You may have missed… foot arches give us a spring in our step; self-healing artificial skin; faintest galaxy seen in the early universe; and termite mounds

Your hit of the best of last week’s science.

Self-healing artificial skin 

Human skin has some pretty incredible qualities that are highly attractive to engineers creating robots and prosthetic limbs.

Now, researchers are another step closer to mimicking the skin’s ability to heal – specifically to rebuild tissue with its original layered structure.

“We’ve achieved what we believe to be the first demonstration of a multi-layer, thin film sensor that automatically realigns during healing. This is a critical step toward mimicking human skin, which has multiple layers that all re-assemble correctly during the healing process,” said Chris Cooper, a PhD candidate at Stanford University and co-author of a new study in Science.

The team created the artificial skin with polymers which, when heated to just 70°C, self-align and heal within about 24 hours. The team also added magnetic materials to the polymer layers, allowing it to self-assemble from separate pieces.

“Our long-term vision is to create devices that can recover from extreme damage. For example, imagine a device that, when torn into pieces and ripped apart, could reconstruct itself autonomously,” says Cooper.

The arch of our feet gives us a spring in our step

Researchers investigating the evolution of human feet have discovered that the flexible arches of our foot helps us walk and run more efficiently, according to a new study in Frontiers in Bioengineering and Biotechnology.

The study involved seven participants with varying arch mobility, who walked and ran while their feet were filmed by high-speed x-ray motion capture cameras. The height of each participant’s arch was measured, and their right feet were CT-scanned. 

The team found that the recoil created by the flexible arch of human feet helps to reposition the ankle upright – the optimal posture for moving forward in bipedal walking. The effects were even greater in running, suggesting that the ability to run efficiently could have been a selective pressure for a flexible arch, which made walking more efficient too. 

“Our work suggests that allowing the arch to move during propulsion makes movement more efficient. If we restrict arch motion, it’s likely that there are corresponding changes in how the other joints function,” says first author Dr Lauren Welte, who conducted the research while at Queen’s University, Canada.

The researchers say that this is a limited sample and further research is required to verify that differences in foot mobility across the population lead to the changes seen in this study.

Termite mounds can be copied to optimise buildings

Researchers studying the mounds of a species of termite from Namibia, Macrotermes michaelseni, have shown how special structures in the mounds allow for the evaporation of excess moisture, while maintaining adequate ventilation. They suggest that these features could be incorporated into buildings to create comfortable interior climates, without the need for air conditioning.

“Here we show that the ‘egress complex’, an intricate network of interconnected tunnels found in termite mounds, can be used to promote flows of air, heat, and moisture in novel ways in human architecture,” says Dr David Andréen, a senior lecturer at Lund University, Sweden, and first author of the study in Frontiers in Materials.

“We imagine that building walls in the future, made with emerging technologies like powder bed printers, will contain networks similar to the egress complex. These will make it possible to move air around, through embedded sensors and actuators that require only tiny amounts of energy,” says Andréen.

The faintest galaxy ever seen in the early universe

Astrophysicists have confirmed the existence of the faintest galaxy ever seen in the early universe. The galaxy, called JD1, is one of the most distant identified to date – seen as it was approximately 13.3 billion years ago, when the universe was only about 4% of its current age.

Approximately 13.8 billion years ago, just after the Big Bang, the universe expanded and cooled enough for hydrogen atoms to form. Then, when the first stars and galaxies appeared a few hundred million years later, they released ultraviolet light which began ionising that hydrogen fog. This is what enabled the universe to become transparent, as photons could now travel unimpeded through space.

“Most of the galaxies found with [the James Webb Space Telescope] so far are bright galaxies that are rare and not thought to be particularly representative of the young galaxies that populated the early universe. As such, while important, they are not thought to be the main agents that burned through all of that hydrogen fog,” says first author Dr Guido Roberts-Borsani, a postdoctoral researcher at the University of California – Los Angeles, in the US.

“Ultra-faint galaxies such as JD1, on the other hand, are far more numerous, which is why we believe they are more representative of the galaxies that conducted the reionisation process, allowing ultraviolet light to travel unimpeded through space and time.”

The research is published in Nature.