SAFE® 2D Tubes Selection FAQ –
Configuration & Product Comparison
The selection of SAFE® 2D tubes, SBS racks, closure systems, cappers, readers, and labeling solutions should always be considered as a system decision. In this FAQ section, we answer key questions regarding selection criteria, internal vs. external threads, SBS formats, cryogenic storage, capping, LIMS integration, and product comparison.
It is not just the individual 2D tube that matters, but the interplay of material quality, sealing, rack geometry, identification, and automation capability. For applications down to −196 °C, validated sealing systems, low gas permeability, reproducible torque, and stable SBS structures are particularly important. At the same time, format choice, sample volume, throughput, and digital traceability must match the existing laboratory infrastructure.
Especially in biobanking, pharmaceutical research, diagnostics, and high-throughput environments, a systematic selection of SAFE® components supports stable, traceable, and automatable sample processes.
Fundamental Selection Criteria
Key criteria include:
- Cryogenic application (e.g., LN₂ vapor down to −196 °C)
- Sample type (e.g., DNA, proteins, chemical substances)
- Level of automation
- Desired traceability
- Regulatory requirements
For long-term cryogenic applications, material purity, low gas permeability, and validated sealing systems are especially important.
2D sample tubes are recommended when:
- Machine-readable identification is required
- LIMS integration is planned
- High-throughput processing is expected
- Long-term archiving is needed
- Regulatory documentation is necessary
Manual labeling systems are more error-prone and less suitable for automated processes.
The higher the level of automation, the more important the following are:
- SBS-compliant geometry
- Precise dimensional accuracy
- Stable rack structure
- Compatible capper and reader systems
In validated pick-and-place tests with 3,465 cycles, an error rate of 0.086 % was measured.
Precise geometry supports reproducible robotic processes.
Internal vs. External Threads
External-thread 2D tubes are especially suitable for cryogenic applications and environments requiring enhanced contamination control.
Since the thread is outside the sample chamber, the risk of sample liquid entering the threaded area is reduced.
Internal-thread tubes can be used in standardized automation environments if requirements for contamination control and cryostability are met.
Selection should depend on the specific application scenario.
Format & Capacity
The choice depends on:
- Sample throughput
- Sample volume
- Available infrastructure
- Storage strategy
96-format racks are commonly used in high-throughput screening.
24- or 48-position formats may be preferable when larger volumes or specific cryogenic applications need to be considered.
Larger formats increase the number of samples per rack.
Smaller formats can offer advantages for specific volume requirements or handling conditions.
Existing storage and robotic systems should also be considered.
Closure System & Capping
Selection depends on:
- Storage conditions (e.g., LN₂)
- Frequency of opening
- Automation requirements
For cryogenic applications, screw caps with axial TPE sealing systems and controlled torque are recommended.
Sealing performance was validated at a defined torque of 7 Ncm (for SBS 96) and 15 Ncm (for SBS 48 and SBS 24).
After 15 automated open/close cycles, no leakage was observed.
Reproducible torque reduces the risk of inconsistent closures.
Automatic capping systems are suitable for high sample throughput or regulated environments where reproducible processes are required.
They reduce manual variability and support stable operations.
Identification & Labeling
The 2D code enables machine-readable identification and digital traceability.
Additional laser marking is useful when visual or study-specific information is required directly on the tube.
The laser engraving is material-integrated and remains permanently readable at −196 °C.
When samples are digitally managed, the entire system – tube, rack, reader, and optionally laser marking – should be aligned for seamless LIMS integration.
Unique ID generation and rack-wise verification support consistent digital documentation.
Comparison & System Thinking
SAFE® components have been validated as a tube–cap–rack system.
Systemic coordination reduces potential interface risks such as:
- Inconsistent thread tolerances
- Variable sealing forces
- Rack position deviations
This is particularly relevant in automated high-throughput environments.
SAFE® components are geometrically and functionally aligned.
This supports stable automation processes and reduces mechanical or functional deviations that can occur with mixed systems.
- Is cryogenic storage down to −196 °C required?
- Is high-throughput processing planned?
- Are there regulatory requirements (e.g., GMP or ISO-adjacent environments)?
- Should automated capping or rack scanning be integrated?
- Is additional laser marking necessary?
These points determine the optimal system configuration.
