The present application provides a self-powered drug-delivery device. The device includes a chamber having a wall. The chamber contains a fluid and is in connection with an administration means. The device also includes a displacement-generating battery cell. The device further includes an electrically-controlled battery unit, which includes the displacement-generating battery cell coupled to the chamber by a coupling means. The displacement-generating battery cell includes an element that changes shape as a result of charge or discharge of the battery cell so as to cause a displacement within the battery unit. The arrangement of the battery unit, the coupling means, the wall, the chamber, and the administration means is such that the displacement derived from the battery unit is conveyed by the coupling means to cause displacement of the wall of the chamber such that the fluid is expelled from the chamber to force a drug towards the administration means.