Mimicking elements of the natural world — also known as biomimicry — so that manmade objects can be imbued with properties found in nature is a device often used by engineers when developing new materials.

Like Engineering360’s recent examination of nature’s impact on robot designs, this article will explore how nature has influenced the making of assorted materials, including barnacle-inspired glue and plant-inspired oil-absorbing textiles.

Barnacles

Engineers from Massachusetts Institute of Technology (MIT) have developed a blood-repelling tissue glue to treat traumatic injuries or to control bleeding during surgery that was inspired by barnacles — small crustaceans that attach to rocks, ship hulls and other animals.

Source: MITSource: MIT

According to its developers, the biocompatible glue tightly seals damaged tissue, even clinging to surfaces that are covered in blood, to halt bleeding. Reportedly, a tight seal is achieved in just 15 seconds following application.

The glue is composed of a polymer called poly(acrylic acid), which features an organic compound called NHS ester and chitosan. The NHS ester makes the material adhesive while the chitosan, which is a sugar, fortifies the material.

To create the paste, the team froze sheets of the material, ground it into microparticles and suspended the microparticles in medical-grade silicone oil. Once applied to a wet surface, the oil in the paste repels blood, along with other substances, thereby encouraging the adhesive microparticles to crosslink and thus form a tight seal over the wound within 15 to 30 seconds — significantly faster than the hemostatic agents currently used to halt bleeding.

Plant life

Researchers from Germany’s Universities of Bonn and Aachen and the Heimbach-GmbH are applying the super water repellant (or super hydrophobic) properties found in a family of floating ferns to textiles designed for removing oil from bodies of water.

Inspired by the floating super hydrophobic yet oil-loving fern Salvinia, which when submerged in water encases itself in an air pocket to keep dry, researchers have transferred those properties to a textile that can adsorb oil from the surface of water and carry it like a film to floating containers for reuse.

Because the oil is transported on the surface of the textile, it is not absorbed by the textile or mixed with chemicals to ensure that it is absorbed. Instead, the oil is clean and can be reused once it is skimmed off and deposited in a floating container, according to researchers.

Squid

Researchers from Penn State University and the Max Planck Institute have developed a self-healing, biodegradable and biosynthetic material inspired by the protein in squid ring teeth.

Mimicking features of the appendages, or teeth, on the suction cups that squids use to capture prey, which, when broken or damaged can heal themselves, the researchers have developed material that self-heals via water and heat in a one-second long process.

Like squid ring teeth, which regenerate when the soft protein components of the ring teeth fuse the proteins together as the hard protein components strengthen the material, the new material is a rapidly healing polymer.

With funding from the U.S. Army, the research team believes the material could be used to repair tiny cracks and tears in material sustained by repetitive motion such as those encountered by prosthetic legs, robotic machines, ventilators, actuators, personal protective equipment (PPE) and hazmat suits. Applied to any of these, and the researchers believe tiny cracks and tears can be fixed immediately before developing into bigger holes that cause the material to fail. The U.S. Army is particularly interested in the material for its potential in future Army applications, including for PPE and for flexible robots that can adapt to and navigate confined spaces.

Grapefruit and mollusks

Inspired by the tough exterior of grapefruit and fragment-resistant mollusks, engineers from Durham University, U.K., and Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz in Germany, have developed a new material that can not be cut with machine tools.

The patent-pending material, called Proteus — in a nod to the shape-shifting mythical god — is composed of ceramic spheres enveloped in a cellular aluminum structure. According to developers who call it the first of its kind, the material is light, strong and non-cuttable.

During its development, the engineers discovered that the material could not be cut by machine tools such as drills, angle grinders or high-pressure water jets. Instead, vibrations within the ceramic spheres blunted and eroded the drills and angle grinders.

Reportedly, the ceramics fragmented into fine particles, thereby filling the cellular structure of the material and hardening in response to the increased speed of the cutting tool, thwarting both drilling and cutting attempts.

Additionally, high-pressure water jets were also unsuccessful due to the material’s curved construction, which widened the water jet stream, consequently reducing the water jet’s cutting power.

According to the engineers, the material could one day be used in products like armor, bike locks and protective equipment worn by those working with dangerous machinery.

Lobster tails

Researchers from Australia’s RMIT University have strengthened steel-fiber reinforced concrete by 3D printing it in a helicoidal lobster shell design.

The spiral, or helicoidal, design of the 3D-printed concrete was inspired by the biological design of lobster shells.

Reportedly, printing steel-fiber enhanced concrete in the helicoidal design resulted in concrete that was stronger than traditional concrete and stronger than concrete 3D printed in unidirectional, or single direction, patterns.

Additionally, the team reports that the design allowed for more creative structures via 3D printing. Although 3D printing allows for some creativity, free form structures created through this technology are not as structurally sound when printed in unidirectional patterns and using standard, unenhanced concrete.

Leaves

Researchers from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences have developed a new biomimetic antibiofouling diamond film.

The creators of the diamond film were reportedly inspired by the nano-structures on lotus and taro leaves to prevent biofouling, or biological fouling, which is the accumulation of microorganisms, plants, algae and other objects on surfaces submerged in water, such as the hull of a boat, that cause structural or other functional damage. To achieve the new film’s self-cleaning, superhydrophobic, antibacterial, mechanically robust, chemically stable and antibiofouling properties, the researchers built a hierarchically structured diamond film.

The team constructed the film using a strategy that involved hot-filament chemical vapor deposition (HFCVD) and two-step self-assembly seeding processes.

During testing, the diamond coatings formed on assorted commercial substrates such as alloys, silicon, ceramics and quartz glass with large scale and complex geometries that were superhydrophobic and that also repelled microbial adhesion.

According to researchers, the diamond coating prevented the attachment of bacteria by 90% to 99%. Likewise, in the marine environment, the film prevented the adhesion of green algae by more than 95%.

Other similar antibiofouling films have been developed but have largely demonstrated inadequate mechanical and chemical stability. Such inadequacies reportedly lessen the antibiofouling and antibacterial properties of the coatings.

This article barely scratches the surface of materials that have been inspired by nature. Check back with Engineering360 for more on nature’s influence on engineers.

To contact the author of this article, email mdonlon@globalspec.com