Geometric design and surface morphology of sieve electrodes-nerve regeneration and biocompatibility studies

A neural interface could be used to control a limb prosthesis. Such an interface can be achieved by implanting a sieve electrode in the peripheral nerve trunk proximal to an amputation and subsequently record nerve signals intended to control the prostheses. To achieve a long-term stable implantable sieve electrode the implant must fulfil all requirements regarding biocompatibility. This paper therefore addresses cellular reactions in soft tissue induced by silicon and titanium (planar and porous) implants. All implant types displayed the same density of ED1 and ED2 positive macrophages but regarding the capsule formation planar implants displayed an increased capsule formation while the porous implants displayed a constant capsule thickness over time. This paper also addresses the quality of regeneration through four sieve electrode geometries (hole size 30 or 90 μm and transparency 20 or 30%). After 12 weeks of nerve regeneration, electrodes with a hole size of 30 μm and a 30% transparency displayed the most favourable result as judged by the regained gastrocnemius muscle force