Since I have some time before getting around to this, I wasn’t sure if I should post it in the lounge, but I decided that even if it’s a conceptual idea for now, it could go here since it really isn’t far off at all.
I was browsing Amazon and saw a smart watch advertising the ability to read some vitals, and I thought about the idea of writing an app for android’s smartwatch os to pulse an NFC signal, and have one of the xLEDs installed close enough to pulse along with your heartrate.
Would writing an app for that be hard, and is this a practical idea? Anything obvious I’m missing here? Because implants are coming in between a few months each over the span of the next year, and if I can write an app for that… I am so in.
I wonder how much battery drainage that would actually run, and if getting one of the more expensive watches for the battery would be big enough, or at least programmed well enough? We could get it to run in battery saving mode, and skip a lot of other processes… toggle it when user turns screen off.
The reason why batteries last a decent amount of time in cellphones and smartwatches is because the OS tries to turn everything off as much as possible. They only works because those devices works for a few minutes at a time and sleep the rest of the time.
If your app runs, it’ll keep the CPU awake. Not to mention, the NFC itself. Even with the screen off, it’ll drain the battery fast.
Also, I’m 100% certain you can’t control the EM field directly without rooting the device. And even if you do, there’s a very good chance you won’t be able to anyway, because the chip doesn’t support it or something.
If you want to investigate the technical side of it, this might give you some ideas.
Interestingly enough, a Samsung smartwatch with 470mah would run about 5ma per pulse, which we can run up to 160bpm for each heartbeat at maximum. Reading and writing costs about 40ma, but all it needs is a blank pulse, so you could probably get away with about 10ma each pulse
If it’s pulsing to the heart rate and we want to support say, a maximum of 160 beats per minute to account for exercise or possible tachycardia, that comes out to about 2.67 beats per second, or three for good measure. That makes this even medically useful, if they aren’t dead or dying at 160bpm or higher.
Proceeding with maximum capacity measurements, at 3-5ma per pulse, or 5 as we proceed, and up to 3 pulses a second, that is 15ma per second at most.
And this is where I began to realize it is not going to work with where we’re at. Remember, this is just purely NFC power consumption, not including the device.
At 15ma a second, it would cost the device 900ma per minute, or 54,000mah.
Damn.
Worth a try!
A typical desktop USB reader uses about 70 mA. Let’s say 50 mA in a cellphone.
Assuming your heartbeat pulses last, say 2/10th of a second, and the person has a HR of 120 bpm, that’s 50 x 0.2 x (120 / 60) = 20 mA average. For one hour: 20 mAh
EDIT: God I’m not so hot with math either when I’m drunk
Oh, crap! Yeah, I suck if I have to keep track of it and I was doing that all mentally.
Hellll yeah! That sounds pretty doable. I think I can give it a shot when I get my implants. Guess I’ll keep the forum updated around then as well. If it works out, and anyone wants it, I’ll open source it on github.
Thanks for the math
