is it possible to make an implant that is body powered (like an led that work whit the body energy) its just a little question and i wnated to know
I’m french so please be indulgent
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Assuming that you are talking about body heat, I am not sure how you would capture it. A pelletier junction requires both a hot side and a cold side in order to generate electricity, so without a heatsink you wouldn’t have too much chance there.
I suppose you could try and use piezo crystals in or on joints, but that sounds like it would hamper movement.
As for the northstar that seems like a rather clunky solution to having to carry a compass.
i was wondering if it was possible to make a thing like the north star v1 but less thick and that can recharge whit the energy that our body produce.
Not possible at this stage. As Zwack has mentioned, you need a heat gradient to generate power for heat, and motion is not enough to be viable (and probably far too large of a device to be practical even if it was). You’d also need to store it, and rechargeable battery tech isn’t safe enough yet. Pacemakers, etc, use non-rechargeable batteries.
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Implantable medical devices usually require a battery to operate and this can represent a severe restriction. In most cases, the implantable medical devices must be surgically replaced because of the dead batteries; therefore, the longevity of the whole implantable medical device is determined by the battery lifespan. For this reason, researchers have been studying energy harvesting techniques from the human body in order to obtain batteryless implantable medical devices. The human body is a rich source of energy and this energy can be harvested from body heat, breathing, arm motion, leg motion or the motion of other body parts produced during walking or any other activity. In particular, the main human-body energy sources are kinetic energy and thermal energy. This paper reviews the state-of-art in kinetic and thermoelectric energy harvesters for powering implantable medical devices. Kinetic energy harvesters are based on electromagnetic, electrostatic and piezoelectric conversion. The different energy harvesters are analyzed highlighting their sizes, energy or power they produce and their relative applications. As they must be implanted, energy harvesting devices must be limited in size, typically about 1 cm3. The available energy depends on human-body positions; therefore, some positions are more advantageous than others. For example, favorable positions for piezoelectric harvesters are hip, knee and ankle where forces are significant. The energy harvesters here reported produce a power between 6 nW and 7.2 mW; these values are comparable with the supply requirements of the most common implantable medical devices; this demonstrates that energy harvesting techniques is a valid solution to design batteryless implantable medical devices.
An abstract from the full paper which can be found right here.
Edit: Full paper is available upon request if anybody wants I could upload the PDF?
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Yes, that is the abstract, which can be found at that link. The full paper is not however available there.
They are talking about piezo electric implants at hip, knee or ankle. None of these are great locations for a “northstar” type electronic compass. It was also pointed out in one of the papers that referenced this one that the energy harvesters are typically larger than the electronics that they power.
The size of harvester they are describing is around 1 cm³. That might seem small sitting in the palm of your hand, but assuming that you wouldn’t want it more than 2mm thick for implant that would require a strip one centimeter wide across the best part of my hand, and that is just for the energy harvester.
I am not saying that this is impossible but it isn’t practical. This Paper concludes that at the moment inductive coupling is the best option currently available. That is essentially a device which receives it’s power from outside the body through an induction coil.
Now what does that sound like to you?
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What about Solid State Batterys?
Summary
Is that a Tracking Link? its soooo long and the stuff after the ? is normally tracking stuff, but if i remove it i cant access the page.
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The paper is certainly available upon request at the provided link. I’m not trying to mislead anybody I just tried to answer the question at the start of the thread. Which technically is the correct answer regardless of what we consider “practical” and what is “possible”. I thought it would be interesting to further the conversation that is all.
Adding this link as a joke as something we can all laugh at, together.
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I’m sorry if I gave the impression that you were deliberately trying to mislead anyone. I was pointing out that the full paper was not immediately available, and your phrasing could be read in more than one way. I was interested enough to go look for the paper.
Theoretically there are multiple possibilities, what is currently practical is a different matter. While it might be possible to build a slimmer Northstar like device, it is not going to be as easy to power it as just grabbing some off the shelf parts and hooking them up.
It is interesting how two similar papers appear to reach two completely different conclusions. Although both are positive about the future of biomedical devices they differ in what they consider will be the most likely outcome.
That’s why I came here to DT originally 
Inductive or resonant coupling to an exterior power source is really our best bet.
- Thermal energy harvesting requires a temperature differential which does not exist in the body
- Kinetic generates intermittent high voltage but low wattage spikes of energy that can’t be used for anything
- Photovoltaics don’t work well on red light and all the blue/UV light that would reach them is attenuated by the skin
- Harvesting chemical energy from the body requires a lot of maintenance, because the interface point will always be prone to biofouling
You could use betavoltaics as a battery, but they generate modest amounts of power and are not currently available in the scale we need for implantation.
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and what if we use a microrechargable battery and we use wireless charging to recharge it (we could use solid state batterys like @mrln just said)
I am interested in the solid state batteries… need more info like charge cycle count and energy density… but it seems very promising
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yeah i know but if we power someting that dont use that much energy (like an led)
we could take a very small battery that recharges quickly enough and since the led does not use a lot of electricity there would be a longer life for the charging time
(we could also make a “button” to open and close the led) so we dont have to charge the battery that often
*check this video about solid state battery its seem very promising they have already flexible one : https://youtu.be/kJXRyWQgOY4
Actually, an LED pulling 10mA - 20mA (as is typical) is a very serous drain on a battery small enough to be implanted. Let’s take a look as a Li-ion pacemaker battery… it could function as a descent stand-in for a generic implant battery. If we look at the discharge profile, it’s clear the discharge capacity drops significantly as we pull more current over a range from 0mA to 30mA;
From BATTERY FOR CARDIAC PACEMAKER: AN ALTERNATIVE TOLITHIUM-IODINE SYSTEM.pdf (27.8 KB)
As you can see, pulling 20mA from such a battery reduces it’s useful discharge capacity by 75%! As such, chemical wear on the battery increases significantly as does the need to charge much more frequently.
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so it would be difficult to make such a thing?
as far as i understood the battery life decreases over time so the battery would be dead after a short time? is that what you mean
you mentionned Li-ion pacemaker battery
but i was talking of FLCB (the solid state battery) which can be mush larger beacause this on is flexible (i was thinking of something like the flexNExT)
Just throwing one thing in cause I have a halfway related thing
Harvesting thermal energy from the body via a peltier element:
I am wearing a watch that harvests some thermal energy from the place where it contacts on the wrist.
On my best day this far the watch was able to harvest 3.45 mWh. That’s over 24 hours.
And that’s from an up to 40mm diameter peltier element having a thermal difference of 1-3°C
I’m sure you’d get a tiny bit of a thermal difference in the body if placed right, but you’d be in the very low µW range I’d say
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The watch is able to have a temperature differential by being placed outside the body. You probably wont get that gradient if it was implanted.
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Yes. I’d guess you’d get some thermal difference if implanted. But it would probably be not enough for charging anything, let alone run something.
Just felt like it would fit to have a value of how little an external device produces to begin with
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