Technologies

Fiber Bragg grating (FBG) sensors

B-SENS designs and develops fully-customizable FBG sensing solutions that can yield quasi-distributed measurements and communicate the processed data to the end user.

These developments encompass the production of the FBG sensors (1), their functional coating, protection or packaging (2) and the read-out unit (3).

1. FBG

FBGs are produced in telecommunication-grade optical fibers (outer diameter of 250 µm) by local laser irradiation transversely to the optical fiber axis.

They are usually short in length (<1 cm) and act as bandpass filters in reflection around the so-called Bragg wavelength.

They are inherently sensitive to temperature changes and axial strain, which induces a shift of their Bragg wavelength. Tracking this shift allows to determine the actual temperature or strain value after calibration.
Nominally, they can reflect the temperature value at +/- 0.1 °C and the strain value at +/- 1µε.

This emerging technology brings the following advantages that are decisive in numerous applications:

  • Small dimensions (<1/4 mm for bare fibers, flexibility with high integration and embedding capabilities)
  • Quasi-distributed sensing (up to 40 sensors cascaded in 1 fiber and connected to 1 device, much less cables, easy installation)
  • Long-haul measurements (20+ km)
  • High fatigue resistance
  • Reliability (passive devices, life time > 20 years, stability over time, no corrosion, use of telecommunication-grade cables/connectors)
  • Use of light (immunity for electromagnetic radiation & radio frequency interference, immune for high voltage discharge, explosion safe, suitable for use in harsh environment)

2. Coating/Protection/Packaging

Specific coatings can be applied to the optical fiber surface at the FBG location to widen the sensing modalities. We have solutions to enable hydrogen sensing and early fire detection.

Our expertise in this field is quite unique and multifold. We make use of organic, inorganic & metal coatings. Their synthesis is ensured by various physical/chemical processes.

Depending on the target application, a specific protection and/or packaging can be applied around the FBG. Metal layers, glass, aluminum, ceramic or Teflon tubing are some prominent examples.

3. Read-out unit

The read-out unit is the measurement device that launches light within the optical fiber cable and collect the FBG spectrum. While optical fibers can be considered the nervous system of the sensing solution, the interrogator is its core.

We have developed two complementary devices:

Both solutions are very competitive in terms of performance and cost. They are provided with a user-friendly interface (Labview or Python) that can be adapted depending on customer’s requirements.

Communication can be provided through Ethernet, WiFi, Bluetooth or LoRa.

Semiconductor sensors

B-SENS designs and develops fully-customizable chemical resistive sensors , compatible with IoT standards.

These developments encompass the production of the resistive sensors (1), their functional coating and packaging (2) and their driving electronic circuit (3).

1. Resistive sensors

Resistive sensors make use of interdigitated electrodes coated by a specific sensitive film.

The detection principle of resistive sensors relies on the variation of the resistance of a film upon adsorption of gas molecules on the surface of a semiconductor.

The latter induces variations of the electrical conductivity so that a measurement of the resistance can be correlated with the gas concentration.

B-SENS offers high performance semiconductor gas sensors for outdoor air quality (OAQ), indoor air quality (IAQ), and industrial gas leak detection.

B-SENS develops room-temperature, heated and light-assisted gas sensors.

This gas sensing technology brings the following assets:

  • Small dimensions
  • Mass production capability at low cost
  • Self compensation of drifts
  • Low electrical power consumption
  • Calibrated output that provides the actual gas concentration in ppb or ppm

2. Sensitive layer/Packaging

Selective coatings are applied on the interdigitated electrodes. B-SENS gas sensors are capable of accurate detection of Volatile Organic Compounds (Alcohol, Formaldehyde), Nitrogen oxides (NOx), Ozone (O3), Hydrogen (H2), Ammonia (NH3) and other flammable gases, with good stability and reliability.

Our expertise in this field is quite unique and multifold. We make use of various types of coatings. Their synthesis is ensured by various physical/chemical processes.

A specific packaging is provided around the sensors to make them immune from dust particles.


3. Electronic circuit

The electronic circuit drives the resistance sensor and is calibrated to provide the gas concentration in ppm or ppb.

We have developed the AirQI platform, a smart object that is battery-operated and communicates the measured data to the end user.

This solution is highly competitive in terms of performance and cost.

It is provided with a user-friendly interface (Python) that can be adapted depending on customer’s requirements.

Communication can be provided through Ethernet, WiFi, Bluetooth or LoRa.