Nanoscale Materials for Artificial Muscles

In robotics, orthopedics, and other fields, there is a need for electrically controllable artificial muscles.  As a result, there is a lot of interest in electro-active polymer actuators, which convert electrical energy into linear mechanical motion.  Researchers are trying to find light-weight materials and structures based on soft polymers (elastomers) that will permit large deformation.  One example, the dielectric-elastomer actuator, is like a soft capacitor and provides very high motion when voltage is applied.  Although actuators have been made that can stretch more than 100%, reliable and repeatable actuation levels seem to be around 10–20%, with applied voltages of several thousand volts.  Since high voltage levels are impractical and unsafe, researchers are seeking materials that can operate at voltages below a few hundred volts.  An actuator’s activity can be improved by raising its ability to store electrical energy or dielectric constant.  However, many existing approaches lead to reduced mechanical properties and strongly reduce the electrical-breakdown field above which the material will suffer catastrophic electrical failure.  [SPIE Newsroom, 15 Jun 2010]

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