Electrorheological (ER) fluids are suspensions of extremely fine non-conducting particles (up to 50 micrometres diameter) in an electrically insulating fluid. The apparent viscosity of these fluids changes reversibly by an order of up to 100,000 in response to an electric field. For example, a typical ER fluid can go from the consistency of a liquid to that of a gel, and back, with response times on the order of milliseconds. The effect is sometimes called the Winslow effect, after its discoverer the American inventor Willis Winslow, who obtained a US patent on the effect in 1947 ^[1] and wrote an article published in 1949 ^[2].

I thought Batman’s cloak changing, in Dark Knight, is amazing, 

and I found that this is a good practical example of electrorheological fluid.
ER fluid can be used in many different ways such as flexible electronics, and
flexible shape changing gadgets.
It seems that Sony is already working on using this  next PS4, maybe.
US Patent for Sony