A wire construct is ferromagnetic and/or biocompatible, while also having a size and geometry appropriate for use as an electrode for insertion into an in vivo implant site. In ferromagnetic embodiments, the wire is magnetically insertable via an electromagnetic driver, which uses high-speed magnetic acceleration to drive the wire material into a neural or other implant site. A helical thread may be formed on the external surface of the wire to facilitate rotational fine positioning after initial implantation. The wire may be formed as a monolithic structure with a magnetic metal alloyed with an inert and biocompatible metal, or may be a bimetallic structure in which a magnetic outer shell has an inert and biocompatible inner core. The wire is sized to allow transmission of electrical signals either to or from the implant site while avoiding immune response, thereby ensuring a long service life.
