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Four misalignment coil conditions. (A) Perfectly aligned coil; (B) lateral coil misalignment; (C) angular coil misalignments; (D) general coil misalignments.
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Abstract Use of transcutaneous inductive links is a widely known method for the wireless powering of bio-implanted devices such as implanted microsystems. The design of the coil for inductive links is generally not optimal. In this study, inductive links were used on the basis of the small loop antenna theory to reduce the effects of lateral coil m...
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... analytical and empirical methods are mathematically investigated to address coil misalignment on the basis of the assumption that the coils are separated by air. Four coil misalignment condi- tions, namely, aligned case, lateral misalignment case, angular coil misalignments, and general case, have been well studied theoretically and mathematically as shown in Figure 1 [1,12,14]. ...
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... the lateral misalignment case, the mutual inductance between the two coils is derived from (a, b, d, Δ) and other partial derivatives. Our proposed inductive coil radius dimensions are a = 28 mm, b = 5.8 mm, d = 5 mm, and variable Δ. Figure 1B shows that both coils are in paral- lel planes, but their centers moved a side by Δ distance. The value of Δ was changed parametrically to the X-axis or Y-axis from > 0 to 4 mm, and this value was smaller than the radius of the implanted coil. ...
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... slight drop in the gain at some specific angles can be observed. Figure 10 shows the E-Total gain in the near field when the azimuthal plane θ = 90° was very stable and had a value that ranged from 24.35 to 25.35 dB depending on lateral misalignments. The radiation around the coil was omnidirectional, and there was a very slight drop at angle 150°. ...
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... loss is negligible. Figure 11 shows an accurate presentation of results. In the two-dimensional (2D) simulated radiation pat- terns of the total near field in the elevation plane when Φ = 90°, the gain ranged from 37.65 to 38.30 dB, and for the azimuthal plane when θ = 90°, the gain ranged from 24.35 to 25.35 dB. ...
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... same scenario presented in Figure 8 was achieved with the use of dry skin as shown in Figure 12. The lateral misalignment distance between the reader and the implanted coil was smaller than the radius of the implanted coil (Δ < b). ...
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... these results with those obtained when coil alignment Δ = 0 given in Figure 7, coil performance was not affected by lateral misalignments although dry tissue separated the coils. Figure 13 shows the E-Total gain simulated with para- metric lateral misalignment moving from 0 to 8 mm by 25 2-mm steps. The E-Total gain in near field when the eleva- tion plane Φ = 90° was 37-38 dB, with slight drops in gain in some specific angles. ...
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... E-Total gain in near field when the eleva- tion plane Φ = 90° was 37-38 dB, with slight drops in gain in some specific angles. Figure 14 shows that the E-Total gain in the near-field when the azimuthal plane θ = 90° was simulated was from 24.35 to 24.70 dB. A slight drop in angle 150° and a very slight drop in angles 290°-320° were observed. ...
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... the loss in gain when the lateral misalignment was from Δ = 0 mm to Δ = 8 mm was < -1 dB, which is negligible. Accurate results are shown in Figure 15. In the 2D simulated radiation pattern, the gain in the elevation plane when Φ = 90° was up to 38 dB, and the gain in the azimuthal plane when θ = 90° was 24.35-24.70 ...
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Misalignments between the transmitter and receiver coils are unavoidable in practical wireless power applications. Therefore, the computation of mutual inductance (MI) of coils with misalignments is valuable in terms of its engineering aspects. In this article, an analytical model of MI between two rectangular spiral coils with misalignments is pro...
Citations
... There are devices that can be energized with batteries and implanted in an organism; however, this method is not viable owing to the size and lifetime of the batteries and their energization. The alternative considered in most studies focuses on inductive links using planar antennas (Abbas, Hannan, Samad, & Hussain, 2014). ...
... A factor to consider when designing planar antennas is the misalignment of the inductors, which decreases the link efficiency. Abbas et al. (2014) establishes these cases considering four in specific, as shown in Figure 2. In the first case, both coils were perfectly aligned (Figure 2 A). In the second case, they were laterally misaligned (Figure 2 B). ...
... In the same way, this device was used to measure the voltage amplitude on the induced signal in the receiving coil. To control the alignment and separation between transmitter and receiver antennas, different models of brackets were created with the Pro2 3D Printer (Shi et al., 2014) shown in Figures 5 and 6 where case "A" mentioned by Abbas et al. was used (Abbas, Hannan, Samad, & Hussain, 2014). These parts were designed as supports for each coil and cabinet of the BNC connectors. ...
Advances in medical technology suggest that the application of implantable medical devices or Smart Hospital Devices (SHD) can enhance the control and treatment of chronic disorders. However, most of these developments require an electrical power source for operation, making the use of batteries unfeasible. This paper presents the design and resonance analysis of four different geometries for the fabrication of planar antennas as an alternative to a contactless power supply. Previously published software [19] was used to calculate the electrical parameters for each coil design. Operating trials were executed under laboratory conditions, and a bracket manufactured using polylactic acid (PLA) through a 3D printer was used to accurately define the distances between coils to achieve correct alignment between them. Based on the experimental results, it was possible to calculate the resonant frequency of the inductive links at a 5 mm spacing. Similarly, it is possible to calculate the capacitive effect necessary to improve the resonant circuit in different transmitter-receiver planar antenna pairs. The most efficient combination to induce voltage in these links is to use the hexagonal profile design as a transmitter and receiver antenna, applying a sinusoidal signal with 8 MHz frequency.
... Moreover, the sensitivity of the two coils to the alignment between the coils was very high. 18 Thus, instead of two coils, the WPT system utilized multi-coils. As a special case, the design of a three coil structure involved including an additional component to the WPT system. ...
Wireless power transfer technology features shorter power transmission distances in biomedical applications. This is a result of the small size of the implanted coils, biocompatible material conductivity, and the large distances between the receiving and transmitting coils. There have been numerous attempts to improve the power transfer efficiency across longer distances. Multiple coils, including 2-, 3-, 4-, and multi-layered coils, were previously considered. This study proposes a novel approach to achieve higher power transmission efficiency by integrating a single coil on the receiving side and three asymmetric coils on the transmitter side. As such, it delivers power to the sensor implanted within the coronary artery that monitors the blood pressure while introducing a uniquely shaped stent. The efficiency of power transmitted to the stent in its dual implanted forms, helical and zigzag helical, was examined as well, with the wireless power transmission system thereby analyzed at the 27 MHz Industrial Scientific Medical band operating frequency. For the four-coil technique, the power transmission efficiency at a distance of 25 mm between the receiver and transmitter sides by using biological human tissue as a medium between the transmission coils and the receiver stent can reach 56.42%, whereas other approaches show lower efficiencies: the three-coil method's efficiency is 32.88%, the double-layer parallel method's efficiency is 27.75%, the two-coil method's efficiency is 24.76%, the triple-layer parallel method's efficiency is 17.31%, the double-layer series method's efficiency is 0.501%, and the triple-layer series method's transmission efficiency is 0.092%. In addition, the suggested approach is demonstrated to be more efficient than prior designs with regard to the size of the implanted coils, which represent stents.
... Equivalent circuit of a flat coil, L represents the inductance, R ac resistive component and Cd the capacitance for the resonant circuitThe resistive component is made up of three types of resistance, direct current , skin effect δ and proximity(Abbas, 2014) (Yousaf, 2013). ...
The AISI 316L steel is a material used to manufacture prostheses and medical instruments due to its high corrosion resistance. However, its wear resistance is low, but it can be improved by synthesizing thin films of titanium nitride (TiN) on the surface. This compound is a hard material that improves its tribological and corrosive properties, in addition to presenting good adhesion to the substrate. In this work, a Ti/TiN thin film was obtained using the Physical Vapor Deposition (PVD) technique. This coating was characterized by scanning electron microscopy, energy dispersion spectroscopy (EDS), and light microscopy; additionally, tribological tests under wet conditions and adhesion tests were conducted. The coating showed good adhesion to the substrate according to the VDI standard. In tribological tests, a low coefficient of friction vs. a polyethylene pin in a wet environment (bovine serum) was obtained. The EDS showed a high concentration of Ti and N on the substrate even after wear tests.
... However, the modulation method of multiple transmitting coils topology is complex,which limited its application [16,17]. In ref. [18] proposed crossed dipole coils for the wide-range 3-D omnidirectional inductive power transfer, and 3-D omnidirectional WPTS was realized. The maximum overall efficiency was 33.6% when the input power was 100 W [18]. ...
... In ref. [18] proposed crossed dipole coils for the wide-range 3-D omnidirectional inductive power transfer, and 3-D omnidirectional WPTS was realized. The maximum overall efficiency was 33.6% when the input power was 100 W [18]. In ref. [19] presented series-parallel topology of magnetic coupling system whose efficiency was 17%, when the deflection angle was π/4 [19]. ...
In order to solve the misalignment problem of wireless power transmission, this paper designed and analyzed the omnidirectional receiver with multi-coil. The circuit models and transmission characteristics of the wireless power transfer system (WPTS) containing multi-coil were established. Besides, an accurate mutual inductance modelling method of the circular coil under different horizontal offset and angular deflection was presented. Based on the circuit models and the mutual inductance model, the relationship between transmission characteristics and the coil parameters were studied. Simultaneously, the design method which can synthetically and quantificationally consider the radius of the coil and the number of turns was proposed. Finally, an omnidirectional receiver with multi-coil using the quantificational model and transmission characteristics in different horizontal offset and angular deflection was designed. The transmission efficiency of three-coils-receiver system was up 12.3% higher than that of one-coil-receiver system and 4% higher than that of two-coils-receiver system when horizontal offset was between 0 cm and 30 cm. Similarly, when angular deflection was between 0 and π/2, the efficiency of three-coils-receiver system was up 73.25% higher than that of one-coil-receiver system and 1.6% higher than that of two-coils-receiver system.
... For different axial distance, the equation of M between two square-shaped planar inductors can be determined as the method presented in [9,10,11]. ...
... The simulation process implemented by sweeping the PSCs model around the operating frequency f o =13.56MHz at a fixed distance between PSCs (D=10mm) to find the Z-Parameters for both PSCs at the operating frequency. The output variables of the simulation process like inductance L, quality factor Q, mutual inductance M, and the coupling coefficient k of the modelled system can be determined using the Z parameters equations in [10]. The final geometries and parameters result of the applied WPT link are defined in Table 3. ...
The efficiency of a WPT system greatly depends on both the geometry and operating frequency of the transmitting and receiving structures. Genetic optimizations algorithms are presented to prepare the proposed design parameters using MATLAB to optimize the link efficiency. Single and double layer PSCs are optimally designed with minimal proximity losses effect. In this paper, we used the benefit of a double layer technique to miniaturize the receiver PCS size. The proposed single layer (10×10) mm2 and double layer (8×8) mm2 PSCs are validated and simulated using HFSS 15.03 software at a frequency of 13.56MHz in both cases of the air, and human biological skin tissue as intermediate material between the transmitter and receiver PSCs. The calculated and simulated results of both proposed receiver PSCs are compared for both cases of intermediate materials for their efficiency behaviours. The results show that in the case of biological tissue, the deterioration in PTE using 8mm double layer receiver is only 6.5 % (PTE =70.96%), which is less than 13.5 % (PTE=68.6%) using single layer 10mm receiver. A comparative survey has been done for similar works of different authors in the last decade. In comparison with other works, the proposed double layer (8×8) mm2 PSCs is smaller in size and more efficient for use in the IMDs.
... The mutual inductance M between the PSCs is mainly affected by the geometric shape and parameters. For different axial distance, the equation of M between two square-shaped planar inductors can be determined as the method presented in [8], [9], [10]. ...
The efficiency of the wireless power transfer system is greatly affected by the geometry of the planar spiral coils and operating frequency. The size of the implanted PSC is the main challenge to the designers. In this paper, the generic optimizations algorithms are used to prepare the proposed design parameters using the MATLAB program to optimize the planar spiral coil inductive link efficiency. Single and double layer planar spiral coil is optimally designed with minimum losses effects of proximity for efficiency and performance comparison purposes. In this work, the advantage of the double-layer technique in improving the power transfer efficiency has been used in order to miniaturize the implantable coil size and recover the degradation in power transfer efficiency caused by this miniaturization. The proposed single layer (10×10) mm 2 and double layer (8×8) mm 2 with FR4 substrates are simulated using HFSS 15.03 software at a frequency of 13.56MHz and validated experimentally in both cases of the air, and real biological skin tissue as an insulating material between the transmitter and receiver coils. The calculated and simulated results of both proposed PSC receivers are compared for their performance. The results show that in the case of biological tissue the deterioration in PTE using 8mm double layer receiver is only 6.5 %, which is less than 13.5 % using single layer 10mm receiver. The fabricated prototype of transmitter and 8mm double layer receiver is tested and the experimental results show that the power transfer efficiency is 51.9%, and 44 % in the case of using air, and biological tissue as intermediate material between coils respectively, and it is more efficient
... For different axial distance, the equation of M between two square-shaped planar inductors can be determined as the method presented in [9,10,11]. ...
... The simulation process implemented by sweeping the PSCs model around the operating frequency f o =13.56MHz at a fixed distance between PSCs (D=10mm) to find the Z-Parameters for both PSCs at the operating frequency. The output variables of the simulation process like inductance L, quality factor Q, mutual inductance M, and the coupling coefficient k of the modelled system can be determined using the Z parameters equations in [10]. The final geometries and parameters result of the applied WPT link are defined in Table 3. ...
Abstract
The efficiency of a WPT system greatly depends on both the geometry and operating frequency of the transmitting and receiving structures. Genetic optimizations algorithms are presented to prepare the proposed design parameters using MATLAB to optimize the link efficiency. Single and double layer PSCs are optimally designed with minimal proximity losses effect. In this paper, we used the benefit of a double layer technique to miniaturize the receiver PCS size. The proposed single layer (10×10) mm2 and double layer (8×8) mm2 PSCs are validated and simulated using HFSS 15.03 software at a frequency of 13.56MHz in both cases of the air, and human biological skin tissue as intermediate material between the transmitter and receiver PSCs. The calculated and simulated results of both proposed receiver PSCs are compared for both cases of intermediate materials for their efficiency behaviors. The results show that in the case of biological tissue, the deterioration in PTE using 8mm double layer receiver is only 6.5 % (PTE =70.96%), which is less than 13.5 % (PTE=68.6%) using single layer 10mm receiver. A comparative survey has been done for similar works of different authors in the last decade. In comparison with other works, the proposed double layer (8×8) mm2 PSCs is smaller in size and more efficient for use in the IMDs
... The mutual inductance M between the PSCs is mainly affected by the geometric shape and parameters. For different axial distance, the equation of M between two square-shaped planar inductors can be determined as the method presented in [8], [9], [10]. ...
... It can be said that inductive coils misalignments are one of the main restraints to wider implementation of IMDs wireless powering [3,20,21]. Changes in the tissue state and the patient activity can cause such misalignments, which, in its own turn, cause changes in the inductive powering unit (IPU) output characteristics [18,20,22]. At the same time, reliability and stability are one of the fundamental requirements for medical devices. ...
... Nevertheless, it can be said that the simple choice between "large" and "small" values should be done at first. It is possible to estimate these ranges on the basis of achievable values of L T , L R and predefined value of f o using (20), (21). In general, values of the order of 10 nF and higher can be considered "large", and values of about 1 nF and lesser can be considered as "small". ...
Coils misalignments restrain wider implementation of inductive powering of implantable medical devices. The misalignment problem can be overcome with a help of the coils geometry optimization. Coil couple design implies simultaneous adjustment of the several parameters (coils radii, turns numbers, pitch). Thus, it is desirable to have the means for a computer-aided design of the system. An algorithm for the coil couple design is devised. The key feature of the algorithm is use of predefined maximum and minimum acceptable values of the load power as a performance metric. The algorithm gives the coils geometry which ensures the inductive powering unit provides the given range of the load power for the given range of the misalignments. A formal method is proposed for the calculation of the initial coils characteristics as well as consequent adjustment of the transmitting coil external radius, transmitting coil turns number, coils internal radii (simultaneously) and receiving coil turns number. The software implementing the proposed algorithm was developed. Eight design runs were performed in order to evaluate the algorithm performance in various conditions, including different power ranges (10 W, 100 mW, 300 μW), operating frequencies (0.2 MHz, 1 MHz, 6.78 MHz, 13.56 MHz) and possible implementations (ventricular assist devices, cochlear implants, spinal cord stimulators). It was proved that the power drop as low as 10% of the mean load power can be ensured for the lateral misalignments up to the receiving coil external radius. The low-power inductive powering unit was constructed and tested. Experimental results confirm the numerical modeling.
... According to the (17), we determine the relation between the distance and coils dimension proposed and presented in Figure 6, for a proposal geometry coil, the distance between coils is equivalent to 22.5 mm in the air. The factor coupling K is validated using (21). The relationship between coupling coefficient and separation distance of the coils can be obtained as shown in Figure 7, the coupling factor k decreases with the mutual distance between the external and implant coils. ...
Due to the development of biomedical microsystems technologies, the use of wireless power transfer systems in biomedical application has become very largely used for powering the implanted devices. The wireless power transfer by inductive resonance coupling link, is a technic for powering implantable medical devices (IMDs) between the external and implanted circuits. In this paper we describe the design of an inductive resonance coupling link using for powering small bio-implanted devices such as implantable bio-microsystem, peacemaker and cochlear implants. We present the reduced design and an optimization of small size obtained spiral coils of a 9.5 mm<sup>2</sup> implantable device with an operating frequency of 13.56 MHz according to the industrial scientific-medical (ISM). The model of the inductive coupling link based on spiral square coils design is developed using the theoretical analysis and optimization geometry of an inductive link. For a mutual distance between the two coils at 10mm, the power transfer efficiency is about 79% with , coupling coefficient of 0.075 and a mutual inductance value of 2µH. In comparison with previous works, the results obtained in this work showed better performance such as the weak inter coils distance, the hight efficiency power transfer and geometry.
