Shape-transformable switch apparatus based on electrorheological fluid

In an embodiment a shape-transformable switch apparatus includes a housing comprising an accommodating region with a high voltage electrode, a Electrorheological (ER) fluid located in the accommodating region, the ER fluid configured to change viscosity and rigidity, a switch cover shielding an upper portion of the housing, the switch cover configured to change a shape based on changes of the viscosity and of the rigidity of the ER fluid; and a controller configured to allow a voltage to be applied to the high voltage electrode such that an electrostatic attraction is generated so that the ER fluid flows and is pressed against the switch cover thereby changing a shape of the switch cover.