ABSTRACT It has been reported that, through the evanescent near fields, the strongly coupled magnetic resonance is able to achieve an efficient mid-range Wireless Power Transfer (WPT) beyond the characteristic size of the resonator. Recent studies on of the relay effect of the WPT allow more distant and flexible energy transmission. These new developments hold a promise to construct a fully wireless Body Sensor Network (wBSN) using the new mid-range WPT theory. In this paper, a general optimization strategy for a WPT network is presented by analysis and simulation using the coupled mode theory. Based on the results of theoretical and computational study, two types of thin-film resonators are designed and prototyped for the construction of wBSNs. These resonators and associated electronic components can be integrated into a WPT platform to permit wireless power delivery to multiple wearable sensors and medical implants on the surface and within the human body. Our experiments have demonstrated the feasibility of the WPT approach.
Cite this paper
nullF. Zhang, J. Liu, Z. Mao and M. Sun, "Mid-Range Wireless Power Transfer and Its Application to Body Sensor Networks," Open Journal of Applied Sciences, Vol. 2 No. 1, 2012, pp. 35-46. doi: 10.4236/ojapps.2012.21004.
 A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher and M. Soljacic, “Wireless Power Transfer via Strongly Coupled Magnetic Resonances,” Science, Vol. 317, No. 5834, 2007, pp. 83-86.
 F. Zhang, S. A. Hackworth, W. Fu, C. Li, Z. Mao and M. Sun, “Relay Effect of Wireless Power Transfer Using Strongly Coupled Magnetic Resonances,” IEEE Transactions on Magnetics, Vol. 47, No. 5, 2011, pp.1478-1481.
 A. Karalis, J. D. Joannopoulos and M. Soljacic, “Efficient Wireless Non-Radiative Mid-Range Energy Transfer,” Annals of Physics, Vol. 323, No. 1, 2008, pp. 34-48.
 C.-J. Chen, T.-H. Chu, C.-L. Lin and Z.-C. Jou, “A Study of Loosely Coupled Coils for Wireless Power Transfer,” IEEE Transactions on Circuits and Systems, Vol. 57, No. 7, 2010, pp. 536-540.
 Y. Hori, “Motion Control of Electric Vehicles and Prospects of Supercapacitors,” IEEJ Transactions on Electrical and Electronic Engineering, Vol. 4, No. 2, 2009, pp. 231-239. doi:10.1002/tee.20401
 B. L. Cannon, J. F. Hoburg, D. D. Stancil and S. C. Goldstein, “Magnetic Resonant Coupling as a Potential Means for Wireless Power Transfer to Multiple Small Receivers,” IEEE Transactions on Power Electronics, Vol. 24, No. 7, 2009, pp. 1819-1826.
 R. E. Hamam, A. Karalis, J. D. Joannopoulos and M. Soljacic, “Efficient Weakly-Radiative Wireless Energy Transfer: An EIT-Like Approach,” Annals of Physics, Vol. 324, No. 8, 2009, pp. 1783-1795.
 A. Kurs, R. Moffatt and M. Soljacic, “Simultaneous Mid-Range Power Transfer to Multiple Devices,” Applied Physics Letters, Vol. 96, No. 4, 2010, Article ID: 044102.
 F. Zhang, S. A. Hackworth, X. Liu, C. Li and M. Sun, “Wireless Power Delivery for Wearable Sensors and Implants in Body Sensor Networks,” 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Argentina, 31 August-4 September 2010, pp. 692-695.
 S. Cheon, Y. Kim, S. Kang, M. Lee, J. Lee and T. Zyung, “Circuit-Model-Based Analysis of a Wireless Energy- Transfer System via Coupled Magnetic Resonances,” IEEE Transactions on Industrial Electronics, Vol. 58, No. 7, 2011, pp. 2906-2913. doi:10.1109/TIE.2010.2072893
 S. L. Ho, J. Wang, W. Fu and M. Sun, “A Comparative Study between Novel Witricity and Traditional Inductive Magnetic Coupling in Wireless Charging,” IEEE Transactions on Magnetics, Vol. 47, No. 5, 2011, pp. 1522- 1525.
 S. Ho, J. Wang, W. Fu and M. Sun, “A Novel Resonant Inductive Magnetic Coupling Wireless Charger with TiO2 Compound Interlayer,” Journal of Applied Physics, Vol. 109, No. 7, 2011, p. 07E502.
 A. RamRakhyani, S. Mirabbasi and M. Chiao, “Design and Optimization of Resonance-Based Efficient Wireless Power Delivery Systems for Biomedical Implants,” IEEE Transactions on Biomedical Circuits and Systems, Vol. 5, No. 1, 2011, pp. 48-63.
 H. Haus, “Waves and Fields in Optoelectronics,” Prentice-Hall, Englewood, 1984.
 B. L. Ooi, D. X. Xu and P. S. Kooi, “A Comprehensive Explanation on the High Quality Characteristics of Symmetrical Octagonal Spiral Inductor,” Proceeding of IEEE RFIC Symposiumi, 28 July 2003, pp. 259-262.
 H. M. Hsu, “Improving the Quality Factor of a Broadened Spiral Inductor with Arithmetic-Procession Step Width,” Microwave and Optical Technology Letters, Vol. 45, No. 2, 2005, pp. 118-120. doi:10.1002/mop.20741
 C. A. Chang, S. P. Tseng, S. S. Jiang and J. A. Yeh, “Characterization of Spiral Inductors with Patterned Float- ing Structures,” IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 5, 2004, pp. 1375-1381.
 C. P. Yue and S. S. Wong, “On-Chip Spiral Inductors with Patterned Ground Shields for Si-Based RFICs,” IEEE Journal of Solid-State Circuits, Vol. 33, No. 5, 1998, pp. 743-752. doi:10.1109/4.668989
 A. P. Sample, D. A. Meyer and J. R. Smith, “Analysis, Experimental Results, and Range Adaptation of Magnetically Coupled Resonators for Wireless Power Transfer,” IEEE Transactions on Industrial Electronics, Vol. 58, No. 2, 2011, pp. 544-554.