Application Disorder causes Material (lead, electrode, and case) Sensor/electrode Size range References Intracortical microstimulation Brain lesion Iridium Deep electrode Tens of μ m in diameter, 250–750 μ m between pins [4 ]25 ] Stimulation of the motor and sensory thalamus, subthalamic nucleus, and basal ganglia nuclei Parkinson Platinum-iridium Metal wire Length: 15 mm or 25 to 50 μ mμ m to 1.2 mmμ m [56 ]58 ]57 ]59 ] Motor cortex stimulation Stroke Platinum Electrocorticography grid 1–10 mm in diameter [31 ]5 ] Retinal ganglion cell stimulation (photoreceptors) Retinitis pigmentosa Platinum 4 by 4 array of light-sensitive diodes Diameters range from 30 μ m to 520 μ m [52 ]49 ]50 ]46 ] Cochlea stimulation (auditory nerve of the inner ear) Birth defects Platinum-iridium Array with 12–24 electrode contacts Length: 31.5 mmμ m [44 ]101 ]34 ] Stimulation of heart chamber (sinoatrial node, septum) Sinus bradycardia, tachycardia Platinum-iridium Array/electrode Length: 4–8 mm2 [77 ]78 ]82 ]84 ]87 ] Sacral nerve root stimulation Urinary incontinence NA Quadripolar electrode NA [91 ]90 ] Recording neural activities Brain lesions Nanowire field-effect transistor Nanostructure 1,100 nm [70 ]68 ]99 ] Stimulation of electrical activity Not specific Nanotube Nanostructure NA [102 ] Control, monitoring, and activation of action potentials Brain lesions Optogenetic Nanostructures and nanoparticles Nanometric scale [103 ]
