Autofocus systems and methods for particle analysis in blood samples

Inventors

Wanders, Bart J. • Jordan, Brett • Farrell, Gregory A. • Adams, Thomas H. • Groner, Warren

Assignees

Iris International Inc

Abstract

Particles such as blood cells can be categorized and counted by a digital image processor. A digital microscope camera can be directed into a flowcell defining a symmetrically narrowing flowpath in which the sample stream flows in a ribbon flattened by flow and viscosity parameters between layers of sheath fluid. A contrast pattern for autofocusing is provided on the flowcell, for example at an edge of a rear illumination opening. The image processor assesses focus accuracy from pixel data contrast. A positioning motor moves the microscope and/or flowcell along the optical axis for autofocusing on the contrast pattern target. The processor then displaces microscope and flowcell by a known distance between the contrast pattern and the sample stream, thus focusing on the sample stream. Blood cell images are collected from that position until autofocus is reinitiated, periodically, by input signal, or when detecting temperature changes or focus inaccuracy in the image data.

Core Innovation

The disclosure describes an automated hematology/particle imaging analyzer in which a flowcell forms a ribbon-shaped sample stream that is enveloped by a higher-viscosity PIOAL/sheath fluid, including geometric hydrofocusing achieved by a symmetrically narrowing flowpath. The imaging device captures a set of cell images at an image capture site within the flowcell while the analyzer determines a cell parameter from a separate volume received by a cell counter. The system provides combined particle/cell alignment and imaging at improved optical resolution for automated downstream classification/counting.

The high-resolution imaging device includes a focusing mechanism that is auto-focused by first imaging a fixed, flowcell-relative high-contrast autofocus target, and then focusing the imaging device on the ribbon sample stream by displacing the objective/flowcell by a calibrated constant displacement distance. The autofocus target is described using illumination opening border/iris-type structures, and the focusing process is controlled using contrast-based focus metrics such as edge contrast or pixel contrast. Focus can be re-initiated periodically, based on an input signal, or upon detecting temperature changes or focus-quality degradation.

The disclosure further links focusing accuracy to improved particle/cell alignment and improved in-focus content for downstream automated classification/counting, including WBC differential classification and morphology-based imaging for cell types such as RBCs, reticulocytes, nucleated RBCs, and platelets. Optional temperature-based focus adjustment is described using a sensor and a known temperature–focus relationship to maintain focus quality over temperature changes. The system includes structural and operational details of motor-driven relative motion and focus control using autofocus patterns and positional offsets fixed relative to the flowcell.

Claims Coverage

The independent claim describes a system that combines a cell counter and a visual analyzer with a focusing mechanism, processors, and a non-transitory computer readable medium that controls focusing and outputs both a cell parameter and captured cell images. The inventive features are directed to performing cell-parameter determination from a first volume, capturing cell images from a second volume at a flowcell image capture site, controlling a focal state of an imaging device to focus on the sample at that site, and displaying the determined cell parameter alongside the captured images; dependent claims further specify hematology sample context, specific counting modalities, and focusing based on a fixed imaging target and a non-zero distance relationship, plus image storage and retrieval for display.

Across the independent claim and its refinements, the claimed coverage centers on combining cell counting from a first volume with flowcell-based imaging from a second volume, using a focusing mechanism that sets the imaging-device focal state for capturing the set of cell images, and using processors/computer application to output both the determined cell parameter and the captured images to a display; dependent claims narrow the biological sample to blood/hematology, specify counting modalities and size/volume channel criteria, refine focusing using a fixed imaging target with a non-zero distance relationship, and specify storing images for display.

Stated Advantages

Documented Applications