In situ scanning electron microscopy study of strains of ionic electroactive polymer actuators

We have developed a technique to determine the bending strain of ionic electroactive polymer actuators without the use of the macroscopic bending geometry. In situ comparisons of the scanning electron microscope micrographs from a bending ionic electroactive polymer actuator, using a digital image correction methodology, identify its bi-directional deformation field. The developed technique allows verification of the factual axial and thickness strains of any notional layer of the actuator, including the outer surfaces of the electrodes. Thus, calculation of the bending and thickness strains of the ionic electroactive polymer laminate becomes possible. Moreover, the technique allows the determination of the position of the neutral layer of bending that is an important requirement for the calculation of the second area and bending moments of the beam. The four examples presented demonstrate the potential variations of the bending schemes, in cases where the neutral layer is at the centroid and shifted away from the centroid.