This may be of interest:
I just came across fNIRS, which stands for Functional Near InfraRed Spectroscopy.
In short (like, in ultra-short), it’s a technique to measure blood saturation in the upper layers of the brain by shining infrared light (810 - 900 nm) through the scalp and skull, detecting the returned light and measuring absorption in-between: the harder you think, the more blood floods to the bit of the brain involved in the thinking, the more the light dims. The wavelength of the IR light is chosen so absoption is minimum through skin and bone, and maximum through blood.
The hardware is very simple: one IR laser diode or IR LED, one photodiode. That’s it. Well, not quite, but close enough. The signal processing and math after that isn’t simple, but that’s another problem. Most importantly, it’s a problem that can be solved outside the body.
How could DT add value to this? Well, if you put the IR LED and photodiode onto a Flex-style implant and implant it subdermally, the light only has to cross the skull barrier. The LED could be lower-powered, and the S/N ratio could be higher than with an external device, because the light wouldn’t have to cross the scalp twice.
This means it could be powered by induction through the scalp with a low-power Qi-like thing. Possibly even only with NFC. And if it was possible to power it with NFC alone, then it would be possible to use the protocol to get the returned signal measurement from the photodiode.
Imagine that: a basic brain interface with a simple Flex device, a cellphone and an NFC patch kit. Wouldn’t that be nice?
Damn, we manufacture laser rangefinders at work, and one model we sell uses 905 nm lasers. I’m almost tempted to stick one onto my forehead and see if I can see something in the signal histogram. At 2000 euros a pop, I’m not sure my company would like that too much though - not to mention, I’m not paid to do that… Still, tempting.