Is Neuromancer closer than you think?

Could contemporary technology be used to build a Gibson-esque implant that could connect a human brain to a computer? Maybe more practical, what would it take to curve spinal cord injuries like Christopher Reeve’s using this kind of technology?

Basically, you’d need a computer chip attached to a human nerve. In an age of VLSI, I doubt that building the chip would be that hard. To tackle the spinal cord injury, for example, I’d imagine a chip built into a titanium vertebrae, and connected to a control unit much like a pacemaker. Probably two chips built into two titanium vertebrae, one to attach to either side of the spinal cord break.

The surface of the chip would be an dense grid of electrodes, each capable of sending or receiving small electrical impulses. A microprocessor would be responsible for mapping electrodes on one chip to electrodes on the other, thus insuring that electrical impulses were communicated across the break. Building a chip with a dense enough grid doesn’t seem like anything that can’t be done using contemporary technology.

The hard part, I think, would be attaching the chip to the spinal cord. I think an anisotropic conductive adhesive, probably an epoxy, should do the trick. You’d need an conductive adhesive (obviously) to transmit the nerve impulses, but it couldn’t conduct in any direction. Imagining the spinal cord connected vertically to the chip (in the x-y plane), you’d need an adhesive that would only conduct in the z-direction (that’s the anisotropic part).

Conductive adhesives are available, and in fact widely used in the electronics industry for connections that can’t be done with solder, either because of the heat required or because the materials (like silicon) won’t stick to solder. They’re generally made by suspending tiny spheres of silver in the epoxy, which touch each other and conduct after the epoxy dries around them. That’s an isotropic adhesive, which conducts in all directions.

That wouldn’t work for our purpose, because we’d need an anisotropic adhesive. Such things exist, mostly in film form, where the film has been designed to conduct only along its narrow width. I don’t think a film would do, either.

We’d need an anisotropic epoxy. For starters, how would we set the direction of the anisotropism? My first idea would be to use a magnetic field while the epoxy is setting, much like the way iron shavings line up in a magnetic field. In fact, this might be almost exactly what is needed. Instead of tiny spheres of metal, we need to figure a way to manufacture tiny slivers of metal, coated with an insulator except at their tips. Maybe shape the tips like a ball and socket so they tend to link up in a chain instead of touching laterally. Or maybe something else is needed, some kind of chemical conductor that would line up at the molecular level.

In any event, it seems like something worthwhile investigating. I’m not a doctor, but the adhesive seems to me to be the main obstacle to this.

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