Researchers from Massachusetts Institute of Technology (MIT) and Harvard Medical School have developed a biocompatible and highly stretchable optical fiber which can be implanted in the body to deliver therapeutic pulses of light or light up at the first sign of disease.

According to the study, the researchers suggested that such stretchable, strain-sensing optical fibers could be implanted or fitted along the length of a patient’s arm or leg to monitor for signs of improving mobility.

The study also suggested that the fibers may also serve as sensors, lighting up in response to signs of disease.

“We may be able to use optical fibers for long-term diagnostics, to optically monitor tumors or inflammation. The applications can be impactful,” said Xuanhe Zhao, Associate Professor, MIT in the study published in the journal Advanced Materials.

The fiber, made from hydrogel is as bendable and is an elastic, rubbery material composed mostly of water and may serve as a long-lasting implant that would bend and twist with the body without breaking down.

Using light to activate neurons in the brain, which is a highly active field known as optogenetics, in which researchers delivered short pulses of light to targeted tissues using needle-like fibers, through which they shine light from an LED source.

“But the brain is like a bowl of Jell-O, whereas these fibers are like glass — very rigid, which can possibly damage brain tissues. If these fibers could match the flexibility and softness of the brain, they could provide long-term more effective stimulation and therapy,” Zhao added.

For the study, the researchers began to play with the fiber’s optical properties, to see if they could design a fiber that could sense when and where it was being stretched.

Then they shone a laser light through the fiber and stretched and measured the spectrum of light.

By measuring the amount of light at the far end of the fiber, the researchers could quantitatively determine where and by how much a fiber was stretched.