A transdermal device such as a patch can include a drug source, a porator, and an energy storage device on-board the patch. The porator operates free of any concurrent connection to any external source of power. A switch can be used to make the selective electrical connection between the porator and the energy storage device. The switch can be arranged to respond to a manual user action after the patch has been adhered to skin, including separation of the porator from a remainder of the patch. Optionally, a series of switches can make electrical connections between the porator and respective individual energy storage devices.