CNT Based Actuators: Experimental and Theoretical Investigation of the In-Plain Strain Generation

Actuators based on carbon nanotubes (CNT) have the potential to generate high forces at very low voltages. The density of the raw material is just 1330 kg/m³, which makes them well applicable for lightweight applications. Moreover, active strains of up to 1% can be achieved—due to the CNTs dimensional changes on charge injection. Therefore the nanotubes have to be arranged and electrically wired like electrodes of a capacitor. Immersing the nanotubes in an electrolyte increases the capacity of the system by allowing electro-chemical double layers to be built around the CNT. For the experimental investigation of the strain generation, carbon nanotube sheets are manufactured by vacuum filtration. The in-plain strain response is being examined, when applying a voltage to the system. This paper presents experimental investigations of the systems response in dependence of varying system parameters like capacity and resistance. Dependencies of the actuator system were formulated from these experimental results. A guideline of how to improve a CNT based actuator is derived from these dependencies.