COUNTESS® II FL Automated Cell Counter

Overview

The COUNTESS® II FL Automated Cell Counter is a benchtop, image-based cell analysis platform engineered for rapid, reproducible quantification and viability assessment of mammalian, insect, yeast, and bacterial cells in suspension. It operates on high-resolution brightfield microscopy coupled with dual independent fluorescence detection channels (excitation/emission configurable via interchangeable filter sets), enabling simultaneous morphological evaluation, fluorescent protein expression monitoring (e.g., GFP, RFP), and viability determination using fluorescent dyes such as Trypan Blue (brightfield) or propidium iodide (PI)/calcein-AM (fluorescence). Designed for routine QC in bioprocessing, academic research labs, and cell therapy development workflows, the system delivers statistically robust cell concentration (cells/mL), viability (%), average cell diameter (µm), and total count per sample—without requiring user calibration or manual threshold adjustment.

Key Features

• Triple-Mode Imaging Architecture: Integrated brightfield channel plus two independently controllable fluorescence channels (user-selectable excitation/emission bands via snap-in filter cubes), supporting multiplexed assays including dual-color viability staining and reporter gene expression.
• Auto-Focus & Adaptive Image Acquisition: Motorized Z-stage with real-time contrast-based autofocus ensures optimal focus across variable sample thicknesses and cell densities; eliminates operator-dependent focusing errors and enhances inter-operator reproducibility.
• Touchscreen-Driven Workflow: Intuitive 7-inch capacitive touchscreen interface with guided step-by-step protocols; no PC dependency required for basic operation—ideal for shared core facilities and GMP-aligned environments where software validation is critical.
• Reusable Counting Chambers: Compatible with Thermo Scientific™ COUNTESS™ Reusable Slides (glass-based, precision-etched chambers), reducing consumable cost by >60% versus disposable slides over 12 months of moderate usage (≈200 counts/month).
• Onboard Data Management: Internal storage for up to 1,000 sample records with timestamp, operator ID, instrument serial number, and full image archive; exportable via USB 2.0 to CSV or PDF report formats compliant with GLP documentation requirements.

Sample Compatibility & Compliance

The COUNTESS® II FL accepts standard suspension cell types—including adherent cells detached via enzymatic (trypsin) or non-enzymatic methods—with recommended concentrations ranging from 1 × 10⁴ to 1 × 10⁷ cells/mL. It supports common viability dyes (Trypan Blue, PI, 7-AAD, calcein-AM) and fluorescent fusion proteins without cross-channel bleed-through when appropriate filter sets are installed. The instrument complies with IEC 61010-1:2010 for laboratory equipment safety and meets electromagnetic compatibility (EMC) standards per FCC Part 15 Class B and CE directives. While not pre-validated for FDA 21 CFR Part 11, its audit-trail-capable data logging architecture enables lab-specific validation under ISO/IEC 17025 or internal SOPs for regulated biomanufacturing applications.

Software & Data Management

All image capture, segmentation, and calculation algorithms reside onboard the device firmware—no external software installation is required for daily operation. Advanced image processing includes dynamic background subtraction, adaptive thresholding, and circularity-based debris rejection to minimize false positives in heterogeneous samples (e.g., clumped primary T cells or apoptotic fragments). Raw images and processed results are stored with metadata including exposure time, gain setting, focus position, and user-defined sample ID. For integration into LIMS or ELN systems, optional Thermo Fisher Connect™ cloud services provide secure, encrypted data synchronization with role-based access control and automated backup—fully traceable for audit readiness.

Applications

• Bioreactor inoculum preparation and harvest titer verification in upstream bioprocessing
• CRISPR-edited cell line expansion monitoring with GFP/RFP co-expression tracking
• Primary immune cell viability assessment pre- and post-cryopreservation
• Yeast fermentation kinetics and budding index quantification
• Stem cell passaging QC with trypan blue exclusion and DAPI nuclear staining
• Support for USP <71> sterility testing workflows requiring viable cell enumeration

FAQ

Does the COUNTESS® II FL require regular optical recalibration?
No—factory-calibrated optics and embedded reference image routines eliminate scheduled recalibration; only periodic verification using Thermo Scientific™ COUNTESS™ Calibration Beads is recommended per ISO 21501-3.
Can I use third-party counting chambers with this instrument?
Only Thermo Fisher–certified reusable or disposable slides are supported; non-OEM chambers may cause focus drift, chamber height miscalculation, and inaccurate volume derivation.
Is fluorescence quantification absolute or relative?
Fluorescence intensity is reported as mean gray value per cell (arbitrary units); for quantitative comparisons, users must normalize to internal controls or reference standards run in parallel.
What is the minimum viable cell concentration detectable?
At ≥90% viability, the lower limit of quantification is 5 × 10³ cells/mL with ≤15% CV (n = 6 replicates), validated using NIST-traceable microsphere suspensions and Jurkat cell dilutions.
How does the system handle cell clumps during analysis?
The algorithm applies size- and shape-based clustering logic to identify and optionally exclude aggregates >2× median cell area; users may adjust the “clump sensitivity” parameter within defined operational ranges.