Flow cell and system for simultaneous measurement of absorbance and emission in a sample

Inventors

Coombs, David • Coombs, August

Assignees

Biocomp Instruments Inc

Abstract

The flow cell of the present application simultaneously monitors and measures light absorbance and fluorescence of particles in a flowing liquid. The flow cell comprises a housing having a light input face, an absorbance output face and first and second emission output faces; a fluid flow section within the housing that comprises a bottom funnel through which fluid enters the flow cell, a core chamber into which fluid flows from the bottom funnel, and a top funnel into which fluid flows from the core chamber, wherein the bottom and top funnels each comprise a first end which extends at an angle to a second end that is wider in diameter than the first end, and said second end of each is adjacent to and aligned with the core chamber; and a center section within the housing center having a recess formed therein which houses the core chamber of the fluid flow section, wherein said center section comprises a first pair of opposing channels formed in the light input face and the absorbance output face, respectively, and a second pair of opposing channels formed in the first emission output face and the second emission output face and which are perpendicular to the first pair of opposing channels, and wherein the first pair of opposing channels and second pair of opposing channels are in communication with the core chamber. An apparatus comprising the flow cell is also provided.

Core Innovation

The disclosure provides a modular optical flow cell for simultaneous absorbance and fluorescence measurements in a flowing liquid sample. Absorbance measurements are made along a straight-path using an absorbance output face, while fluorescence measurements are made at a right angle using perpendicular emission output faces. The flow path includes a tapered, cone-to-square funnel geometry feeding a core chamber with a square cross section and rounded corners, and the rounded corners are described as preventing liquid trapping to support measurement in flowing samples.

A housing provides multiple light input and light output faces arranged to support the simultaneous optical paths for absorbance and fluorescence. Light is delivered and collected through light pipes communicating with channels in a center section, with absorbance photodiodes facing the input path and fluorescence photodiodes positioned at the perpendicular emission faces. The modular design supports dual/tri-wavelength and tri-wavelength measurement using multiple light input/output modules, with LEDs, fiber optic bundles, optional filters, and normalization/reference photodiodes for digitized absorbance.

An emission filter holder is included to reduce scattered-light and false fluorescence interference affecting fluorescence measurements. The disclosure also describes flow testing of the funnel geometry, correlating funnel length/angle with flow detachment behavior to select funnel geometry for given flow rates, and bubble elimination and bubble-free start behavior based on meniscus behavior. The disclosure notes calibration/measurement advantages for density-gradient fractionation.

Claims Coverage

The provided claim content includes one independent claim relevant to an emission filter holder, with dependent claims refining the construction by adding quantitative constraints and material limitations. The inventive focus is on the structural arrangement of a filter slot and a photodiode slot around aligned light-pipe apertures so that fluorescent emissions pass through the light pipe and exit toward a photodiode.

The independent claim covers an emission filter holder that structurally aligns central holes in upper and lower opposing faces with a light pipe of matching diameter, while positioning a photodiode slot so the photodiode receives light exiting the upper-face hole after passing through the light pipe and emission filter.

Stated Advantages

Documented Applications