The electrolyte layer composition: A key element for improving the performance of carbon nanotube actuator

Bucky gel actuators are typically fabricated by having an electrolyte layer sandwiched by two carbon nanotubes electrodes. They possess outstanding electrical and mechanical properties thanks to their composition, which make them very attractive for robotics applications. Even though carbon nanotube electrodes have been extensively studied in the recent years, the electrolyte layer has not been investigated in depth yet. In this study, we demonstrate that the performances (strain and blocking force) of carbon nanotubes actuators can be improved by tuning the electrolyte layer composition. The viscosity and the ionic conductivity of various binary solvent–ionic liquid mixtures (ethylene glycol, polyethylene glycol, acetonitrile, propylene carbonate, 4-methyl-2-pentanone as solvents and 1-butyl-3-methylimidazolium tetrafluoroborate as the ionic liquid) were first examined and used as key parameters to select the optimal electrolyte layer composition. We observed a remarkable increase of strain and blocking force when the ionic conductivity and the viscosity of the electrolyte were maximum and minimum respectively.