Researchers at VTT Institute in Finland developed an optical fibre made of cellulose, which could be used in sensor applications.

The core of the new optical fibre is made of cellulose, modified for the purpose using iconic solvents. The cladding is made of cellulose acetate.

Light travels through the fibre, because the core is surrounded by cladding material with a lower index of refraction. The light is kept in the core as it is refracted back into the core from the interface of the core and the cladding.

The researchers say the cellulose optical fibres are suitable for the use in sensors. Cellulose reacts with the substances measured, like moisture, and absorb them, which is difficult for glass or plastic fibres. Cellulose is also easy to modify and biodegradable.

In the future optical cellulose fibres may allow detecting changes in moisture levels of buildings. However, the material does not compete with glass based optical fibres in telecommunication applications.

Photo: VTT