Sharks have tough skin that is worthy of biomimicry by nanotechnology designers and engineers. New coatings, textiles and other technologies that mimic the special biological properties of shark skin have been developed in recent years and many more such innovations are emerging across multiple industries.
Designers and engineers charged with solving problems related to the efficiency of movement like to focus on the overall shapes of objects. Advances in nanotechnology have allowed these movement-efficiency problem solvers to not only focus on ever smaller objects such as the dermal denticles on a shark’s skin, but to construct materials such as polymer coatings that imitate, or mimic, nature’s microscopic designs.
Examining the special characteristics of a shark’s tough skin that are worthy of biomimicry requires powerful magnification. The outer layer of a shark’s skin is composed of dermal denticles, also referred to as placoid scales, which are geometrically arranged, toothlike scales. This pattern of arrangement allows for reduced drag and anti-fouling properties that can translate into extreme marketability for multiple industries, including medicine and sanitation.
Seawater contains innumerable particles, not to mention potentially parasitic algae, bacteria and other organisms, which pose a constant flow hazard for sharks. To survive, sharks must minimize drag and move efficiently through water in order to obtain sufficient oxygen through their passive gills and to maintain buoyancy. The dermal denticles on sharks’ skin not only reduce surface drag because of their hydrodynamic shapes, but they serve an auto-cleaning function as well due to their texture, removing ecto-parasites from the skin’s surface in a process called anti-fouling, which even further reduces drag.
Taking a lead from swimsuit designers, vehicle researchers are testing coatings or surfaces for cars, boats and planes that reduce the friction drag experienced by ships, submarines, aircraft and automobiles. Nanotechnology construction capabilities even allow for the design of a “smart” surface that can sense and react to local fluid flow conditions to reduce drag even further. Scientific studies are ongoing in this arena.
Good design is not just a matter of mimicking the tough skin of a shark – the actual skin itself can be a valuable material. Items made from the tough skin of sharks and rays (sharks’ close relatives) have been highly prized for centuries. Leatherworkers note that shark is relatively thicker as a finished hide than other exotic leathers such as alligator or stingray, and remark that shark is a particularly resilient leather in that it resists scarring and wear, retaining a fresh look for decades. As such it is ideal for items that receive daily use such as belts, wallets, shoes, boots, and vehicle and household upholstery.
If the hydrodynamic qualities of shark skin were not enough to make shark skin scientifically and economically fascinating enough for biomimicry, the skin itself is just plain tough. Shark leather is said to be five times stronger than cow leather. However, it is unlikely that sharks will become a new substitute for red meat because, since sharks are an apex species, mercury tends to build up in their systems. The FDA and other organizations have advised consumers, especially pregnant women, to avoid shark meat, although the FDA is currently revising its position on the matter.
Not only do sharks have tough skin that is worthy of biomimicry, but they are creatures that stand as a testament to the value of conserving biodiversity. The more natural adaptations nanotechnology designers and engineers have to choose from, the more technological innovations can result.
By Lane Therrell