ABSTRACT
This paper describes an innovative integrated micro flow cytometer that presents a new arrangement for the excitation/detection system. The sample liquid, containing the fluorescent marked particles/cells under analysis, is hydrodynamically squeezed into a narrow stream by two sheath flows so that the particles/cells flow individually through a detection region. The detection of the particles/cells emitted fluorescence is carried out by using a collection fiber placed orthogonally to the flow. The device is based on silicon hollow core antiresonant reflecting optical waveguides (ARROWs). ARROW geometry allows one to use the same channel to guide both the sample stream and the fluorescence excitation light, leading to a simplification of the optical configuration and to an increase of the signal-to-noise ratio. The integrated micro flow cytometer has been characterized by using biological samples marked with standard fluorochromes. The experimental investigation confirms the success of the proposed microdevice in the detection of cells.
Subject(s)
Flow Cytometry/instrumentation , Silicon/chemistry , Electrodes , Equipment Design , Equipment Failure Analysis , Fiber Optic Technology , Sensitivity and Specificity , TemperatureABSTRACT
Foveal and parafoveal spectral sensitivities of the G cone mechanism were used to derive the difference spectrum for the macular pigment for 12 observers. Measurements of the peak density of the macular pigment were obtained with a shortened version of the same procedure for an additional 15 observers. The mean density for all 27 observers at 460 nm was 0.77 +/- 0.06 with a range of 0.21-1.22. The mean density is higher than that previously reported and, compared to the standard absorbance curve (Wyszecki and Stiles, 1967), the results indicate higher density values for wavelengths on the long wavelength side of the absorption maximum.
