Here the research is in the walls

Moisture is a problem that can be both expensive and difficult for property owners. LiU’s Studenthuset has 750 built-in sensors that detect moisture at an early stage. The technology is based on LiU-based research into printed electronics.

Thor Balkhed

At Linköping University there was Magnus Berggren and his research group at the Laboratory of Organic Electronics. It was 2005 and their assignment was to determine whether printed electronics could be used to measure moisture in building walls. The background was the problems that appeared in the Hammarby Sjöstad project in Stockholm, where the walls of the properties suffered extensive moisture damage.

In a completely different place there was Björn Garplind – salesman, businessman and entrepreneur. By chance he and Magnus Berggren met, and the result was the spin-off company, InviSense.
“We started commercialisation as early as 2013. At that time, the external research institute RISE Acreo had done research on the original idea. But we couldn’t quite get it to work – we threw in the towel several times. Then RISE Acreo found a function where the idea is the same, but the design is different. Not until 2016 were we ready to take the plunge – quit our jobs and invest money in the business”, says Björn Garplind, InviSense CEO.

Changing an entire industry

Detecting moisture damage is time-consuming. Often it has become quite large. And to actually determine its existence you have to tear down walls or drill through the sealing layer.
InviSense’s solution is a super-thin passive sensor, an electronic circuit, that is placed behind the sealing layer in a construction. If moisture is present, it eventually reaches the sensor. The more the water molecules, the lower the frequency.
The sensor has no source of electricity; measurement is done using a scanner that swipes across the frequency range and the spool/antenna in the sensor translates the frequency to relative humidity. In a cloud-based solution, developed by InviSense, the sensors are registered on a drawing, which makes measurement simple.
Photo credit Thor Balkhed“You could say that we’re changing an entire industry – a fairly conservative industry. The sensors are of particular interest to property owners and material suppliers, who install the sensors in the wall blocks, but also for private individuals. The measurement can be done when the building guarantee expires, if one suspects water damage, or when selling. And hopefully, having sensors installed encourages companies to build more carefully.

Studenthuset was built and is owned by Akademiska Hus, a state-owned property developer and owner. Right from the concept stage, there has been a focus on environmental and sustainability practices. Even before completion, the building had got top marks: GreenBuilding Gold.
“Studenthuset has 750 moisture sensors installed in the exterior walls below the windows. It’s great to know that our sensors are being used in a building like Studenthuset”, says Björn Garplind.

InviSense fortsätter att samarbeta med forskare på RISE Acreo. Flera forskare sitter också som delägare i företaget.
- Det vi tittar på nu är taksensorer för platta tak och sensorer för att mäta uttorkning av betong, säger Björn Garplind. Det går inte att läsa av standardsensorerna genom betong. Istället tittar vi på en lösning där själva sensorn sitter i betongen med spolen sticker upp.

InviSense continues to collaborate with researchers at RISE Acreo, and several of them are part-owners of the company.
“Now we’re looking at roof sensors for flat roofs, and sensors to measure the curing of concrete. Our standard sensors can’t be read through concrete. So we’re looking at a solution where the sensor is positioned inside the concrete but the spool sticks out”, says Björn Garplind.

Translated by Martin Mirko

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