Parts for reading Bioelectrical signals
while searching for a bunch of amplifiers to do non-implantable ecg reading i stumbled across a nice part that qualifies for implantable stuff, too.
http://www.ti.com/product/ads1191
it is pretty much a "everything in one chip" sollution to get feedback from nerves into a microcontroller. that means. electrodes on one end, μc on the other, done. it contains the entire analog frontend that would usualy fill up a box.
this friend comes with 1 channel input, has a bunch of bigger brothers that can handle 2, 4 and 8 channels.
it comes in packages that are small, but still possible to solder without expensive reflow equipment.
they also are reasonably low power, theoretically run several days on i tiny rechargeable lithium battery.
in short. i am hyped up about those things, they could be the ticket to real interaction with active-implants. and up to 8 channels would be quite a lot of data you can use.
i ordered a whole bunch of samples to build some test boards. they wont ship cause they are backordered. but i hope to get them end of january.
comments or previous expericences are welcome :)
cheers
http://www.ti.com/product/ads1191
it is pretty much a "everything in one chip" sollution to get feedback from nerves into a microcontroller. that means. electrodes on one end, μc on the other, done. it contains the entire analog frontend that would usualy fill up a box.
this friend comes with 1 channel input, has a bunch of bigger brothers that can handle 2, 4 and 8 channels.
it comes in packages that are small, but still possible to solder without expensive reflow equipment.
they also are reasonably low power, theoretically run several days on i tiny rechargeable lithium battery.
in short. i am hyped up about those things, they could be the ticket to real interaction with active-implants. and up to 8 channels would be quite a lot of data you can use.
i ordered a whole bunch of samples to build some test boards. they wont ship cause they are backordered. but i hope to get them end of january.
comments or previous expericences are welcome :)
cheers
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Could be worth being checked out
i made a small breakout board for experimentation but it is at the limits of what i can manufactor ( given the tiny size). so i might need to have it made in a real pcb factory. so far, the part is very promising, it's pinout is really nicely done too. given an industrial production, an implant with that chip would be quite tiny. even DIY boards fit on very small space.
i think will get a premade lab-breakout (16€ :( ) and wire it up, just to see if i can avoid a bunch of parts by using battery supply etc. once i settled on a circuit , i will do a propper layout.
since the pcb's end up really small. it would be best to order 50 or so at once, the price difference compared to just a few is almost nil. so, we better have a good design to on the first order.
2. absolutely no idea. but with that, and some regular electrodes for stimulation you have a basic input output system between you, and your implant. think of something useful that can communicate with a button and buzzer, morse-code being a great example.
Multiplexing for writing/output is easier, as there are no pulses you can miss. so a single electrode driver can drive a whole bunch of electrodes at the same time, and even a greater range of outputs if you don't need to drive them all at once. there are a couple of good parts available and i already have 2 analog mux/demux in use in the concept of the electrode driver circuit.
So let's say that we could fit two of these eight-input ICs on a small enough board, so that we could simultaneously receive and process sixteen signals total. If we can fit 4-to-1 analog multiplexing on there, that would allow us to read sixteen signals at a time out of a total of 64 of them, which is a pretty significant fraction of the 96 (plus four grounded ones) electrodes that many modern MEAs, including the Utah array, possess. That's in addition to being able to write to potentially all of them, if we can fit enough multiplexers as well. How small a board would you say we'd need to fit everything on?
in worst case you'd need to pull in a custom made IC. not cheap. but certainly possible.
As for custom-making an IC, we could theoretically do that for the entire multiplexing + frontend hardware, right? Although pricey, that would have advantages with regards to miniaturization, I imagine.