DW-Micro DW-JURAY Series Automated Gravimetric Microbial Sample Dilutor

Overview

The DW-Micro DW-JURAY Series Automated Gravimetric Microbial Sample Dilutor is an ISO-compliant, precision-engineered instrument designed for standardized pre-analytical sample preparation in microbiological testing laboratories. Unlike volumetric dilutors, the DW-JURAY employs real-time gravimetric feedback control: it first measures the exact mass of the undiluted sample placed in a sterile stomacher bag, then calculates and dispenses the precise mass of diluent required to achieve the target dilution factor—eliminating manual weighing errors and operator-dependent variability. This closed-loop mass-based methodology ensures traceable, reproducible dilutions across heterogeneous or viscous samples (e.g., ground meat, dairy products, herbal powders), directly supporting regulatory requirements under GB 4789 (China National Food Microbiology Standards), ISO 6887-1 (Microbiology of food and animal feeding stuffs — Preparation of test samples, initial suspension and decimal dilutions), and ISO 7218 (General requirements and guidance for microbiological examinations). The system operates without requiring pre-weighed samples—users simply place the sample into the bag, select the dilution ratio (e.g., 1:10), and initiate the cycle.

Key Features

• Gravimetric closed-loop control architecture: Integrated high-stability analytical balance (±0.01 g resolution) continuously monitors sample mass and dynamically adjusts diluent dispensing (±0.1 g accuracy) to maintain >99% dilution fidelity.
• Single- or dual-pump configurations: DW-JURAY (single-arm) supports sequential dilution workflows; DW-JURAY-2 (dual-arm) enables parallel processing of two samples or simultaneous diluent + neutralizer delivery, reducing turnaround time to under 20 seconds per 250 mL dilution.
• Modular, sterilizable fluid path: All wetted components—including disposable or autoclavable dispensing tubes, peristaltic pump heads, and quick-release nozzles—are fully separable from drive electronics. Tubing materials comply with USP Class VI biocompatibility standards.
• Full audit trail capability: Onboard microprocessor logs timestamped records including operator ID, sample ID, gross/net weight, dilution factor, diluent lot number, final total mass, and system calibration status—exportable via USB to CSV for GLP/GMP documentation.
• Ergonomic, mobile design: Compact footprint (320 × 280 × 310 mm), lightweight chassis (6.5 kg), and integrated carrying handle allow deployment inside laminar flow hoods, biosafety cabinets, or ISO Class 5 cleanrooms without structural modification.

Sample Compatibility & Compliance

The DW-JURAY accommodates standard 3M™ Petrifilm™ bags, Seward Stomacher® bags (up to 400 mL capacity), and custom polyethylene or nylon-coated sterile pouches. Its open-bag loading geometry—enabled by a 120° rotating dispensing arm—ensures full access to the bag opening during filling, minimizing splash and aerosol generation. All firmware and operational logic are validated against ISO/IEC 17025:2017 clause 5.9 (method validation) and align with FDA 21 CFR Part 11 requirements for electronic records and signatures when paired with optional password-protected user roles and digital signature modules. The device meets IP54 ingress protection rating for splash resistance and conforms to IEC 61010-1 safety standards for laboratory electrical equipment.

Software & Data Management

A touch-enabled LCD interface supports intuitive programming of up to 99 customizable dilution protocols, each configurable with variable diluent density compensation (e.g., for buffered peptone water vs. saline), hold times, and post-dispense mixing triggers. Raw data—including weight-vs.-time curves and real-time deviation alerts—is stored in non-volatile memory with cyclic overwrite protection. Export functions support direct printing via thermal label printers or structured CSV export compatible with LIMS platforms (e.g., LabWare, STARLIMS) and statistical process control (SPC) software. Optional firmware upgrade enables HL7 messaging integration for enterprise-level lab informatics interoperability.

Applications

• Routine enumeration of aerobic plate counts (APC), coliforms, E. coli, Salmonella, and Staphylococcus aureus per GB 4789.2, GB 4789.3, and GB 4789.10.
• Preparation of serial dilutions for antimicrobial susceptibility testing (AST) in pharmaceutical QC labs compliant with USP <61> and <62>.
• Standardized dilution of environmental swab eluates, cosmetic challenge test suspensions, and probiotic powder formulations.
• Support for ISO 11133:2014 culture media performance qualification through consistent inoculum preparation.
• High-throughput sample batching in contract testing laboratories serving food, nutraceutical, and personal care industries.

FAQ

Does the DW-JURAY require calibration before each use?
No. The integrated balance is factory-calibrated with NIST-traceable weights and features automatic internal drift compensation. Daily verification using certified test masses (supplied) is recommended per ISO/IEC 17025.
Can the system be validated for GMP environments?
Yes. IQ/OQ documentation packages are available upon request, including test scripts for accuracy, repeatability, linearity, and system suitability per ASTM E2656-18.
Is the firmware compliant with 21 CFR Part 11?
Out-of-the-box compliance requires optional user authentication module and electronic signature license; both enable role-based access, audit trail locking, and secure data export.
What maintenance is required for the fluid path?
Daily rinsing with deionized water and weekly disinfection with 70% ethanol are sufficient. Tubing sets are consumable and should be replaced after 500 cycles or per visual inspection for cracking.
Can the DW-JURAY integrate with robotic liquid handlers?
Yes. RS-232 and TTL-level GPIO interfaces support handshake-triggered operation and status reporting for integration into automated sample prep workcells.