title: Evanescent wave absorbance based fiber optic biosensor for label-free detection of E. coli at 280 nm wavelength.
abstract: A novel label-free technique for the detection of pathogens based on evanescent wave absorbance (EWA) changes at 280 nm from a U-bent optical fiber sensor is demonstrated. Bending a decladded fiber into a U-shaped structure enhances the penetration depth of evanescent waves and hence sensitivity of the probe. We show that the enhanced EWA response from such U-bent probes, caused by the inherent optical absorbance properties of bacterial cells or biomolecules specifically bound to the sensor surface, can be exploited for the detection of pathogens. A portable optical set-up with a UV light emitting diode, a spectrometer and U-bent fiber optic probe of 200 μm core diameter, 0.75 mm bend radius and effective probe length of 1cm demonstrated an ability to detect less than 1000 cfu/ml.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India.
authors.forename: Reshma
authors.initials: R
authors.lastname: Bharadwaj
authors.forename: V V R
authors.initials: VV
authors.lastname: Sai
authors.forename: Kamini
authors.initials: K
authors.lastname: Thakare
authors.forename: Arvind
authors.initials: A
authors.lastname: Dhawangale
authors.forename: Tapanendu
authors.initials: T
authors.lastname: Kundu
authors.forename: Susan
authors.initials: S
authors.lastname: Titus
authors.forename: Pradeep Kumar
authors.initials: PK
authors.lastname: Verma
authors.forename: Soumyo
authors.initials: S
authors.lastname: Mukherji
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D004926:Escherichia coli / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000175:diagnosis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D005516:Food Microbiology; D006801:Humans; D057230:Limit of Detection; D014871:Water Microbiology