title: Microfluidic refractometer with micro-image defocusing.
abstract: We herein report on a novel micro-refractometer with a self-calibration function. A micro-image defocusing (µ-ID) technique using optical path separation via a three-pinhole aperture is adopted to measure refractive index (RI). In order to achieve self-calibration, the microfluidic device is designed to have a self-calibration region into which reference fluids with known RIs are injected, as well as a measurement region into which a sample fluid is injected. In this way, the RI of the sample fluid is calculated automatically. In order to demonstrate the application of our proposed micro-refractometer, certified RI liquids with RIs of 1.300, 1.400, 1.450, 1.500, 1.550, 1.600, and 1.700 were used. The experimental demonstration described herein shows that the measured RIs have a deviation of less than 0.0009 with an uncertainty of ±0.001 refractive index unit (RIU) compared with their certified values.
authors.affiliation: Graduate Program of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju, Republic of Korea 500-712.
authors.forename: Sang Youl
authors.initials: SY
authors.lastname: Yoon
authors.forename: Sung
authors.initials: S
authors.lastname: Yang
mesh_terms: D002138:Calibration; D004209:Disposable Equipment; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D055620:Optical Phenomena; D012031:Refractometry / Q000295:instrumentation*