Electromechanically active polymer actuators based on biofriendly choline ionic liquids

Smart and soft electroactive polymer actuators have many beneficial properties, making them attractive for biomimetic and biomedical applications. However, the selection of components to fabricate biofriendly composites has been limited. Although biofriendly options for electrodes and membranes are available, the conventional ionic liquids (ILs) often used as the electrolytes in the actuators have been considered toxic in varying degrees. Here we present a smart electroactive composite with carefully designed and selected components that have shown low toxicity and a biofriendly nature. In the present study, polypyrrole-PVdF trilayer actuators using six different choline ILs were prepared and characterized. Choline ILs have shown promise in applications where low environmental and biological impact is critical. Despite this, the anions in ILs have a strong impact on toxicity. To evaluate how the anions effect the bioactivity of the ILs used to prepare the actuators, the ILs were tested on different microbial cultures (Escherichia coli, Staphylococcus aureus, Shewanella oneidensis MR-1) and HeLa cells. All of the selected choline ILs showed minimal toxic effects even at high concentrations. Electro-chemo-mechanical characterization of the actuators indicated that polypyrrole-PVdF actuators with choline ILs are viable candidates for soft robotic applications. From the tested ILs, choline acetate showed the highest strain difference and outperformed the reference system containing an imidazolium-based IL.