CARBON NANOMATERIALS FOR CHEMICAL AND BIOLOGICAL SENSING

Carbon nanotubes (CNTs), first discovered in 1991, are cylindrical structures composed of atomically thin sp2 hybridized carbon which can be visualized as a rolled up sheet of graphene. CNTs have excellent mechanical and electronic properties which make them a very promising new material. Typically, CNTs have diameter between one and several nanometers, comparable to the size of individual molecules, and lengths that can exceed several micrometers, which enables integration into microscale electronics. Most interestingly, CNTs electronic properties are very sensitive to changes in their local chemical environment, as all carbon atoms are located on the surface. By placing CNTs between two electrodes, they can function as a resistor or transistor for sensor applications, and through addition functionalization, the CNTs can serve as ultrasensitive, selective devices.\ud Herein, we report the specific functionalization of single-walled carbon nanotubes (SWNTs) for chemical and biological sensing. First, SWNTs have been decorated with metal oxide nanoparticles and a hydrophilic polymer for the detection of CO2 gas. The interactions of the SWNTs with the functional layers have been characterized in detail. Secondly, oxidized SWNTs functionalized with a pH sensitive polymer have been developed for selective detection of the pH of buffered solutions, with the ability to distinguish between 0.1 pH units. This device was also further functionalized to demonstrate detection of CO2 and H2 gas. \u