Characterization of encapsulation materials for implantable DBS device/Sapiens Steering Brain Stimulation

This report presents the results of the work of one year in Sapiens Steering Brain Stimulation. A general description of the company objective is given and later the project is defined. The project has two main sub-projects: the characterization of the materials to be used as encapsulation for electronics and the mechanical testing of the isolative layers of the thin film, as an essential part of the implantable part of the device. For the first sub-project, the coating parameters are investigated through time experiments of samples exposed in saline. For the second part, samples are put under bending stress and mechanical tolerance is tested. Any mechanical failure or defective coating will have as a consequence an amount of current to leak out of the insulation layers. Both characterization and film testing are realized through leakage current measurements after applying a specific value of voltage. The setup is also validated. For the encapsulation materials, a well-defined process flow is suggested for sample preparation and coating in the clean room, pointing out the significance of cleaning the samples in the efficiency of the coating. Combinations of materials such as parylene and silicone or parylene and PU are tested and evaluated. For the thin film testing, bending test results are compared with theoretical strain calculations and safety specifications. The results of both the sub-projects indicate that leakage current measurement is a reliable method for evaluating the performance of both encapsulation materials and thin film.