Abstract: An endovascular device includes a thin film polymer strip having an electrode array. The thin film polymer strip includes a thin film polymer shaped into a strip having a distal end and a proximal end and a plurality of exposed metal electrodes positioned at the distal end of the thin film polymer. Each metal electrode is composed of a metal film. The thin film polymer strip also includes a plurality of bond pads positioned at the proximal end of the thin film polymer. A plurality of insulated traces connect each electrode to a single bond pad. The thin film polymer strip also includes insulated micro-wires connected to bond pads and recording or stimulation equipment. Characteristically, the thin film polymer strip has a helical or cylindrical shape configured to fit around a commercial vascular guide wire.