ABSTRACT
Owing to the large specific surface area as well as unusual electrical, thermal, and mechanical properties, carbon nanotubes are useful for various measurement devices, including electrochemical biosensors. There are mainly three different methods for carbon nanotube synthesis: arc discharge, laser ablation, and chemical vapor deposition (CVD). In an arc discharge method, either single- or multi-walled CNTs can be produced by applying a high DC voltage onto two graphite electrodes embedded with metal catalysts in a helium atmosphere. By performing pyrolysis of acetylene on cobalt catalyst within an alumina membrane template, Li et al. prepared vertically aligned carbon nanotubes (VA-CNTs). For many applications (e.g., sensor chips), it is highly desirable to produce VA-CNTs into micropatterned structures. In an independent study, Yang et al. developed a photolithographic micropatterning method for patterned growth of VA-CNTs. Soft-lithographic techniques, including the micro-contact printing and micro-molding, have also been used to prepare micropatterns of VA-CNTs.
