The microelectronic fibers fabricated by the thermal drawing process and its fabrics for sweat sensing. (Image: The researchers)

We recently heard from a team in Brazil about an easily sampled portable sensor made of simple materials to detect heavy metals in bodily fluids. Now, a team led by Dr. Yuanyuan Guo, Tohoku University assistant professor, has developed a microelectronic fiber with microscopic parameters capable of analyzing electrolytes and metabolites in sweat.

Plus, the technology’s micrometer scale allows it to be woven into clothes for healthcare applications.

To produce the fiber, the researchers leveraged the thermal drawing process, during which heat is applied to draw out micro-structured fiber from its macroscopic preform. The group also added two sensing electrodes for sodium and uric acid on the fiber’s longitudinal surface.

“Our breakthrough is the first successful attempt at using thermally drawn fiber in wearable bioelectronics for monitoring biochemical signatures,” said Guo.

“Since most developments so far could not be considered clothing, we devoted our effort to transforming fiber, to make truly wearable smart fabric,” Guo added.

The microelectronic fibers woven into textiles. (Image: The researchers)

The development could lead to fiber-based smart clothes that provide greater versatility in functions, larger sensing areas, and greater comfort. The team hopes that their work can revolutionize the textile and healthcare industries.

Here is a Tech Briefs interview with Guo, edited for length and clarity.

Tech Briefs: What inspired your research?

Guo: I have always been fascinated by the complexity of biological systems, particularly the brain. I have a background in biomedical engineering, so I have been very much interested in engineering better biointerface tools to unravel the complexity and beauty of biological systems. In our group, as one main direction, we have been developing thin strands of fibers that could be implanted in vivo for mechanistic studies of biology.

Particularly, we expanded biosensing functions in fibers to probe the intrinsic language of biological systems — the chemical signals. However, so far as such implantable technologies have been invasive, they have been mainly used in fundamental biological studies based on animal models. We believe in the greater impact of our technologies and are pushing its application on a broader scale — we were wondering if our fibers could be applied in textiles, which could gather our vital health information seamlessly.

As we are specialized in fiber-based biosensing, sweat, which can be obtained non-invasively, became our first detectable target. We believe, it can not only potentially transform self-monitoring healthcare technologies, but also enable fundamental studies on brain-body-environment interactions. Ultimately, it could help address pressing societal issues, such as rising mental health concerns.

The smart fibers and textiles. (Image: The researchers)

Tech Briefs: What were the biggest technical challenges you faced?

Guo: We are a leading group in enabling biosensing in microelectronic fibers. As one may imagine, the fibers are almost as thin as hairs; it is very challenging to enable biosensing functions at a localized targeted area and have the signal transferred along a long fiber without signal attenuation. We were able to address these challenges for microelectronic fibers by designing new fiber structures and further combining that with laser machining techniques.

Tech Briefs: Can you explain in simple terms how the technology works?

Guo: We leveraged thermal drawing technology from the telecommunication industry, which has been mainly used for producing silica-based optical fibers. We adapted it for producing microelectronic fibers primarily based on polymers. It is very similar to Japanese candy — Kintatoame — fabrication. First, we designed the preform with needed functions, then we applied heat and pulled the preform into thin fibers with conserved structures at microscale.

Tech Briefs: How do you plan to further the research? What’s the next step(s) with regards to your research/testing?

Guo: In addition to expanding the dateable analytes in sweat, which are biomarkers for diseases, we are also trying to expand the functionalities of such fibers for body temperature, heartbeat and breath-rate sensing, etc. In addition, we are trying to combine with digital printing technologies to have an information-processing unit fully integrated into the fiber-based textiles.

Tech Briefs: How much closer to reality are we with regards to t-shirt-testing?

Guo: We are starting to collaborate with companies, and we believe the change from the fashion-based textile industry into high-tech and value-added ones is happening.

Tech Briefs: Do you have any advice for engineers aiming to bring their ideas to fruition/market?

Guo: I think it ultimately comes down to ideas or research development. You need to have a good product or research outcome that could address the issues existing in society, exerting positive impacts and bringing sunshine into people’s life.

This will be highlighted in the March 2023 issue of Medical Design Briefs magazine.