Development of a 3D Printing Strategy for Completely Polymeric Neural Interfaces Fabrication

The fabrication of neural interfaces (NIs) typically relies nowadays on the implementation of complex, expensive, and time-consuming photolithographic processes. Metals and polymers are the materials currently used to fabricate NIs. Conductive polymers could be an alternative to metals to enhance the biocompatibility of the devices. Additive manufacturing techniques provide an easier and low-cost approach to process and finely tuning the geometrical and morphological features of polymers. Here, we propose a 3D printing strategy for the fabrication of completely polymeric neural interfaces, based on extrusion printing. The materials have been chosen to enhance the biocompatibility of the devices. PDMS has been chosen as insulating substrate, while a PEDOT:PSS-based ink has been selected for the conductive component. Morphological, mechanical, and rheological analyses on the inks have been carried out and a first prototype of a neural interface has been fabricated. The PDMS has a Young Modulus of 600 kPa, in the same order of magnitude as peripheral nerves, with a thickness of 160 µm. The PEDOT:PSS inks fabricated present a shear thinning behavior, ideal for an extrusion printing process This approach could represent a valuable alternative to photolithography and an innovative method for the fabrication of NIs, due to the high degree of customization, ease of implementation, low-cost and flexibility in materials choice.