This paper presents non-coil sources to improve the wireless power transfer efficiency for implantable device used in various medical applications --- cardiovascular devices, endoscope in the small intestine, and neurostimulator in the brain. For each application, a bound on the power transfer efficiency and the optimal source achieving such bound are analytically solved. The results reveal that depending on the depth of the implantable devices, power can be transferred to a sub-millimeter scaled receiver with the efficiency ranging from -57 dB to -33 dB, which is up to 6.6 times higher than the performance of existing coil-based source systems. The technique introduced in this paper can be broadly applied to other medical applications.
2. Heetderks, W. J., "RF powering of millimeter- and submillimeter-sized neural prosthertic implants," IEEE Trans. Biomed. Eng., Vol. 35, 323-327, May 1988.
3. Donaldson, N. N. and T. Perkins, "Analysis of resonant coupled coils in the design of radio frequency transcutaneous links," Med. Biol. Eng. Comput., Vol. 21, 612-627, Sep. 1983.
4. Chen, C.-J., T.-H. Chu, C.-L. Lin, and J.-C. Jou, "A study of loosely coupled coils for wireless power transfer," IEEE Trans. Circuits Syst. — II: Express Briefs, Vol. 57, 536-540, Jul. 2010.
5. Ho, J. S., S. Kim, and A. S. Y. Poon, "Midfield wireless powering for implantable systems," Proceedings of the IEEE, Vol. 101, No. 6, 1369-1378, 2013.
6. Poon, A. S. Y., S. O’Driscoll, and T. H. Meng, "Optimal frequency for wireless power transmission into dispersive tissue," IEEE Trans. Antennas And Propagation, Vol. 58, 1739-1750, May 2010.
7. Kim, S., J. S. Ho, and A. S. Y. Poon, "Wireless power transfer to miniature implants: Transmitter optimization," IEEE Trans. Antennas and Propagation, Vol. 60, No. 10, 2012.
8. Kim, S., J. S. Ho, and A. S. Y. Poon, "Midfield wireless powering of subwavelength autonomous devices," Physical Review Letters, Vol. 110, 1-5, May 2013.
9. Ho, J. S., A. J. Yeh, E. Neofytou, S. Kim, Y. Tanabe, B. Patlolla, R. E. Beygui, and A. S. Y. Poon, "Wireless power transfer to deep-tissue microimplants," Proceedings of the National Academy of Sciences, Vol. 111, No. 22, 7974-7979, 2014.
10. EBR System Inc., Implantable systems for wireless heart stimulation, www.ebrsystemsinc.com, 2011.
11. Lenaerts, B. and R. Puers, "An inductive power link for a wireless endoscope," Biosnes. Bioelectron., Vol. 22, 1390-1395, 2007.
12. Biederman, W., D. J. Yeager, N. Narevsky, A. C. Koralek, J. M. Carmena, E. Alon, and J. M. Rabaey, "A fully-integrated, miniaturized (0.125mm2) 10.5 μw wireless neural sensor," IEEE Journal of Solid-State Circuits, Vol. 48, No. 4, 960-970, 2013.
13. Harrington, R. F., Time-Harmonic Electromagnetic Fields, IEEE Press, 2001.
14. Ko, W. H., S. P. Liang, and C. D. F. Fun, "Design of radio-frequency powered coils for implant instruments," Med. Biol. Eng. Comput., Vol. 15, 634-640, Feb. 1977.
15. Strang, G., Linear Algebra and Its Application, 3rd Ed., Saunders College Publishing, 1988.
16. O’Driscoll, S., A. S. Y. Poon, and T. H. Meng, "A mm-sized implantable power receiver with adaptive link compensation," Proc. IEEE Intl. Solid-State Circuits Conf. (ISSCC), Feb. 2009.
17. Yakovlev, A., D. Pivonka, T. H. Meng, and A. S. Y. Poon, "A mm-sized wirelessly powered and remotely controlled locomotive implantable device," Proc. IEEE Intl. Solid-State Circuits Conf. (ISSCC), Feb. 2012.
18. We solve Maxwell’s equations for all physical sources using the method-of-moments (Mentor Graphics, IE3D),.
19. Chew, W. C., Waves and Fields in Inhomogeneous Media, IEEE Press, 1995.