Yohei Maeno

Geckolike high shear strength by carbon nanotube fiber adhesives

Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

Adhesive Behavior of Single Carbon Nanotubes

We examined the adhesion of a carbon nanotube (CNT) tip using a manipulation technique with a transmission electron microscope. In addition, we estimated the maximum normal adhesion possibility of a CNT-based gecko tape. The adhesive behavior of a single isolated CNT to Au solid surfaces has high normal strength (6.84 nN), which has a linear relation to the cross section of a CNT, indicating the mechanism: van der Waals force was inferred from the contact of two flat surfaces. Adhesion measurements conducted on several surface materials verify that the surface chemistry affects adhesive properties of CNT tips.

Experimental Investigation of Adhesive Behavior in Carbon Nanotube Based Gecko Tape

To elucidate the adhesion mechanism of carbon nanotubes (CNTs) designed to mimic natural contact surfaces in the gecko, their contact behavior was investigated using a scanning electron microscope (SEM) equipped with manipulation stages. The normal adhesion of CNTs increases in direct relation with a preload, which is true also for gecko setae. The CNT shear strength increases concomitantly with increasing CNT length, indicating that the length is an important factor enabling conformation to the surface roughness and enabling generation of a strong contact by side contact. Results revealed the CNT configuration and surface physics as important factors for synthetic gecko adhesion.