Structure Health Monitoring with RFID Sensors into Concrete

UHF RFID Sensor in Construction

Concrete is the most widely used man-made building material. Controlling its properties at every stage of the construction process and afterwards is of biggest importance for the safety of buildings and occupants.

The French Grenoble-based semiconductor and sensor specialist Asygn is developing passive UHF RFID sensors that can reliably monitor concrete in structures for years, even in humid and harsh environments. The product is already available on the market.

Company Story powered by: the Think WIOT Group and Asygn.

UHF RFID Sensor in Construction

UHF RFID Sensor in Construction

From IC design house to a driver of innovation for passive UHF RFID sensors in five years.

Asygn was founded in Grenoble, France in 2008

Asygn was founded in Grenoble, France in 2008.

Asygn was founded in 2008 by Daniel Saias and Nicolas Delorme. The founders brought expertise in 'RFID IC design' in the field of microelectronics and software development to the start-up. At the beginning of the company's history, Asygn offered development competences to other companies such as semiconductor IDMs, sensor system integrators or even laboratories, and created integrated circuits for these clients.

In 2016, the trend-setting decision was made to develop own products for analog sensor interfaces and wireless sensors.

The first product, AS3125, a prototyping platform for Micro-Electro- Mechanical-Systems (MEMS) was launched in 2015. The latest product, the AS321x Battery-Less UHF RFID Sensors was launched in 2021, after a five-year development effort. This passive UHF sensor is the first of its kind in the world.

Asygn had the basic idea for the development of this passive sensor as early as 2018. The first tests with a prototype started in 2020, and series production started in the first quarter of 2023. The passive UHF chip is to be available in the millions.

Asygn – Highly experienced IC design and IC provider company

  • Foundation: 2008 in Grenoble, France
  • Products: Passive UHF RFID sensors for temperature, light, humidity and strain as well as high performance electronic for MEMS sensors
  • Services: ASIC Development Services
  • Locations worldwide: France, Denmark and USA
  • Employees: 50
  • Web:

1st Passive UHF SENSOR in the World

Asygn offers different sensor IC's. All sensors are delivered with a temperature sensor as standard. In addition, the humidity sensor or the strain sensor can be added. The strain sensor detects a bend or strain directly on the chip. It is very sensitive. Due to the small amount of memory, the measurement data is stored in the cloud or a database.

The IC is coupled with an antenna. This is followed by packaging in a hardened housing. The biggest challenge for the tag's manufacturers is to adapt the antenna to the environment, as the antenna performance behaves differently on a metal object or in open air, for example.

The chip enables a measurement every 20 milliseconds. It can be connected to any standard reader without the need for a special command or precharge sequence. Both the European and US frequency ranges are supported.

The chip itself has no lifespan limitation because it is made of silicon. The only limitation on lifespan can come from the plastic housing or the material used to protect the antenna. Possible materials for these housings are epoxy resin and PVC.

Typically, the housing is designed by the tag manufacturer specifically for harsh environments. It should be designed to last for several decades.

  • Specification:
    UHF EPC Class1 Gen2, ISO 18000-63
  • Connection:
    Can be read by any RAIN RFID reader
  • Data Capture:
    Sensors can be read out within 10 ms
  • Temperature monitoring: -40 to +125 °C
  • Embedding:
    In hardened or flexible labels
  • Reading Distance:
    six to seven meters

Using a wireless and battery-free system offers several advantages. Predictive maintenance, improvement of maintenance schedules, cost savings, and the prevention of risk situations are among them.

Numerous parameters can be collected for monitoring purposes. For example, it is possible to control the cold chain in logistics, the temperature of medicine or the moisture content in concrete, buildings or vehicles without using costly data loggers.

The passive UHF sensors measure pressure, acceleration, temperature, humidity and also vibration. The areas of application are therefore extremely diverse. One important area of application is the construction industry.

The use of UHF RFID sensors in concrete processing helps builders and architects improve the management of all manufacturing processes and the assurance of quality.

World's first UHF RFID chip that enables battery-free sensor measurements such as temperature, strain, humidity, motion or pressure.

World's first UHF RFID chip enabling battery-free sensor measurements

AS321X is a passive UHF RFID chip family with an embedded analog sensor interface and internal sensors. It achieves state-of-the-art sensitivity performance including sensor biasing and readout.


Safety for Builders

The sensor tags are attached to the metal grids

The sensor tags are attached to the metal grids before the concrete is poured. They withstand the casting and drying process undamaged.

Humidity sensor for moisture detection

Humidity sensor (embedded into thin films) for moisture detection in new buildings, e. g. bathrooms.

Strain sensors for monitoring anchor bolts

Strain sensors for monitoring anchor bolts (assessing the degree of tightening).

Detect cracks and deformations in walls with passive RAIN sensor tags.

Concrete is made from cement, sand and water. The building material is particularly interesting because, as free-flowing fresh concrete, it can take on all conceivable forms and then be extremely resilient after a curing phase. Fresh concrete needs 24 hours to reach the first hardening stage and to completely change its consistency. This phase is also called the setting period.

During this time, hydration takes place. Overall, concrete curing is a lengthy process that can last anywhere from four weeks to several months. In the course of hydration, the concrete releases water and loses its moisture.

To ensure the stability of a building, the concrete must be perfectly cured before additional floors, piers, foundations or roadways can be added to the structure. Each stage of construction must be completed in a qualified manner. The hardness of concrete, foundation slabs or walls can be monitored using passive RAIN RFID moisture sensors.

The sensor tags are installed between 10 to 20 centimeters deep on metal grids in the concrete and are thus enclosed by the concrete. A reader can be used to read this tag regularly, so that the drying process of the concrete can be monitored seamlessly.

To generate sensor information from the passive tags and store it for long-term monitoring, the tags are queried cyclically by polling. In the process, energy and data streams are transmitted. Due to the alkaline concrete millieu, it is necessary to encapsulate the sensor tags.

Battery-less sensor tags in concrete can be used to monitor buildings for decades to come. Therefore, Asygn recommends that builders not only integrate a moisture sensor to monitor the drying process, but also a strain sensor. This sensor can measure the deformation of the concrete for decades and thus the changes in the stability of the building.

Long-term monitoring is particularly useful for monitoring bridges or very large building complexes and can indicate risks at an early stage. Monitoring concrete deformation can reveal that the building is no longer stable, especially in earthquake regions with steady low-level shaking.

Any homeowner could use a simple smartphone equipped with a RAIN reader to read the passive tags themselves and monitor their own home. Asygn calls this functionality "Leave and Forget" because years after installation, when the construction phase is already a thing of the past, the sensor tag is still functional.

Structure Monitoring

Residential buildings, public buildings or structures such as bridges, wind turbines, power plants, roadways or tunnels are technically complex entities. Their functionality must be maintained over many years and decades.

For the public sector or building owners, this entails a personnel and monetary investment. Buildings can be damaged not only by weather events or earthquakes, but also by toxic emissions caused by increasing environmental pollution.

Among other things, technical solutions are also used to monitor the building structure. Frequently, cost-intensive detectors that often only have a service life of a few years are used.

The construction industry, public agencies and real estate owners are looking for energy-saving, long-lasting and easy-to-use sensor solutions to safeguard the quality of the construction process and the existence of the buildings. The solutions should be battery- less. A battery-based application with an average runtime of two years does not meet the requirements for years of building control.

With passive sensor tags, measurement data about the condition of a structure can be generated in any number and frequency without having to run cables into the component and create weak points. In this way, the system detects leaks earlier, for example, so that corrosion activities can be prevented. The sensor tags can be read with simple handheld readers or even drones.

As far as the cost of sensor-based monitoring is concerned, it is not the number of sensor tags that is critical, but the technological infrastructure. Overall, the sensor solution ensures a reduction in maintenance costs, since numerous damages to the building can be detected at an early stage and eliminated with minor interventions.

  • Strain:
    The deformation provides an indication of whether the concrete has warped or cracked, thus compromising stability.
  • Moisture:
    This value indicates whether liquid has penetrated the concrete, bridge piers or walls, which could make the building material porous.
  • Temperature:
    The overheating of building materials can also negatively affect the stability of the structure.

The combination of sensors for condition monitoring and RFID offers the possibility to develop sensor systems that are integrated into components.

Asygn's passive sensors measure moisture, cracks and changes in material structure

Asygn's passive sensors measure moisture, cracks and changes in material structure. Measurement data indicate the degree of damage.

Measurement data indicate the degree of damage
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