Putting a battery inside your eye socket seems incredibly risky to me, though. Especially one that can power a bright light like this for a while...
On the other hand, every mirror would be a great chance to lose your other eye as well, so maybe disregard my ideas.
One cool use, IMO, would be a time of flight distance-measuring laser: With only a single working eye, OP lacks binocular vision for distance measuring. With the equivalent to a Bushnell rangefinder, they could stare at an object, blink twice, and hear a tiny voice literally in their head say "37.84 meters".
Would probably require some kind of crazy training for it to work. Plus I have no clue what I’m talking about!
Heck, the old skool 1st/2nd ACs in the camera department would kill for this. No need to "pull tape" any more.
At those power levels? Probably every surface in general. A beam powerful enough to light a match or burn through a balloon is powerful enough for the diffuse reflection off a table or wall to blind you.
Wait..
I have some laser pointers capable of lighting matches. They get hot.
With great powers comes great responsibility.
The other problem is that this small battery won't have that much current capacity
A scaled-up version of this : https://www.youtube.com/watch?v=UQ3K0suY1Dc
To provide more power to the led you probably need a bigger coil inside the eye, it should work if you hide the induction transmission loop inside a hat.
I guess it might not matter much because the battery is so small that you’d be lucky to get more than a handful of minutes running that LED at max power.
This is all speculation based on a 30 second video though.
I mean...isn't it effectively water cooled?
All I know is my headlamp gets mighty hot when it is running at peak intensity. Like hard to touch levels of hotness.
We already do this with pacemakers
Whether it is worth it for a cool gadget, is another question.
Would you rather have a battery in your eye socket catch fire and explode, or one in your pants pocket/on your wrist?
Pacemakers are typically lithium iodide which do not have the same risk of uncontrolled burning (that's the nickel variety).
But also, the pacemaker sits outside the body with probes going inside. You'd not want another surgery just to change a battery.
They can implant basically under the fat layer or under the pectoral muscle. Beneath the fat layer is easier both from a surgery and recovery standpoint, but less secure.
The downside of that is that it's possible for the device to flip over. They usually try to avoid securing the device to anything because that can lead to discomfort or pain if the device wants to move around, but they can if they have to.
And yes, they do have to repeat surgery to replace the device when the battery gets low. The leads AIUI are usually a lifetime part (hopefully for all the right reasons). For defibrillators, battery life will be maximized if the device doesn't have to deliver shocks and can stick to just pacing. It turns out if they implant a defibrillator, you get a pacemaker for free.
https://www.reuters.com/article/health-heart-pacemaker-dc-id...
There used to be nuclear-powered pacemakers that could last many lifetimes but nowadays the doctors say it's better to replace the whole thing every once in a while, so the nuclear option is overkill.
"The History of Nuclear Powered Pacemakers" - http://large.stanford.edu/courses/2015/ph241/degraw2/
> Despite the often longer life-expectancies, nuclear pacemakers quickly became a part of the past when lithium batteries were developed. Not only did the technology improve, allowing for lighter, smaller, and programmable pacemakers, but doctors began to realize that this excessive longevity of nuclear pacemakers was excessive.
https://en.wikipedia.org/wiki/Betavoltaic_device says betavoltaic "devices include a 100 μW tritium-powered device weighing 20 grams".
That's about 5x the weight of a glass eye - https://www.muellersoehne.com/907.html .
Assuming linear scaling, an energy budget of 2μW isn't going to provide much light.
You could use the 2μW to charge up a capacitor for 24 hours and then have a minute and a half of 2mW, which is enough for a visible laser pointer reaching a few meters. 2mW light output is quite a bit brighter than that but requires more like 20mW power input.
A 220 μF cap at 48 volts would hold 35 hours of 2μW, and there are ceramic caps that big that would easily fit into your eyeball.
How much does that weigh? How big is it? What's the leakage current?
If it takes enough space away from the betavoltaic device, and thus reduces the power generation, then the cap will never fully charge.
Not knowing what you're thinking of, I picked https://www.mouser.com/datasheet/2/427/134d-1763800.pdf mostly arbitrarily. Note that I'm a programmer, not a hardware person.
The lightest weights 2.6 g, which is 1/2 the weight of the eyeball, so cuts the power generation to 1μW.
I think it's telling me there's a 10μA leakage current, which I think means the cap will power up to 0.1V before the leakage rate matches the power rate.
Now that you know my level of ignorance, what's your take?
Leakage current usually increases superlinearly with voltage, though. If the tantalum's DC leakage is 10 μA at 50 volts, it's probably closer to 0.1 μA at 5 volts.
In capacitors with a given dielectric, the maximum energy is proportional to the volume of the dielectric, so although a 47 μF cap charged to 108 volts stores the same energy as a 220 μF cap charged to 50 volts, it also needs the same volume.
(I'm not an EE either; I only play one on HN.)
https://en.wikipedia.org/wiki/Human_eye says an adult human eyeball is about 23.7 mm × 24.2 mm × 23.4 mm, and a spheroid like that is π/6 of the corresponding cuboid, so you only have about 7.03 cc to work with.
So probably you'd have to settle for under 1 cc of capacitor, which (in the case of X7R anyway) means storing more like 15 seconds of 2 mW.
It might get a bit annoying when you want to go to sleep though.
2 cd/m2 * (7mm * 7mm * pi) = 0.00030787608 candelas = 307 µ candela.
Doesn't seem like much light.
This introduces an opening into the body that will almost certainly result in infection.
Probably much less risky to periodically change the battery than get the portal infected
Anyway, your statement about the pacemaker sitting outside the body with probes going inside is not correct; maybe it once was, but that was decades ago.