||Carbon nanotubes are cylinders of rolled graphene sheets that have fascinating mechanical and electronic properties. In the field of carbon nanotube research, fundamental science studies carried out over the past years have provided a good starting point for commercialization. In order to fully realize the commercial potential of carbon nanotubes, integrated efforts have been devoted to the manufacturing, processing, and applications of carbon nanotubes. With regard to the manufacturing of carbon nanotubes, since their discovery in 1991, a plethora of synthesis and purification techniques have become available, resulting in difficulties for fast and efficient process design. In response to this problem, the first part of this study focused on the process design for large-scale production of carbon nanotubes. More specifically, systematic procedures and design heuristics, which are supported by a knowledge base in manufacturing techniques and in-house purification experiments, were formulated to allow for quicker and more efficient process design. Besides process design, processing techniques that enable final applications are also of paramount importance for the commercialization of carbon nanotubes. In the second part of this study, single-wall carbon nanotubes (SWNTs) have been purified and functionalized with an organic compound called copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (CuTBPc). A new method has also been developed to quantify the extent of functionalization. The amount of phthalocyanine immobilized onto the walls of carbon nanotubes was found to be ~0.046 [g-Pc/g-SWNT]. This constitutes a useful and relevant body of information that has been neglected in the literature thus far. Finally, a composite of CuTBPc and SWNT was envisaged to be a possible sensing element for nitrogen dioxide. As a proof-of-concept study, sensor prototypes with the composite as sensing films were fabricated and tested. The highest room-temperature sensitivity was found to be 1.63 (at a CuTBPc to SWNT ratio of 2:1). Albeit the sensor design has yet to be optimized, their sensitivities towards nitrogen dioxide were confirmed. Moreover, introduction of SWNT into CuTBPc also provided a significant reduction in film resistance (from 530kΩ to less than 20kΩ), offering a competitive advantage of less power consumption.