researchers say that people can use their bodies as ‘batteries’

Power-over-skin can turn people’s bodies into batteries

Researchers from Carnegie Mellon University and the Future Interfaces Group have introduced Power-over-Skin, a study and experiment that uses a single worn transmitter to turn people’s bodies into ‘batteries’ and power wearable electronics. When people put on this powered transmitter, it sends a frequency of 40 MHz to their bodies. At these high frequencies, the bodies become conductors of energy, allowing the radiofrequency energy to travel easily through them. Because the energy is ‘stored,’ it can then be transferred to devices, but these electronics should have the ‘receiver’ board to absorb the electricity coming from the bodies.

In this way, people act like ‘batteries’ for wearable gadgets by supplying them power when the gadgets’ own batteries are discharged or no longer working. Users only need to hold the device with a receiver board to transfer the stored energy from their bodies into the electronics. The research team, composed of Andy Kong, Daehwa Kim, and Chris Harrison, details the findings’ potentials and processes in their recent study. They have also applied their research, which focuses on ‘intra-body power transfer,’ to a number of small devices, including a calculator, an earring, an input ring used as a joystick, and some medical patches.

all images and video stills courtesy of researchers from Carnegie Mellon University and the Future Interfaces Group

Transmitter charges the bodies so they can transfer power

The way it works is that people wear one transmitter, which resembles a wearable accessory (but it can also be attached to the back of a phone or embedded into a headset). This device ‘charges’ the bodies, and users can then channel this power into the wearable electronics they have, including smartwatches and AR glasses. ‘We ran a series of studies to quantify the performance of our approach and found that we could deliver up to 61 microwatts of power from head to toe and up to 1500 microwatts of power for closer arrangements of transmitter and receiver, such as wrist to fingertip,’ says Andy Kong.

The transmitter doesn’t necessarily need direct skin contact. It absorbs energy from bodies and transfers it to electronics, even if users are wearing clothes or if it’s embedded into another device like an AR headset. During one of their tests, the researchers from Carnegie Mellon University added a receiver board onto a pocket calculator. This harnessed energy from the body and transferred it into the device, and once that was done, the video documenting the experiment showed that the battery-free calculator still functioned as it normally would.

Power-over-Skin is a study that uses a worn transmitter to turn people’s bodies into ‘batteries’

Power-over-skin can be useful for small devices

They’ve also applied their Power-over-Skin study to other applications and achieved successful results. They were able to charge and discharge a capacitor that allowed the LED light integrated into an earring to blink. They powered a ring controller with a miniature joystick that gamers can use to control an interface or their games over Bluetooth. The Power-over-Skin approach also powered small screens, such as e-ink display devices.

So far, the power is limited to around a milliwatt at max, but Andy Kong says, ‘This is still useful because there are existing devices that use this much power, like CGMs or fitness trackers.’ Because the power transfer is capacitive, it still works even if users are wearing clothes, especially with conductive fabrics. For those who want to try out their study and be their own batteries, the research team has made the transmitter hardware open source.

view of the Power-over-Skin transmitter