Experimental investigations on carbon nanotube actuators defining the operation point and its standard deviation

Abstract

Carbon nanotube (CNT) actuators have been extensively investigated from the perspective of materials, their composition, and system construction as well as from three main performance features, which are displacement, force and velocity. However, up till now none of the CNT actuators have reached the stage of implementation into products. It is due to the fact that even though from the point of view of performance each property can reach satisfactory values, their combination is much more difficult, as they are not proportional. This relation of properties motivated the work to test and investigate currently available CNT-polymer actuators to define their operation point. Under this term one should understand a performance of actuator where displacement, force and velocity do not affect each other. In other words, any change in one of the properties will adversely affect at least one of the remaining ones. The measurements are performed in out-of-plane mode on 2 cm diameter samples in low frequency range (0.01 - 1 Hz) under application of low voltage (2 V). Measurement curves of three main actuator properties are plotted together against the frequency resulting in operation point as the intersection point of those curves. Additionally the deviations in actuator performance are assessed to reflect the actuators' reproducibility and their production process stability by means of standard deviation. Knowledge about the relation between actuator properties and the value of operation point will facilitate evaluation of the existing CNT actuator against its potential applications.