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Title: Design and study of noninvasive electric and magnetic stimulation circuits
Authors: Ganesh Bharadwaj CV.
Keywords: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
DRNTU::Engineering::Electrical and electronic engineering::Integrated circuits
DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
DRNTU::Engineering::Electrical and electronic engineering::Applications of electronics
Issue Date: 2013
Abstract: The need for stimulation modalities capable of relieving diseases without surgical complications has motivated researchers to move to non-invasive or minimally invasive stimulation. Nerve stimulation is intended to help patients suffering from diseases like chronic pain, depression, osteoarthritis of knee joints e.t.c, for whom pharmacological or surgical options are in-effective or limited. The design of these stimulators requires careful understanding of the nerve mechanism during stimulation and also correspondingly choosing stimulator parameters for effective disease cure. The aim of this project is to investigate and design non-invasive pulsed radiofrequency and magnetic stimulator capable of nerve stimulation. Pulsed radiofrequency is a method by which repetitive burst-like electric currents at RF frequencies are applied. Magnetic stimulation is another treatment modality, using changing magnetic flux to drive electric currents, thereby stimulating the nerve. Mathematical analysis of the nerve during stimulation is performed so as to get a basis for circuit design. This is followed by developing the circuits for performing stimulation using the aforementioned methods. The requirements of the pulsed radiofrequency electric stimulator is to provide burst like electric currents at RF frequencies, which are charge balanced to the nerve, at settings provided by the clinical practitioner. Desirable properties are low voltage, large current compliance, high output impedance, low average power consumption and small silicon area. The Pulsed Radiofrequency system is designed using a voltage controlled oscillator, biphasic signal generation circuit, a CMOS Schmitt trigger to convert sine wave to a pulsed waveform, a clock generator, logic circuits and current buffer. These sub-blocks work in unison in providing a biphasic pulse signal that can be programmed to oscillate at different frequencies and also provide variable pulse width and pulse duration. The circuit is designed on a 0.18 μm CMOS process. High programmability will enable doctors to test the use of the system and estimate the optimum settings for the patients. A magnetic stimulator is also designed which uses the principle of magnetic resonance to increase the electric field at the nerve. This involved placing ferrite cores in the source coil for flux concentration and ferrite cores and coils below the tissue. Electromagnetic simulations and study and design of coils for performing wireless power transfer were performed. Maximum electric field improvement of 122 % at a frequency of 450 KHz was obtained compared to the case when only source coil was used.
Fulltext Permission: restricted
Fulltext Availability: With Fulltext
Appears in Collections:EEE Theses

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