Wireless power transfer for implantable biomedical devices using adjustable magnetic resonance
Date
2016-05-03
Authors
Badr, Basem M.
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Abstract
Rodents are essential models for research on fundamental neurological processing and for testing of therapeutic manipulations including drug efficacy studies. Telemetry acquisition from rodents is important in biomedical research and requires a long-term powering method. A wireless power transfer (WPT) scheme is desirable to power the telemetric devices for rodents. This dissertation investigates a WPT system to deliver power from a stationary source (primary coil) to a moving telemetric device (secondary coil) via magnetic resonant coupling. The continuously changing orientation of the rodent leads to coupling loss/problems between the primary and secondary coils, presenting a major challenge. We designed a novel secondary circuit employing ferrite rods placed at specific locations and orientations within the coil. The simulation and experimental results show a significant increase of power transfer using our ferrite arrangement, with improved coupling at most orientations. The use of a medium-ferrite-angled (4MFA) configuration further improved power transfer. Initially, we designed a piezoelectric-based device to harvest the kinetic energy available from the natural movement of the rodent; however, the harvested power was insufficient to power the telemetric devices for the rodents. After designing our 4MFA device, we designed a novel wireless measurement system (WMS) to collect real-time performance data from the secondary circuit while testing WPT systems. This prevents the measurement errors associated with voltage/current probes or coaxial cables placed directly into the primary magnetic field. The maximum total efficiency of our novel WPT is 14.1% when the orientation of the 4MFA is parallel to the primary electromagnetic field, and a current of 2.0 A (peak-to-peak) is applied to the primary coil. We design a novel controllable WPT system to facilitate the use of multiple secondary circuits (telemetric devices) to operate within a single primary coil. Each telemetric device can tune or detune its resonant frequency independently of the others using its internal control algorithm.
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Keywords
Wireless Power Transfer, Biomedical Applications, Telemetric Devices, Implantable Devices, Magnetic Resonance, Energy Harvesting, Piezoelectric