Researchers looking to fishes for designing biomimetic systems for flexible Armor, faster aircraft and camouflaging skin

Rajesh Uppal June 6, 2019 BioScience, Navy Comments Off on Researchers looking to fishes for designing biomimetic systems for flexible Armor, faster aircraft and camouflaging skin 547 Views

It was in the oceans that life first evolved and where complex animals have thrived for over 600 million years. Marine animals survive in environments as diverse as tropical coral reefs, polar ice-capped oceans, and the lightless abyssal depths, says Frank E. Fish from West Chester University and Donna M. Kocak from HARRIS CapRock Communications. Millions of years of evolution have endowed biological systems with morphological, neurophysiological, and behavioral features that enable them to survive and thrive in their environments.

“To deal with the rigors of the marine environment, animals have developed specialized sensory systems (e.g., echolocation, electroreception), mechanisms to deal with pressure (e.g., buoyancy control), strategies to economize on energy (e.g., fusiform body design, schooling, burst-and-glide swimming), armor (e.g., bony scales, mollusk shells), stability mechanisms (e.g., paired and median fins), maneuverability (e.g., flexible bodies, vectored thrust), speed (e.g., high-aspect-ratio oscillatory propulsors, jet propulsion), stealth (e.g., camouflage, low acoustic signature), and use of compliant materials (e.g., collagen, protein rubbers, mucous),” they further write.

Biologically inspired engineering is a new scientific discipline that applies biological principles to develop new engineering solutions for medicine, industry, environment and the military. The emergence of this new discipline unifies the life sciences with engineering and the physical sciences. Biologically inspired engineering involves exploration into the way that living cells, tissues, and organisms build, control, manufacture, recycle, and adapt to their environment. Bioinspired engineers leverage this knowledge to develop new technologies and translate them into products that meet real world challenges.

Nature is a rich source of inspiration for robot development. Bio-inspired robotics is about studying biological systems, and look for the mechanisms that may solve a problem in the engineering field for example biosensors (e.g. eye), bioactuators (e.g. muscle), or biomaterials (e.g. spider silk).

Navies are also interested in biomimetic systems for developing more efficient propulsion systems, stealthy submarines, UUV (unmanned undersea vehicle) and improved military armor. Many countries including the US, Japan, India and China are involved in research of bio-inspired systems.

Fish Scales Inspire Flexible, Bulletproof Armor for Soldiers, Astronauts

Researchers at MIT are studying some of the sturdiest forms of animal armor, particularly fish scales, and designing gear that matches the flexibility, comfort and durability found in the natural world using 3D printing. “We want to understand how the scales interact with each other to provide mobility, but then also how the scales, at a global level, provide structure, rigidity and flexibility at the same time,” Swati Varshney, a graduate student at MIT, told LiveScience.

Researchers at the Technion-Israel Institute of Technology and the Massachusetts Institute of Technology have developed a material with a flexible liner topped with one covered in armor-like scales suitable for military or space applications. The bio-inspired Flexible Scale Armor is 3D printed and can be customized for body type, add areas with additional protection or better range of motion.

The development of the fish-scale inspired Flexible Armor was led by Assistant Professor Stephen Rudykh, head of the Technion’s Mechanics of Soft Materials Laboratory. “Fish are flexible creatures, but are protected by hard scales. Their ‘secret’ is the combination of the scales and the soft tissue beneath them, and that is what I tried to mimic here,” explains Rudykh. “The materials that I am designing are also made of two layers – one soft (the ‘body’) and the other (‘scales’) constitutes the ‘armor’. These two components provide the combined property of protecto-flexibility that we want.”

Rudykh and his team are 3D printing this material, which could be used in military armor or even space suits. Their work has allowed them to increase the penetration resistance by a factor of 40. With military uniforms there is the potential to custom design the joint areas to add more flexibility and beef up other areas, like the chest, to improve strength. For space suits, the material would make them impervious to micro-meteorites and radiation, which offers better protection for astronauts while on spacewalks. Rudykh’s work was recently published in the journal of Soft Matter.

US Army-funded research into mako shark skin to build faster aircraft

The US Army has funded research to study the skin of the shortfin mako shark as part of efforts to construct faster aircraft and helicopters.Also known as the ‘cheetahs of the ocean’, mako sharks can achieve speeds of up to 70mph or 80mph. The investigation is expected to provide insights into how the mako shark is able to achieve high speeds.

Results could help engineers in understanding how the pressure drag on aircraft can be reduced and make them more agile and responsive. The research is being carried out by aeronautical engineer Amy Lang of the University of Alabama. Lang, along with colleagues, has studied how the nearly 0.2mm-sized scales can flex at angles more than 40° from the shark’s body. These flexible scales are located in particular areas of the shark’s body and help the animal control flow separation to reduce pressure drag.

Lang said: “It impedes the flow from reversing near the skin, which would otherwise lead to what we call flow separation. “This is the drag you experience if you stick your hand out your car window vertical to the airflow.” The research team conducted water tunnel experiments using real mako shark skin samples. The skin samples were taken from the shark’s flank region. Lang explained: “We set up an experiment in the tunnel with a measured amount of flow separation induced on a smooth surface. Then we replaced the smooth surface with shark skin and re-quantified the flow separation.

“In all cases with the flank skin, we saw the size of the separated flow region reduced significantly by the presence of the skin.” “The potential for a man-made surface to utilise this entirely passive mechanism even in the air is very exciting.” The research work was also funded by Boeing

Researchers at the University of Texas, Austin looks to fish for Camouflaging

Researchers at the University of Texas, Austin, are studying the remarkable ability of some fishes to hide from plain sight by adjusting to the light in certain angles. They have been funded by Navy with the aim to employ this technology in designing of stealthy submarines. In a paper published this week in Science researchers reports that certain fish use microscopic structures called platelets in their skin cells to scatter polarized light differently depending on the angle which allows the fish to seemingly disappear from their predators. Under the surface of the water, light tends to be polarized, that is all the light waves travel in the same plane.

“Fish have evolved the means to detect polarized light,” said Molly Cummings, professor of integrative biology in the College of Natural Sciences. “Given that, we suggested they’ve probably evolved the means to hide in polarized light. If we can identify that process, then we can improve upon our own camouflage technology for that environment.”

Visual Detection of targets can be through brightness contrast, color contrast or polarization contrast, among them polarization contrast is considered most effective for detection in the open ocean. In a previous study, the researchers demonstrated in the lab that a fish called the lookdown was able to manipulate polarized light to its advantage. The new study—conducted in the actual ocean, shows lookdowns and other fish that live in the open ocean camouflage themselves this way.

Scientists design ‘camouflaging skin’ inspired by octopus

A master of disguise, the octopus can change the colour and texture of its skin to blend in with its environment. Inspired by this sea creature, researchers from the University of Pennsylvania and Cornell University developed a silicone skin for robots that can change texture for 3D camouflage. The synthetic cephalopod skin can transform from a 2D surface into a 3D one with bumps and pits. The researchers took inspiration from the 3D bumps, called papillae, that octopuses can inflate using muscle units. They can change appearance as fast as one fifth of a second. In soft robots, air pockets have already been used as papillae. These pockets are inflated at different times in different spots to generate locomotion.

In the new research, the scientists embedded small fibre-mesh spheres into the silicone, so they could control and shape the texture of the inflated surface, just as an octopus can retexture its skin. In their proof-of-concept prototype, the silicon bubbles were divided with concentric circles of fibre-mesh frames. With this, the researchers can control the shape of the silicone as it inflates. They managed to mimic rounded stones in a river, as well as a succulent plant (Graptoveria amethorum) with leaves arranged in a spiral pattern. The skin could be used for soft robots, to blend in with their environment, for instance to prevent them to be detected by animals in order to study them in their natural habitat, or for military applications.

Engineers at Cornell University report on their invention of stretchable surfaces with programmable 3D texture morphing, a synthetic “camouflaging skin” inspired by studying and modeling the real thing in octopus and cuttlefish. The engineers, along with collaborator and cephalopod biologist Roger Hanlon of the Marine Biological Laboratory (MBL), Woods Hole, report on their controllable soft actuator in the October 13 issue of Science.

Led by James Pikul and Robert Shepherd, the team’s pneumatically-activated material takes a cue from the 3D bumps, or papillae, that cephalopods can express in one-fifth of a second for dynamic camouflage, and then retract to swim away without the papillae imposing hydrodynamic drag. “Lots of animals have papillae, but they can’t extend and retract them instantaneously as octopus and cuttlefish do,” says Hanlon, who is the leading expert on cephalopod dynamic camouflage. “These are soft-bodied molluscs without a shell; their primary defense is their morphing skin.” “We were drawn by how successful cephalopods are at changing their skin texture, so we studied and drew inspiration from the muscles that allow cephalopods to control their texture, and implemented these ideas into a method for controlling the shape of soft, stretchable materials.”

Papillae are examples of a muscular hydrostat, biological structures that consist of muscle with no skeletal support (such as the human tongue). Hanlon and members of his laboratory, including Justine Allen, now at Brown University, were the first to describe the structure, function, and biomechanics of these morphing 3D papillae in detail.

“The degrees of freedom in the papillae system are really beautiful,” Hanlon says. “In the European cuttlefish, there are at least nine sets of papillae that are independently controlled by the brain. And each papilla goes from a flat, 2D surface through a continuum of shapes until it reaches its final shape, which can be conical or like trilobes or one of a dozen possible shapes. It depends on how the muscles in the hydrostat are arranged.” The engineers’ breakthrough was to develop synthetic tissue groupings that allow programmable, 2D stretchable materials to both extend and retract a range of target 3D shapes. “This is a classic example of bio-inspired engineering” with a range of potential applications,” said Roger Hanlon of Marine Biological Laboratory in Massachusetts, US.

Turkish Defense Disguises Underwater Drone as Sneaky ‘Wattozz’ Stingray

A Turkish defense company named Albayraklar Savunma has now released a video showing an unmanned underwater vehicle that uncannily resembles the size, movement and appearance of a stingray. Named “Wattozz”, the Turkish word for stingray, the country’s first locally developed and armed underwater drone is sinister for more than just it’s unnerving camouflage.

The video shows a school of the stingray drones swimming in formation, controlled from a central command. Coated in silicone, the drone has the ability to lie still on the ocean floor in ‘sleep mode’. Due to a signal-absorbing inner coating, the drones are impossible to detect by radar either in sleep mode or when in motion, the company says in their video.

While the stingray is reported to be primarily an “observation vehicle”, it also operates as a “mobile naval mine”, and has the capability to attach to the hull of enemy vessels invading the country’s waters using electromagnetic magnets and then detonate on command. Using encrypted acoustic sound waves, “similar to that of animals such as whales and dolphins”, the Wattozz can communicate with its central command base.