Self-assembly carbon nanotubes on cantilever biosensor for sensitivity enhancement

Abstract

In recent years, highly sensitive and selective as well as cost-effective sensing and detection of biomolecules (e.g. virus, bacterial, DNA and protein) by MEMS/NEMS (Micro- /Nano Electro- Mechanical-System) structures have attracted extensive attention for its importance in clinical diagnostics, treatment, and various genome projects. Meanwhile, Substantial research efforts have been spent on the improvement of sensitivity of bioMEMS structures. Among a variety of methods that have been investigated, surface modification by nanoparticles (NPs) turns out to be an attractive way, which provides a platform for the enhancement of the sensitivity for biosensor devices. However, conventional applications for surface modification were mostly implemented on microelectrodes. Thus, in this paper, we demonstrate a new approach for surface enhancement on Au-coated silicon microcantilevers in micro-/nano-system. By self-assembly surface binding of multi-walled carbon nanotubes (MWCNTs) on the Au monolayer on top of the Si microcantilever surfaces, much larger surface area could be created for bio-molecular binding (such as antibodies or single DNA strands, which act as probes to capture target molecules). Therefore, this could enable specific interactions and selective binding to target biomolecules with a very low sample size, which greatly increases the sensitivity of detection. It should be noted that functionalization of MWCNTs with terminal carboxylic functionalities (in DCC solution) onto the Au surfaces of Si microchips have been introduced in our study. Further applications of MWCNTs functionalization are worth exploring in biomolecular detection for their exceptional mechanical and unique electronic properties. The successful binding of MWCNTs was testified as shown obviously on AFM image (Figure 1 and 2). © 2006 IOP Publishing Ltd.