Early-generation penetrating waveguide arrays made of glass (SiO2) were micromachined for optogenetic stimulation in able to provide comprehensive and selective access to distributed targets in three dimensions. We characterized light delivery of the device in order to facilitate design optimization and understand its application in tissue. The glass optrodes were formed by dicing, etching, and annealing. A fused silica/quartz substrate was used to produce 10×10 arrays of optrodes with constant geometry having a pyramidal tip at the end of a straight-edge shank; length, width, spacing, tip angle, and even array size can be varied indepedently. Visible light transmission effciency of optrodes was investigated with input from an optical fiber as well as microscope objective lenses. With a 120-µm wide and 1.5-mm long optrode having a tip taper angle of 30º with respect to the optical axis, almost 90% of visible and IR light from a butt-coupled 50-µm multimode fiber is transmitted out of the optrode tips when optrode shanks are surrounded by tissue. In air, the normalized output power decreases according to the area mismatch betweeen optrode shank and the focused beam width from the microscope; visible light transmission is as much as 90% as well.

Date Published: 8 March 2013
PDF: 5 pages
Proc. SPIE 8586, Optogenetics: Optical Methods for Cellular Control, 85860V (8 March 2013); doi: 10.1117/12.2004502

Published in SPIE Proceedings Vol. 8586:
Optogenetics: Optical Methods for Cellular Control
Samarendra K. Mohanty; Nitish V. Thakor, Editor(s)