| KIST, without post-processing process and catalyst
| Development of fiber with sensing function for detecting harmful gases
| Expected to be used in next-generation wearable sensors


Wearable sensors are sensors that can detect conditions and environments in real time by being worn, and their shapes and functions can be changed by combining them with various materials. The fiber form is flexible and can be woven into general fibers, so it is attracting attention as an ideal platform.

The research team of Dr. Hyunsoo Jeong and Dr. Seungki Lee from the Functional Composite Materials Research Center of the Korea Institute of Science and Technology (KIST) and the research team of Professor Heetae Jeong from the Korea Advanced Institute of Science and Technology (KAIST) announced on the 3rd that they had developed a fiber-type nitrogen dioxide ( _NO2 ) sensor that does not require a post-processing process and can be continuously mass-produced.

Most existing fiber-based sensor materials were manufactured by coating general fibers with conductive materials and sensor materials. However, the resistance was high, requiring high voltage, and above all, the bonding strength between the fibers and the materials being coated was low, resulting in poor durability.

To solve this problem, graphene oxide fibers, which are conductive fibers themselves, have emerged. However, graphene fibers have been criticized for having the disadvantages of being uneconomical due to the necessity of a post-processing process, significant reduction in flexibility, and high process and material costs.

The KIST research team developed a nitrogen dioxide sensor material that does not require post-treatment or catalyst by extracting nanocellulose from sea squirt shells and manufacturing a composite fiber by combining it with carbon nanotubes.

Nanocellulose is a component of the cell walls of green plants and various forms of algae and oomycetes, and is a substance that is made by breaking down cellulose, the most abundant organic compound on Earth, to the nano level.

The developed composite fiber possesses both mechanical strength and flexibility, so it can be woven with regular fibers. The research team actually succeeded in creating a fabric with composite fibers inserted and detecting nitrogen dioxide, a harmful gas. Since composite fibers can be continuously produced using the existing industrialized wet spinning method, it is expected to be advantageous for commercializing inexpensive wearable gas sensors in the future.

The research team calculated the manufacturing cost based only on the price of the materials used in the study, and confirmed that the cost is less than 10 won per meter of fiber. The composite fibers manufactured by this method have conductivity, porosity, and high selectivity and sensitivity (ppb level) for nitrogen dioxide gas in one step from the manufacturing stage.

Dr. Jeong Hyeon-su of KIST said, “Through this research, we were able to find out that the basic properties required for a wearable sensing material can be manufactured at once through material composites,” and added, “In the future, we will strive to develop economically viable wearable materials for detecting other harmful gases in addition to nitrogen dioxide.”

Meanwhile, this study was conducted through the KIST Open Research Program and the National Research Foundation of Korea Nanomaterial Technology Development Project with support from the Ministry of Science and ICT. The research results were published in the latest issue of 'ACS Nano', an international journal in the materials field, and KIST has completed application for a domestic patent for the manufacturing technology.