Browsing by Author "Singer, M"

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    Circuit topology and control principle for a first magnetic stimulator with fully controllable waveform.
    (Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference, 2012-01) Goetz, SM; Pfaeffl, M; Huber, J; Singer, M; Marquardt, R; Weyh, T
    Magnetic stimulation pulse sources are very inflexible high-power devices. The incorporated circuit topology is usually limited to a single pulse type. However, experimental and theoretical work shows that more freedom in choosing or even designing waveforms could notably enhance existing methods. Beyond that, it even allows entering new fields of application. We propose a technology that can solve the problem. Even in very high frequency ranges, the circuitry is very flexible and is able generate almost every waveform with unrivaled accuracy. This technology can dynamically change between different pulse shapes without any reconfiguration, recharging or other changes; thus the waveform can be modified also during a high-frequency repetitive pulse train. In addition to the option of online design and generation of still unknown waveforms, it amalgamates all existing device types with their specific pulse shapes, which have been leading an independent existence in the past years. These advantages were achieved by giving up the common basis of all magnetic stimulation devices so far, i.e., the high-voltage oscillator. Distributed electronics handle the high power dividing the high voltage and the required switching rate into small portions.
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    Magnetic stimulation with arbitrary waveform shapes
    (IFMBE Proceedings, 2013-04-16) Goetz, SM; Singer, M; Huber, J; Pfaeffl, M; Marquardt, R; Weyh, T
    Device technology for magnetic stimulation is still extremely limited regarding waveform dynamics and flexibility. Existing systems are well-known to be very inefficient from an energy perspective. In addition, neither a noninvasive analysis of different neuron dynamics nor an adjustment of the pulse waveform for a more specific stimulation is possible with existing equipment as a matter of principle. The uncontrollable high power in the Megawatt range obstructs such aims with classical means. This contribution introduces a novel stimulator technology which gives up the traditions from classical pulse-source topologies. The design forgoes any high-voltage devices in the actual pulse circuitry, but is based on mass-produced high-power lowvoltage components instead. It enables the generation of almost arbitrary waveforms, including all classical waveforms in magnetic stimulation, with a single device. For any of these pulses the field energy, except the unavoidable basic ohmic losses, can be retrieved from the stimulation coil and be fed back into the internal energy storages. This also applies to classical monophasic pulses, which converted all their energy into heat in classical systems. The power requirements of this technology are comparably low accordingly. The combination of switching control and big highly flexible energy storages moreover enables even high pulse trains as in theta-burst protocols with one pulse source. © 2013 Springer-Verlag.