The geometric design of micromachined silicon sieve electrodes influences functional nerve regeneration

A neural interface could be used to control a limb prosthesis. Such an inte rface can be created by facilitating axonal regeneration through a sieve el ectrode and then register nerve signals intended to control the prosthesis. A key question is how to design the electrodes to ensure the best possible regeneration. Our previous studies have indicated that regeneration can be achieved using electrodes with square-shaped, 100 x 100 mum, via holes (ho les that axons will regenerate through). Other reports have indicated a sui table range of those holes between 40 and 65 mum. In the present study we u sed silicon sieve electrodes with via holes of either 30 or 90 mum The tran sparency, i.e. the percentage of the total via hole area, of these electrod es was either 20 or 30%. The electrodes were inserted into a silicone chamb er which was used to bridge a gap in a rat sciatic nerve. After 12 weeks of nerve regeneration electrodes with a hole size of 30 mum and a 30% transpa rency had the most favourable result as judged by the regained gastrocnemiu s muscle force and the Formation of reactive tissue inside the chamber. The sieve electrode transparency is crucial for ensuring regeneration. (C) 200 1 Elsevier Science Ltd. All rights reserved.