An object of the present invention is to enhance a converging property of an electron beam in an electron-emitting device in which a cathode electrode, an insulating layer, and a gate electrode are laminated and a through hole is formed by partially removing the gate electrode so as to obtain an exposed portion of the cathode electrode. The regulator includes a charge pump, a voltage comparator circuit, and a latch circuit. For example a mobile client may request to perform one or more identity management operations associated with an account of a service provider. Furthermore, a smaller chamber in an enhanced entrochemical cell is encapsulated by a larger chamber in an adjacent enhanced entrochemical cell, thus forming a nested structure between the two enhanced entrochemical cells.