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This paper provides a review and survey of research on power transfer for biomedical applications based on inductive coupling. There is interest in wireless power transfer (WPT) for implantable and wearable biomedical devices, for example, heart pacemaker or implantable electrocardiogram (ECG) recorders. This paper concentrates on the applications...
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We developed an implantable electrocardiogram (ECG) monitoring system and demonstrated its performance through an in vivo test. In the system, the implantable device senses not only the ECG signal of the animal but also the voltage level of the secondary cell and temperature inside the implantable device, and users can check the transmitted informa...
![Examples of MD and MQ [39].](publication/353475365/figure/fig5/AS:1080286616006754@1634571808797/Examples-of-MD-and-MQ-39_Q320.jpg)
Magnetic resonant coupling (MRC) is one of the techniques that are widely used in wireless power transfer (WPT) systems. The technique is commonly used for enhancing distance while maintaining power transfer efficiency (PTE). Many studies have investigated new technologies to extend the distance of MRC while maintaining high PTE values. The most pr...
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... Implementing micro coils through MEMS technology opens the flour to implement micro-transformers efficiently. Generally, miniaturized transformers that use MEMS techniques have many potential advantages, such as low power consumption, low cost, high efficiency, high quality factor (QF), and high-frequency operation (Shadid et al. 2018;Rizou et al. 2018;Lee et al. 2016;Jean-Philippe et al. 2019a). ...
This work introduces the design, analysis, simulation, and a standard MEMS fabrication process for a three-dimensional micro-coil with a magnetic core and a digital switch configuration using a completely integrated, fully MEMS-compatible process to achieve a digitally controlled inductance. The proposed design can also be utilized as a micro-transformer. The proposed design consists of five identical 3D coils and their corresponding MEMS switches. These coils are digitally controlled to achieve a variable inductor ranging from one-fifth of the coil inductance up to five times the coil inductance. A standard five-layer Polymumps process is proposed to fabricate the micro-coils and the integrated switches. Each micro coil is anchored directly on-chip, which is connected to the input signal from one side, and the other is connected to the switch. The Ni-based magnetic core improves the coil’s response by confining and guiding the magnetic field in the magnetic device compared to Si core based by more than five times. The presented coil has the number of windings limited by the designed length and the minimum spacing that can be realized by standard optical lithography. The coil’s diameter is also restricted by the limits defined by optical lithography, whereas the maximum height realizable by the Polymumps process limits the height of the magnetic core and accordingly results in lower inductor performance. Based on this technique, we present coils ranging from 100 μm length and ten winding up to 1000 μm length and 100 windings. The new monolithically integrated MEMS switches act as selectors to achieve a variable inductance with digital control to allow the selection among n(n + 1)/2 inductance steps, where n is the number of coils.
... A promising avenue to address the limitations of batteries is through wireless power transfer, enabling rechargeable or batteryfree IMDs that can function indefinitely within the body. WPT enables miniaturized devices that can be implanted through minimally invasive procedures and the fabrication of novel types of devices that are impractical with wired power delivery (Khalifa et al. 2019;Shadid and Noghanian 2018;Khalifa et al. 2021). ...
Wireless power transfer (WPT) within the human body can enable long-lasting medical devices but poses notable challenges, including absorption by biological tissues and weak coupling between the transmitter (Tx) and receiver (Rx). In pursuit of more robust and efficient wireless power, various innovative strategies have emerged to optimize power transfer efficiency (PTE). One such groundbreaking approach stems from the incorporation of metamaterials, which have shown the potential to enhance the capabilities of conventional WPT systems. In this review, we delve into recent studies focusing on WPT systems that leverage metamaterials to achieve increased efficiency for implantable medical devices (IMDs) in the electromagnetic paradigm. Alongside a comparative analysis, we also outline current challenges and envision potential avenues for future advancements.
... Furthermore, WPT techniques such as inductive coupling have been applied in multiple biomedical applications such as hospital-electric vehicles (EVs), Implantable Medical Devices (IMDs), wearable and implantable biomedical devices such as cardiac pacemakers or implantable ECG recorders [80]. Recently, few studies have been proposed on wireless charging scheduling schemes, aiming at enhancing the performance of power-limited devices by optimizing charging scheduling schemes and load scheduling. ...
Wireless Power Transfer (WPT) is a disruptive technology that allows wireless energy provisioning for energy-limited IoT devices, thus decreasing the over-reliance on batteries and wires. WPT could replace conventional energy provisioning (e.g., energy harvesting) and expand to be deployed in many of our daily-life applications, including but not limited to healthcare, transportation, automation, and smart cities. As a new rising technology, WPT has attracted many researchers from academia and industry about WPT technologies and wireless charging scheduling algorithms. Therefore, in this paper, we review the most recent studies related to WPT, including classifications, advantages, disadvantages, and main domains of application. Furthermore, we review the recently designed wireless charging scheduling algorithms (schemes) for wireless sensor networks. Our study provides a detailed survey of wireless charging scheduling schemes covering the main scheme classifications, evaluation metrics, application domains, advantages, and disadvantages of each charging scheme. We further summarize trends and opportunities for applying WPT at some intersections.
... The far-field transmission uses electromagnetic waves propagating through space and covering long distances. In contrast, near-field transmission uses magnetic induction or electric fields to transfer energy over short distances [9,10]. IBMs and biomedical sensor systems often rely on nearfield wireless power transfer for energy harvesting and transmission. ...
... The primary categories of near-field WPT thoroughly explore the advantages, limitations, and associated equations for each WPT type extensively investigated in our research [12]. Moreover, the main advantage and disadvantages of the main near-field WPT categories of the three WPT systems are summarized in Table 1 [8,9,11,13]. However, WPT can potentially revolutionize powering and charging devices, including IBMs. ...
Implantable biomedical (IBM) systems and biomedical sensors can improve life quality, identify sickness, monitor biological signs, and replace the function of malfunctioning organs. However, these devices compel continuous battery power, which can be limited by the battery's capacity and lifetime, reducing the device's effectiveness. The wireless power transfer (WPT) technique, specifically magnetic resonator coupling (MRC), was utilized to address the limited battery capacity of IBMs. By using WPT-MRC, the device can obtain power wirelessly, thereby reducing the need for frequent battery replacements and increasing the device's potential. In this research, spider-web coil (S-WC) based MRC-WPT was conceived and carried out experimentally to enhance low-power IBM's rechargeable battery usage time. The presented S-WC-MRC-WPT design uses series-parallel (S-P) configuration to power the IBM. Both transmitter and receiver coils exhibit an operating oscillation frequency of 6.78 MHz. The paper reports on experiments performed in the laboratory to assess the performance of the proposed design in terms of output DC at three different resistive loads and transmission distances with alignment conditions among the receiver and the transmitter coils. Various transfer distances ranging from 10 to 100 mm were investigated to analyze the DC output current (Idc). Specifically, under a 30 V voltage source (VS) and a transfer distance of 20 mm, the DC output current was observed to be 330, 321, and 313 mA at resistive loads of 50, 100, and 150 Ω, respectively. This is an open-access article under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/) Publisher: Middle Technical University
... Wireless energy transmission via electromagnetic waves is performed with an increase in operating frequency and a consequent increase in transmission efficiency. 38 However, this increase in frequency leads to an increase in energy absorption by biological tissues, which causes tissue heating. As a result, excessively strong electromagnetic waves can cause dangerous tissue burns and unexpected tissue irritation. ...
Traditional tethered nerve implants have many limitations since they rely on physical wires for power and signal transmission. Wireless stimulation technology can promote the exploration of neurological diseases and meet patient requirements, stemming from its portability and efficiency. In this paper, the link transmission characteristics of a sub-millimeter inductor are investigated by simulation, electrical tests, and theoretical analysis. The inductor acts as the receiving coil of a wireless stimulation device, and the wireless energy transmission process based on magnetic induction coupling is analyzed. Second, a novel millimeter-scale wireless stimulator device for neuromodulation is designed based on the parameters of transmitting and receiving coils obtained from the simulation. Finally, rat electrophysiological experiments are conducted to assess the feasibility of the device. The field Excitatory Post Synaptic Potential baseline is first recorded in the CA1 radiation area for 10 min, followed by the addition of high-frequency stimulation, and after successful induction of long-term potentiation (LTP) and recording for 10 min, the two coils are fixed at a distance of 1 cm and the hippocampal Schaffer-CA1 pathway is added. The experimental results show that the addition of wireless stimulation can modulate the transmission of synaptic electrical activity in the hippocampal Schaffer-CA1 pathway and significantly increase the level of (LTP) induction. A millimeter-scale wireless stimulation device is investigated and designed in this paper, the feasibility of the device is demonstrated through ex vivo electrophysiological experiments, and its effects on the targeted modulation of the Schaffer-CA1 pathway in the rat hippocampus are described.
... Our proposed system consists mainly of two coils L1 outside and L2 implanted in the patient's body, with their parasitic resistances respectively R1 and R2. Also the resonance frequencies of the two system components must be synchronized [14], [15]. To make primary and secondary resonant circuits, two capacitors C1 and C2 are used in the primary and secondary circuits respectively [13], [16]. ...
p>One of the greatest techniques, inductive coupling is frequently utilized in the biomedical sector for wireless energy transfer to implants. The aim of this article is to develop and analyze the effect of inductor geometrical characteristics, distance between transmitter (TX) and receiver (RX) and also the operating frequency on the wireless power transfer system, using grey wolf optimizer-based cuckoo search (GWO-CS) algorithm. Power transfer efficiency (PTE), power provided to load, and other critical components must all be improved or maximized and miniaturaze the microsystem proposed. The invention, design, and optimization of coils square spirals in a wireless energy transfer system using a resonant inductive link are the emphasis of this paper. The GWO-CS approach is evaluated to existing methods, demonstrated by simulations and to demonstrate the effectiveness of the suggested strategy.</p
... Shadid et al. [26] worked on WPT and presented comparisons of the different WPT methods. The authors in [27], wrote on the timeline of the application of WPT in the biomedical field and tabled literature in the subject up to 2017. The study emphasized inductive WPT, which is preferred for implants because of the risk of battery breakage or the inconvenience of repeated surgeries. ...
... Wearable biomedical devices are popularly used, especially in body-centered systems. For this purpose, the need for flexible antennas that can be applied in biomedical applications, wearable applications [1,2] and body-mounted applications has increased [3][4][5]. Various antennas are used for wireless communication in clinical treatment and remote monitoring devices. Antennas typically need to be flexible, highly efficient to facilitate all on-body wireless systems. ...
... The assessments are done for SAR 10 g. SAR limits above any 10 g of tissue are set by international standards [4,14,26 ]. According to these standards, the average SAR should be 2 W/kg over any 10 g of tissue (SAR 10 g ). ...
This study presents a novel UWB flexible antenna with a dual band-notched design for wearable biomedical devices. The proposed antenna is designed on Kapton Polyimide-based flexible substrate. This includes a CPW-fed circular and triangle structure. The dual notched bands are realized by using two triangular-shaped spiral slots defected ground structures. The first notched band (2.4-3.7 GHz) is generated for rejecting WLAN and WiMAX, the second notch (5.15-5.725 GHz) is generated for rejecting HyperLAN/2. The designed UWB antenna has approximately a bandwith of 159% (2.05-14 GHz) in simulation. Thus, the designed UWB antenna meets FCC standards. The antenna has an omnidirectional radiation pattern with a maximum gain of 12.7 dB in 8.4 GHz. The proposed antenna is fabricated with the low-cost airbrush printed technique. In this technique, a higher gain value is obtained by controlling the thickness of the conductive layer. Effect of flexibility on the antenna performance is tested for different configurations in the simulation and anechoic chamber environments. According to the results obtained, the overall performance is not affected except for the shift in frequency. Since the antenna has a UWB structure, the frequency shift that occurs in bending is at a tolerable level. The proposed UWB antenna is suitable for wearable biomedical devices, with a high UWB performance.
... Some research attempts to strengthen the advantages of current WCEs, such as reducing the size of the capsule, calculating and improving the propagation and efficiency of transmitting and receiving antennas. Others strive to minimize the drawbacks of capsule endoscopy such as the antenna, printed circuit board (PCB), and battery [5,6]. In a WCE system, a capsule antenna is the key component, and many efforts have been made in recent years. ...
... WPT is based on the IPT concept for biomedical applications. The delivered power to biomedical devices reported in the collected papers ranges from few mW to 48 W, with maximum efficiency of up to 95% for 20 mm range [12]. Electrical engineering could experience a significant shift thanks to wireless power transfer, which does away with the need for traditional copper connections and current-carrying wires. ...
Wireless power transmission (WPT) has covered a wide range of subjects in many fields and become a highly active research area for students, scientists, and many others because of their potential to provide new technology to our daily lives. Wireless power transmission will have a bright future because this technology is used in the transmission of electrical energy from a power source to an electrical load across an air gap without any wires. This paper presents a design implementation and working principle of wireless power transfer. The paper describes different studies of existing technologies in wireless power transmission. Also, the working of the circuit has been described along with the results.
