WIRELESS POWER TRANSFER TO BIOMEDICAL IMPLANTS

Ph.DDOCTOR OF PHILOSOPH

Miniaturised Wireless Power Transfer Systems for Neurostimulation: A Review

In neurostimulation, wireless power transfer is an efficient technology to overcome several limitations affecting medical devices currently used in clinical practice. Several methods were developed over the years for wireless power transfer. In this review article, we report and discuss the three most relevant methodologies for extremely miniaturised implantable neurostimulator: ultrasound coupling, inductive coupling and capacitive coupling. For each powering method, the discussion starts describing the physical working principle. In particular, we focus on the challenges given by the miniaturisation of the implanted integrated circuits and the related ad-hoc solutions for wireless power transfer. Then, we present recent developments and progresses in wireless power transfer for biomedical applications. Last, we compare each technique based on key performance indicators to highlight the most relevant and innovative solutions suitable for neurostimulation, with the gaze turned towards miniaturisation

Wireless Power Transfer For Biomedical Applications

In this research wireless power transfer using near-field inductive coupling is studied and investigated. The focus is on delivering power to implantable biomedical devices. The objective of this research is to optimize the size and performance of the implanted wireless biomedical sensors by: (1) proposing a hybrid multiband communication system for implantable devices that combines wireless communication link and power transfer, and (2) optimizing the wireless power delivery system. Wireless data and power links are necessary for many implanted biomedical devices such as biosensors, neural recording and stimulation devices, and drug delivery and monitoring systems. The contributions from this research work are summarized as follows: 1. Development of a combination of inductive power transfer and antenna system. 2. Design and optimization of novel microstrip antenna that may resonate at different ultra-high frequency bands including 415 MHz, 905 MHz, and 1300MHz. These antennas may be used to transfer power through radiation or send/receive data. 3. Design of high-frequency coil (13.56 MHz) to transfer power and optimization of the parameters for best efficiency. 4. Study of the performance of the hybrid antenna/coil system at various depths inside a body tissue model. 5. Minimizing the coupling effect between the coil and the antenna through addressed by optimizing their dimensions. 6. Study of the effects of lateral and angular misalignment on a hybrid compact system consisting of coil and antenna, as well as design and optimize the coilâs geometry which can provide maximum power efficiency under misalignment conditions. 7. Address the effects of receiver bending of a hybrid power transfer and communication system on the communication link budget and the transmitted power. 8. Study the wireless power transfer safety and security systems

Wireless Power Transfer Techniques for Implantable Medical Devices:A Review

Wireless power transfer (WPT) systems have become increasingly suitable solutions for the electrical powering of advanced multifunctional micro-electronic devices such as those found in current biomedical implants. The design and implementation of high power transfer efficiency WPT systems are, however, challenging. The size of the WPT system, the separation distance between the outside environment and location of the implanted medical device inside the body, the operating frequency and tissue safety due to power dissipation are key parameters to consider in the design of WPT systems. This article provides a systematic review of the wide range of WPT systems that have been investigated over the last two decades to improve overall system performance. The various strategies implemented to transfer wireless power in implantable medical devices (IMDs) were reviewed, which includes capacitive coupling, inductive coupling, magnetic resonance coupling and, more recently, acoustic and optical powering methods. The strengths and limitations of all these techniques are benchmarked against each other and particular emphasis is placed on comparing the implanted receiver size, the WPT distance, power transfer efficiency and tissue safety presented by the resulting systems. Necessary improvements and trends of each WPT techniques are also indicated per specific IMD

Past, Present and Future Trends of Non-Radiative Wireless Power Transfer

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Enhancing wireless power transfer efficiency for potential use in cardiovascular applications

Left Ventricular Assist Devices (LVAD) are being used to assist blood circulation in heart failure patients. The requirement to have a continuous energy supply is deteriorating the patients’ life quality since they need either to carry along two heavy battery packs or to attach a power cable. For this reason, a wireless power transmission (WPT) system is developed to power the LVAD. Within its effective charging region, the WPT system will offer an autonomous charging process which may lead to a smaller battery pack and cableless experience to the user. Previous WPT systems for cardiovascular applications are either compromised by poor transfer efficiency, short transmission distance or safety issues. To address these problems, an impedance matching WPT system is being designed. For increasing the overall transfer efficiency, both sides impedance matching technique and low loss matching networks are being worked on. In addition, efficiency specific design approach is being developed to reduce design complexity. As a result, the transfer efficiency and transmission distance of the impedance matched WPT have been increased by a factor of 7 and 6 times respectively. The conceptual idea for implementing such a system is also discussed in this thesis. Furthermore, safety measurements have been performed to ensure the system is safe to be used

The design of an efficient class E-LCCL capacitive power transfer system through frequency tuning method

In this work, the optimum zero voltage switching (ZVS) of Class E-LCCL capacitive power transfer (CPT) was determined via frequency tuning method. Through this an efficient system can be guanranteed although there is a change in the capacitive plates distance. This study used a Class-E LCCL inverter, as it can operate at a high alternate current frequency, besides producing low switching losses and minimal power losses. Specifically, this study conducted simulations and experiments to analyse the performance of an LCCL CPT System at 1 MHz operating frequency and 24 V DC supply voltage. Using an air gap distance of 0.1 cm, the designed CPT system prototype successfully achieved an output power of 10W and an efficiency of 95.45%. This study also found that by tuning the resonant frequency of the Class E-LCCL system, the optimum ZVS can be obtained although capacitive plate distance was varied from 1-3 cm via experimental. The results of this study could benefit medical implant and portable device development, consumer electronics, and environments that involve electrical hazards

A New Design of Capacitive Power Transfer Based on Hybrid Approach for Biomedical Implantable Device

This paper presents the development of a new design method of capacitive power transfer (CPT) which is based on hybrid concept for Biomedical Implants. This method is able to improve various issues found in the widely used CPT system that is bipolar CPT method. Based on the ability of this purposed, the simulation of the CPT system has been designed to prove an amount of power transferred through a layer of tissue. The design used to validate the suggested model which to powering implanted device, and it was performed with 3cm square plates, which have a layer of beef with the 5mm thickness in between 2 coupling plate. Power signal was generated by Class E zero voltage switching. The Class E zero voltage switching has been designed to generating alternate current with the 1MHz frequency appropriate to the hybrid CPT system specification.