Absorption Measurements in Microfluidic Devices Using Ring-Down Spectroscopy

dc.contributor.authorTrefiak, Nicholas R.en
dc.contributor.authorBarnes, Jack A.en
dc.contributor.authorRask, Fionaen
dc.contributor.authorCourtney, Daniel G.en
dc.contributor.authorWalford, Richarden
dc.contributor.authorLi, Runkaien
dc.contributor.authorOleschuk, Richarden
dc.contributor.authorLoock, Hans-Peteren
dc.date.accessioned2016-03-29T17:56:00Z
dc.date.available2016-03-29T17:56:00Z
dc.date.issued2016-03-29
dc.description.abstractWhen monitoring separation events in microfluidic devices, one frequently needs to detect small amounts of analyte in picolitre sized volumes with a time response of milliseconds. Fluorescence detection is typically the method of choice due to its very high sensitivity and fast response. However, since many analytes are not naturally fluorescent, labelling protocols may have to be introduced and thereby increase the complexity of the analysis. Here, we present an alternative method that is based on optical absorption, or more specifically on the ring-down time of an optical signal in a cavity or loop made of waveguide material. This optical decay constant changes as small liquid samples containing absorbing species are introduced into a fiber-optic loop. It is demonstrated that one can obtain the optical decay constant using a continuous wave laser beam that is intensity modulated and then coupled into an optical fiber loop. The inherent exponential decay in the fiber loop introduces a phase shift of the light emitted from the loop with respect to the pumping beam. By measuring this phase shift, one can readily determine the concentration of the analyte introduced between the two fiber ends and a model is established to describe the relationship. It is demonstrated that this technique, dubbed “phase-shift fiber-loop ring-down spectroscopy” (PS-FLRDS), is well suited as an absorption detector for any flow system in which the optical absorption path is limited by the instrument architecture.en
dc.identifier.issn0277-786X
dc.identifier.otherDOI: 10.1117/12.629756
dc.identifier.urihttp://hdl.handle.net/1974/14152
dc.language.isoenen
dc.subjectFiber-Loop Ring-Down Spectroscopy (FLRDSen
dc.subjectPhase-Shiften
dc.titleAbsorption Measurements in Microfluidic Devices Using Ring-Down Spectroscopyen
dc.typejournal articleen
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