»Intelligent fluids« for mechanically adaptable systems 

In general, it's just solids that come to mind when you hear the word "materials". However, in recent times soft materials have been drawing a lot of attention for generating special functions. Special fluids have the potential for farreaching benefits for adaptive dampeners, clutches and brakes since their consistency can be controlled to a great extent with electrical signals. 

Electro- and magnetorheological fluids (ERF or MRF) are liquid composite materials whose flow properties can be quickly and reversibly changed in an electrical or magnetic field over several orders of magnitude. This provides the foundation for a new class of electromechanical converters where friction forces can be controlled on a continuous basis. 

The electro- and magnetorheological effect can be used in traffic engineering. A case in point is shock absorbers, whose damping properties have to quickly adapt to changing requirements. There are also applications in adaptive damping of vibrations in cars, machines or medical prostheses. The possibility of changing friction forces taps an potential for a wide variety of intriguing products such as brakes, small controllable clutches, muscle trainers and haptic systems. This new technology is at the threshold of market roll-out. 

Muscle trainer with ERF dampening (© Fludicon)