This Scanning Electron Microscope image shows a multicore optical fibre probe consisting of 19 individual cores which guide light, comparable to the multiple electrical wires within a cable.
The fibre cores have been etched to produce concave pits, and multiple types of silica (glass) microsphere sensors embedded. This produces a miniaturised sensor with the ability to simultaneously measure multiple parameters from the individual probes, all in a diameter comparable to a (thick) human hair.
This allows the Proteus project to sense physiological changes in the body in places other sensors can not reach.
Tanner Lab 