Controlling and/or manipulating the magnetic fields
I plan to have the magnets place in my fingers by the end of this semester. im not particularly well versed in how this works so I may ask one of the scientific minds at my college to help me. As I was thinking about the procedure I wanted to take it to the next level, so my question is, would it be possible to manipulate these magnetic fields if say there was some sort of power source and/or an electrical current running through the hand/body, this is all theoretical, and again I am not well versed in this subject, so forgive me if this question is moronic, i was just wondering if someone has at least thought about it.
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Size: The overall size of the device, and the number of turns of wire around the core provide the upper limit of the device. The bigger it is, the more power it will require, the more heat it will produce, and the more difficult insertion will be.
Heat: The size of the wire gauge and the type of wire will determine resistance and the amount of heat produced. You don't want to have something getting to hot under the skin.
Power: A battery may work, but for how long? If you're going to recharge the device, then how? Many suggest and induction coil charger, but this increases the size of the device and depending on your design may require many hours for a charge. Beyond this, rechargeable batteries eventually fail and contain nasty poisonous crap that can either kill you or cause necrosis of the tissue if you bio-proofing fails.
Control: Are you going to have an on off switch? Because you say "manipulate" I assume you want to be able to ramp the power up or down. The circuit to do this increases the size and complexity of the device, and I'm not sure how you'd incorporate a mechanical switch that's bioproofed. Perhaps some kind of RF transmitter reciever? But this take even more power, complexity, and size.
Bioproofing: Not the biggest issue. I'm sure you could coat the hell out of your device, but this once again increases the size and if you incorporate any nasty metals or batteries a failure would be catastrophic.
Overall, I think this would be a great project to collaborate on. Because each of these issues would NEED to be addressed for ANY major project, this relatively simple circuit might be a great starting point that would provide data/technique/experience for later larger projects.
Heat is not so much a problem, the body can transport a lot of it away, ways more than you would want to feed any implanted device with.
Power, electromagnets demand tons of current. i'd drain any mattery in a matter of minutes. Inductive sollutions would be pointless as you'd have to carry around a big inductive supply,too. so you could connect the electromagnet to a battery with all benefits but no additional hassle.
overall. having a tiny electromagnet in your fingertip would be pretty much pointless. big problems to overcome and i coludn't come up with a single possible use.
even for a starting project it's not really suited. altho other circuits may be a bit more complex, they are easier to handle (due to less current demand) and a lot more useful.
Size: Pacemakers are relatively bulky but this is mediated by long electrode wire. The pacemaker device itself is subcutaneous in the upper chest with an electrode passing into the appropriate region of the heart. Is this useful to us? Well, it could be... if one of two innovations occurred. If one were to place the "power pack" or bulk of a device in the abdomen or chest, one would need either biosafe wires (There is a thread for this) or conductive tattoos (There is a thread for this) or some combination of both.
Heat: Not an issue for modern pacemakers. I couldn't find specifics on the voltage output, although I know that they must be >4 millivolts. Pacer spikes show up on ECGs with a 4 millivolt or so spike and some of the voltage must be lost before being sensed. Heat WOULD be an issue with any device of larger draw.
Power: I really liked this read - (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1502062/) Very interesting. Lithium Iodine are apparently top of the line at this point. Unlike earlier sources, Li batteries lose very little charge over time at rest and can last over 10 years (for a pacer). I can attest to seeing patients (Not MD, RN) that have had them for longer without issue. I've also seen patients who have failing pacers at like year 6. Another advantage is that Lithium Iodine doesn't produce gas and thus can be sealed inside a biosafe container. Too much draw though and these suckers can get hot or even explode. Something to keep in mind. Early models DID attempt to use induction charging, but these were forgotten as it requires the patient to maintain the charge. Many think this is too chancy.
Control: Yes, modern pacers have some serious functionality. Pacer reps go into hospitals and query pacers all the time using an RF interface. From what I've read, half of the power used by modern pacers are the microcontrollers. Pacers no longer blindly discharge; they have many many different modes such as "On-demand" pacing which fires only when the heart "waits too long." So, it seems the optimal means of control may end up being a non-mechanical option... which unfortunately means a very small but constant drain on power. PERHAPS the best way to do this would be a Lithium Iodine battery to power the microcontroller over a ten year period, and an induction charged battery pack for the actual function which may require much larger voltage, but for short periods.
Bioproofing: My god, this I think was the best part: Hermetically sealed titanium units. I've been reading a lot about welding titanium, which seems to be a bit complicated.... but if we had one person skilled at welding titanium, then bioproofing would be a moot issue for many types of implants. Titanium also prevents interference from devices such as microwaves. I picture a small sealed titanium unit coated first in parylene, and then in a more durable biosafe material. This seems optimal, and would have the benefit of sequestring the really nasty stuff inside the battery from release into the body.
titanium cases, i'd have no idea where to get it from. guess welding it would require tooling etc too. for now the best options we have is ptfe and parylene-c. both are readily available.
as for feedback. you'd most likely want to go with regular electrodes. any sort of magnet or mechanical motion eats quite a lot of power. so for most basic feedback you'd probably end up tingling a bunch of nerves in your skin. tapping directly into neurons would be possible if you can get hands on the right electrodes and someone who can implant it. simply putting 2 electrodes into the skin would be a tingling sensation at first. and over time, your brain will probably adapt to whatever makes sense.
It might be handy to have an electromagnet and use it to switch other implants on and off via reid switch. Bar tricks would be awesome too.
As far as hermetically sealed titanium goes, there are 3d printing services that can do that. http://i.materialise.com/
for those that didn't see this:
http://www.kurzweilai.net/the-brain-computer-interface-goes-wireless
and referenced paper:
http://iopscience.iop.org/1741-2552/10/2/026010
I doubt any of us are up to making neural interfaces like that, there is some potentially useful info about making bio-safe containers.