Converting Wi-Fi signals to electricity with new 2-D materials

[Technobabble_]

This popped up on my feed today. Any thoughts on it?

Article: http://news.mit.edu/2019/converting-wi-fi-signals-electricity-0128

Actual paper: https://www.nature.com/articles/s41586-019-0892-1

Meta: I'm somewhat pissed that the MIT article didn't link directly to the Nature paper.

[timelessbeing]

so? 

[Daixiwen]

I don't see why it wouldn't be possible. But the real question is would it be practical?
40 microwatts to power a LED though... it would need to be a very small LED!
The other problem I see for "small communicating devices" is that you can only use a fraction of those 40 microwatts to transmit a signal back. I'm not sure the transmission would be reliable. If you need more power you'd need a capacitor that gets charged when not transmitting, and that can deliver more juice when needed. But at that point it might be more practical and economical to just put there a small lithium cell.

[Technobabble_]

so? 

Your comment isn't helpful. What do you mean?

[KaneTW]

Rectennas aren't new technology. Just, not very useful. 50 uW on a LED isn't going to be more than a few millicandela, so I'm not sure what's the point of that example. Maybe coupled with some sort of energy storage for devices that are on for a short while with long periods of rest.

[timelessbeing]

so? 

Your comment isn't helpful. What do you mean?

I mean is there a particular reason you bring this up? RFID tags and proximity cards have been using RF energy for a decades. It's pretty common stuff.