The excellent optoelectronic, mechanical, and thermal properties of carbon nanotubes have made them very attractive for a wide range of potential applications. However, many applications require the growth of aligned/micropatterned carbon nanotubes, along with their surface modification. We have developed a simple pyrolytic method for large-scale production of aligned carbon nanotube arrays perpendicular to the substrate surface. We have also used photolithographic and soft-lithographic techniques for patterning the aligned carbon nanotubes with a sub-micrometer resolution. These aligned carbon nanotube arrays can be transferred onto various substrates of particular interest (e.g. polymer films for organic optoelectronic devices) in either a patterned or non-patterned fashion. The well-aligned structure further allows us not only to prepare novel aligned conducting polymer-carbon nanotube coaxial nanowires by electrochemically depositing a concentric layer of an appropriate conducting polymer onto the individual aligned carbon nanotubes, but also to develop a facile approach for modification of carbon nanotube surfaces via plasma activation followed by chemical reactions characteristic of the plasma-induced functionalities. These surface modification methods are particularly attractive, which allow surface characteristics of the aligned carbon nanotubes to be tuned to meet specific requirements for particular applications while their alignment structure can be retained. In this talk, results from our recent work on microfabrication and chemical modification of aligned carbon nanotubes for certain device applications (e.g. biosensors) will be presented.