Fabrication and testing of a multi-electrode spiral nerve cuff

Abstract

The methodology, technology of fabrication and testing a multielectrode spiral cuff for selective activation of fibres in particular superficial regions of a peripheral nerve is presented. Stimulating electrodes were made of 0.03-mm-thick platinum foil strips with 99.99 wt.% purity. Optimum conditions for welding the stainless steel wire with the platinum foil and to reveal the microstructure of the welds were defined using the scanning electron microscopy. The electrochemical performance of platinum electrodes within a multi- electrode spiral cuff was investigated “in vitro” while stimulating performance was tested “in vivo”. The fabricated cuff consists of 33 electrodes organised in eleven longitudinal groups of three electrodes. The total cuff length is 17 mm and internal diameter is 2.5mm to fit the size of the human cervical vagus nerve. Results show that welds do not show any welding defects. The results of “in vitro” testing showed that potentials across the electrode-electrolyte interface did not exceed the safe potential limits for water electrolysis. The observed effects of “in vivo” testing with a stimuli train via triplet of electrodes 1 and current intensity ic=2.5 mA, modified selectively autonomic control of the SA and/or AV node.