Mimicking a gecko's foot with strong adhesive strength based on a spinnable vertically aligned carbon nanotube array

To mimic gecko foot adhesion, spinnable vertically aligned carbon nanotube (VACNT) arrays, which have a higher density and cleaner surface than ordinary VACNT arrays, were prepared by a normal chemical vapor deposition (CVD) process that is simple and easy to operate for large-scale fabrication, particularly compared with the low-pressure CVD process. The height of the spinnable VACNT array was tuned by varying the reaction time. The shear adhesion strength of the spinnable VACNT array (0.16 cm²) was increased from 21.4 ± 1.7 to 85.8 ± 8.7 N cm^-2 when the length of the spinnable VACNT array increased from 35 to 110 μm. Based on the enhanced van der Waals force induced by the large number of contact points on the high-density spinnable VACNT array, the maximum shear adhesion strength of the spinnable VACNT array (0.16 cm²) is 91.8 N cm^-2, which is comparable to that of the CNT-based adhesive (∼100 N cm^-2) prepared by the low-pressure CVD process. Moreover, a spinnable VACNT array adhesive was prepared over a large area, and a maximum weight of 3.0 Kg was supported successfully by a spinnable VACNT array adhesive with a contact area of 0.96 cm².