Various embodiments of the present invention comprise a signal generator for sending an electrical signal from an expandable, flexible layer of material, the signal generator comprising an upper layer of flexible, resilient material and a lower layer of flexible, resilient material which between them define a cavity for enclosing an expandable material such as a cellular foam or gas, whereupon localized distortion of one of the layers of flexible material, effects a signal generation within the structure, which is transmissible through a proper circuit to an outside electrical device. A circuit may be arranged adjacent a plurality of said keys which senses when several of said keys are depressed in a skewed or sideways manner, so as to effect movement of a cursor or pointer on a monitor in communication with a processing unit and said keyboard.