The design and testing of a magnetic biostimulator : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy, Massey University, Palmerston North

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A commercial pulsed electromagnetic field therapy unit, typical of those used in current medical practice, is evaluated. The principle of operation is determined, and the magnetic field output quantified. The unit is trialed on a human subject to verify the manufacturer's claims regarding the physiological responses of both vasoconstriction and vasodilation. The results do not confirm the manufacturer's claims. A programmable magnetic biostimulator is designed and tested. This approach is unique, featuring a transconductance amplifier to drive the stimulation coil. Significant increases in performance are obtained in comparison to standard voltage feedback amplifiers, particularly with rapid rise-time waveforms, such as square waves. The magnetic biostimulator is trialed in a clinical setting on four experimental subjects to determine the claimed vasodilation response of pulsed magnetic fields. Two subjects are normal, healthy individuals, and two have been diagnosed as having Primary Raynaud's Disease, a disorder of peripheral circulation. Various responses are recorded and discussed in the text. The magnetic biostimulator is trialed in a laboratory situation in order to determine the effect of magnetic fields on the cytogenetics of the broad bean, Viciafaba. No significant differences in the number of chromosome or chromatid breaks are recorded between the control and test groups. Significant differences at the 95% probability level between the control and test groups are recorded, however, for various stages of the cell cycle. This finding may imply that various forms of exogenous magnetic fields may affect the cellular mechanisms involved in mitosis. The clinical and laboratory trials verify the effectiveness and practicality of the chosen design. In reviewing the performance of the magnetic biostimulator, suggestions for future implementations are discussed.