SFCal™ Portable Calibration Technology

Two metallic flow meters with orange borders, one empty and one filled with orange liquid, placed on a white surface with a ruler below for scale.

Liquen is developing SFCal™, a compact calibration platform designed to generate known concentrations of target compounds where sensors and analytical instruments are used. The system combines small supercritical-fluid cartridges with controlled temperature, pressure, flow and dynamic dilution—reducing dependence on bulky compressed-gas cylinders and laboratory-only infrastructure.

The SFCal Prototype

At the center of the prototype is a machined aluminum housing designed for a compact 80-gram CO₂ cartridge. The housing provides even heating and controlled operating conditions while remaining small enough for future portable and on-site applications.

The prototype includes temperature feedback, an independent thermal cutoff, pressure-relief protection and a reinforced cartridge housing. These multiple layers of protection are designed to support safe and repeatable operation.

How It Works

  1. A compact cartridge is prepared with a known quantity of the target calibration compound and a CO₂ or N₂O carrier.

  2. The cartridge is brought to controlled temperature and pressure conditions.

  3. Its output is released through a controlled flow system.

  4. The output is dynamically mixed with scrubbed ambient air.

  5. The resulting calibration stream is delivered to a sensor or analytical instrument at the required concentration.

This approach can generate multiple calibration levels from a single compact source.

Demonstrated Performance

Phase I research established the technical feasibility of the SFCal approach. Testing produced highly linear calibration responses for carbon monoxide, nitrogen dioxide and sulfur dioxide, with R² values between 0.9986 and 0.9999.

Testing with BTEX compounds also showed close agreement between the cartridge system and conventional compressed-gas standards. Particle-delivery capability has been demonstrated with 2-µm polystyrene latex particles and remains under development.

Why It Matters

SFCal is being developed to make calibration:

  • Portable enough for on-site use

  • Adaptable across gases and semi-volatile compounds

  • Less dependent on large compressed-gas cylinders

  • More accessible for remote and underserved locations

  • Scalable for environmental, industrial and research applications

From Prototype to Field Deployment

Liquen is continuing to refine the prototype for field validation, manufacturability and integration with sensors and analytical instruments. Future applications include air-quality monitoring, industrial measurement, research instrumentation and PFAS destruction verification.

Collaborate With Liquen

We welcome discussions with sensor manufacturers, researchers, environmental and industrial organizations, and technology-development partners interested in evaluating or advancing the SFCal platform.