Sheet-type Braille displays by integrating organic field-effect transistors and polymeric actuators

A large-area, flexible, and lightweight sheet-type Braille display has been successfully fabricated on a plastic film by integrating high-quality organic transistors and soft actuators. An array of rectangular plastic actuators is mechanically processed from a perfluorinated polymer electrolyte membrane. A small semisphere, which projects upward from the rubberlike surface of the display, is attached to the tip of each rectangular actuator. The effective display size is 4 x 4 cm(2). Each Braille letter consists of 3 x 2 dots and 24 letters; in other words, 6 letters x 4 lines can be displayed. Pentacene field-effect transistors with top-contact geometry have a channel length of 20 mu m and a mobility of 1 cm(2)/V . s. The Braille dots on one line are driven for 0.9 s. The total thickness and weight of the entire device are 1 nun and 5.3 g, respectively. The present scheme will enable people with visual impairments to carry the Braille sheet display in their pockets and read Braille e-books at any time. Since all the device components are manufactured on plastic films, these sheet-type Braille displays are mechanically flexible, lightweight, shock resistant, and potentially inexpensive to manufacture; therefore, they are suitable for mobile electronics.