Proof of concept
First, let me applaud Professor Yang for pointing out that there's a long way to go before this bears fruit, if it ever does.
I do wonder if it could be improved with a plugged in device broadcasting at a specific frequency to enable over-the-air wireless charging.
As far as charging wearables and implants, I would think that extracting energy from body heat shows more promise.
Personally, I can't wait for it to be able to replace my damn smoke detector battery .