How Folium Sensing uses fibre networks to monitor infrastructure

Folium Sensing has developed a fibre-optic monitoring system that detects sound, temperature changes and strain along cables already used for communication. It matters because bridges, railway tracks and pipelines can extend across long distances, while conventional sensors usually measure conditions at one point and need local power.

The startup offers distributed acoustic sensing, distributed temperature sensing and distributed strain sensing. Its DATSS product combines all three. The technology has been tested on IIT Madras test beds representing pipelines, underwater assets, railway tracks and bridges. It can also identify events such as walking, bike engines, JCB work and leaks.

Folium Sensing sells hardware and software to businesses and government agencies in oil and gas, defence, railways and infrastructure. It supplied temperature-sensing units for a Mumbai-Pune Expressway tunnel and has projects involving pipelines, mines and bridges. It plans to focus next on data centres, border intrusion detection, pipelines, railways and tunnels.

Distributed fibre-optic sensing is a way to monitor conditions continuously along a fibre-optic cable. Rather than measuring only at one installed sensor, the system detects events at points along the cable. This makes it useful for infrastructure that stretches over long distances, such as pipelines, railway tracks, bridges and tunnels.

Folium Sensing sends a pulse of laser light through a communication fibre. Disturbances cause some light to scatter back toward the source. The return time identifies where the disturbance happened. Different forms of returned light provide different information: Rayleigh scattering detects sound, Raman scattering measures temperature, and Brillouin scattering measures strain.

The returned signals create large amounts of data. Folium Sensing processes them with machine-learning models using edge hardware and cloud systems. Filters remove background noise, and a pattern-recognition model identifies unusual changes. The system then produces an alert and marks the location on a map through a Google Maps link.

Folium Sensing says its technology can detect sound, temperature changes and strain along a fibre cable extending 100 km or more. That distance allows a single monitoring setup to cover infrastructure spread across a large area. The system uses fibre cables that may already have been laid for communication.

The equipment is connected at only one end of the cable. It sends laser pulses through the fibre and analyses light that scatters back toward the source. Because the return time indicates where a disturbance occurred, the system can locate events along the cable rather than merely reporting that something happened somewhere.

This approach reduces the need to install powered sensors at many separate locations. Folium Sensing is developing products for pipelines, railways, tunnels, bridges and other assets. Its current work includes a tunnel deployment, pipeline monitoring proofs of concept, mine monitoring and bridge monitoring. The company plans further expansion into several infrastructure markets.

Folium Sensing begins by sending a pulse of laser light through a fibre-optic cable. Under normal conditions, the cable carries the light along its length. When the cable is disturbed, some of that light scatters back toward the equipment at the source.

The key measurement is timing. The system records how long the scattered light takes to return. It uses that time to determine the point along the cable where the disturbance occurred. This allows one cable to provide location information across a long route, rather than simply indicating that a change happened somewhere in the system.

The returning light also contains different signals. Rayleigh scattering detects sound, Raman scattering measures temperature, and Brillouin scattering measures strain, including stretching and compression of the cable. Machine-learning models process these signals, remove background noise and recognise unusual patterns. When an event is detected, the system sends an alert and marks the location on a map.

The three scattering signals carry different kinds of information about conditions around or within the fibre cable. Rayleigh scattering detects sound. Raman scattering measures temperature changes. Brillouin scattering measures strain, meaning the stretching and compression of the cable.

Folium Sensing uses these signals in separate products. Its portfolio includes distributed acoustic sensing, or DAS, distributed temperature sensing, or DTS, and distributed strain sensing, or DSS. Its DATSS system combines all three capabilities. This gives the system a broader view of infrastructure condition than a single measurement type.

The signals produce large amounts of data, so the company processes them with edge hardware and cloud systems. Filters remove background noise, while a pattern-recognition model identifies unusual changes. The company says its AI can distinguish events such as a person walking, a bike engine, JCB work or a leak, with about 96-97% accuracy. Alerts include the event’s location.

After detecting an unusual vibration, temperature change or strain, Folium Sensing processes the signal through filters and machine-learning models. The filters remove background noise. A pattern-recognition model then looks for unusual changes and interprets what may be happening along the cable.

The system can identify examples including a person walking, a bike engine, a JCB at work or a leak, according to CEO Sanidhya Chaturvedi. When it detects an event, it generates an alert. The alert includes the location of the event, marked on a map through a Google Maps link. This gives users both an interpretation and a place to investigate.

The models were trained on test beds at IIT Madras for pipelines, underwater assets, railway tracks and bridges. Chaturvedi says the system identifies events with about 96-97% accuracy. The company has moved beyond testing through a tunnel deployment and proof-of-concept projects involving pipelines, mines and bridges.

An existing fibre-optic cable can act as a sensing route across a long stretch of infrastructure. Folium Sensing sends laser light through the cable and reads scattered light returning from disturbances. The system can detect and locate sound, temperature changes and strain along the cable.

Conventional sensors generally measure conditions at a single point. They also need a power supply at that location. By contrast, Folium Sensing says its equipment can connect at just one end of a cable extending 100 km or more. This avoids installing powered sensing units repeatedly along the route, while still providing location information for detected events.

The approach is particularly relevant to bridges, railway tracks and pipelines, which can span long distances. Folium Sensing has tested the technology on infrastructure test beds and begun field work. Its projects include tunnel temperature monitoring, pipeline leak monitoring, mine monitoring and bridge monitoring. The company plans to expand into more infrastructure markets and regions.