Shuttle-assisted insertion

Ultraflexible probes buckle rather than penetrate when pushed against the pia, so they must be delivered by a temporary stiffening scheme. Common strategies include a rigid microneedle or tungsten shuttle that carries the probe to depth and is then withdrawn; a dissolvable or biodegradable stiffener (polyethylene glycol, maltose or other sugars, silk fibroin) that rigidifies the probe for entry and melts or hydrolyses away in tissue; and robotic threading, in which a needle-and-cannula mechanism inserts many soft filaments one at a time while a computer-vision system steers around surface vasculature.

Insertion is not a solved detail but a primary constraint: shuttle diameter sets the acute wound and bleeding risk, adhesion between shuttle and probe governs placement accuracy, and any residual stiffener must clear without provoking its own inflammatory response. Much of the practical value of a flexible interface is won or lost at this step.