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Conformal phased surfaces for wireless powering of bioelectronic microdevices


Wireless powering could enable the long-term operation of advanced bioelectronic devices within the human body. Although both enhanced powering depth and device miniaturization can be achieved by shaping the field pattern within the body, existing electromagnetic structures do not provide the spatial phase control required to synthesize such patterns. Here, we describe the design and operation of conformal electromagnetic structures, termed phased surfaces, that interface with non-planar body surfaces and optimally modulate the phase response to enhance the performance of wireless powering. We demonstrate that the phased surfaces can wirelessly transfer energy across anatomically heterogeneous tissues in large animal models, powering miniaturized semiconductor devices (<12 mm3) deep within the body (>4 cm). As an illustration of in vivo operation, we wirelessly regulated cardiac rhythm by powering miniaturized stimulators at multiple endocardial sites in a porcine animal model.

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Figure 1: Phased surface wireless powering system.
Figure 2: Wireless powering performance of the phased surface.
Figure 3: Performance variation with geometry and thermal characteristics.
Figure 4: Wireless powering of microdevices in pig abdomen and neck.
Figure 5: In vivo wireless cardiac pacing in pig.


  1. 1

    Chandrakasan, A. P., Verma, N. & Daly, D. C. Ultralow-power electronics for biomedical applications. Annu. Rev. Biomed. Eng. 10, 247–274 (2008).

    CAS  Article  Google Scholar 

  2. 2

    Dagdeviren, C. et al. Conformal piezoelectric energy harvesting and storage from motions of the heart, lung, and diaphragm. Proc. Natl Acad. Sci. USA 111, 1927–1932 (2014).

    CAS  Article  Google Scholar 

  3. 3

    Leonov, V. Thermoelectric energy harvesting of human body heat for wearable sensors. IEEE Sens. J. 13, 2284–2291 (2013).

    Article  Google Scholar 

  4. 4

    Schuder, J., Stephenson, H. Jr & Townsend, J. High level electromagnetic energy transfer through a closed chest wall. Inst. Radio Engrs. Int. Conv. Record. 9, 119–126 (1961).

    Google Scholar 

  5. 5

    Jow, U.-M. & Ghovanloo, M. Design and optimization of printed spiral coils for efficient transcutaneous inductive power transmission. IEEE Trans. Biomed. Circuits Syst. 1, 193–202 (2008).

    Article  Google Scholar 

  6. 6

    Liu, W. et al. A neuro-stimulus chip with telemetry unit for retinal prosthetic device. IEEE J. Solid-State Circuits 35, 1487–1497 (2000).

    Article  Google Scholar 

  7. 7

    RamRakhyani, A. K., Mirabbasi, S. & Chiao, M. Design and optimization of resonance-based efficient wireless power delivery systems for biomedical implants. IEEE Trans. Biomed. Circuits Syst. 5, 48–63 (2011).

    CAS  Article  Google Scholar 

  8. 8

    Waters, B. H., Sample, A. P., Bonde, P. & Smith, J. R. Powering a ventricular assist device (VAD) with the free-range resonant electrical energy delivery (FREE-D) system. Proc. IEEE 100, 138–149 (2012).

    Article  Google Scholar 

  9. 9

    Ahn, D. & Ghovanloo, M. Optimal design of wireless power transmission links for millimeter-sized biomedical implants. IEEE Trans. Biomed. Circuits Syst. 10, 125–137 (2016).

    Article  Google Scholar 

  10. 10

    Kim, S., Ho, J. S. & Poon, A. S. Y. Midfield wireless powering of subwavelength autonomous devices. Phys. Rev. Lett. 110, 203905 (2013).

    Article  Google Scholar 

  11. 11

    Ho, J. S. et al. Wireless power transfer to deep-tissue microimplants. Proc. Natl Acad. Sci. USA 111, 7974–7979 (2014).

    CAS  Article  Google Scholar 

  12. 12

    Chow, E. Y. et al. Wireless powering and the study of RF propagation through ocular tissue for development of implantable sensors. IEEE Trans. Antennas Propag. 59, 2379–2387 (2011).

    Article  Google Scholar 

  13. 13

    Ling, H. & Lee, S. W. Focusing of electromagnetic waves through a dielectric interface. J. Opt. Soc. Am. A 1, 965–973 (1984).

    Article  Google Scholar 

  14. 14

    Li, X., Davis, S. K., Hagness, S. C., van der Weide, D. W. & Van Veen, B. D. Microwave imaging via space–time beamforming: experimental investigation of tumor detection in multilayer breast phantoms. IEEE Trans. Microwave Theory Techn. 52, 1856–1865 (2004).

    Article  Google Scholar 

  15. 15

    Ling, H., Lee, S. & Gee, W. Frequency optimization of focused microwave hyperthermia applicators. Proc. IEEE 72, 224–225 (1984).

    Article  Google Scholar 

  16. 16

    Meaney, P. M., Fanning, M. W. & Li, D. A clinical prototype for active microwave imaging of the breast. IEEE Trans. Microwave Theory Tech. 48, 1841–1853 (2000).

    Article  Google Scholar 

  17. 17

    Wu, L., McGough, R. J., Arabe, O. A. & Samulski, T. V. An RF phased array applicator designed for hyperthermia breast cancer treatments. Phys. Med. Biol. 51, 1–20 (2005).

    Article  Google Scholar 

  18. 18

    Xu, S. et al. Soft microfluidic assemblies of sensors, circuits, and radios for the skin. Science 344, 70–74 (2014).

    CAS  Article  Google Scholar 

  19. 19

    Hussain, A. M. et al. Metal/polymer based stretchable antenna for constant frequency far-field communication in wearable electronics. Adv. Funct. Mater. 25, 6565–6575 (2015).

    CAS  Article  Google Scholar 

  20. 20

    Yu, N. & Capasso, F. Flat optics with designer metasurfaces. Nat. Mater. 13, 139–150 (2014).

    CAS  Article  Google Scholar 

  21. 21

    Ho, J. S. et al. Planar immersion lens with metasurfaces. Phys. Rev. B 91, 125145–12514 8 (2015).

    Article  Google Scholar 

  22. 22

    Harrington, R. F. Reactively controlled directive arrays. IEEE Trans. Antennas Propag. 26, 390–395 (1978).

    Article  Google Scholar 

  23. 23

    Grbic, A., Merlin, R., Thomas, E. M. & Imani, M. F. Near-field plates: metamaterial surfaces/arrays for subwavelength focusing and probing. Proc. IEEE 99, 1806–1815 (2011).

    Article  Google Scholar 

  24. 24

    Ozeki, T. et al. Functions for detecting malposition of transcutaneous energy transmission coils. ASAIO J. 49, 469–474 (2003).

    PubMed  Google Scholar 

  25. 25

    IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, IEEE Standard C95.1 (Institute of Electronic and Electrical Engineers, 2005).

  26. 26

    Montgomery, K. L. et al. Wirelessly powered, fully internal optogenetics for brain, spinal and peripheral circuits in mice. Nat. Methods 12, 969–974 (2015).

    CAS  Article  Google Scholar 

  27. 27

    Meng, C., Maeng, J., John, S. W. M. & Irazoqui, P. P. Ultrasmall integrated 3D micro-supercapacitors solve energy storage for miniature devices. Adv. Energy Mater. 4, 1301269 (2013).

    Article  Google Scholar 

  28. 28

    Birmingham, K. et al. Bioelectronic medicines: a research roadmap. Nat. Rev. Drug Discov. 13, 399–400 (2014).

    CAS  Article  Google Scholar 

  29. 29

    Zhao, Y. & Alu, A. Manipulating light polarization with ultrathin plasmonic metasurfaces. Phys. Rev. B 84, 205428–20542 6 (2011).

    Article  Google Scholar 

  30. 30

    Pfeiffer, C. & Grbic, A. Metamaterial Huygens’ surfaces: tailoring wave fronts with reflectionless sheets. Phys. Rev. Lett. 110, 197401–19740 5 (2013).

    Article  Google Scholar 

  31. 31

    Gabriel, S., Lau, R. W. & Gabriel, C. The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues. Phys. Med. Biol. 41, 2271–2293 (1996).

    CAS  Article  Google Scholar 

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We acknowledge support from grants from the Singapore Institute for Neurotechnology, US National Science Foundation (ECCS-1351687), the US National Institutes of Health (National Institute of Biomedical Imaging and Bioengineering grant R21EB020894) and the Hong Kong Innovation and Technology Fund (ITS/087/14).

Author information




H.F.T., A.S.Y.P. and J.S.H. jointly supervised this work. D.R.A., Y.T., D.W., A.M., S.H., C.S., Z.D., F.Y., A.S.Y.P. and J.S.H. built and characterized the wireless powering system. Y.T., A.M., S.H., S.-Y.L., Z.Z., Z.-Y.Z., H.F.T., A.S.Y.P. and J.S.H. performed the in vivo experiments. D.R.A., H.F.T., A.S.Y.P. and J.S.H. wrote the manuscript.

Corresponding author

Correspondence to John S. Ho.

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Competing interests

This work relates to patent PCT/US2015/052642.

Supplementary information

Supplementary Information

Supplementary methods, figures and tables. (PDF 2723 kb)

Supplementary Video 1

Magnetic-field amplitude as the position of a bone structure is varied along the lateral direction (x direction, at z = 25 mm). (MOV 1238 kb)

Supplementary Video 2

Magnetic-field amplitude as the position of a bone structure is varied along the vertical direction (z direction, at x = 0 mm). (MOV 694 kb)

Supplementary code—sample data

Sample data for the MATLAB scripts. (TXT 76 kb)

Supplementary code

MATLAB scripts. (TXT 4 kb)

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Agrawal, D., Tanabe, Y., Weng, D. et al. Conformal phased surfaces for wireless powering of bioelectronic microdevices. Nat Biomed Eng 1, 0043 (2017).

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