Researchers from Harvard Medical School and MIT developed a highly flexible, biocompatible fiber out of hydrogel, a rubbery material that is mostly water. It is envisioned that the devices could be implanted in the human body, including the brain, and move within the surrounding tissue. The fibers carry light, and so could be used to light up when disease is detected or to direct therapeutic pulses of light at anomalies.
The field of optogenetics – using pulses of light to stimulate cells – is active, an MIT News report explains. Stimulating brain neurons with light has shown promise, as a way of manipulating the body’s circadian rhythms, and stimulating other cells in this way may be a key to reversing blindness or managing pain, News Atlas reports, even for treating depression.
However, carrying light within the body has often been done using hard, glasslike fibers that can damage human tissue, including the delicate human brain.
The brain "is like a bowl of Jell-O," said Xuanhe Zhao, associate professor in MIT’s Department of Mechanical Engineering. "If these fibers could match the flexibility and softness of the brain, they could provide long-term more effective stimulation and therapy," he told MIT News.
Researchers from MIT's Department of Mechanical Engineering paired with the bio-optics group at Harvard Medical School to develop a more biologically-friendly material. Together, they created the soft, highly-flexible hydrogel fiber. They then developed a way for the fiber to show how much and where it is bending or stretching, based on the way that light moves through it.
"This is like a multistrain sensor through a single fiber," MIT graduate student Hyunwoo Yuk, a member of Zhao's department, told MIT News. "So it can be an implantable or wearable strain gauge." The fibers could be implanted along the length of a patient's limbs to monitor mobility, the researchers suggest.
The device could also serve as a sensor that would light up if it encounters inflammation, often a sign of disease, or anomalies like tumors, Zhao said, according to MIT. "The applications can be impactful."
The application of light treatments is already known or guessed at, but non-traumatic delivery systems are still scarce. "These efforts in optimizing and managing the physical and mechanical properties of fibers are necessary and important next steps that will enable practical applications of medical relevance," remarked Fiorenzo Omenetto, a professor of biological engineering at Tufts University who was not involved in the research, to MIT, regarding the work.
The team's research was published in the journal Advanced Materials and was supported, in part, by the National Institutes of Health and the Department of Defense.
