Slow deformation seriously restrains application development of IPMC actuator, especially for thick and ionic liquid-based IPMC. Inspired by the action potential of muscle cell, this letter proposes a concept of high electrical pulse stimulus to accelerate IPMC deformation. By analyzing the dynamic process of voltage drop at the electrode-polymer interface, high voltage pulse is proved theoretically to be safe for IPMC in a short time. After charging the electrical double layer at the interface, the voltage pulse should be reduced to a safe level before electrochemical reactions. In our experiments, applying various high voltage pulses to a thick IPMC, the deformation can be sped up a few hundred times at most without any electrolysis damage. The results strongly support the practicability of the impulsive driving method.

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Ionic electroactive polymers (iEAPs) are electroactive polymers that have been used as artificial muscles and have broad application potential. Although iEAPs show large bending deformation under low electric stimulus, the low output force significantly restricts their application. Based on an ionic polymer-metal composite (IPMC) actuator, we proposed a bending stacking structure principle which adapts the bending deformation cooperation conditions. According to the principle, the width stacking structure and thickness stacking structure were designed that can improve the output force, maintain a high stacking efficiency, and eliminate degradation to the deformation ability. The advantages of the proposed stacking structures were identified using theoretical analysis and experimental verification based on IPMC actuators. Compared with an ultra-wide actuator, the wide stacking structure can resist undesirable width deformation. Compared with a traditional stacking structure, the proposed thickness stacking structures solved the bending deformation coordination problem to get a high stacking efficiency and significantly enhance the output force.

Slow deformation is an issue that restrains engineering applications of ionic electroactive polymers (EAP). The application of a high impulse voltage has been proposed to accelerate the deformation of water based ionic polymer-metal composites (IPMC). In this paper, focused on ionic liquid (IL) based ionic EAPs, ionic polymer carbon composites (IPCC), IL-IPMC, ionic and capacitive laminates, and bucky gel actuators were selected to verify the effectiveness of the high impulse voltage method. All four were able to be accelerated more than tenfold under high impulse voltages. To investigate the limitations of the high impulse voltage method, constant pulse width measurements were performed on IPCC and IL-IPMC. The deformation speed was almost linear with the pulse amplitude before it reached the maximum deformation. On setting a constant pulse width, a large deformation and a higher speed could be obtained by increasing the pulse amplitude. Additionally, by fixing the pulse amplitude, extending the pulse width induced a larger deformation at a certain speed. Finally, the consumption power and heat issues were investigated via cycling tests. A shorter cycle time (higher frequency) and a higher pulse amplitude led to larger power consumption and higher temperature. The ionic EAPs damaged at high temperature (usually over 100 °C), which is probably due to the positive feedback between Joule heating and ion mobility. In addition to the pulse width, the pulse frequency and amplitude require carefully control when using a high impulse voltage.