Design of Misalignment Tolerant WPT System for Deep Brain Stimulator
TL;DR: In this article, the design details of two and four coil systems are discussed and various coil structures are considered and modelled on dual layer FR4 sheet to improve low coupling factor and misalignment.
Abstract: The paper presents the wireless power transfer (WPT) system for Deep Brain Stimulator. In WPT system, low coupling factor (k) and misalignment are the two challenges due to size limitation of implanted coils. In this paper, the design details of two and four coil systems are discussed. To improve k in the system, various coil structures are considered and modelled on dual layer FR4 sheet. The implanted coils are made of nearly 6mmX6mm dimensions for all models. To obtain allowable misalignment range, the proposed models are tested at various lateral displacements. Out of the models presented, hexagonal planar spiral type 4-coil WPT system provides maximum k of 0.029 with misalignment permissible range up to 6 mm. The simulated models are tested at 13.56 MHz using Ansys Electronic Desktop. In addition, experimental results are documented.
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TL;DR: In this article , the authors designed two coil antennas for wireless implant communication, including a small dual-band transmitting antenna and a corresponding receiving antenna that can be mounted on the abdomen of the human body.
Abstract: Low-frequency communication is one of the best ways to reduce signal attenuation from the human body, although slow data rates make stable wireless communication within the human body difficult. In this paper, we designed two coil antennas for wireless implant communication, including a small dual-band transmitting antenna that can be placed inside the human body and a corresponding receiving antenna that can be mounted on the abdomen of the human body. The proposed antenna is fed from a battery-powered impulse radio (IR) transceiver peaking at 10–60 MHz, and the antenna is designed to be wideband for higher data communication rate. Simulation and measurement of reflection and transmission coefficients confirmed operation at 40–60 MHz. In addition, a battery-powered IR transceiver is used to measure the transmission performance in a 2/3 muscle phantom. As a result, communication at a data rate of 20 Mbps is achieved at a distance of 90 mm in the 2/3 muscle phantom.
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06 Sep 2022
TL;DR: In this article , the authors presented an efficient wireless power transfer (WPT) system for implantable deep brain stimulation (DBS) devices, where the LCC compensation network was used in the transmitter side and two receiver coils using series compensation were located in the receiver side.
Abstract: This paper presents an efficient wireless power transfer (WPT) system for implantable deep brain stimulation (DBS) devices. A head-mounted DBS device is taken into account in the design procedure of the presented WPT system. A three coil system is designed to provide high efficiency power transfer. The LCC compensation network which has constant voltage characteristic is used in the transmitter side and two receiver coils using series compensation are located in the receiver side, into the human tissue. Finally, performance of the proposed WPT system is tested by a 3D electromagnetic simulation work at a 10 mm distance. Based on the simulation results, 1.19 V DC output voltage is regulated while the DC output current is 24 mA. The power transfer efficiency is achieved as 4.63% at full load condition.
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DOI•
TL;DR: In this paper , the authors designed two coil antennas for wireless implant communication, including a small dual-band transmitting antenna and a corresponding receiving antenna that can be mounted on the abdomen of the human body.
Abstract: Low-frequency communication is one of the best ways to reduce signal attenuation from the human body, although slow data rates make stable wireless communication within the human body difficult. In this paper, we designed two coil antennas for wireless implant communication, including a small dual-band transmitting antenna that can be placed inside the human body and a corresponding receiving antenna that can be mounted on the abdomen of the human body. The proposed antenna is fed from a battery-powered impulse radio (IR) transceiver peaking at 10–60 MHz, and the antenna is designed to be wideband for higher data communication rate. Simulation and measurement of reflection and transmission coefficients confirmed operation at 40–60 MHz. In addition, a battery-powered IR transceiver is used to measure the transmission performance in a 2/3 muscle phantom. As a result, communication at a data rate of 20 Mbps is achieved at a distance of 90 mm in the 2/3 muscle phantom.
References
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TL;DR: This work has analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency, and a proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques.
Abstract: Resonance-based wireless power delivery is an efficient technique to transfer power over a relatively long distance. This technique typically uses four coils as opposed to two coils used in conventional inductive links. In the four-coil system, the adverse effects of a low coupling coefficient between primary and secondary coils are compensated by using high-quality (Q) factor coils, and the efficiency of the system is improved. Unlike its two-coil counterpart, the efficiency profile of the power transfer is not a monotonically decreasing function of the operating distance and is less sensitive to changes in the distance between the primary and secondary coils. A four-coil energy transfer system can be optimized to provide maximum efficiency at a given operating distance. We have analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency. Design steps to obtain the efficient power-transfer system are presented and a design example is provided. A proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques. In the prototype system, for a power-link frequency of 700 kHz and a coil distance range of 10 to 20 mm, using a 22-mm diameter implantable coil resonance-based system shows a power-transfer efficiency of more than 80% with an enhanced operating range compared to ~40% efficiency achieved by a conventional two-coil system.
894 citations
01 Jan 1996
TL;DR: In this paper, a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils is presented, where the turns of the coils are not concentrated at the Circumferences, but distributed across the diameters.
Abstract: This paper presents a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils. It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the Circumferences, but distributed across the diameters. For analysis, each of the two coils is assumed to be composed of concentric circular loops. The experimental results are in very good agreement with the theoretical results.
401 citations
TL;DR: It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the circumferences, but distributed across the diameters.
Abstract: This paper presents a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils. It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the circumferences, but distributed across the diameters. For analysis, each of the two coils is assumed to be composed of concentric circular loops. The experimental results are in very good agreement with the theoretical results.
401 citations
"Design of Misalignment Tolerant WPT..." refers background in this paper
...Thus, the size of the coils is required to be optimized for achieving maximum power transfer efficiency [10-11]....
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TL;DR: In this paper, the effects of coil misalignment and geometry are addressed in a single mathematical expression for inductively coupled wireless power transfer, and a novel analytical power transfer efficiency model is presented.
Abstract: A novel analytical model of inductively coupled wireless power transfer is presented. For the first time, the effects of coil misalignment and geometry are addressed in a single mathematical expression. In the applications envisaged, such as radio frequency identification (RFID) and biomedical implants, the receiving coil is normally significantly smaller than the transmitting coil. Formulas are derived for the magnetic field at the receiving coil when it is laterally and angularly misaligned from the transmitting coil. Incorporating this magnetic field solution with an equivalent circuit for the inductive link allows us to introduce a power transfer formula that combines coil characteristics and misalignment factors. The coil geometries considered are spiral and short solenoid structures which are currently popular in the RFID and biomedical domains. The novel analytical power transfer efficiency expressions introduced in this study allow the optimization of coil geometry for maximum power transfer and misalignment tolerance. The experimental results show close correlation with the theoretical predictions. This analytic technique can be widely applied to inductive wireless power transfer links without the limitations imposed by numerical methods.
355 citations
"Design of Misalignment Tolerant WPT..." refers background in this paper
...Due to symmetric topology it has a higher tolerance for variation in positions of coils [13-15]....
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TL;DR: A detailed model that includes the effects of the surrounding environment on the PSC parasitic components and eventually on the power transfer efficiency is constructed and an iterative design method that starts with a set of realistic design constraints and ends with the optimal PSC geometries is applied.
Abstract: Printed spiral coils (PSCs) are viable candidates for near-field wireless power transmission to the next generation of high-performance neuroprosthetic devices with extreme size constraints, which will target intraocular and intracranial spaces. Optimizing the PSC geometries to maximize the power transfer efficiency of the wireless link is imperative to reduce the size of the external energy source, heating of the tissue, and interference with other devices. Implantable devices need to be hermetically sealed in biocompatible materials and placed in a conductive environment with high permittivity (tissue), which can affect the PSC characteristics. We have constructed a detailed model that includes the effects of the surrounding environment on the PSC parasitic components and eventually on the power transfer efficiency. We have combined this model with an iterative design method that starts with a set of realistic design constraints and ends with the optimal PSC geometries. We applied our design methodology to optimize the wireless link of a 1-cm 2 implantable device example, operating at 13.56 MHz. Measurement results showed that optimized PSC pairs, coated with 0.3 mm of silicone, achieved 72.2%, 51.8%, and 30.8% efficiencies at a face-to-face relative distance of 10 mm in air, saline, and muscle, respectively. The PSC, which was optimized for air, could only bear 40.8% and 21.8% efficiencies in saline and muscle, respectively, showing that by including the PSC tissue environment in the design process the result can be more than a 9% improvement in the power transfer efficiency.
233 citations
"Design of Misalignment Tolerant WPT..." refers background in this paper
...signifies the fill factor of a coil [5]....
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...Some of such implants are Left Ventricle Assist Devices (LVAD), Pace Makers and Deep Brain Stimulators (DBS) etc [5-7]....
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