Frequently asked questions

Com&Sens turns composite and steel structures into intelligent assets. We design fiber optic strain sensors (FBG), integrate them into or onto the structure, and turn the data into decisions through our software. A Ghent University spin-off founded in 2012, we have delivered over 200 projects and deployed more than 5,000 sensors. Sensors. Data. Decisions.

A fiber Bragg grating is a short section of optical fiber, a few millimetres long, that reflects one specific wavelength of light. When the fiber is stretched or compressed, that wavelength shifts, and the shift gives the local strain. Several gratings can be written on one fiber, each at its own wavelength, so a single fiber carries many measurement points.

FBG sensors are passive: there is no electrical current at the measurement point and no sensitivity to electromagnetic interference. The fiber is thin enough to be embedded inside a composite laminate, and many sensors share one cable, which keeps wiring minimal on large structures. This makes them well suited to long-term monitoring.

CS Engine is the data layer. CS Guard handles logging, events and triggering, and the Datastore structures and stores the measurements. CS Monitor is the decision layer on top, turning data into indicators for a specific application. CS Engine data is also available through an API, so you can feed it into your own systems.

Com&Sens BV is based in Eke, near Ghent, Belgium. Use our contact form or write to info@com-sens.eu and tell us what you need to measure. We usually reply within one working day.

Low intrusivity is a design result, not a given. In a peer-reviewed study published in Sensors in 2024, embedded FBGs left tensile stiffness and strength unchanged, with an apparent interlaminar shear strength about 8% lower on small coupons. We keep that effect low through fiber diameter, coating, alignment with the tow, routing and the fiber exit point.

Yes, when they are in the right places. A pressurized COPV responds in a highly repeatable way, so sensors placed in zones identified by FEA give a representative picture. In our tests, local axial strain matched global axial elongation, hoop sensors responded consistently and the correlation between sensors exceeded 0.9. Strain per bar stayed stable and reproducible, layer by layer, up to burst.

Our test data says yes, with the right design. Embedded fibers have passed more than 500,000 cycles on CFRP coupons without degradation, and embedded lines stayed intact up to burst at 1,855 bar on a Type IV hydrogen vessel. Coated fibers in the outer layer and dome connections passed 22,000 pressure cycles, including hot cycles. On the surface, CS Patch passed 50,000 cycles on coupons without signal loss. We have also lost sensors in testing, and each failure changed our design rules, for example no bare fiber in the outermost layers.

Each vessel gets a strain fingerprint at its factory proof test. In service, we compare its response with that fingerprint, corrected for pressure and temperature. A drop in stiffness or a build-up of residual strain shows that the structure is changing: in fatigue tests, the stiffness drop was visible in the FBG data before failure. Today this gives a transparent alert. Health scores and remaining life estimates are in development in CS Predict and require test data to failure for each vessel type. The service decision remains with the operator and the inspection body.

They measure different layers, with a stable relationship between them. On four vessels tested at 1,050 bar, the ratio of surface strain to outer-layer strain was 0.94 to 1.08, and the ratio to inner-layer strain was a reproducible 0.65 to 0.69. Once this ratio is calibrated in production, a CS Patch in service tracks what happens inside the laminate. Embedded sensing suits design and qualification. CS Patch suits vessels in service and retrofit, and it provides a fallback if an embedded line is lost.

A single sensor failure never condemns a vessel. Each vessel carries several measurement points, and a surface patch can take over from an embedded line.

CS CoWind is a plug-and-play FBG assembly that places fiber optic strain sensors inside the laminate during filament winding. It is delivered on a compact spool that mounts on the winding head with the CS CoWind kit, so the sensors are laid down as part of the winding process.

Two configurations: Circular, with three FBGs in the hoop direction, and Helical, with three FBGs following the helical direction at low and/or high angles. Both are in stock. Typical delivery time is 5 to 10 days.

Yes. CS CoWind can also be mounted on an automated fiber placement (AFP) robot head.

CS Patch is a surface-bonded FBG sensor for in-service monitoring and retrofit. It comes in three variants: Single, with one FBG; Dual 0°/90°, with two FBGs locked in a T layout; and Dual Free, with two FBGs whose orientation and spacing you set.

With CS UVACR, the UV-curing adhesive that is part of the CS Patch solution. Installation follows a step-by-step manual, and the UV bonding kit is available in our webshop.

CS Vision is our web-based FBG data processing and visualization software for R&D. COPV manufacturers use it during development to retrieve strain data from inside the laminate, understand how their design behaves and refine design parameters.

CS CoWind arrays, CS Patch, the UV bonding kit and a cabling starter kit are available in our webshop. For other configurations, contact us.

CS Monitor MEGC helps you switch from calendar to condition-based operations. It follows each COPV in your MEGC individually: pressure cycles, capacity, strain fingerprint and an event log, so you know how every vessel has actually been used.

Existing MEGCs can be equipped. CS Patch is bonded on the outside of each vessel, with no modification to the vessel itself. A typical configuration uses four FBGs in the hoop direction per vessel, with minimal cabling.

CS Monitor: cycle count, capacity, fingerprint and event log. CS Predict (in development): health score, estimated residual cycles and life, vessel-level incidents. CS Certify: an evidence report for each vessel.

CS Predict will combine each vessel's measured strain history with a fatigue model of its vessel type. That model needs cycling and burst test data on the specific vessel design before it can run. CS Predict is in development. If you want your vessel type covered, talk to us.

No. Periodic requalification remains a regulatory requirement. CS Monitor gives you a continuous record of how each vessel has been used and how it responds, and CS Certify turns that record into an evidence report. Moving from periodic requalification to continuous certification is our goal, but it is not an approved alternative today.

From your existing MEGC telematics platform, through a database connection. The FBGs measure strain, and CS Monitor combines it with pressure and temperature from telematics. No extra temperature sensor is needed on each vessel.

CS Monitor calculates the hydrogen mass on board from pressure, temperature and vessel volume, and compares it with the filling station's meter. It is a cross-check, not an approved metering instrument.

CS FSR (Fiber Sensing Rod) is an array of FBGs inside a glass fiber reinforced composite rod. It is UV bonded onto existing structures or cast into new concrete, and measures strain at many points along its length through a single fiber.

Steel and civil engineering structures such as beams, piles, tunnels, lock gates, dikes and bridges, as well as composite structures. Typical uses are following a structure during construction and understanding how it behaves under live loads in operation.

Yes. CS Engine structures and stores the measurements, and its API gives you direct access to your data from your own tools, digital twin or asset management system.

In development. CS Monitor Structures is the version of CS Monitor for steel and civil structures, focused on live load monitoring. Until it is available, your data is accessible through CS Engine and its API.

Contact us with a description of your structure, what you need to know and the conditions on site. We will come back to you to discuss the sensor layout and how the data will reach you.