A Comparative Study between Knocked-Down Aligned Carbon Nanotubes and Buckypaper-Based Strain Sensors.

Carbon nanotubes (CNTs) are one of the most promising materials in sensing applications due to their electrical and mechanical properties. This paper presents a comparative study between CNT Buckypaper (BP) and aligned CNT-based strain sensors. The Buckypapers were produced by vacuum filtration of commercial CNTs dispersed in two different solvents, N,N-Dimethylformamide (DMF) and ethanol, forming freestanding sheets, which were cut in 10 × 10 mm squares and transferred to polyimide (PI) films. The morphology of the BP was characterized by scanning electron microscopy (SEM). The initial electrical resistivity of the samples was measured, and then relative electrical resistance versus strain measurements were obtained. The results were compared with the knocked-down vertically aligned CNT/PI based sensors previously reported. Although both types of sensors were sensitive to strain, the aligned CNT/PI samples had better mechanical performance and the advantage of inferring strain direction due to their electrical resistivity anisotropic behavior.