Twisted microfiber's network responses to water vapor

June 11, 2020

Researchers at Japan Advanced Institute of Science and Technology (JAIST): graduate student Kulisara Budpud, Assoc. Prof. Kosuke Okeyoshi, Dr. Maiko Okajima and, Prof. Tatsuo Kaneko reveal a unique polysaccharide fiber in a twisted structure forming under drying process which showed spring-like behavior. The spring-like behavior of twisted structures is practically used as a reinforced structure in a vapor-sensitive film with millisecond-scale response time. This work is published in Small Full Paper titled "Vapor-Sensitive Materials from Polysaccharide Fibers with Self-Assembling Twisted Microstructures".

Polysaccharides play a variety of roles in nature, including molecular recognition and water retention. Still, there is a lack of study in vitro microscale structures of polysaccharides because of the difficulties in regulating self-assembled structures. If the self-assembled structures of these natural polysaccharides can be reconstructed in vitro, it will lead not only to an increased understanding of the morphological changes involved in polysaccharide self-assembly in water but also to the development of a new class of bio-inspired materials, which exhibit regulated structures on a nanometer scale. In this research, it is demonstrated that a cyanobacterial polysaccharide named sacran, can hierarchically self-assemble as twisted fibers from nanoscale to microscale with diameters of ?1 μm and lengths >800 μm. this is remarkably larger than polysaccharides previously reported. Unlike other rigid fibrillar polysaccharides such as cellulose, the sacran fiber is capable of flexibly transforming into two-dimensional snaking and three-dimensional twisted structures at an evaporative air-water interface (Fig.1). This twisted sacran fiber behaves like a mechanical spring under a humid environment.

To optimize the condition of the twisted structure is formed by controlling drying speeds. Actually, the drying speed and the capillary force are the dominant factors in creating these formations. To show the potential use of this spring-like polysaccharide fibers, a crosslinked polysaccharide film is prepared as a vapor-sensitive material and the effects of the microfiber's spring behaviors in an environment with humidity gradient are demonstrated (Fig.2). The film reversibly and quickly switched between flat and bent states within 300-800 ms. This repulsive motion displayed by the film is caused by the snaking and twisted structures of the fibers responding to the change of moisture. The sacran film shows a fast response to the water drop retreating, changing from the bent state to the flat state. Because the extended sacran fibers have extension stress like a spring, the network could quickly release water by shrinking. As a result, the bent film becomes flat immediately. Thus, the snaking and twisted fiber network enable millisecond bending and stretching responses to changes in local humidity.

From the simple method, JAIST researchers could create unique micro-spring from natural polysaccharide which is practically used as a vapor-sensitive material. Besides, by introducing functional molecules into the microfiber, it would be possible to prepare a variety of soft actuators responding to other changes in the external environment, such as light, pH, and temperature. The method for preparing vapor sensors developed by this study not only improves understanding of how the motion of self-assembled structures responds to stimuli. But also contributes toward the design of environmentally adaptive materials with a high potential for sustainable use.
"Vapor-Sensitive Materials from Polysaccharide Fibers with Self-Assembling Twisted Microstructures", Kulisara Budpud, Kosuke Okeyoshi*, Maiko Okajima and, Tatsuo Kaneko*, Small, 2020 (DOI: 10.1002/smll.202001993)

Japan Advanced Institute of Science and Technology

Related Behavior Articles from Brightsurf:

Variety in the migratory behavior of blackcaps
The birds have variable migration strategies.

Fishing for a theory of emergent behavior
Researchers at the University of Tsukuba quantified the collective action of small schools of fish using information theory.

How synaptic changes translate to behavior changes
Learning changes behavior by altering many connections between brain cells in a variety of ways all at the same time, according to a study of sea slugs recently published in JNeurosci.

I won't have what he's having: The brain and socially motivated behavior
Monkeys devalue rewards when they anticipate that another monkey will get them instead.

Unlocking animal behavior through motion
Using physics to study different types of animal motion, such as burrowing worms or flying flocks, can reveal how animals behave in different settings.

AI to help monitor behavior
Algorithms based on artificial intelligence do better at supporting educational and clinical decision-making, according to a new study.

Increasing opportunities for sustainable behavior
To mitigate climate change and safeguard ecosystems, we need to make drastic changes in our consumption and transport behaviors.

Predicting a protein's behavior from its appearance
Researchers at EPFL have developed a new way to predict a protein's interactions with other proteins and biomolecules, and its biochemical activity, merely by observing its surface.

Spirituality affects the behavior of mortgagers
According to Olga Miroshnichenko, a Sc.D in Economics, and a Professor at the Department of Economics and Finance, Tyumen State University, morals affect the thinking of mortgage payers and help them avoid past due payments.

Asking if behavior can be changed on climate crisis
One of the more complex problems facing social psychologists today is whether any intervention can move people to change their behavior about climate change and protecting the environment for the sake of future generations.

Read More: Behavior News and Behavior Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to