Using skin as a battery for smart rings or watches? Technology has been discovered that can make it possible

Wearable technology has advanced enormously in the last decade, but there is still something with much room for improvement: battery life. While we have managed to improve charging times and efficiency of devices, there remains a limitation for small wearables that rely on their own battery in terms of design, sustainability, and comfort.

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In this line, a new research from Carnegie Mellon University might be about to change the situation. We are talking about Power-over-Skin, a technique that allows devices like the Apple Watch or other wearables to obtain energy through our skin, thus eliminating the need for an incorporated battery.

In simple terms, Power-over-Skin allows the energy from a single transmitter we carry on the body to be distributed to different devices attached to the skin. This method uses our body’s natural ability to conduct radiofrequency energy at 40 MHz, allowing a single power source to feed multiple devices across the body.

Let’s imagine a future where a small patch on the arm powers not only our Apple Watch Series 10, but also other devices like smart rings or even patch-sensors for different health measurements. Instead of having to recharge or replace the batteries of these devices, we could carry a single transmitter that keeps them running all day. But is it a good idea?

Possible applications: An Apple Watch without a battery?

This transmission and reception system is capacitive, which means that the contact between the device and the skin does not require a direct physical connection. The energy can travel through clothing, allowing, for example, the transmitter to be carried in the pocket while still powering devices located in other parts of the body.

During the tests, the researchers managed to power an LED earring, a calculator, and a Bluetooth ring. In this context, imagining an Apple Watch or equivalent that operates without a battery is truly interesting. Without the weight and volume of a battery, the device could be made much lighter and thinner.

On the other hand, by eliminating the need to recharge it, we could use it continuously. From here, questions arise. What happens if we remove the battery from the pocket? Do we have to put a new and charged one in the pocket before removing the discharged one so that the watch doesn’t turn off?

Although Power-over-Skin technology has enormous potential, there is still much to refine before this technology can even be considered in the market. Firstly, the amount of energy that can currently be transferred through the skin is quite limited. Although it is sufficient for small devices like rings or health sensor patches, for now, it seems insufficient for high-energy demand devices, such as mobile phones or high-performance smartwatches (although these always become more and more efficient).

The most important thing, however, is that although the experiments conducted did not discover adverse effects, and the use of RF on the human body raises questions about its long-term safety. Further investigation is needed to determine if using the skin as an energy conductor has any negative health effects, especially if used continuously. One of the most important aspects is to avoid the formation of energy hotspots, which could cause discomfort or even damage upon contact with the skin.

Are we ready for a world without batteries in wearables?

Power-over-Skin is a technology that, although still in its early stages, presents a truly interesting idea in the world of wearables. A vision of a future where several of the devices we normally use can operate without batteries, using our own body as a conductor of energy.

In the field of wireless energy transfer, we have had more promises than realities for a long time. Remote charging systems, for example, have left us with more than one prototype and have never achieved commercial viability. The interesting thing is that this research goes beyond the applications we have addressed here.

Better understanding how our skin conducts electricity in relation to the devices we increasingly wear is truly useful. It may not be ready for a smartwatch yet, but it does make sense to think of something smaller—a ring, perhaps. A ring that does not require a battery and can use the energy provided by our phone in the pocket to perform certain readings.

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For now, we will have to wait, but it is from investigations like the one at hand that advancements emerge. Power-over-Skin shows us an intriguing future, at the very least, where instead of worrying about charging our devices, we could simply have them with us and let them do their work. Perhaps in a few years, we will wonder how we managed to live without it.