1. A medical device wearable by a subject, the device comprising: an implantable component having a housing and a first antenna coupled to the housing, wherein at least one of the housing or the first antenna is made of a flexible material such that the housing and the first antenna follow a curvature of a skull of the subject when implanted between the skull and a scalp of the subject, wherein the implantable component measures EEG signals representing brain activity; an external second antenna, the second antenna having a loop portion sized to fit over a head of the subject; and an external control module configured to interact with the implantable component via the external second antenna and receive and process the EEG signals from the implantable component.