Stuart SC6PLUS Semi-Automatic Colony Counter

Overview

The Stuart SC6PLUS Semi-Automatic Colony Counter is an ergonomically engineered microbiological counting instrument designed for precise, repeatable enumeration of microbial colonies on standard agar plates. It operates on a tactile pressure-sensing principle: users sequentially depress colonies using a precision-tipped stylus on a responsive silicone pad, triggering an audible beep and incrementing the digital counter. This manual actuation method eliminates optical miscounting artifacts common in image-based systems—such as overlapping colonies, faint or translucent growth, or condensation interference—making the SC6PLUS particularly reliable for routine QC microbiology, environmental monitoring, and food & beverage testing labs where robustness and operator control are prioritized over full automation. The device is not dependent on image capture or software-based segmentation algorithms; instead, it delivers deterministic, user-verified counts traceable to individual colony touches—a critical advantage in GLP-compliant environments requiring audit-ready procedural transparency.

Key Features

• Pressure-sensitive counting pad with adjustable activation threshold—calibrated to accommodate varying user hand strength and plate surface conditions.
• Built-in statistical processor calculating mean colony count and standard deviation (SD) across multiple plates—essential for ISO 4833-1:2013 and FDA BAM Chapter 3 compliance reporting.
• High-luminance white LED backlight providing uniform, flicker-free illumination; supports both bright-field (white background) and dark-field (black background) modes to enhance contrast for translucent, mucoid, or low-pigment colonies.
• Antimicrobial coating applied to all high-contact surfaces—including the counting pad and housing—to minimize cross-contamination between samples and support ISO 14644-1 cleanroom-compatible workflows.
• Three-digit LED display with audible confirmation tone per count (mute function available); zero-reset and memory retention for multi-plate batch processing.
• Dual Wolffhügel grid inserts (supplied) and centering disc enable accurate alignment and sector-based counting for 50 mm, 60 mm, and 90 mm Petri dishes—fully compliant with ASTM D4785 and USP <61> plate geometry requirements.

Sample Compatibility & Compliance

The SC6PLUS accommodates standard non-inverted and inverted Petri dishes ranging from 50 mm to 90 mm in diameter, including polystyrene, polypropylene, and glass variants. Its mechanical counting paradigm ensures compatibility with opaque, pigmented, or filamentous colonies that challenge optical systems—such as Aspergillus, Mucor, or slow-growing Actinomycetes. The device meets essential design criteria referenced in ISO 7218:2017 (Microbiology of food and animal feeding stuffs — General requirements and guidance for microbiological examinations) and supports laboratory adherence to EU Annex 1 (sterile manufacturing) and FDA 21 CFR Part 11 when used in conjunction with validated data transfer protocols. Optional accessories—including transparent protective discs (SC6/4) and sterile receiving trays (SC6/5)—facilitate aseptic handling in Class B and C cleanrooms.

Software & Data Management

While the SC6PLUS is hardware-centric and does not incorporate onboard firmware or embedded OS, it provides standardized USB 2.0 connectivity (via supplied cable) for direct integration with Windows-based LIMS or ELN platforms. Count data—including plate ID, count value, timestamp, operator ID (manually entered), and calculated statistics—is transmitted as plain-text CSV or tab-delimited format, ensuring interoperability with LabWare, Thermo Fisher SampleManager, or custom SQL databases. When paired with the optional thermal printer (SC6/5), hard-copy output includes automatic date/time stamping and conforms to ALCOA+ principles (Attributable, Legible, Contemporaneous, Original, Accurate) for regulatory submissions. No proprietary drivers or cloud dependencies are required—data integrity is preserved through deterministic serial transmission without intermediate caching or compression.

Applications

• Routine total viable count (TVC) and aerobic plate count (APC) in pharmaceutical water systems (USP <1231>) and bioburden testing of non-sterile products.
• Environmental monitoring of Grade A–D cleanrooms per ISO 14644-2, including settle plate and contact plate enumeration.
• Food safety laboratories performing ISO 4833-1:2013 (microbial enumeration by colony count) and ISO 6887-1:2017 (preparation of test samples).
• Educational microbiology teaching labs—its tactile interface reinforces fundamental colony recognition skills without algorithmic abstraction.
• Water quality testing per EPA Method 1681 and APHA Standard Methods 9215B (heterotrophic plate count).

FAQ

Is the SC6PLUS suitable for regulatory audits under GMP or ISO 17025?
Yes—the device’s deterministic, user-verified counting mechanism, combined with auditable CSV export and optional printed records, fulfills traceability and data integrity requirements outlined in EU GMP Annex 11 and ISO/IEC 17025:2017 clause 7.5.2.
Can the pressure sensitivity be calibrated per operator?
Yes—the activation threshold is manually adjustable via internal potentiometer, enabling lab-wide standardization across staff with differing dexterity or ergonomic needs.
Does it support 100 mm Petri dishes?
No—the mechanical design and included grids are validated only for 50–90 mm diameters per manufacturer specifications; use outside this range voids metrological assurance.
Is firmware update capability available?
No—the SC6PLUS contains no programmable logic or flash memory; its operation is purely analog-electromechanical, eliminating cybersecurity risks and validation overhead associated with embedded software.
What is the service life expectancy of the pressure pad?
Rated for ≥500,000 actuations under normal laboratory use; replacement pads (SC6/PAD) are available as consumables with NIST-traceable calibration verification documentation.