Electro-mechanical actuator with muscle memory

Electro-mechanical memory (EMM) is a type of actuator material that incorporates memory and control in the material itself. Thus its actuation can be manipulated, stored, read, and restored independently. We demonstrate here a realization of such a material by combining ionic actuation with shape memory polymer properties. The ionic actuation function and amplitude can be tuned or completely switched off by uniaxial mechanical programming. The shape transformations are reversible, and states can be selectively restored by exposure to pre-programmed temperature levels. Programming at two different temperatures is used to demonstrate storage and later recall of multiple shapes and actuation responses. Upon recall, the EMM's function and actuation amplitude are recovered and the restored states can also be cycled thousands of times using low voltage inputs. We analyse the dependence of the electrical actuation on the amount of mechanical programming, and the mechanism behind the behaviour.