This disclosure describes various modular electrode assemblies. For example, an implantable modular electrode assembly may include a hub including a plurality of electrical contacts configured to receive electrical signals from an implantable medical device, a first electrode module including a first substrate and a first plurality of electrodes on the first substrate, and a second electrode module including a second substrate and a second plurality of electrodes on the second substrate. The first and second electrode modules may be connectable to the hub, where the plurality of electrical contacts electrically communicate with the first and second plurality of electrodes.
