Concept of an add-on tactile display for smart phones as a helping device for blind users

The aim of this work is to develop a system able to assist blind users during navigation over the touch-screen of smart phones. This kind of user interface is widely used in the field of communication devices and poses significant problems for the blinds, owing to the lack of tactile references. Our idea is to create a plastic frame (case) for a smart phone, integrating a number of 'active' dots that can be dynamically raised or lowered, so as to serve as variable tactile references controlled by the application currently run by the smart phone. Such a sort of 'mapping' via an external hardware to be used with and controlled by the phone provides new tactile functionality for the blinds, without any (industrially unrealistic) modification of the phone itself. So, the proposed system is a sort of hardware add-on for the smart phone. To reduce encumbrance and costs, we are developing such a system using dielectric elastomer actuators (DEAs). In particular, the tactile dots are being developed as inherently active elements, consisting of hydrostatically coupled DEAs. They are based on an incompressible fluid that mechanically couples a DE-based active membrane to a passive membrane interfaced to the user's finger. This presentation describes the current developmental stage with reference to selected navigation contexts: operative system home page, Gmail home page, email-writing, phone key pad.