Design of Experiment Evaluation of a 2.5D Printing Process for Implantable PDMS-based Neural Interfaces

Current laser fabrication processes for PDMS-based neural interfaces are associated with excessive costs, due to time-consuming manual handling and expensive machinery. The products of this process, specifically embedded metallic electrical tracks, are prone to breakage under mechanical loading, as well as delamination from their surrounding PDMS substrates. In this work, we develop an alternative 2.5D printing process, using electrically conductive PDMS material for the tracks. The entire electrode was fabricated in a custom-made printing setup, which features the possibility of rapid prototyping. The printing performance of the selected materials was evaluated with the aid of statistical methods for experimental design. We found optimal printing parameters for conductive and non-conductive PDMS which allows the fabrication of flexible and stretchable neural interfaces, while simultaneously minimizing the track resistivity.Clinical Relevance— 2.5D printing processes pave the way for individualized neural interfaces to suit the specific needs of every single patient.