I take it you are
If not, well, where should I start?
'metamaterial'? Its a loop etched on a PCB, Ive done this myself before, I wired half a dozen crystal sets in parallel each with its own 30m longwire. This was many years ago so dont have the results any more, but from 'lost waves' ie ordinary receive level signals, yes the voltage was quite high, a few whole volts, but the actual power was miniscule.
They dont even know the difference between voltage and power in this article (or its deliberate to mislead), likewise they only say it converted 'microwaves', but dont say at what level. Yes, I could easily get 7v from that array if I stuck it next to the UHF transmit array at work (a mere 7MW), I suspect that they also had the source of the energy rather close at hand
If all these so called wireless energy transfer methods were at all usable, well, we'd have been charging our handhelds with them for about 50 years already
Im afraid I can no longer access current science journals, but im sure someone on here will be able to get at Decembers Applied Physics Letters
. I'd like to see their paper, if any good it would be possible to replicate what they did and get the same results, but somehow I doubt their paper will be repeatable