News - Batteryless wireless devices are powered by 'ambient backscatter'

Quote:

---

An important step in the creation of 'the internet of things'?

---

Read more.

"Can be embedded deeply in inaccessible sites, such as concrete walls, floors, or roofs. Since embedded devices have no battery, they last forever and require zero maintenance."

Anyone else worried about privacy in the future?

When I first looked at 'ambient backscatter', I thought it said 'ancient backscratcher'.

amazing!!!!!!

I think it's the embedded sensor aspect of this that is most exciting. Being able to monitor conditions round a building or other structure without having to run wires through or across it or provide power to the sensors does open the doors to what can be done. Truly smart buildings can cut running costs and energy usage dramatically if done right.

I've been powered by backscatter in the past. Monster Tindaloo! :P

Interesting concept, but I don’t think these devices are "unpowered", they can’t be, they get their energy from the radio transmission, therefore whoever is paying for the transmission is providing the power. This is similar to running fluorescent lights near a power transmission line - which I think is considered as theft.

Another thought. Would it be possible to block transmission paths by the use of these devices as energy absorbers?

These devices don't increase the drain on the RF source unlike putting fluorescent lights near a transmission line therefore it's not costing any more to run the RF source than before.
Although the energy they use isn't "free" per say it's as close as you'll get, and the loss of signal near the devices due to the drain will be insignificant (unless you hold your iPhone wrong), so no impact on signal strength for mobiles.

Taking power from HV lines is through induction rather than RF emission - induction places load on the source, like a transformer/inductive charging/etc. RF energy is radiated from the source constantly, you don't 'pull' any of that energy, it's just there. There's really not very much of it at all though - a decent cell signal might be 10 picowatts, or 0.00000000001 watts, despite the tower transmitting with on the order of a kilowatt. Starting out with such small amounts of energy to work with, the receiving end is going to have to be damn close, and have a good SNR. Too many of these things, you're going to need some (conventionally powered) RF processing to distinguish between signals.

Interesting idea, but I don't buy the hype - read between the lines in the blog. If you happen to be within a few miles of an immensely powerful transmitter, presumably with decent line-of-sight, you can send a small amount of information a few metres. Unless every flag in every street has a receiver connected to a wired backhaul, I don't see how they're expecting to sent text messages/email over it. And that's ignoring the not-insignificant issue of powering enough of the phone to compose it.

Sounds like a new application of "the crystal set" amateur radio to me...