Increased actuation rate of electromechanical carbon nanotube actuators using potential pulses with resistance compensation

The results of this study demonstrate that resistance compensation can provide significant improvement in the charging rate, and consequent actuation strain rate, for carbon nanotube sheets operated in an organic electrolyte. The strain rate increased with increasing potential pulse amplitude and a more negative potential limit. The amount of strain produced also increased with longer pulse times. The highest strain rate achieved was 0.6% s⁻¹, producing a strain amplitude of 0.3% in 0.5 s. This performance is significantly better than previously reported. The improvements in strain rate are somewhat offset when large negative potential limits are used due to the introduction of faradaic reactions in the electrolyte medium that do not contribute to actuation. Efficiency of operation is, therefore, reduced under such conditions. Some slight differences were observed between the actuator responses for the negative and positive pulses, which are partly explained by the basic mechanism of actuation and partly by instrumental effects.