Energy scavenger eats leftover wireless signals
Nikola Tesla high-fives from the grave
No, it’s not another cute-but-useless contactless charger: a group of researchers led by Manos Tentzeris at Georgia Tech are working on antennae that could scavenge stray wireless signals to power small sensors or microprocessors.
If you’re close enough to a large radio transmitter, harvesting stray energy is pretty straightforward: an old-fashioned long fluorescent tube will at least glow if it’s close enough to a high-power radio transmitter (or, as demonstrated in an art installation, near power transmission lines).
Harvesting “random” signals from the air is more difficult. The ambient signals that surround us all, causing cancer (or not), headaches (or not), or irrational panic (too often) among anyone who notices the transmitter, is of much lower power, and isn’t concentrated around a single frequency.
To turn those stray signals into electricity – in small quantities, so don’t expect a “free” laptop charger anytime soon – the Georgia Tech researchers designed an ultra-wideband antenna that can pick up signals from 100 MHz to around 15 GHz.
The Georgia Tech research has another cool angle to it: the antennas were printed onto flexible material using a modified inkjet that uses refills containing silver and other nanoparticles in an emulsion. By printing onto polymer instead of paper, the group hopes to create antennae operating at up to 60 GHz.
In experiments so far, the antennas have been able to harvest “hundreds of microwatts” from TV bands, successfully powering a temperature sensor using power scavenged from a transmitter a kilometer distant.
You can find more info about Georgia Tech's power forager here. ®
Energy Scavenger - I remember when .. ..
As an exercise in "green" electronics, some 40 years ago, I built a two tuner radio using low power transistors, the first tuner was used to hunt for a signal strong enough to put static through a crystal earpiece - and was normally Long Wave Radio 2 , the second tuner was then used to locate the station I wanted to listen to.
For extra boost the aerial could be crocodile clipped to a wire fence / frame ( such as a bed frame ) and provided free listening almost anywhere. It was also built from Balsa wood about the size of 20 ciggies.
I live in a city saturated with WiFi provided by a Telecom providor, so it would be quite feasible to suck all that free energy instead of hunting for a radio broadcast station.
We MK already make a remote hand-held lighting control equipment that is battery free collecting energy from the aether.
By the way nice comment: "causing cancer (or not), headaches (or not), or irrational panic (too often)". Nail on head.
What's the decimal point?
"hundreds of microwatts" sounds SO much better than "a few milliwatts"