Office of Technology Transfer – University of Michigan

Pneumatic Haptic Display for Touchscreens

Technology #5195

We have developed a pneumaticlly actuated hapic display device that is thin and sheet-like, compliant, and optically clear. Its properties make it compatible with certain touchscreens, so that soft-buttons, scrollbars and other interface elements can be given tactile features and force-motion behaviors. The sheet is fabricated using polydimethylsiloxane (PDMS) with chambers and channels embedded within. The chambers communicate through the channels and off-board miniature proportional or solonoid valves to an off-board pressurized resevoire. Variations in material hardness or embedded structures of various shape and configuration are used to govern the manner in which the compliant PDMS structure deforms under pressure. For example, plates embedded (or surface-bonded) above chambers provide for the creation of flat-topped buttons of various size and shape. Manfacturing challenges are addressed with the design of stiff structures that incorporate strategically located thin-walled sections. These thin-walled sections facilitate coating or insert molding with PDMS, yet subsequent free motion of a particular walled-area of a chamber by virtue of purposeful and timely breakage. The thin-walled sections can be designed to break, for example, on first inflation, leaving a sealed chamber with an actuated wall to create the moving button feature. When coupled with a position and/or force sensing surface technology (such as a touchscreen), micro-processor mediated feedback control can be used to create the haptic features of buttons and scrollbars and other interaction elements. Refreshable Braille displays are also possible.