Escherichia coli fiber sensors using concentrated dielectrophoretic force with optical defocusing method
Journal
ACS Sensors
Journal Volume
3
Journal Issue
6
Pages
1196-1202
Date Issued
2018
Author(s)
Abstract
A sensitive tapered optical fiber tip combined with dielectrophoretic (DEP) trapping was used for rapid and label-free detection of bacteria in water. The angular spectrum of the optical field at the fiber tip was changed with the surrounding refractive index (RI). By measuring far-field intensity change at the defocus plane, the intensity sensitivity was up to 95 200%/RIU (RI unit), and the detection limit was 5.2 × 10-6 RIU at 0.5% intensity stability. By applying an AC voltage to a Ti/Al coated fiber tip and an indium-tin-oxide glass, the DEP force effectively trapped the Escherichia coli ( E. coli) near the fiber tip. Those bacteria can be directly measured from optical intensity change due to the increase of surrounding RI. By immobilizing the antibody on the Ti/Al fiber tip, the tests for specific K12 bacteria and nonspecific BL21 bacteria verified the specificity. The antibody-immobilized Ti/Al coated fiber tip with DEP trapping can detect bacteria at a concentration about 100 CFU/mL.
Subjects
defocused image; dielectrophoretic force; E. coli; fiber tip; refractive index detection
SDGs
Other Subjects
aluminum; glass fiber; titanium; chemistry; electrophoresis; Escherichia coli; genetic procedures; isolation and purification; Aluminum; Biosensing Techniques; Electrophoresis; Escherichia coli; Optical Fibers; Titanium
Type
journal article