Nature Inspires Intelligent Design

Scientists are inspired by nature’s designs, why? Maybe it’s because they are designed.

Human Exoskeleton

A mind-controlled robotic “exoskeleton” is helping a man with paralysis walk again (New Scientist). Here’s an inspiring story about engineers trying to help a man walk who became paralyzed four years ago in a fall. He can almost control a new exoskeleton suit with his thoughts! Implants in his brain known to be involved with movement allow him to “think” of how he wants to move, and the device responds. Practice with simulators is giving Thibault hope of regaining independent movement.

It’s an amazing breakthrough, but has a long way to go. For now, the scientists monitor his movements as he tries the device while suspended in a harness for safety.

A paralysed man has been able to walk again using an exoskeleton suit he controls with his mind. Although it doesn’t yet let him walk independently – the suit is suspended from an overhead harness to stop him from falling – the advance represents the first steps down the road to this goal.

The take-home message of the article is just how difficult it is to think of everything involved in successful walking. Those of us not handicapped take for granted even the most simple motions, but the engineers are struggling to get the robotic device to know how to do simple things like turning a wrist or reaching out and touching an object. The device needs to be able to control eight directions of motion simultaneously, and needs to be recalibrated periodically. So far, Thibauld has learned the thoughts to start and stop the walking system, which moves his legs similar to walking. The video clip in the article says, “But while this is a promising demonstration, there is still a long way to go.”

Imitating Other Natural Designs

Detailed picture reveals how tooth enamel is strong enough to last a lifetime (Phys.org). Tooth enamel is the hardest mineral in the human body, but is not repaired, like bone. For many people, it can last a lifetime. Intrigued by its durability, scientists at the University of Wisconsin-Madison studied its structure at the nanoscale.

“We apply huge pressure on tooth enamel every time we chew, hundreds of times a day,” says Pupa Gilbert, professor of physics at the University of Wisconsin–Madison. “Tooth enamel is unique in that it has to last our entire lifetime. How does it prevent catastrophic failure?“

They determined that the enamel crystals are composed of bundles of rods, but the rods are not parallel to adjacent rods. That’s apparently the secret: cracks starting to propagate will not traverse an interface if it is at a slight angle. As it turns out, the angle between adjacent rods is just in the right range for optimum resistance to crack propagation. They built a model and used a computer to find that out. Although they don’t mention applications for this discovery, it wouldn’t be hard for materials scientists to take note and think of how to use that secret for stronger ceramics.

Multibioinspired slippery surfaces with wettable bump arrays for droplets pumping (PNAS). Here’s a case of “multi-bioinspired” engineering. Both plants and animals gave these scientists ideas about how to create more “wettable” surfaces that bead water off without absorbing it.

Efficient droplet manipulation has been widely studied and used in various applications, including water treatment, chemical and biological analysis, etc. However, most of the approaches for droplet manipulation still face many challenges such as external energy dependence, single-directional droplets handling, and nonrecyclability. In this study, inspired by the features and strategies of Namib desert beetles, Nepenthes pitcher plants, and emergent aquatic plants, we present a multibioinspired slippery surface for efficient droplet manipulation by combining bottom-up colloidal self-assembly, top-down photolithography, and microstructured mold replication. It has been demonstrated that the prepared surface could well address these challenges and behave well in conducting multiplexed tasks including droplet capturing, pumping, and collecting.

A filament fit for space—silk is proven to thrive in outer space temperatures (Phys.org). Silkworms and spiders are two unrelated classes of animals that make silk. Silk has been prized since ancient times for clothing and art, but now it’s suiting up for space. Unlike other polymer-based fibers, natural silk does not become brittle at low temperatures. In fact, it can survive intact down to -200° C, scientists at Oxford University found. That’s because its fibers are slippage-resistant and crack-resistant at the nanoscale. And it doesn’t need human help to enjoy a bright future in space:

The discovery is pushing boundaries because it studied a material in the conceptually difficult and technologically challenging area that not only spans the micron and nano-scales but also has to be studied at temperatures well below any deep-freezer. The size of scales studied range from the micron size of the fibre to the sub-micron size of a filament bundle to the nano-scale of the fibrils and last but not least to the level supra-molecular structures and single molecules. Against the backdrop of cutting edge science and futuristic applications it is worth remembering that silk is not only 100% a biological fibre but also an agricultural product with millennia of R&D.

Spider silk: A malleable protein provides reinforcement (Science Daily). Speaking of silk, German researchers looked further into the nature of spider silk that makes it so tough while remaining flexible.

Why are the lightweight silk threads of web spiders tougher than most other materials? Scientists from the Universities of Würzburg and Mainz teamed up to find answers to this question. They were able to show that the natural amino acid methionine provides plasticity to a protein domain, which is a constitutive part of spider silk. This plasticity increases the strength of bonding between the individual domains substantially. The scientists have published their findings in the current issue of Nature Communications.

The finding makes progress in understanding spider silk, but scientists are still far behind mimicking its qualities, even though manufacturers are marketing lookalikes. The “marvellous [sic] material with many applications” may get better with the understanding of methionine’s role in providing flexibility. “The unique combination of toughness and elasticity makes it highly attractive for industry,” the article says. “Whether in aviation, textile industry or medicine, potential applications of this outstanding material are numerous.”

Bioinspired supramolecular nanosheets of zinc chlorophyll assemblies (Nature Scientific Reports). An organism doesn’t have to be large to promote biomimetics. Lowly bacteria inspired scientists to write this paper: photosynthetic bacteria, to be specific.

Two-dimensional sheet-like supramolecules have attracted much attention from the viewpoints of their potential application as functional (nano)materials due to unique physical and chemical properties. One of the supramolecular sheet-like nanostructures in nature is visible in the self-assemblies of bacteriochlorophyll-c–f pigments inside chlorosomes, which are major components in the antenna systems of photosynthetic green bacteria…. The kinetically and thermodynamically formed self-assemblies had particle-like and sheet-like supramolecular nanostructures, respectively. The resulting nanosheets of biomimetic chlorosomal J-aggregates had flat surfaces and well-ordered supramolecular structures. The artificial sheet-like nanomaterial mimicking chlorosomal bacteriochlorophyll-c–f J-aggregates was first constructed by the model molecule, and is potentially useful for various applications including artificial light-harvesting antennas and photosyntheses.

Louisiana hopes to fight coast erosion by mimicking nature (Phys.org). One might call this a case of geomimetics instead of biomimetics. The scientists in Lousiana, trying to prevent further erosion of soil along the state’s coastline, realize that human techniques of dredging aren’t working. How is sediment resupplied naturally? Well, it does involve plant life as well as river flow.

Engineers hope to remake some eroded marshes by cutting into the levees and siphoning off sediment-rich water that can be channeled into coastal basins. When the sediment settles out of the water, it will slowly accrue into soil.

“The fundamental problem in coastal Louisiana is that lack of sediment, and so we’re trying to mimic the way Mother Nature would have delivered that sediment to our coast in the past,” said Bren Haase, who leads the state’s Coastal Protection and Restoration Authority.

Without the marsh grass and willow trees, the sediment would likely erode away. Plants are, therefore, an essential part of the coastal recovery effort. Oyster fishermen, with their livelihoods at stake, are watching the progress eagerly.