An adhesive polymer matrix for the delivery of an active principle via iontophoresis. The matrix having a first face intended to be applied onto skin and a second face intended to cooperate with electrodes. The matrix comprises electrically conductive zones and at least one electrically insulating zone, each conductive zone being insulated from another conductive zone by an insulating zone. The techniques involve the use of an electric current in order to facilitate the transdermal diffusion of active substances, and relates more particularly to an iontophoresis device.