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Investigation of Ultrasonically Powered Implantable Microdevices for Wireless Tissue Impedance MeasurementsJanuary 2015 (has links)
abstract: Bioimpedance measurements have been long used for monitoring tissue ischemia and blood flow. This research employs implantable microelectronic devices to measure impedance chronically as a potential way to monitor the progress of peripheral vascular disease (PVD). Ultrasonically powered implantable microdevices previously developed for the purposes of neuroelectric vasodilation for therapeutic treatment of PVD were found to also allow a secondary function of tissue bioimpedance monitoring. Having no structural differences between devices used for neurostimulation and impedance measurements, there is a potential for double functionality and closed loop control of the neurostimulation performed by these types of microimplants. The proposed technique involves actuation of the implantable microdevices using a frequency-swept amplitude modulated continuous waveform ultrasound and remote monitoring of induced tissue current. The design has been investigated using simulations, ex vivo testing, and preliminary animal experiments. Obtained results have demonstrated the ability of ultrasonically powered neurostimulators to be sensitive to the impedance changes of tissue surrounding the device and wirelessly report impedance spectra. Present work suggests the potential feasibility of wireless tissue impedance measurements for PVD applications as a complement to neurostimulation. / Dissertation/Thesis / Masters Thesis Bioengineering 2015
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Wide-Range Highly-Efficient Wireless Power Receivers for Implantable Biomedical SensorsOuda, Mahmoud 11 1900 (has links)
Wireless power transfer (WPT) is the key enabler for a myriad of applications,
from low-power RFIDs, and wireless sensors, to wirelessly charged electric vehicles,
and even massive power transmission from space solar cells. One of the major challenges in designing implantable biomedical devices is the size and lifetime of the
battery. Thus, replacing the battery with a miniaturized wireless power receiver
(WPRx) facilitates designing sustainable biomedical implants in smaller volumes for
sentient medical applications. In the first part of this dissertation, we propose a miniaturized, fully integrated, wirelessly powered implantable sensor with on-chip antenna, designed and implemented in a standard 0.18μm CMOS process. As a batteryless device, it can be implanted once inside the body with no need for further invasive surgeries to replace batteries. The proposed single-chip solution is designed for intraocular pressure monitoring (IOPM), and can serve as a sustainable platform for implantable devices or IoT nodes. A custom setup is developed to test the chip in a saline solution with electrical properties similar to those of the aqueous humor of the eye. The proposed chip, in this eye-like setup, is wirelessly charged to 1V from a 5W transmitter 3cm away from the chip.
In the second part, we propose a self-biased, differential rectifier with enhanced
efficiency over an extended range of input power. A prototype is designed for the
medical implant communication service (MICS) band at 433MHz. It demonstrates
an efficiency improvement of more than 40% in the rectifier power conversion efficiency
(PCE) and a dynamic range extension of more than 50% relative to the conventional
cross-coupled rectifier. A sensitivity of -15.2dBm input power for 1V output voltage
and a peak PCE of 65% are achieved for a 50k load. In the third part, we propose
a wide-range, differential RF-to-DC power converter using an adaptive, self-biasing
technique. The proposed architecture doubles the dynamic range of conventional
rectifiers. Unlike the continuously self-biased rectifier proposed in the second part,
this adaptive rectifier extends the dynamic range while maintaining both the high
PCE peak and the sensitivity advantage of the conventional cross-coupled scheme,
and can operates in the GHz range.
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Textile Integrated Induction : Investigation of Textile Inductors for Wireless Power TransferYring, Malin January 2016 (has links)
This research has its basis in developments within the field of inductive powering and wireless power transfer, WPT, and more specifically one the branch within this field, which is called magnetic resonance coupling. This principle enables efficient power transfer from a transmitting unit to a receiving unit at a distance of some times the unit diameter. The developments within magnetic resonant coupling are together with the possibilities and challenges of today’s smart textile industry the starting point to investigate a novel textile-based product concept for WPT by combining both technologies. Multiple textile samples, consisting of cotton and electrically conductive copper yarns, were produced by weaving technique, additional assembling of electronic components were performed manually and several measurements were carried out to investigate the sample characteristics and the sample performance in terms of power transfer. The produced samples showed to behave similarly to conventional inductors and were able to transfer power over some distance.
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Capacitive Wireless Power Transfer to Biomedical Implants: Link Design, Implementation, and Related Power Management Integrated CircuitryErfani, Reza 02 September 2020 (has links)
No description available.
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