SIMULTANEOUS CONCENTRATION AND DETECTION OF ESCHERICHIA COLI USING CARBON NANOTUBE DEVICES

Abstract

The performance of a nanoscale sensor is not limited by the sensitivity of the sensor itself but rather by the diffusion time required for target molecules to reach to the extremely small sensor surface. In this work, we developed a carbon nanotube device that performed the dual functions of concentrating and detecting microorganisms in a sample solution. The sensor surface area was increased by fabricating a carbon nanotube network device using thermal chemical vapor deposition and standard microfabrication techniques. The target Escherichia coli (E. coli) cells were concentrated at the sensor surface via dielectrophoretic concentration by the carbon nanotube network channels. After 10 min of collection, the chip was washed with ample amounts of a clean buffer solution, and only the E. coli cells that were bound to the antibodies remained on the sensor surface. The binding of E. coli to the CNT network device decreased the conductance, presumably due to an increase in the scattering at the sensor surface. The detection limit and the time required for microorganism detection was greatly improved by combining dielectrophoresis with the carbon nanotube devices.