Improving The Durability Of Micro Er Valves For Braille Displays Using An Elongational Flow Field

The restrictions of Braille standard make the microER valves for Braille display have the characteristics of micro channel and micro flux, which lead to the poor durability of micro electro-rheological (also called ER) valves. To solve the problem, several comparison experiments were designed and the effects of the actions of an elongational flow field on the durability of micro ER valves were studied in this paper. In the experiment without elongational flow field, when removing the external electric field, the nano-particles aggregated under the external electric field for a long period in polarmolecule ER fluids had no ability to restore to the original dispersing state just by their Brownian movements, which lead to the blockage of micro ER valves, and independent recovery time of the valves became longer. Moreover, the pressure drops of valves reduced greatly after several cycles of experiments, which indicated the operational instability of the micro ER valves. In the experiment with elongational flow field, the micro ER valve runs normally. It was proved that the micro ER valves with the actions of the elongational flow field have the ability to keep the micro ER valves stable operation and meet the demand of durability for Braille displays.