“Because Prometheus offers several maximum output voltages (VOUT) between 2V and 5V it can directly power integrated circuits and charge various battery chemistries without the need for additional charger circuitry.
Each module’s integrated VOUT regulation prevents voltage overshoot, securing reliable operation with various battery types.”
ding ding we have a winner it looks like!
Here, Tear-Based Aqueous Batteries for Smart Contact Lenses:
https://pubs.acs.org/doi/full/10.1021/acs.nanolett.0c04362
A really good solution.
Accid and some components of most of actual batteries are really discouraged for use inside human body…
Anyways in my opinion, i think sugar blood bateries would be the future…
I don’t know if this is helpful, but I signed up for the Mojo AR Contact Lens.
If I actually receive it I’ll let you know how it performs. I’m pretty sure they’re looking to release this year after performing so well at CES.
I read a paper about rubber based piezoelectric materials but i haven’t heard of that since then. It was theorised to be used to recharge pacemakers by muscle movenent. But i don’t believe you can get much power out of it.
Never heard of north star before but after a quick google search i don’t believe you could power that with the tech i described earlier. It wouldn’t even work if you had a big peltier element sitting on your skin with a block of ice on the other side. North star has alot of leds and quite a large microprocessor. Even in low power mode it draws way to much.
This sounds like the stuff i read about a few years back (10 years ago or so?). But yeah it’s not alot of power you get from that. Even though 7.2mW might be enough to power northstar for a moment, there is no way tech like that would ever be placed by a piercer. Those power harvesting devices have to be secured to the underlying tissue and not just brought under the skin. The one using stretchy piezoelectric rubber needs to be secured along side a muscle so it stretches when the muscle stretches.
This might work but they are not that cheap and are not that common. A quick search on mouser brings up 2 results for solid state batterys with ceramic electrolyte.
The power from betavoltaic cells are so low in power generation that you can forget powering an led with that if you don’t want it to take weeks to recharge.
That is true. The solid state battery i found on mouser has a maximum rated discharge current of 5mA which is 50c. The capacity dips to about 80% at 1000 cycles. With a rated capacity of 100uAh at 1,5V it’s not alot of charge.
The fun thing about melanin is it converts uv into infrared when i remember the paper i read a while ago. It also does that with an impressive efficiency of above 80%
The ones in the videos were only prototypes. Alot are not on the market yet. It’s actually very very hard to get your hands on one at the moment.
I’m more concerned with the chemicals in the batteries leaking. There are some really nasty things in batteries. Even lithium salts can mess you up big (which is one of the things in solid state batterys)
The thing is power harvesting radio waves is one thing but doing it inside of an implantable device? Good luck. First of all your antenna needs a specific length to pick up anything at all. The next thing is the higher the frequency the better the water of your body shields to a point where it doesn’t even penetrate a few millimeters. Wifi for example is roughly at 2,4GHz and your microwave runs at that frequency too and as you probably know for everything to get warm in your microwave you need to stirr your food. It’s very unlikely you pick up enough power with an antenna in an implant to power something usefull even if it’s sending a single puls onto a nerve exept when you are standing within a few hundred meters to the radio tower.
Placing things inside the body is always a bit tricky. Using the blood or flesh as an electrolyte is also a thing where i say hmm… rather not. Blood tends to clott quite easily even if it’s kept at 37°c inside your body. Also most batteries work by having a metal disolve in the electrolyte which for pretty much any metal is a bad thing inside your body.
To the peltier element stuff i have very efficient industrial peltier elements so i could place it on my arm with a heatsink on top and measure output power but i can tell you you don’t want this inside your body. First if all those things are big. The second is there are none that are even remotely bendy. And third the compounds in there are not really what you call biocompatible.
Anyways… i produced a wall of text but i gave some of my knowledge to it.
All very valid points, but to turn the conversation the other direction
So where should we be focusing our energy?
Beta voltaic or solar seem like the only ones so far that doesn’t have a fundamental roadblock
(Poisonous, frequency limitation and interaction, poor thermal differential, metal corrosion)
Beta and solar “work” on paper, just not enough juice from the squeeze
Induction
Huzzah!
Traditional RF communications links are not possible for a device this small because the wavelength of the electromagnetic wave is too large relative to the size of the device. Because the wavelengths for ultrasound are much smaller at a given frequency because the speed of sound is so much less than the speed of light, the team used ultrasound to both power and communicate with the device wirelessly. They fabricated the “antenna” for communicating and powering with ultrasound directly on top of the chip.
That’s… interesting.
…bet the “range” is shit 
Bet That’s why they can only use ultrasound due to their coils being pitiful
Also if I remember when I read the article, it can only talk in ultrasound as well, so no 125 or 13.56
So super proprietary, niche and or useless
I guarantee that is the article author not getting it. It’s as clear as mud, and the parts that are clearly stated are clearly wrong. Clearly.
Agreed. Physics is hard, m’kay
Oof. I see that the writers of these articles have no idea what they are talking about. They at least need an ultrasound imager to power it because otherwise there is no way to get ultrasound into the body strong enough to power this. It might be small and low power but it’s still inefficient. Next thing is that with a piezo crystal the direction in which the ultrasonic wave arrices is really critical. I can’t really see how they want to make sure it stays in the right orientation without introducing some material to encase it in, which would produce problems due to the difference in refractive index.
This article has pictures too. Also… they use bare copper to connect the upper part of the piezo to the chip on the bottom? Last time i checked copper was not really that biocompatiple.
Anyways… it’s an interesting tech demo even though it’s a bit overhyped by the author of the article. Also i searched for the patents filed with one of the people that worked on this. I could find the names on the page of columbia innovation to this. When you search for Kenneth Sheppard on Espacenet - Advanced search you find loads of filings. One of them for example is for a “Fully Implanted, wireless, flexible CMOS surface recording device” .
Anyways there is also one for “Micron scale Ultrasound Identification sensing Tags” which is probably the patent to this little device. US2018193000 (A1) is the patent number for those interested.
Ok just started with the claimes and they say it the frequency it works at is 1-50MHz so the wavelength would be 1,5mm for 1MHz (assuming speed of sound in flesh is the same as in water so 1500m/s) and 0,03mm for 50MHz. Wavelenth wise this seems about right although there might be big differences in receiving efficiency depending on frequency.
It also says they’re using a coating of Parylene for biocompatability. I don’t know how much this affects the piezo or if parylene may develop cracks when blasted with high power ultrasound.
Anyways… if you’re curious read up in the patent
This energy harvesting chip from Analog Devices could be interesting.
https://www.analog.com/en/products/ltc3588-1.html#product-overview
I’m not a big fan of the piezo approach, because reliance on mechanical components places an inherent lifespan on the implant. If you were going to do it though, something like this would be a huge benefit.
