Owlstone product SiHuB hero

SiHuB Sensor Calibration System

Calibrate your breath sensor with accurate VOC mixtures and humidity control

  • Precise and repeatable calibration gas mixes
  • Traceable to primary standards
  • Concentrations from part per billion to part per million levels
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Simply and flexibly create gas mixtures as facsimiles for breath

Owlstone SiHub system

We developed SiHuB, a cost-effective modular calibration gas system, as a way to create consistent and controllable mixtures of different gases, including trace volatile organic compounds (VOCs) in order to test breath sensors – and now you can use SiHuB to streamline complicated calibration processes in your lab too.

Our modular system can be adapted to your particular needs. Every system includes a humidity generator (OHG-4) and a flow controller (OFC-1), and one or more vapor generator units (either OVG-4 or V-OVG) depending on your budget and the calibration requirements of your system. The complete SiHuB system is capable of generating mixtures of multiple gases, with controllable humidity levels, in order to mimic the conditions in which breath sensors would be deployed.

Using permeation or diffusion tubes to provide the test compounds, SiHuB is a simple and flexible calibration system that replaces the need for multiple gas cylinders, while offering greater control over precise gas mixing. SiHuB has been used by leading breath researchers around the world to test various detection devices, including FAIMS systems.

  • Reliable

    Accuracy and precision even at very low concentrations with superior long term stability and repeatability

  • Economical

    Reduces operating costs by replacing multiple gas cylinders

  • Versatile

    Easy to change gases/VOCs by swapping permeation tubes, rather than large gas cylinders

  • Safe

    Small quantity of target chemicals reduces exposure risks

  • Space-saving

    Compact footprint for significant laboratory space savings

  • Traceable

    Our permeation tubes are traceable to NIST standards, and are supplied with their own calibration certificates

Access the ability to generate controllable gas mixtures for breath sensor testing

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How it works

Using SiHuB for breath sensor development

A typical workflow in sensor development for breath diagnostics might look something like this:

  • Stage 1: Can the sensor detect the compound of interest?
  • Stage 2: Can the sensor detect the compound at the required concentration levels?
  • Stage 3: Can the sensor still detect the compound in a background of other compounds typically found in breath?
  • Stage 4: Can the sensor detect the compound if the sample is also at humidity levels representative of breath?
  • Stage 5: Can the compound be detected in a sample of real human breath?
Owlstone product SiHuB hero

SiHuB allows each of these stages to be performed in turn.

In Stages 1 & 2, the output from a single vapor generator provides a controllable concentration of the compound under investigation.

In Stage 3, combining the outputs of multiple vapor generators allows a matrix of gases approximating the makeup of human breath to be generated.

In Stage 4, a humidity generator is used to add humidity to the gas mixture.

Finally, in Stage 5, the sensor is ready for testing with real breath samples.

Simulating human breath with SiHUB: Learn more about calibrating gas sensors

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Simulating Human Breath - The Complete Guide to Generating VOC and Humidity Calibration Standards book cover



SiHuB is a modular calibration system that can be adapted to your needs. All systems include the OFC-1 flow controller to regulate flow through the system. The OHG-4 allows you to control the humidity of the air produced, while multiple OVG-4 or V-OVG units can be included to allow various trace gases or VOCs to be included in the final mix.

SiHuB Schematic

Modular SiHuB Components

In addition to an OFC-1 flow controller, each SiHuB can contain:

The OVG-4 is a compact, cost effective calibration gas system, which can generate NIST traceable, precise, repeatable and accurate concentrations of chemicals and calibration gas standards. Each OVG-4 has capacity for one permeation tube. The V-OVG generates precise, repeatable trace concentrations of gases. By using permeation and diffusion tube technology, a range of concentrations from low parts per billion to high parts per million levels can be achieved. The large permeation oven allows the use of up to six permeation tubes to create multiple-component mixtures, or a diffusion tube to generate high ppm concentrations. The OHG-4 is a versatile humidity generator that is used to produce a range of relative humidity concentrations from 1 to 90%rh (±1%). Designed to be used in conjunction with OVG-4 and/or V-OVG units to generate a wide range of vapor standards for calibration of sensors.
Each SiHuB includes 1 or more V-OVG or OVG-4 units Each SiHuB includes 1 or more V-OVG or OVG-4 units One per SiHuB

Technical specifications

Browse a comprehensive collection of insightful whitepapers, posters and multimedia

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