An implantable, miniaturized SU-8 optical probe for optogenetics-based deep brain stimulation.

This paper reports a method of making optical probes for optogenetics-based deep brain optical stimulation using SU-8, which effectively increases light coupling efficiency, has excellent mechanical stiffness, and reduces fabrication complexity. By mounting microscale LEDs (μLEDs) at the tip of a SU-8 probe and directly inserting the light source into deep brain regions, attenuation caused by light transmission in wave-guided structures such as optical fibers or optrodes can be minimized. Compared to silicon neural probes, SU-8 is more biocompatible and flexible, which can reduce brain damage. Parylene-C encapsulation can potentially improve the long-term biocompatibility and reliability of the device for chronic implantation. The functionality has been proven by clearly light-induced neural activity.