Fig. 1: Fabrication process and shape design of the MEA.

a Three layers, containing the insulating layer, conducting layer, and substrate, were patterned to form the structure of the MEA. b Optical photograph of the tip of the MEA. c Illustration of the arrangement of MEA probes according to the shape of the MEC (left) and a sagittal brain section with red traces of the implanted MEA (right)