Micro-folded 3D neural electrodes fully integrated in polyimide

Recent neural interfaces are characterized by high functionality and good adaptation to the target tissue. Still, the underlying manufacturing process is mainly planar and so are the device and contact surface. Therefore, three-dimensional structures to contact neuronal tissue are desired to gain higher selectivity. In the present study, local bending structures integrated in flexible electrode arrays based on polyimide are investigated. The bending is achieved by the contraction of a second polyimide (Durimide) that is embedded into grooves with a width of a few micrometers. The angle of the bending can be controlled with a high accuracy from 3 to 20 degrees by changing the geometry of the grooves and the imidization temperature These bending structures can be combined to achieve any desired angle for specific applications.