Embodiments of the present invention relate to implantable sensors for obtaining hemodynamic data andor physiologic data. The upper enclosure is vertically spaced from the metalized plate. A modified image is computed by the sum of the reference digital document and the secondary digital information such that the modified digital document approximates the initial document but integrating substantially indiscernible the primary digital information to be hidden. In particular, the risk involved with the spying out of master keys stored in autonomously operating terminals, such as vending machines or cardphones, is eliminated or at least reduced, thus counteracting the misuse of cash-reloadable chipcards increasingly used today. The user manipulates the position of the cursor on the display screen by moving the StickMouse towards the desired position on the display screen.