HMI-60 Multi-Point Cell Inoculator

Overview

The HMI-60 Multi-Point Cell Inoculator is an automated microbiological inoculation platform engineered for high-throughput antimicrobial susceptibility testing (AST) in compliance with CLSI M07 and EUCAST guidelines. It operates on a precision mechanical pin-based transfer principle—utilizing calibrated stainless-steel inoculation pins to deliver defined volumes of bacterial suspension onto agar surfaces in parallel array format. Unlike manual loop-based or streaking methods, the HMI-60 eliminates inter-operator variability by standardizing contact time, immersion depth, and withdrawal velocity across all 60 positions. Its core function is to enable reproducible, quantitative, multi-drug gradient inoculation within ≤13 seconds per plate—supporting critical workflows in clinical microbiology labs, pharmaceutical quality control (QC), and antibiotic development pipelines.

Key Features

• 60-position stainless-steel inoculation pins fabricated from medical-grade 316L stainless steel, electropolished and hydrophilically treated to eliminate surface hydrophobicity and prevent droplet carryover during withdrawal.
• Integrated position-determining needle for unambiguous spatial registration of colony growth on 90 mm Petri dishes—enabling direct correlation between inhibition zone location and corresponding drug concentration.
• Motor-driven rotating sample tray with programmable angular indexing; automatic alignment eliminates manual repositioning—only plate and inoculation frame replacement required between runs.
• Three configurable inoculation modes: 24-pin (5 µL per pin), 60-pin (1 µL), and 96-pin (1 µL), supporting flexible experimental design for serial dilution matrices and MIC endpoint determination.
• Reproducible volumetric delivery validated per ISO 8655-7 (volumetric piston pipettes); coefficient of variation (CV) <3% across repeated cycles under controlled humidity and temperature conditions.
• Compact benchtop footprint (335 × 250 × 415 mm) with CE-marked electrical safety compliance and IP20-rated enclosure for laboratory environments.

Sample Compatibility & Compliance

The HMI-60 accommodates standard 90 mm Petri dishes filled with Mueller-Hinton agar (MHA), chocolate agar, or other CLSI-recommended media formulations. It supports both Gram-positive (e.g., Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (e.g., Escherichia coli, Pseudomonas aeruginosa) isolates suspended at 0.5 McFarland turbidity (≈1–2 × 10⁸ CFU/mL). All components contacting biological samples are autoclavable at 121°C for 20 min. The instrument meets IEC 61010-1 safety standards and supports GLP-compliant documentation when paired with audit-trail-enabled LIMS integration. While not FDA 21 CFR Part 11 certified out-of-the-box, its operational logs (timestamped run records, pin configuration, inoculation duration) can be exported in CSV format for regulatory submission.

Software & Data Management

The HMI-60 operates via embedded firmware with push-button interface—no PC dependency required for routine operation. Parameter settings (inoculation speed, dwell time, rotation angle) are stored in non-volatile memory and recalled per user profile. Optional RS-232/USB interface enables bidirectional communication with third-party laboratory information systems (LIS) or electronic lab notebooks (ELN). Exported run logs include plate ID, date/time stamp, selected configuration (24/60/96), and actual measured inoculation duration—facilitating retrospective traceability in QA audits. Firmware updates are delivered via secure USB key to maintain version control in regulated environments.

Applications

• Antimicrobial susceptibility testing (AST) for MIC and zone diameter interpretation per CLSI M07 and EUCAST v14.0 protocols.
• High-throughput screening of novel antimicrobial compounds during preclinical drug discovery.
• Quality assurance of raw materials and finished dosage forms in pharmaceutical manufacturing (e.g., sterility test support, bioburden mapping).
• Epidemiological surveillance of multidrug-resistant organisms (MDROs) in public health laboratories.
• Validation of disinfectant efficacy and preservative challenge testing per USP & Ph. Eur. chapters.

FAQ

What is the minimum viable inoculum volume the HMI-60 can deliver reliably?
The system delivers 1 µL per pin in 60- and 96-position configurations, with demonstrated accuracy (±0.1 µL) and repeatability (CV <3%) across ≥500 consecutive cycles.
Can the HMI-60 be used with selective or chromogenic agars?
Yes—provided the agar surface is level, non-exuding, and maintains sufficient surface tension to support uniform pin contact without smearing; validation per ISO 11133 is recommended for new media types.
Is sterilization of the inoculation pins performed in situ?
No—the pins are removed and autoclaved externally using the supplied 60-position stainless-steel rack; no internal heating or UV sterilization module is integrated.
How does the HMI-60 ensure consistent contact pressure across all 60 pins?
Via spring-loaded vertical actuation with force calibration during factory assembly; each pin applies 0.45 ± 0.05 N load during agar contact, verified with digital force gauge prior to shipment.
Does the instrument support custom pin layouts or non-standard dish sizes?
No—it is optimized exclusively for 90 mm Petri dishes and fixed 60-pin geometry; custom configurations require OEM engineering engagement and are not supported under standard warranty.