Researchers developed a bio-compatible and stretchable optical fiber read more at here www.spinonews.com/index.php/item/1307-researchers-developed-a-bio-compatible-and-stretchable-optical-fiber

Researchers from MIT and Harvard Medical School developed a biocompatible and highly stretchable optical fiber made from hydrogel. The researchers say the fiber may serve as a long-lasting implant that would bend and twist to the body without breaking down.

Xuanhe Zhao, the Robert Norton Noyce Career Development Associate Professor in MIT’s Department of Mechanical Engineering, says, these fibers could match the flexibility and softness of the brain, they could provide long-term more effective stimulation and therapy.

 

Associate Professor Seok-Hyun (Andy) Yun, bio-optics group at Harvard Medical School, had previously fabricated an optical fiber from hydrogel material that successfully transmitted light through the fiber. However, the material broke apart when bent or slightly stretched.

Yun’s design consists of a core material encased in an outer cladding. Zhao’s hydrogel material was highly transparent and possessed a refractive index that was ideal as a core material. But when they tried to coat the hydrogel with a cladding polymer solution, the two materials tended to peel apart when the fiber was stretched or bent.

The researchers tested the optical fibers ability to propagate light by shining a laser through the fibers of various lengths. Each fiber transmitted light without significant attenuation, or fading. They also found that the fibers could be stretched over seven times their original length without breaking.

Now they had developed a highly flexible and robust optical fiber, made from a hydrogel material that was also biocompatible, 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.

They first loaded a fiber with red, green, and blue organic dyes, placed at specific spots along the fiber’s length. Next, they shone a laser through the fiber and stretched, for instance, the red region.

They measured the spectrum of light that made it all the way through the fiber, and noted the intensity of the red light. They reasoned that this intensity relates directly to the amount of light absorbed by the red dye, as a result of that region being stretched.

This is like a multi-strain sensor through a single fiber. So it can be an implantable or a wearable strain gauge.

The researchers imagine 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.