Researchers made shape-changing fibers by encapsulating a balloon-like elastomer tube in a braided textile sheath. Photo: Muh Amdadul Hoque.In two new studies, researchers at North Carolina State University (NC State) designed and tested a series of textile fibers that can change shape and generate force like a muscle.
In the first study, reported in a paper in Actuators, the researchers focused on the materials’ influence on the strength and contraction length of artificial muscles. Their findings could help researchers tailor the fibers for different applications.
In the second, proof-of-concept study, reported in a paper in Biomimetics, the researchers tested their fibers as scaffolds for live cells. Their findings suggest that the fibers – known as ‘fiber robots’ – could potentially be used to develop 3D models of living, moving systems in the human body.
“We found that our fiber robot is a very suitable scaffold for the cells, and we can alter the frequency and contraction ratio to create a more suitable environment for cells,” said Muh Amdadul Hoque, graduate student in textile engineering, chemistry and science at NC State. “These were proof-of concept studies; ultimately, our goal is to see if we can study these fibers as a scaffold for stem cells, or use them to develop artificial organs in future studies.”
The researchers created the shape-changing fibers by encapsulating a balloon-like tube made from an elastomer in a braided textile sheath. Inflating the interior balloon with an air pump makes the braided sheath expand, causing it to shorten.
The researchers measured the force and contraction rates of fibers made from different materials to understand the relationship between material and performance. They found that stronger, larger diameter yarns generated a stronger contraction force. In addition, they found that the material used to make the balloon impacted the magnitude of both the contraction and generated force.
“We found that we could tailor the material properties to the required performance of the device,” said Xiaomeng Fang, assistant professor of textile engineering, chemistry and science at NC State. “We also found that we can make this device small enough so we can potentially use it in fabric formation and other textile applications, including in wearables and assistive devices.”
In the second, follow-up study, the researchers evaluated whether they could use the shape-changing fibers as a scaffold for fibroblasts, a cell type found in connective tissues that helps to support other tissues and organs.
“The idea with stretching is to mimic the dynamic nature of how your body moves,” said Jessica Gluck, assistant professor of textile engineering, chemistry and science at NC State, and a co-author of the second paper.
The researchers studied the cells’ response to the motion of the shape-changing fibers, and to different materials used in the fibers’ construction. They found that the cells were able to cover and even penetrate the fiber robot’s braiding sheath. However, they saw decreases in the cells’ metabolic activity when the fiber robot’s contraction extended beyond a certain level, compared to a device made of the same material that they kept stationary.
The researchers are interested in building on these findings to see if they can use the fibers as a 3D biological model, and to investigate whether movement would impact cell differentiation. They said their model would be an advance over other existing experimental models that have been developed to show cellular response to stretching and other motion, since these existing models can only move in two dimensions.
“Typically, if you want to add stretch or strain on cells, you would put them onto a plastic dish, and stretch them in one or two directions,” Gluck said. “In this study, we were able to show that in this 3D dynamic culture, the cells can survive for up to 72 hours.
“This is particularly useful for stem cells. What we could do in the future is look at what could happen at the cellular level with mechanical stress on the cells. You could look at muscle cells and see how they’re developing or see how the mechanical action would help differentiate the cells.”
This story is adapted from material from North Carolina State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.