Study of a wireless power transmission system for an active capsule endoscope

Institute of Precise Engineering and Intelligent Microsystems, Shanghai Jiaotong University, Shanghai, People's Republic of China.
International Journal of Medical Robotics and Computer Assisted Surgery (Impact Factor: 1.53). 03/2010; 6(1):113-22. DOI: 10.1002/rcs.298
Source: PubMed


An active capsule endoscope (ACE) will consume much more energy than can be power by batteries. Its orientation and position are always undetermined when it continues the natural way down the gastrointestinal track.
In order to deliver stable and sufficient energy to ACE safely, a wireless power transmission system based on inductive coupling is presented. The system consists of a Helmholtz primary coil outside and a multiple secondary coils inside the body. The Helmholtz primary coil is driven to generate a uniform alternating magnetic field covering the whole of the alimentary tract, and the multiple secondary coils receive energy regardless of the ACE's position and orientation relative to the generated magnetic field. The human tissue safety of the electromagnetic field generated by transmitting coil was evaluated, based on a high-resolution realistic human model.
At least 310 mW usable power can be transmitted under the worst geometrical conditions. Outer dimensions of the power receiver, 10 mm diameter x 12 mm; transmitting power, 25 W; resonant frequency, 400 kHz. The maximum specific absorption rate (SAR) and current density of human tissues are 0.329 W/kg and 3.82 A/m(2), respectively, under the basic restrictions of the International Commission on Non-ionizing Radiation Protection (ICNIRP).
The designed wireless power transmission is shown to be feasible and potentially safe in a future application.

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    • "Xin et al. and Guan-ying et al. studied the wireless power transmission efficiency by the theory of coupling coefficients, and a WPT system was developed to power the video CE. They did some study work about the safety of the wireless electromagnetic wave [51, 52]. "
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    ABSTRACT: Wireless capsule endoscopy (WCE) offers a feasible noninvasive way to detect the whole gastrointestinal (GI) tract and revolutionizes the diagnosis technology. However, compared with wired endoscopies, the limited working time, the low frame rate, and the low image resolution limit the wider application. The progress of this new technology is reviewed in this paper, and the evolution tendencies are analyzed to be high image resolution, high frame rate, and long working time. Unfortunately, the power supply of capsule endoscope (CE) is the bottleneck. Wireless power transmission (WPT) is the promising solution to this problem, but is also the technical challenge. Active CE is another tendency and will be the next geneion of the WCE. Nevertheless, it will not come true shortly, unless the practical locomotion mechanism of the active CE in GI tract is achieved. The locomotion mechanism is the other technical challenge, besides the challenge of WPT. The progress about the WPT and the active capsule technology is reviewed.
    Gastroenterology Research and Practice 01/2012; 2012(1):841691. DOI:10.1155/2012/841691 · 1.75 Impact Factor
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    • "Regardless of the kind of circuits driving the transmitting coil, be they a class E amplifier (Vandevoorde and Puers 2001, Catrysse et al 2004), switching circuit (Kim and Cho 1996) or H-bridge circuit (Xin et al 2010), these can be generalized into two types: the SRC and PRC. A lumped SRC model is shown in figure 2. "
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    ABSTRACT: Multipurpose active capsule endoscopes have drawn considerable attention in recent years, but these devices continue to suffer from energy limitations. A wireless power supply system is regarded as a practical way to overcome the power shortage problem in such devices. This paper focuses on the efficiency optimization of a wireless energy supply system with size and safety constraints. A mathematical programming model in which these constraints are considered is proposed for transmission efficiency, optimal frequency and current, and overall system effectiveness. To verify the feasibility of the proposed method, we use a wireless active capsule endoscope as an illustrative example. The achieved efficiency can be regarded as an index for evaluating the system, and the proposed approach can be used to direct the design of transmitting and receiving coils.
    Physiological Measurement 08/2011; 32(10):1561-73. DOI:10.1088/0967-3334/32/10/005 · 1.81 Impact Factor
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    ABSTRACT: In this paper, some EMI aspects of using coreless PCB transformers are addressed. Based on the antenna theory, the radiated power of a coreless PCB transformer is estimated and found to be negligible. The electromagnetic field plot of a power electronic circuit using a gate drive circuit isolated with a coreless PCB transformer has been recorded. The major radiated EMI source in the frequency range of 30 MHz to 300 MHz is found to be the copper tracks of the power circuit, where switching transients occur, rather than the coreless PCB transformer. Coreless PCB transformers essentially operate at relatively low frequency (8 MHz in this case) by near-field magnetic coupling. Experimental results have confirmed that the application of a coreless PCB transformer in a gate drive circuit for power electronic circuit will not impose any serious EMI problem on the power electronic circuit
    Power Electronics Specialists Conference, 1999. PESC 99. 30th Annual IEEE; 02/1999
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