelligence (AI) and development of expert systems for diagnosis of diseases

• Design of closed-loop control systems for drug administration

• Modeling of the physiological systems of the human body

• Design of instrumentation for sports medicine

• Development of new dental materials

• Design of computers and communication aids for the handicapped

• Research in pulmonary fluid dynamics (biorheology)

• Study of the biomechanics of the human body

This list is not intended to be all-inclusive, for there are many other applications that utilize the talents and skills of the biomedical engineer In fact, the list of activities of biomedical engineers depends upon the medical environment in which they work This is especially true for the “clinical engineers,” i.e., biomedical engineers employed in hospitals or clinical settings

The utilization of biomedical engineers offers great potential benefit in the identification of problems and needs of our present health care delivery system that can be solved using existing engineering technology and systems methodology Consequently, the field of biomedical engineering offers hope in the continuing battle

to provide high-quality health care at reasonable cost The purpose of this section, therefore, is to provide a broad overview of biomedical engineering topics of interest to electrical engineers

C proton density

D lateral beamwidth

F Faraday constant

Γ pressure reflection coefficient

I mt minimum threshold current A

k propagation constant

n valence of ion

R universal gas constant

W nodal gap width

Z valence of substance