In one aspect, an ingestible, electrical device, comprises a substrate comprising a reservoir that is configured to hold one or more substances; a first film covering the reservoir, wherein the first film is at least partially metallic; a charge storage system connected to the first film, the charge storage system configured to deliver a transient electrochemical potential to the first film; wherein the first film is configured to prevent exposure of the substance to an aqueous environment in an organism, while the charge storage system delivers the transient electrochemical potential to the first film; and wherein the first film is configured for dissolution to expose the one or more substances to the aqueous environment in the organism, after the charge storage system stops delivering the transient electrochemical potential to the first film.