Fig. 2.

(a) A $13\times 13$ Solidworks^® 3-D model of the high-density UOA with a $Ø1.5\text{-}\mathrm{mm}$ TGV. (b) High density array shown just prior to insertion resting on a marmoset’s primary visual cortex after craniotomy and durotomy have been performed. (c) Postfixation tissue damage assessment shows the array caused vascular damage as well as damage from the trauma of insertion, where high amounts of tissue have been compressed between the array’s optrodes. Histological assessment of tissue damage was not performed due to the level of tissue damage seen following device explantation. The white arrows mark the insertion location of a single $150\text{-}\mu \mathrm{m}$ electrode which was successful in recording neural spiking during postinsertion optrode illumination. Active neural action potentials indicated the neural tissue close to the optrodes around the TGV were still firing.