Influence of aligned carbon nanotube networks on piezoresistive response in carbon nanotube films under in-plane straining

The use of carbon nanotube (CNT) films for strain detection is one of the most encouraging findings in the field of sensors. Our previous studies have shown that the density of the CNT networks (randomly distributed) plays an important role in governing the piezoresistive response in CNT films under the in-plane straining. The influence of aligned CNT networks on the piezoresistive response is presented. In particular, the CNTs are first decorated with iron oxide nanoparticles (to enhance magnetism), and then the decorated CNTs are used to form aligned CNT networks in the films with the aid of a magnetic field. The films are loaded in the three points bending tester, and their piezoresistive response is investigated under a cycled in-plane straining. The results show that the CNT networks aligned at 0° to electrodes and 90° to electrodes exhibit the highest and the lowest piezoresistive sensitivity, respectively, but the poor repeatability (i.e., severe resistant reduction −6% to −27%) is also found in the CNT networks aligned at 0° to electrodes.