New materials are providing exciting new possibilities for liquids. For instance, the stress and strain can change the viscosity of a non-Newtonian liquid – something anyone who has tried to get the last dollops ketchup out of a bottle understands. Imagine using this principle to create better body armor. The result can be protection that is flexible, more comfortable, and lower cost, but just as effective.
Spray-on paint? Nice idea. Now consider the possibilities of spray-on batteries. Rice University researchers have found a way to take advantage of the ease with which liquid can coat other materials to build up layers that can turn almost any surface into an energy storage device.
Perhaps the most exciting possibilities for liquids take advantage of how they can change in response to magnetic and electrical charges. Some Cadillacs already use magnetorheological or MR fluids for dynamic, responsive suspension systems. Japan’s National Museum of Emerging Science and Innovation has a bigger thought – protection against earthquakes. Electrorheological or ER fluids are being developed for brakes and even Braille reading devices.
Liquids can go where solid materials can’t, can create powerful combinations (for instance, drug delivery systems), can be transported through pipes, and can morph into useful shapes. Unfortunately, clumping, limits to the number of cycles, sensitivity to heat, and many other real-world constraints have kept smart fluids from being used in promising applications.
We’ve seen this before. While the initial enthusiasm after their discovery dissipated quickly, they found a second life when the engineers found that water could be replaced with more appropriate fluids. Today, new materials coming out of studies in nanotechnology are extending the range of practical applications once again. Expect keyboards that go from flexible films to hard keys that have more of the feel of traditional keyboards. Look for surfaces that communicate touch (haptics). Or may be we’ll see prosthetics that are more like real body parts – or even better. We may even have devices that protect themselves (smartphones that seal closed when dropped in water?) or heal when damaged.