Design of a Hands-Free Braille Display Using a Pneumatically Controlled Wristband.

About 350 million individuals worldwide suffer from visual impairments (VI), which prevents them from reading information effectively. Currently, there lacks an affordable, portable, and hands-free solution. In this paper, we present a novel wristband-like wearable device for displaying braille texts. The device consists of a pump, solenoid valves, a pressure sensor and a microfluidic silicone strip. The microfluidic silicone strip has an array of six pneumatically actuated braille cells. By controlling the inflation of the silicone braille array using the solenoid valves, the array generates various braille patterns, providing the user with a tactile braille display. We fabricated a prototype and conducted engineering experiments to evaluate the performance of the system. We measured the time of inflation/deflation and the air pressure when displaying different Braille patterns. We found the inflation is nearly instantaneous, whereas the deflation time is substantially slower (0.5 second). This performance enables the current prototype to achieve a maximum refresh rate of 120 words per minute, which is comparable to the average reading speed of a braille user (100 words per minute).