Wireless power transmission and energy harvesting techniques could be used to power and operate devices in, on and around the human body. However, near-field power transmission approaches are limited by distance, and the efficiency of far-field radiofrequency methods is limited by the body shadowing effect. Here, we show that the body-coupling characteristics of electromagnetic waves—which are either artificially introduced or present in the immediate surroundings—can be used to enable a power transmission and energy harvesting method that offers power to locations all around the body. The body-coupled power transmission exhibits a path loss 30- to 70-dB lower than far-field radiofrequency transmission in the presence of body shadowing. The system can recover 2 µW at the head from an ~1.2-mW transmitter placed 160 cm away at the ankle. In the absence of an active power transmitter, we demonstrate placement-independent scavenging of ambient electromagnetic waves coupled onto the human body, resulting in a power recovery of ~2.2 µW from electromagnetic waves of up to −10-dBm on the body.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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We thank A. Thean for helpful discussions, J. Ho and R. J. M. Yap for support with rectifier devices and Y. Kifle for the set-up of the body channel measurements. We acknowledge support from the Semi-anechoic Chamber at Electromagnetic Effects Research Laboratory (EMERL), jointly operated by Nanyang Technological University Singapore and DSO National Laboratories Singapore, and J. M. M. Low for his support at EMERL. This work was funded by the NUS Hybrid-Integrated Flexible Electronic Systems Program (R-263-501-009-731) as well as A∗STAR AME Nanosystems at the Edge Program under grant no. A18A4b0055.
The authors declare no competing interests.
Peer review information Nature Electronics thanks Ada Poon, Jan Rabaey and Jeremy Gummeson for their contribution to the peer review of this work.
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Supplementary Figs. 1–19 and Table 1.
Demonstration of the simultaneous powering of a calculator at three different locations by body-coupled power transmission.
Demonstration of the simultaneous powering of a calculator (after 3 min of charge accumulation) at three different locations by body-coupled ambient energy harvesting.
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Li, J., Dong, Y., Park, J.H. et al. Body-coupled power transmission and energy harvesting. Nat Electron 4, 530–538 (2021). https://doi.org/10.1038/s41928-021-00592-y
Nature Electronics (2021)