Chapters authored
Dielectrophoresis-Assisted Pathogen Detection on Vertically Aligned Carbon Nanofibers Arrays in a Microfluidic Device
In this chapter, we focus on utilizing nanoelectrode arrays fabricated with vertically carbon nanofibers (VACNFs) for pathogen detection based on a “point-and-lid” dielectrophoretic device in a microfluidic channel. This technique is utilized to concentrate particles from the bulk flow and detect pathogens based on fluorescence, surface-enhanced Raman spectroscopy (SERS) and impedance measurements. The advantage of VACNFs is their ultrasmall diameter (~100 nm) and the high aspect ratio (50:1). When coupled with a macroscopic indium tin oxide (ITO) electrode, it produces a large electric field gradient (∇E2 = ~1019 − 1020 V2 m−3) which is harnessed for pathogen detection based on dielectrophoresis. Several noninfectious pathogens including bacteria Escherichia coli DHα5, inactivated vaccinia virus (species: Copenhagen strain, VC-2), and Bacteriophage T4r were utilized as model species to study the size effect and kinetics of dielectrophoretic capture in this study. The comparable size of the nanoelectrode produced strong interaction with virus particles, generating striking lightning capture patterns and high detection sensitivity. The dielectrophoretic capture at the nanoelectrode arrays is successfully integrated with a portable Raman probe as a microfluidic chip for ultrasensitive detection of bacteria E. coli DHα5 using SERS-tagged gold nanoparticles co-functionalized with specific antibodies.
Part of the book: Biosensing Technologies for the Detection of Pathogens