Andy Kong (@oldestasian) on X

2 min read Original article ↗

user avatar

Everyone has a devices like your phone that get charged daily — our approach allows these devices to share their power with other, smaller wearables (Fitbit, CGM) by coupling RF energy through the human body

user avatar

At high frequencies, electricity travels easily through the body. Our powered transmitter sends a 40 MHz square wave -> amplifier -> impedance-matching network, then into a body-contact electrode, filling up the user with RF energy

user avatar

Our tiny receiver can sit anywhere on the body — it rectifies this AC into DC power, storing it in a capacitor. Once we have power, we can do anything we want!

user avatar

We’ve powered bluetooth microcontrollers, custom game controllers, displays, calculators, sensors, and even blinky jewelry.

user avatar

The power transfer is capacitive so it even works through pants! It also integrates well w/ conductive fabrics

user avatar

IMO the most compelling use case is integration w/ existing stuff, like AR headsets w/ our transmitter could power their controllers over the skin, BOOM now those don't have to be charged

user avatar

A limitation is that the power is pretty small, around a milliwatt at max. I argue this is still useful tho because there are existing devices that use this much power like CGMs or fitness trackers

user avatar

Oh and it's totally safe! I read these RF power guidelines and we aren't anywhere near the limit

user avatar

user avatar

Our receiver hardware is also open source if you’d like to make your own, you can find it on my GitHub. More details later: