Fiber Optics, Wounds and Theragnostics, Oh My!

We at SALSA have long been interest in the concept of “you can’t manage what you cant’ measure.” This work is permeating all of medicine, but we are especially interested in its nexus with wound healing and also with prevention. Here’s an article from McKnight’s about some interesting intelligent textile work in wounds by colleagues in Switzerland.


Swiss researchers from the Technology in Textiles (TechinTex) project are working on a new type of wound dressing that could make it easier for providers to monitor how fast a wound is actually healing.

The product they are developing weaves into the dressing optic threads, which are designed to change color. Changes are triggered by changes in a wound’s acidity level. 

Such smart sensing dressings may eventually offer a powerful new resource for the treatment of recalcitrant wounds such as diabetic, pressure and venous leg ulcers, said Bastien Schyrr, a Ph.D. student in biomedical engineering at the University of Fribourg, in Switzerland. Earlier this year, he presented results of a laboratory trial in which the enhanced bandage detected acidity changes in a solution containing human serum.

He said his team’s next step will be to include enzyme monitoring.  

To check on the healing progress, nurses must sometimes take samples from a wound — an invasive process with a risk of infection — and send them to a laboratory, where they are assessed for signs of infection and identification of bacteria. Schyrr’s fiber system, which detects the acid-induced change in the fiber by shining light into one end of a waveguide and measuring the color of the light coming out, could measure such things without having to lift the dressing.

Schyrr’s colleague Lukas Scherer, at the Swiss Federal Laboratories for Material Testing and Research in St. Gallen, says that the main challenge for their optical-fiber biosensor was making the light-carrying fibers flexible enough so they could be included in a regular dressing. 

For two years, the team tried different preparations of their proprietary fibers. The final product had to let enough light through to carry a signal from inside a bandage, like a glass fiber, yet be flexible enough to stitch into a mass-produced bandage. 

“They had to strip the outer layer of the fiber using a press — “basically like doing spaghetti,” Scherer says — before they could replace it with the acid-sensitive outer layer.

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