Title :
Different pulse shapes to obtain small fiber selective activation by anodal blocking-a simulation study
Author :
A. Vuckovic;N.J.M. Rijkhoff;J.J. Struijk
Author_Institution :
Center for Sensory Motor Interaction, Aalborg Univ., Denmark
Abstract :
The aim of this study was to investigate whether it is possible to reduce a charge per pulse, which is needed for selective nerve stimulation. Simulation is performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a human fiber model to simulate the fiber response to simulation. Selective stimulation is obtained by anodal block. To obtain anodal block of large fibers, long square pulses (>350 /spl mu/s) with a relatively high currents (1-2.5 mA) are usually required. These pulses might not be safe for a long-term application because of a high charge per pulse. In this study, several pulse shapes are proposed that have less charge per pulse compared with the conventional square pulse and would therefore be safer in a chronic application. Compared with the conventional square pulse, it was possible to reduce the charge with all proposed pulse shapes, but the best results are obtained with a combination of a square depolarizing pulse and a blocking pulse. The charge per pulse was up to 32% less with that pulse shape than with a square pulse. Using a hyperpolarizing anodal prepulse preceding a square pulse, it was not possible to block nerve fibers in a whole nerve bundle and to obtain reduction of a charge per phase. Reduction of the charge could be achieved only with spatially selective blocking. The charge per phase was larger for the combination of a hyperpolarizing anodal prepulse and a two-step pulse than for the two-step pulse alone.
Keywords :
"Pulse shaping methods","Shape","Optical fiber sensors","Electrodes","Nerve fibers","Biomembranes","Electrical stimulation","Cathodes","Anodes","Conductors"
Journal_Title :
IEEE Transactions on Biomedical Engineering
DOI :
10.1109/TBME.2004.826663