|Electroactive Polymers (EAPs) old|
Biological muscles are amazing actuators with properties, including large actuation strain, high stress and energy density, fast response, resilient and damage tolerant operation, unmatched by any conventional actuator technology such as combustion engines, electric motors, and piezoelectric actuators.
Researchers have realized that many highly anticipated systems such as surgical mini- and microrobots, and biomimetic devices, including limbs and artificial organs cannot be achieved with conventional actuators. Therefore, in the last two decades an increasing number of scientists started to develop novel actuation mechanisms and materials that imitate the functionality of natural muscles. The majority of these emerging artificial muscle technologies are based on polymers that expand or contract when varying electric or magnetic fields, light, pH and heat are applied.
For many years, electroactive polymers (EAPs), which use electrostatic forces, electrostriction, ion insertion, and molecular conformational changes, received relatively little attention. However, the increased demand for electrically controlled compact adaptive structures recently boosted the research efforts, resulting in novel electroactive materials and a large number of prototype devices including robot fish , catheter steering elements , lens positioners , robotic arms , grippers , loudspeakers , a blimp , dust-wipers , hopping robots , heel-strike generators and strain sensors .
Depending on their activation mechanism, EAPs are divided into two major classes:
The following subsections cover, biological muscles and the most promising electronic and ionic EAPs in more detail. Furthermore, the mechanical properties of these actuator technologies are summarized in an overview table.