Wireless system can power devices inside the body | Hacker News Reader

Wireless system can power devices inside the body

news.mit.edu

114 pointstostitos197941 comments

The main thing I got from the MIT article is this:

"This system relies on an array of antennas that emit radio waves of slightly different frequencies. As the radio waves travel, they overlap and combine in different ways."

This is known as constructive interference, pretty nifty to see it used in this context. The range has been increased from 10 cm to 1 meter since the paper I co-authored on this subject. Impressive!

These kinds of applications have also been a long time coming. With IoT devices and NFC readers looming around the corner, I think it is likely that we will see some pretty innovative medical inventions. Likewise, as mentioned by NKosmatos, we need to take the security aspect very seriously. Some of these NFC devices are programmable, and should defend against attacks that could lead to events such as withholding life-saving medicine or misreporting biometrics.

For reference, check out this paper I co-authored:

Suitability of NFC for Medical Device Communication and Power Delivery (2007)

https://ieeexplore.ieee.org/document/4454171/

And if you're interested in an early paper about RFID-delivered viruses, check out this by Tanenbaum et al.:

http://www.rfidvirus.org/papers/percom.06.pdf

Isn't this description flawed though? Waves of different frequencies are independent in power. Thus they don't interfere (when time-averaged) -- at all. Zero. (this is because signals of different frequencies are orthogonal in the time-average integral of product sense)

What creates interference is difference is phase among waves of the exact same frequency.

It's odd that the paper author is making such basic EM theory mistake, and I wonder what the actual device construction is like. (since it cannot work the way he describes at steady state)

Maybe he's interpreting phase modulation as frequency modulation? Of course at steady state all frequencies would be the same, making this a weird/incorrect interpretation I think.

My understanding is all frequencies interfere with all other frequencies. When averaged, the total power is probably not affected, but the power at any given point at a small enough time interval should be noticeable.

But then, I'm not an antenna designer, I may have something fundamentally wrong in my understanding. :)

The problem is as soon as you're speaking of "frequency" you're already on a time-scale where the power doesn't interfere with other frequencies (as long as the medium is linear, etc -- which is almost certainly true here). In the mathematical/technical sense (in linear system theory)it's quite clear that different frequencies would interfere, it's a basic entire principle of linear circuit design that's been used for centuries -- systems have a Frequency Response where each frequency is independent as a result of the eigenfunction property. Personally I just think it's a big oversight, maybe they were trying to give a laymen explanation and confused themselves. What they're doing must be some form of phase modulation, maybe they're interpreting as short bursts of frequency modulation (with a stable steady-state frequency), but as I said this is not an illuminating view imo.

Edit: Actually I think they might have frequency control indeed. That would be a good idea to find a peak in frequency response (i.e. "resonant power transfer"), not for any directivity gains through constructive interference. That might be the source of confusion.

Radio waves are used to power cochlear implants. There is a chip & receiver unit that is inserted under the skin on the head, with electrodes that go into the cochlea. Externally there is an antenna that is held on the head next to the skin, using a magnet to hold it in place. Radio waves are sent across the skin to power the chip and control the electrodes.

Plenty of nefarious applications for this. The range alone blows away existing RFID designs, which will make it the preferred "chipping" technology for surveillance states everywhere.

There are positive uses. I can see this being useful for monitoring health in animals raised for food in addition to the medical applications the article mentioned.

That said, the potential for abuse is limited by what society will tolerate. We tolerate tracking and alcohol monitoring bracelets for people who drive drunk. If we tolerate tracking implants for sex offenders on parole or something I'm sure it'll filter down routine probation sentences eventually.

We tolerate tracking devices with camera, microphones and banking history in our pocket. We even pay for it. So i wouldn't count of the public wisdom on this. Or anything really.

Or fast food restaurants embedding tracking devices in their food... That'll be fun having to review privacy policies at every restaurant you eat at.

Finally, a use case for smart toilets! Imagine getting a bonus on your Taco Bell™ Rewards Card™ for not...expelling any Taco Cabana chips.

Right now the preferred "chipping" technology is your smart phone.

As bad as smartphones might be, I hope you're not seriously trivializing actual implants by comparing them to smartphones.

You can leave your smartphone at home.

The analogy is, retrospectively, not the best. I was alluding to the fact that most people take them almost everywhere they go, which is good enough for a surveillance state.

>The implants are powered by radio frequency waves, which can safely pass through human tissues. In tests in animals

why animals? couldn't the researchers just swallow that "prototype about the size of a grain of rice" themselves and/or get several paid volunteers?

Animals are the first step because testing in humans is more expensive. These devices will likely have to be tested in humans before commercialization.

> why animals? couldn't the researchers just swallow that "prototype about the size of a grain of rice" themselves and/or get several paid volunteers?

Insurance. I assume it's easier to get insurance for human testing if you've shown safety in animals first.

Because animals have no say and they don't have to pay the animals. Once it's done the animals will just be euthanized.

Because if it turned out to be dangerous it has been determined that the animals being hurt/killed is better than that happening to human test subjects.

Contrary to the other answers to this question, I suspect the real reason is that the prototype is expensive, and way easier to recover from a lab animal’s poo than the researcher’s.

One of the first "promises" of nanotechnology I ever read about was that you could create batteries so small that just calling your cellphone would charge them I wonder if that is fundamentally the same idea.

Interesting and for sure there are numerous applications for such devices, but they didn’t mention anything about security and possible interferences. Sounds very promising but scary at the same time.

I want to power my earbuds without ever removing them. If they can do this I would be the first human tester.

I'd also love to start my car, without having to remember where i left my keys.

Can it power tumors?

More seriously, though, nanotech or relatively small implantables/injectables powered by radio or induction could do a lot for medicine... If anyone could afford it.

How much energy could a device extract from blood sugar?

The real question is can that conversion be done in an efficient enough way with materials that are safe to put inside someone and in a small enough package.

"One single implanted GBFC device of 0.24 mL volume (2.4 mL for the whole implant) produced the power required to operate, using a specially designed electronic circuit to charge a capacitor, two types of electronic devices: a LED and a digital thermometer."

https://www.nature.com/articles/srep01516

I'm waiting for someone to invent the implantable chip that converts blood sugar into heat/light purely with the intention of wasting that energy.

Grab enough power to monitor blood sugar, to make sure you aren't putting someone into a coma, but otherwise just try to burn an extra few hundred calories a day.

That's interesting. Seems like a low tech solution would be to give blood every day. I wonder if somebody has already invented the blood donation diet.

Problem with that is that we don't replenish it fast enough for that to work. Maybe with plasma donations but I'm not sure there either.

It would be an enormously complex device, most of the sugar we consume gets converted into fat as we quickly cap out our "energy blocks".

Why waste this energy? Couldn’t they devise a way to mine bitcoin with it? :)

Oh god, just what the world's food distribution problems need.

Good idea, but I’m guessing you’d have fever as a side effect ;)

orgasic

Then you need to radiate heat somewhere. If you heat up the blood the body will spend less energy keeping warm leading to no benefit.

If you generate a lot of heat... it goes really bad.

Easy, simply install a venting port in the patient.

The first patient should be a congressman then, because they already have a hole they blow hot air out of.

Alternatively (and arguably much less complex and much cheaper): 1) eat less, 2) exercise

You're thinking too fancy - with our technology today, we could install a bypass valve at the pyloric sphincter that just dumps chyme into a stoma appliance/bag.

How does the device come out when you need it to?

Texhnolyze here we come.

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