High efficiency electrodes for deep brain stimulation

Deep brain stimulators are powered with primary cell batteries and require surgical replacement when they are depleted. We sought to decrease power consumption, and thereby increase device lifetime by increasing neuronal stimulating efficiency with novel electrode designs. Our hypothesis was that high-perimeter electrodes that increase the variation of current density on their surface would generate larger activating functions for surrounding neurons, hence increasing stimulation efficiency. We implemented finite element models of cylindrical DBS electrodes with conventional circular perimeters, with serpentine perimeters, and with segmented contacts. The high-perimeter electrodes significantly increased the variation of current density on the electrode surface. We randomly positioned a population of 100 model axons around the electrodes and quantified neural activation with 100 mus cathodic stimuli. Input-output curves of percentage axons activated as a function of stimulation intensity indicated that the novel electrode geometries decreased power consumption by up to ~20% for axons parallel to the electrode and up to ~35% for axons perpendicular to the electrode. Reduced power consumption achieved with these designs will reduce the costs and risks associated with surgeries to replace depleted stimulators.