A new Nature article describes research done by T.F. Otero in Spain on a polymer material that serves as both actuator and sensor. The material bends when electrically charged but unlike other materials which exert a constant amount of force, this material moves at a constant velocity, drawing more current to move heavier obstacles in its path. In a robotic hand, the current draw provides a measure of the gripping force exerted by the fingers on an object. For more info visit the Electrochemistry Lab at the University del Pais in Vasco, Spain. Also see Otero's full article, Artificial Muscles with Tactile Sensitivity (requires Wiley Interscience subscription).