Wireless power transfer system for capsule endoscopy based on strongly coupled magnetic resonance theory

Abstract

Capsule endoscopy is a new technique that allows complete exploration of the small intestine, and widely used all over the world, for its convenience and less pains compared with traditional endoscopy. However, the limited power supplies of batteries handicap the development of capsule endoscopy. This paper presents a novel wireless power transfer system for the capsule endoscopy utilizing the strongly coupled magnetic resonances theory. The wireless power transfer system consists of four coils, an excitation source and a load. In order to evaluate the system performance, experiments were carried out in which the working frequency is determined at 8.2MHz. The results demonstrate that the distance between two sets of transmission coils have great effect on the system efficiency and the maximal system efficiency can reach 26.14%. Therefore, this power supply system has a promising prospect on wireless power transfer for capsule endoscopy. Improving the quality factor of coils can effectively increase the efficiency of the system, which is the key to the future work.

Experimental Demonstration of Coexistence of Microwave Wireless Communication and Power Transfer Technologies for Battery-Free Sensor Network Systems

“…Table 1 summarizes important features of each category. Coupling-and resonant-type WPT devices using MHz frequencies have been reported [7,8], but such devices are not suitable for high-speed signal and command transfer or cannot transfer energy over distances of several meters. Microwave WPT shows more promise, since the microwave band is commonly used in applications such as wireless local area network and cellular network systems.…”

Applications of Wireless Power Transfer in Medicine: State-of-the-Art Reviews

“…The distance of the system is 5-30 times greater than other current WCE systems. 10,48 The floor consists of pressure sensors that determine the patient's position, shown in Fig. 18b, and only one transmitter is activated at a time.…”

Influences of Spurious Conductors on Long Distance Inductive Power Transfer Systems

“…ω ω (12) Without the conductors, resonance condition in secondary side depends on only L m , L l2 , and C 2 [10]- [13]. However, when the conductors are around IPTS, resonance condition in (12) changes because L th in (6) determined by R 13 , R 23 , L 13 , and L 13 .…”

“…Even though recent achievement has showed CMRS technique with relatively low quality factor (Q = 2.8) [10]- [11], it requires multi-resonance coils and is very sensitive to its surrounding conditions such as humidity and temperature due to the exact satisfaction of resonance conditions in three stages: source coil to transmitter coil, transmitter coil to receiver coil, and receiver coil to load coil. More importantly, [11] has proved that there is no difference between CMRS and IPTS except for the existence of multi-resonance coils, which are just adopted to change the voltage and the current level [9]- [13]. Inherently, CMRS is relatively bulky due to multiresonance coils and not mandatory for multi-resonance coils to be strongly coupled for long WPT.…”

“…When timevarying magnetic flux is applied to the conductors, eddy currents generated in the conductors can change the resonant conditions for maximum power transfer. For the analysis of WPT circuits, many researches, so far, have been reported [4], [10]- [13], [17]- [20]; explicit modeling for CMRS, phasor transformation, magnetic mirror model.…”