Scaling limitations of laser-fabricated nerve electrode arrays

A laser technology for manufacturing implantable electrode arrays, using spin-on polydimethylsiloxane (PDMS) and platinum foil as materials, was investigated in respect to its scaling limitations. The following aspects were analyzed: Minimal width and centre-to-centre distance of platinum tracks, the ability of spin-on PDMS to flow between platinum tracks with very narrow gaps and the electrical insulation properties of thin spin-coated PDMS.

I. Introduction

FUTURE implantable electrode arrays which can be used for brain monitoring, e.g. in case of presurgical epilepsy monitoring, or, for providing brain-computer-interfaces in order to control prosthetic limbs, require a high integration density of electrode contacts. A fabrication technology for such neural interfaces was developed by Schuettler et al, exclusively using medical grade silicone rubber or polydimethylsiloxane (PDMS) as insulation and substrate material and platinum foil as electrode material [1]. Both materials can be structured with a Nd: YAG laser. This technology was enhanced in the last years, whereas the patterning of silicone rubber played an important role [2].