Power-Over-Skin Makes Powering Wearables Easier

A side view of an Asian woman with brown hair. She has a faint smile and is wearing an earring that looks somewhat like a large copper snowflake. Near the ear hole is a small PCB with a blinking LED. To the right of the image is the text "LED Earring, Recieved power 50 µW"

The ever-shrinking size of electronics and sensors has allowed wearables to help us quantify more and more about ourselves in smaller and smaller packages, but one major constraint is the size of the battery you can fit inside. What if you could remotely power a wearable device instead?

Researchers at Carnegie Mellon University were able to develop a power transmitter that lets power flow over human skin to remote devices over distances as far a head-to-toe. The human body can efficiently transmit 40 MHz RF energy along the skin and keeps this energy confined around the body and through clothing, as the effect is capacitive.

The researchers were able to develop several proof-of-concept devices including “a Bluetooth
ring with a joystick, a stick-and-forget medical patch which logs data, and a sun-exposure patch with a screen — demonstrating user input, displays, sensing, and wireless communication.” As the researchers state in the paper, this could open up some really interesting new wearable applications that weren’t possible previously because of power constraints.

If you’re ready to dive into the world of wearables, how about this hackable smart ring or a wearable that rides rails?

33 thoughts on “Power-Over-Skin Makes Powering Wearables Easier

  1. It’s almost a little sad to see the Personal Area Network (PAN) concept from the 90’s devolve into a “mere” power-delivery system. The original idea had been to use this technology to link worn components in a bodywide network for data transfer and remote sensor deployment (on the body). The fun came in when you made skin-to-skin contact (via handshaking, for example) and two PANs linked up and exchanged credentials. File transfers and contact exchanges would be fast and fairly effortless.

    No, I do not know if research was done to determine if more intimate skin-on-skin contact could be used to transfer malicious files. It seems trivially possible, but who the hell keeps their wearable tech on while canoodling?

        1. More like they intersect. PAN includes anything close (ir, Bluetooth devices) and any wearables, while BAN includes only integral devices. BAN is part of PAN, but Bear was correct in its use. Literal handshaking if network happens in PAN area.

  2. Funny, 40 MHz was historically used for diathermy treatment: Deliberately transmitting RF energy into the body to heat parts up.

    They could have been kinder to the spectrum and used the 27.12 MHz or 13.56 MHz or 6.78 MHz ISM frequencies that are actually intended for such use.

  3. Well, I may be overly cautious, but transmitting RF over the body constantly worries me.
    And I also wonder how such an application would be implemented without privacy sucking as the primary funding.

    1. likely not an issue, i mean as long as you dont put the RG58 from your ham radio in a place it doesnt belong lol, really these kind of things are only dangerous when their is a significant differential present i.e. electron flow direction. thing is, there is just better ways to passively power on body sensors, for example, a self winding watch, or potentially id imagine a piezoelectric generator powered by your heartbeat, or even just thermoelectrics could be used, we are full of so much warm goo that is just giving away all that power for free, like somewhere resting at almost 250 btu’s

      1. No, that’s not how non-ionizing radiation works. You’re constantly bathed in far more RF energy than this, and it doesn’t matter how much of it you get, anything below UV is physically only capable of heating you up. If you can’t feel it, it’s not enough to matter.

        1. Many things that don’t cause cancer can promote its growth and influence it.

          It’s not a usually a subject a knowledgeable person talks about in absolutes.

          The risks in this instance are, to me, substantially higher than the benefits.

          Constant exposure, vs occasional, periodic exposure are substantially different as well.

          If you have me a choice, would I stand the minimum safe distance from a ham radio antenna on 2m or the same distance from an FM broadcast antenna at the same power level and distance; which would I prefer to stand beside?

          The one not constantly transmitting.

          You assume all risk is zero. Good for you.
          I assume all risk is non-zero, and I will choose to balance, limit or eliminate that risk based on a cost/benefit ratio where cost is my current, short term, and long term health.

      1. Maybe it’s the “alt text”? We write it into the images to help people with vision issues. It’s an accessibility thing.

        We don’t do it as frequently as we should — which would be all of the time — because it’s up to the individual authors, but we certainly encourage it, especially when the image is central to explaining the writeup.

        For some real fun with alt text, go check out XKCD comics. If you have been missing them all this time, you’re missing half the fun.

        Anywhoo… we don’t use AI generation. Hackaday is made exclusively by humans for humans.

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