Automatic resistance measurement of carbon nanotube sheet actuators and the parameters influencing the resistance

Recent advances in technology have led to the development of nanostructured materials based on the assembly of carbon nanotubes with applications ranging from micromechanics to electronics and energy storage. An exciting property of carbon nanotubes is its electro-mechanical actuation behavior. The actuation behavior of the carbon nanotube paper (bucky paper) is greatly influenced by its surface resistance. In this work we propose to find out the resistance of the bucky paper, a porous meshwork of carbon nanotubes, automatically in a controlled and reproducible manner. The resistance is measured by using four wire resistance measurement instruments. It has two pairs of identical poles, positive and negative. Opposite polarity poles are short-circuited leading to two probes out of which one is taken as a reference and the other as varying probes. Considering multi walled carbon nanotube (MWNT) paper of 20 mm diameter, the reference probe is kept fixed at a single point a nd the varying probe is moved in different directions of the bucky paper plane. When performed manually the obtained results are highly nonlinear having many disturbances. In order to avoid these disturbances, an automatic movable probe holder has been designed and tested which provides a reproducible condition for the measurement automated by LabVIEW® interfacing. A direct measurement of resistance prior and later to the actuation testing is performed. Based on the results, the influence of resistance on actuation performance has been analyzed.