A Study On The Separation Of Metallic Single-walled Carbon Nanotubes Utilizing Dielectrophoresis Technique Based On Microfluidic Chips

Single-Walled Carbon Nanotubes (SWNTs) have superb electronic andmechanical properties; however, SWNTs come in different chiralities making themeither metallic (MET) or semiconducting (SC). It is desirable to have only one typein electronic applications. In this thesis, the mixture problem of SWNTs wasaddressed through dielectrophoresis in a microfluidic device. By dielectrophoreticforce applied onto electrode arrays, continuous MET carbon nanotubes wereextracted, in which MET and SC nanotubes possess a different force with respect tothe electric field due to their electrical properties. These findings were explained withan advanced theoretical model for nanotube dielectrophoresis, which takes intoaccount the structural and dielectric anisotropy of single-walled carbon nanotubes.An experiment using modified chips and different types of SWNTs was designed tooptimize the efficiency and quality of separate dispersed SWNTs under variation ofthe applied electric field, from which—according to the theoretical predictions—theultra-long and nondestructive MET SWNTs can be separated. To demonstrate theutility of the method, I incorporate separated metallic carbon nanotubes into thin filmnetworks that exploit their enhanced electronic and optical properties. Transparentconductive films exhibit lower sheet resistances at higher optical transmittance levelsthan pristine carbon nanotubes films, and even achieve to the conventionaltransparent conductive electrodes ITO materials. These results demonstrate thatseparated SWNTs are promising candidates for future applications in thin filmelectronics.