Sensitive Detection of Small Particles in Fluids Using Optical Fiber Tip with Dielectrophoresis

This work presents using a tapered fiber tip coated with thin metallic film to detect small particles in water with high sensitivity. When an AC voltage applied to the Ti/Al coated fiber tip and indium tin oxide (ITO) substrate, a gradient electric field at the fiber tip induced attractive/repulsive...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2016-02, Vol.16 (3), p.303-303
Main Authors: Tai, Yi-Hsin, Chang, Dao-Ming, Pan, Ming-Yang, Huang, Ding-Wei, Wei, Pei-Kuen
Format: Article
Language:English
Subjects:
Bacteria
Beads
Dielectric properties
Dielectrophoresis
Drinking water
E coli
Electric fields
Electrodes
Fibers
Immunoassay
Indium tin oxide
Particle size
Photonics
refractive index
Scattering
Sensors
tapered fiber tip
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Summary:This work presents using a tapered fiber tip coated with thin metallic film to detect small particles in water with high sensitivity. When an AC voltage applied to the Ti/Al coated fiber tip and indium tin oxide (ITO) substrate, a gradient electric field at the fiber tip induced attractive/repulsive force to suspended small particles due to the frequency-dependent dielectrophoresis (DEP) effect. Such DEP force greatly enhanced the concentration of the small particles near the tip. The increase of the local concentration also increased the scattering of surface plasmon wave near the fiber tip. Combined both DEP effect and scattering optical near-field, we show the detection limit of the concentration for 1.36 μm polystyrene beads can be down to 1 particle/mL. The detection limit of the Escherichia coli (E. coli) bacteria was 20 CFU/mL. The fiber tip sensor takes advantages of ultrasmall volume, label-free and simple detection system.
ISSN:1424-8220
1424-8220
DOI:10.3390/s16030303