The research team of researcher Hyunseon Seo and senior researcher Dr. Donghee Son of the Korea Institute of Science and Technology’s Biomedical Research Institute, postdoctoral candidate Dr. Jiheong Kang and Professor Zhenan Bao of Stanford University (chemical engineering) announced a new material with high stretchability and high electrical conductivity, with the ability to self-heal even after being subjected to severe mechanical strain. The material could have application in wearable electronic devices.
Prior to this study, Dr. Donghee Son, Dr. Jiheong Kang, and Prof. Zhenan Bao developed a polymer material that is highly elastic, can self-heal without the help of external stimuli even when exposed to water or sweat, and has a mechanical strength similar to that of human skin, making it comfortable to wear for long periods of time.
In its most recent study, the KIST-Stanford research team developed the new material, which can be used as an interconnect, as it has the same properties as existing wearable materials and high levels of electrical conductivity and stretchability, characteristics which allow the stable transmission of electricity and data from the human body to electronic devices.
The genetic code of squid ring teeth holds the key to a multiphase polymer that self-heals by simply adding water, leading to potential innovation from medical implants to deep-sea installations.
The copolymer developed by a Pennsylvania State University, USA, research team features an amorphous segment around a molecular architecture consisting of amino acids connected by hydrogen bonds, forming a pleated sheet. While the sheet gives the polymer strength, the amorphous segment is derived from the squid ring teeth proteins that lends the polymer its regenerative qualities.
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Observing the ubiquitous self-healing qualities of squid ring teeth proteins across the world, the research team began to work to develop a polymer that would benefit from this property. Noting that the ‘yield of this proteinaceous material from natural sources is low (about 1g of squid ring teeth protein from 5kg of squid), the Penn State researchers created artificial proteins in bacteria.
A sample can created and cut in half, before being submerged in water, where the two halves reformed into the original sample shape. Subsequent strength testing indicated that the sample was as strong as when originally created.
This writer would like to confirm that searching for images of squid teeth was a deeply unpleasant experience
Melik Demirel, Professor of Engineering Science and Mechanics at Penn State, commented, ‘What’s unique about this plastic is the ability to stick itself back together with a drop of water. Maybe someday we could apply this approach to healing of wounds or other applications. It would be interesting in the long run to see if we could promote wound healing this way, so that is where I’m going to focus now.’
Inspired by healing wounds in skin, a new approach protects and heals surfaces using a fluid secretion process. In response to damage, dispersed liquid-storage droplets are controllably secreted. The stored liquid replenishes the surface and completes the repair of the polymer in seconds to hours.
The fluid secretion approach to repair the material has also been demonstrated in fibers and microbeads. This bioinspired approach could be extended to create highly desired adaptive, resilient materials with possible uses in heat transfer, humidity control, slippery surfaces, and fluid delivery.
A polymer that secretes stored liquid in response to damage has been designed and created to function as a self-healing material. While human-made material systems can trigger the release of stored contents, the ability to continuously self-adjust and monitor liquid supply in these compartments is a challenge. In contrast, biological systems manage complex protection and healing functions by having individual components work in concert to initiate and self-regulate a coordinated response. Inspired by biological wound-healing, this new process, developed by researchers at Harvard University, involves trapping and dispersing liquid-storage droplets within a reversibly crosslinked polymer gel network topped with a thin liquid overlayer. This novel approach allows storage of the liquid, yet is reconfigurable to induce finely controlled secretion in response to polymer damage.
A collaboration between the lab of Judy Cha, the Carol and Douglas Melamed Assistant Professor of Mechanical Engineering & Materials Science, and IBM’s Watson Research Center could help make a potentially revolutionary technology more viable for manufacturing.
Phase-change memory (PCM) devices have in recent years emerged as a game-changing alternative to computer random-access memory. Using heat to transform the states of material from amorphous to crystalline, PCM chips are fast, use much less power and have the potential to scale down to smaller chips – allowing the trajectory for smaller, more powerful computing to continue. However, manufacturing PCM devices on a large scale with consistent quality and long endurance has been a challenge.
“Everybody’s trying to figure that out, and we want to understand the phase change behavior precisely,” said Yujun Xie, a PhD candidate in Cha’s lab and lead author of the study. “That’s one of the biggest challenges for phase-change memory.”
Researchers at Binghamton and Rutgers Universities, USA, have developed a self-healing fungi concrete mix that could help solve the issue of crumbling infrastructure – caused by cracks in the structure’s concrete. The team received support from the Research Foundation for the State University of New York’s Sustainable Community Transdisciplinary Area of Excellence Program.
Assistant Professor Congrui Jin, Binghamton University, commented, ‘Without proper treatment, cracks tend to progress further and eventually require costly repair […] If micro-cracks expand and reach the steel reinforcement, not only the concrete will be attacked, but also the reinforcement will be corroded, as it is exposed to water, oxygen, possibly CO2 and chlorides, leading to structural failure.’
The team found that mixing Trichoderma reesei – a fungus – with the concrete could solve this issue. The fungus lies dormant in the mix until water and oxygen reach it through cracks in the concrete.
‘With enough water and oxygen, the dormant fungal spores will germinate, grow and precipitate calcium carbonate to heal the cracks,’ commented Jin. ‘When the cracks are completely filled and ultimately no more water or oxygen can enter inside, the fungi will again form spores. As the environmental conditions become favorable in later stages, the spores could be wakened again.’
Further research is needed to ensure the fungus can survive in the concrete mix.
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