Characterization of Vertically Aligned Carbon Nanofibers Without Electrochemical Treatment Using Atomic Force Microscopy

One of the major limitations in the development of ultrasensitive electrochemical biosensors based on 1-D nanostructure is the difficulty involved with reliably fabricating nanoelectrode arrays. In the previous work (Arumugam et al., 2009), a simple, robust, and scalable wafer-scale fabrication method to produce multiplexed biosensors was introduced. Each sensor chip consists of nine individually addressable arrays that uses electron-beam patterned vertically aligned carbon nanofibers (VACNFs) as the sensing element. To ensure nanoelectrode behavior with higher sensitivity, VACNFs were precisely grown on 100 nm Ni dots with 1 mu m spacing on each micropad. However, in order to examine the quality and measure the height and diameter of the VACNFs, some surface detection and measurement tool at the nanoscale level is needed. In this paper, we introduce an approach to measure these nanoscale features through atomic force microscope. With this method, both the 2-D and 3-D images of sample surface are generated and the sizes of carbon nanofibers and cavities are obtained. Furthermore, statistical analysis is carried out to enable the improvement of VACNFs' growth and fabrication.