Bioelectromagnetism

1. Bioelectromagnetism By: Engr. Hinesh Kumar (Lecturer)

2. History • First mentioned when the ancient Egyptians had problems catching a particular kind of fish which would give them powerful electric shocks (>450V), forcing them to drop the fish back into the water • In the first medical application of bioelectromagnetism, a similar kind of fish was used to treat headaches and arthritis from 46CE until the 17th century CE.

3. Bio-Magnetism – The Science The principal of bio-magnetism dates back thousands of years and was practiced and described by ancient civilizations thousands of years ago. Bio-magnetism is the science of applying a supplementary magnetic field to living organisms. Today, we are at an exciting junction in the evolution of health care as bio-magnetic therapy is fast becoming one of the most promising new therapeutic interventions.

4. Cont… • Virtually all scientists and science students are aware of bioelectricity (though they may not call it that) • Not many are aware of the importance of biomagnetism: the magnetic fields surrounding all living organisms produced by the internal ongoing electrical activity • Pioneered by David Cohen – 60's, 70's

5. Body Needs Magnetic Energy! Each cellhas a positive & a negative field in the DNA. Cell divisionis a process responsible for keeping the body healthy & rejuvenated. The forcewhich activates the formation and division of cells is magnetic energy. The proper functionand interaction of all organs and systems in the body depend on the constant presence of adequate magnetic energy. Magnetism is essentialfor the body’s electromagnetic activity and plays a major role in health and disease. Body Is An Electro-Magnetic System

7. Definition • Bioelectromagnetism is interdisciplinary since it involves the association of the life sciences with the physical and engineering sciences. • Bioelectromagnetism refers to electric, magnetic, or electromagnetic fields produced by living cells or organisms • Examples: membrane potentials, action potentials, electric currents that flow through nerves/muscles, Brain Oscillations, magnetic field of the heart (EKG), etc

8. Concept of Bioelectromagnetism • Bioelectromagnetism is a discipline that examines the electric, electromagnetic, and magnetic phenomena which arise in biological tissues. These phenomena include: • The behavior of excitable tissue (the sources) • The electric currents and potentials in the volume conductor • The magnetic field at and beyond the body • The response of excitable cells to electric and magnetic field stimulation • The intrinsic electric and magnetic properties of the tissue

9. Figure. 1 recognized interdisciplinary fields that associate physics and engineering with medicine • and biology: • BEN = Bioengineering, • BPH = Biophysics, • BEM = Bioelectromagnetism, • MPH = Medical Physics, • MEN = Medical Engineering, • MEL = Medical Electronics.

10. Cont… • Figure illustrates the relationships between these disciplines. • The coordinate origin represents the more theoretical sciences, such as biology and physics. • Combining a pair of sciences from medical and technical fields yields interdisciplinary sciences such as medical engineering. • It must be understood that the disciplines are actually multidimensional, and thus their two-dimensional description is only suggestive.

11. SUBDIVISIONS OF BIOELECTROMAGNETISMDivision on a Theoretical Basis • The discipline of bioelectromagnetism may be subdivided in many different ways. One such classification divides the field on theoretical grounds according to two universal principles: • Maxwell's equations(the electromagnetic connection) and • the Principle of Reciprocity. • This philosophy is illustrated in Figure 2 and is discussed in greater detail below

12. Maxwell's Equations • Maxwell's equations, i.e. the electromagnetic connection, connect time-varying electric and magnetic fields so that when there are bioelectric fields there always are also biomagnetic fields, and vice versa (Maxwell, 1865). • Depending on whether we discuss electric, electromagnetic, or magnetic phenomena, bioelectromagnetism may be divided along one conceptual dimension (horizontally in Figure 2) into three subdivisions, namely • Bioelectricity • Bioelectromagnetism • Biomagnetism

13. Reciprocity Principle • Owing to the principle of reciprocity, the sensitivity distribution in the detection of bioelectric signals, the energy distribution in electric stimulation, and the sensitivity distribution of electric impedance measurements are the same. • This is also true for the corresponding bioelectromagnetic and biomagnetic methods, respectively. • Depending on whether we discuss the measurement of the field, of stimulation/magnetization, or the measurement of intrinsic properties of tissue

14. Cont… • Bioelectromagnetism may be divided within this framework (vertically in Figure 2) as follows:- • Measurement of an electric or a magnetic field from a bioelectric source or (the magnetic field from) magnetic material. • Electric stimulation with an electric or a magnetic field or the magnetization of materials (with magnetic field) • Measurement of the intrinsic electric or magnetic properties of tissue

15. Fig. 2. Organization of bioelectromagnetism into its subdivisions.

16. From Figure: 2 • From Fig 2, It is first divided horizontally to: • Bioelectricity • Bioelectromagnetism • Biomagnetism • Then the division is made vertically to: • measurement of fields, • stimulation and magnetization, and • measurement of intrinsic electric and magnetic properties of tissue. • The horizontal divisions are tied together by Maxwell's equations and the vertical divisions by the principle of reciprocity.

17. Description of Subdivisions • Measurement of an Electric or a Magnetic Field It refers, essentially, to the electric or magnetic signals produced by the activity of living tissues. In this subdivision of bioelectromagnetism, the active tissues produce electromagnetic energy, which is measured either electrically or magnetically within or outside the organism in which the source lies. This subdivision includes also the magnetic field produced by magnetic material in the tissue. Examples of these fields in the three horizontal subdivisions are shown in Table #1

18. Table 1  I) Measurements of Fields

19. (II) Electric Stimulation with an Electric or a Magnetic Field or the Magnetization of Materials • In this subdivisions electric or magnetic energy is generated with an electronic device outside biological tissues. When this electric or magnetic energy is applied to excitable tissue in order to activate it, it is called electric stimulation or magnetic stimulation, respectively. • This kind of experiment, called electrifying. • Magnetic energy may also be applied for other therapeutic purposes, called electrotherapy or magnetotherapy. • Examples of this second subdivision of bioelectromagnetism, also called electrobiology and magnetobiology, respectively, are shown in Table 2.

20. Table 2   II ) Stimulation and Magnetization

21. (III) Measurement of the Intrinsic Electric or Magnetic Properties of Tissue • As in Subdivision II, electric or magnetic energy is generated by an electronic device outside the biological tissue and applied to it. • However, when the strength of the energy is subthreshold, the passive (intrinsic) electric and magnetic properties of the tissue may be obtained by performing suitable measurements. • Table 3 illustrates this subdivision:

22. Table 3   III ) Measurement of Intrinsic Properties

23. Importance of Bioelectromagnetism • The main reason is that bioelectric phenomena of the cell membrane are vital functions of the living organism. • The cell uses the membrane potential in several ways. With rapid opening of the channels for sodium ions, the membrane potential is altered radically within a thousandth of a second. • Cells in the nervous system communicate with one another by means of such electric signals that rapidly travel along the nerve processes.

24. Cont…. • In the investigation of other modalities, such as biochemical and biophysical events, special transducers must be used to convert the phenomenon of interest into a measurable electric signal. • In contrast electric phenomena can easily be directly measured with simple electrodes. • As a result of the rapid development of electronic instrumentation and computer science, diagnostic instruments, which are based on bioelectric phenomena, have developed very quickly.

25. Cont… • The development of microelectronics has made such equipment portable and strengthened their diagnostic power. Implantable cardiac pacemakers have allowed millions of people with heart problems to return to normal life. • Biomagnetism applications are likewise being rapidly developed and will, in the future, supplement bioelectric methods in medical diagnosis and therapy. • These examples illustrate that bioelectromagnetism is a vital part of our everyday life.