Implantable Neural Stimulators

Publisher Summary This chapter focuses on the implantable neural stimulators, which are used by the clinicians to execute the various and diverse neuromodulation therapies. Implantable neurostimulators have their technical roots in cardiac pacing, and their primary function is to activate or inhibit the nervous system to augment, improve or replace function lost to a neurological disease or disorder. The neurostimulator generates appropriate electric fields within neural tissues through the application of prescribed currents or voltages to electrodes in contact with the neural tissue. The physical form of the neurostimulator is designed based on constraints, requirements, and ideals from both the engineering and clinical realms. The device design must balance the need for a biocompatible, hermetically sealed, and mechanically robust package that is capable of housing all of the stimulator components and meeting the clinical demands for minimal invasiveness, conformation to anatomy, facilitation of surgical installment, and device cosmesis. The power is supplied by a source that is either internal to the implantable device or external to the body. Internal power sources are batteries whereas the external power sources include inductive radio-frequency (RF) coupling. Some of the other power sources include the use of nuclear powered cells and systems that harvest power from the body. Inductive and RF antenna-coupled links are the most commonly used means of transferring data to and from an implanted device, which are appropriate for low to moderate data rate applications.