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A wireless magnetic resonance energy transfer system for micro implantable medical sensors.

Li X, Zhang H, Peng F, Li Y, Yang T, Wang B, Fang D - Sensors (Basel) (2012)

Bottom Line: The energy transfer efficiency of the four-coil system is greatly improved compared to the conventional two-coil system.In addition, the output current varies with changes in the distance.The whole implanted part is packaged with PDMS of excellent biocompatibility and the volume of it is about 1 cm(3).

View Article: PubMed Central - PubMed

Affiliation: School of Electronics and Information Engineering, Beijing Jiaotong University, Beijing 100044, China. lixiuhan@bjtu.edu.cn

ABSTRACT
Based on the magnetic resonance coupling principle, in this paper a wireless energy transfer system is designed and implemented for the power supply of micro-implantable medical sensors. The entire system is composed of the in vitro part, including the energy transmitting circuit and resonant transmitter coils, and in vivo part, including the micro resonant receiver coils and signal shaping chip which includes the rectifier module and LDO voltage regulator module. Transmitter and receiver coils are wound by Litz wire, and the diameter of the receiver coils is just 1.9 cm. The energy transfer efficiency of the four-coil system is greatly improved compared to the conventional two-coil system. When the distance between the transmitter coils and the receiver coils is 1.5 cm, the transfer efficiency is 85% at the frequency of 742 kHz. The power transfer efficiency can be optimized by adding magnetic enhanced resonators. The receiving voltage signal is converted to a stable output voltage of 3.3 V and a current of 10 mA at the distance of 2 cm. In addition, the output current varies with changes in the distance. The whole implanted part is packaged with PDMS of excellent biocompatibility and the volume of it is about 1 cm(3).

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The diagram of adding magnetic enhanced resonators.
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f12-sensors-12-10292: The diagram of adding magnetic enhanced resonators.

Mentions: In order to improve the energy transfer efficiency at the same distance, two magnetic enhanced resonators (5th and 6th) are added as shown in Figure 12. The efficiency is improved with the increased number of enhanced resonators. Since the magnetic field of each coil is coupled in near-field, that is, the magnetic field is the fading field, the coupling strength becomes weaker as the transmission distance increases and the attenuation magnitude of the magnetic field is reduced by adding enhanced resonators. In addition, the coupling scope of the magnetic field is limited and when there are no extra enhanced resonators (5th and 6th), the coupling efficiency decreases with the increasing transmission distance. The coupling strength at the same distance is strengthened through adding enhanced resonators (5th and 6th) and the energy transfer efficiency (η) is improved. Figure 11(b) gives the experiment results of η for the system with and without the enhanced resonators at the same distance of 5 cm. Also, the position of the resonators has much influence on the efficiency. η versus the gap between enhanced resonators and receiver coils is measured. η of the four-coil system is below 2%, while it can be greatly improved by adding enhanced resonators. η of 43% can be obtained at the gap of 1 cm and it is increased by more than 20 times. The experiment results prove that the magnetic enhanced resonators can effectively improve the energy transfer efficiency.


A wireless magnetic resonance energy transfer system for micro implantable medical sensors.

Li X, Zhang H, Peng F, Li Y, Yang T, Wang B, Fang D - Sensors (Basel) (2012)

The diagram of adding magnetic enhanced resonators.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472828&req=5

f12-sensors-12-10292: The diagram of adding magnetic enhanced resonators.
Mentions: In order to improve the energy transfer efficiency at the same distance, two magnetic enhanced resonators (5th and 6th) are added as shown in Figure 12. The efficiency is improved with the increased number of enhanced resonators. Since the magnetic field of each coil is coupled in near-field, that is, the magnetic field is the fading field, the coupling strength becomes weaker as the transmission distance increases and the attenuation magnitude of the magnetic field is reduced by adding enhanced resonators. In addition, the coupling scope of the magnetic field is limited and when there are no extra enhanced resonators (5th and 6th), the coupling efficiency decreases with the increasing transmission distance. The coupling strength at the same distance is strengthened through adding enhanced resonators (5th and 6th) and the energy transfer efficiency (η) is improved. Figure 11(b) gives the experiment results of η for the system with and without the enhanced resonators at the same distance of 5 cm. Also, the position of the resonators has much influence on the efficiency. η versus the gap between enhanced resonators and receiver coils is measured. η of the four-coil system is below 2%, while it can be greatly improved by adding enhanced resonators. η of 43% can be obtained at the gap of 1 cm and it is increased by more than 20 times. The experiment results prove that the magnetic enhanced resonators can effectively improve the energy transfer efficiency.

Bottom Line: The energy transfer efficiency of the four-coil system is greatly improved compared to the conventional two-coil system.In addition, the output current varies with changes in the distance.The whole implanted part is packaged with PDMS of excellent biocompatibility and the volume of it is about 1 cm(3).

View Article: PubMed Central - PubMed

Affiliation: School of Electronics and Information Engineering, Beijing Jiaotong University, Beijing 100044, China. lixiuhan@bjtu.edu.cn

ABSTRACT
Based on the magnetic resonance coupling principle, in this paper a wireless energy transfer system is designed and implemented for the power supply of micro-implantable medical sensors. The entire system is composed of the in vitro part, including the energy transmitting circuit and resonant transmitter coils, and in vivo part, including the micro resonant receiver coils and signal shaping chip which includes the rectifier module and LDO voltage regulator module. Transmitter and receiver coils are wound by Litz wire, and the diameter of the receiver coils is just 1.9 cm. The energy transfer efficiency of the four-coil system is greatly improved compared to the conventional two-coil system. When the distance between the transmitter coils and the receiver coils is 1.5 cm, the transfer efficiency is 85% at the frequency of 742 kHz. The power transfer efficiency can be optimized by adding magnetic enhanced resonators. The receiving voltage signal is converted to a stable output voltage of 3.3 V and a current of 10 mA at the distance of 2 cm. In addition, the output current varies with changes in the distance. The whole implanted part is packaged with PDMS of excellent biocompatibility and the volume of it is about 1 cm(3).

Show MeSH
Related in: MedlinePlus