Ultra small cross-section photonic probes for deep tissue non-invasive light delivery

We demonstrate a new platform for minimally invasive, photonics light delivery. The fabricated probes have sub-10μm cross-sectional dimensions and lengths greater than 3mm (a 1000:1 aspect ratio). We show mechanical robustness and low optical losses.

Light delivery probes are generally based on fiber-like devices [1]–[3], with very large cross-sections on the order of 100µm across or more and are destructive to the biological tissue [4]. Existing studies regarding damage to the brain as a result of probe insertion suggest that physical probes below a certain diameter have minimal effect on the functioning of the brain by showing negligible microglia response [5], and so little damage to cells that cell replication is unimpeded [6]. Long and narrow photonic probes could enable longer-term chronic studies with more accurate data from less signal disruption.