EpsilonSensor

DFOS sensor with strain range up to 4% and elasticity modulus (E = 3 GPa) not influencing the behaviour of monitored structure.

EpsilonSensor, with its monolithic core of specially designed composite material, provides accurate strain measurement over its entire length and the best strain transfer on the market. This makes it an ideal tool for detecting and analysing cracks in concrete. The braided outer surface improves the bonding properties and interaction with the monitored material.

The sensor can be embedded in new structures (concrete or soil) or installed on the surface of existing structures.

Lightweight, with a small bending radius and low stiffness, the sensor is easy to install in any shape and does not affect the behaviour of the structure being monitored. It is like the nerves in the human body – invisible, but essential to ensure adequate safety and response to even the smallest threats.

Datasheet

EpsilonSensor Advantages

Precise measurements of axial strain along the entire length of the sensor

Detailed analysis of cracks (identification, localisation, width estimation)

No sensor influence on the monitored structure (negligible stiffness)

Monolithic core with no intermediate layers disturbing measurements

Sharp and precise view of any local phenomena (cracks, fractures, damages, stress concentrations, leaks etc.)

Easy installation in any shape – lightweight sensor with small bending radius, ready to use when unrolled from the coil

Resistant to environmental conditions, including corrosion, electromagnetic fields and lightning strikes

Physical Quantities Measured

DSS
Strain and crack

DTS
Temperature

DAS
Vibrations (strain rate)

Typical Materials

Concrete

Soil

Steel

Composite

EpsilonSensor Application Areas

Structures | Bridges | Piles | Slurry walls | Roads | Dams | Embankments | Pipelines | Tunnels | Railways | Earthworks | Geotechnics | Landslides | Minings | Laboratories… and more

EpsilonSensor tight to the reinforcement just before concreting the slab

EpsilonSensor before installation in a lab specimen

Prestressed concrete beam with EpsilonSensor

Crack measurements by EpsilonSensor during bending tests

EpsilonSensor Technical Specifications

¹ Standard (other diameters available on request)
² Standard (extended temperature range available on request
³ Standard (more fibres available on request)
⁴ Standard (other fibres available on request)
⁵ At 1550 nm wavelenght
⁶ Sensors can be connected in series

EpsilonSensor Installation

Each installation should be designed individually, taking into account specific requirements and local conditions. However, there are three typical methods:

1. Embedding inside new structures (concrete or ground). This approach is best because it ensures optimal bonding properties, natural protection against mechanical damage and direct sunlight influence. It also allows measurements to be taken from a true strain-stress state and offers the best aesthetics (no visible components on the surface).

2. Installation in near-to-surface grooves for existing structures. This method requires the preparation of the surface by cutting the grove, the size of which depends on the sensor diameter. It is then filled with a chemical anchor just before mounting the sensor. This method offers similar advantages like embedding.

3. Bonding directly to the sanded, cleaned and degreased structural surface. This approach is relatively simple, but has several drawbacks in terms of durability, resistance and sensitivity to external conditions. It can therefore only be used for short-term measurements with stable thermal conditions. It is also important to choose a suitable adhesive.

Embedding inside new structures (concrete or soil)

Installation in near-to-surface grooves for existing structures

Bonding directly to the sanded, cleaned and degreased structural surface

EpsilonSensor FAQ

When to use the EpsilonSensor and when to use the EpsilonRebar?

The selection of the sensor depends on the installation conditions and the predicted strain to be measured. EpsilonSensor is universal solution for both laboratory and field projects. It can be freely shaped and, thanks to its elastic core, high strain range and low elastic modulus, it is perfect for strain sensing without strenghtening the element, as well as for precise crack detection and analysis. Typically produced in Ø3mm diameter, it is also available in Ø5mm for more demanding field projects. On the other hand, EpsilonRebar has the same parameters as GFRP rebars, and can also be treated as structural reinforcement. It is more robust thanks to its higher stiffness and strength. In short, it usually works in (relatively) straight sections and in challenging field conditions e.g. in geotechnical applications, boreholes injected with concrete, asphalt layers or in densely reinforced structures.

What is the main difference between EpsilonSensor and EpsilonRebar?

The main difference lies in the material used to create the sensors and their mechanical parameters. EpsilonRebar acts as a Glass Fibre Reinforced Polymer (GFRP) reinforcement with a Young’s modulus of 50 GPa and a maximum strain of ±2%. EpsilonSensor has a significantly reduced modulus (3 GPa) with an increased range of up to ±4%. Assuming typical diameters of Ø5 mm for ER and Ø3 mm for ES – this gives an almost 50 times reduction in axial stiffness EA. You can find more information in the article: https://doi.org/10.1016/j.measurement.2023.113480

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