Introduction
Biomimetics is the study of nature and natural phenomena to understand the principles of underlying mechanisms, to obtain ideas from nature, and to apply concepts that may benefit science, engineering, and medicine.
Examples of biomimetic studies include fluid-drag reduction swimsuits inspired by the structure of shark’s skin, velcro fasteners modeled on burrs, shape of airplanes developed from the look of birds, and stable building structures copied from the backbone of turban shells.
If the history of planet Earth was compressed into 1 year, humans would appear in the last 15 minutes of it. Out of those 15 minutes, most recent industrial progress would occur within 1 minute. Despite this small proportion, the industrialization that took place in the last century is much greater than that from the start of mankind. Although the rapid rate of industrialization has helped to prolong life and overcome disease, it has also brought pollution and environmental destruction, which affect human survival itself. In this drift toward industrialization, men have made a continuous effort to create more products that can improve our lives. However, the survival of mankind faces the physical dilemma of living on limited resources. Solutions to the lack of resources and survival problems have not always been clear to us, although the answer can always be found within nature. An interesting method to solve these problems may lie in biomimetics, which uses nature as the ultimate model, standard, and advisor. In recent times, mankind has newly opened its eyes to biomimetic technology, and its efforts are being met with success. This review focuses on recognizing specific examples of biomimetics, their current use, and how they will continue to be used in the future.
Biomimetics: past, current, and future
Definition of biomimetics
The term “biomimetics” originates from the Greek words “bios” (life) and “mimesis” (to imitate), yet its definition is not as simple as just those two words. More specifically, biomimetics is a creative form of technology that uses or imitates nature to improve human lives.
Concept of biomimetics
Biomimetics is not a recent study or trend, but the idea of looking into nature for inspiration has been in practical use for a long time. It has been called by different names such as “intellectual structure” in Japan and “smart material” in the USA. Biomimetics is centered on the idea that there is no model better than nature for developing something new and has produced excellent results in productivity and function. This idea has also opened doors to realistic gains by eliminating waste and saving in research expenses.
Field of biomimetics
Humans have heavily impacted nature with industrialization and resource extraction; however, biomimetics can help to avoid this pattern. Biomimetics goes beyond simply using natural properties as the basis for innovation of new products. Such products can be designed to play a part in general industry as well as to provide human convenience in the fields of chemistry, biology, architecture, engineering, medicine, and biomedical engineering. Such a symbiotic relationship plays a critical role in the coexistence of humans with nature, and the extent of its application can be boundless. It is therefore critical to understand these areas and examples for each of them.
History of biomimetics
The history of biomimetics Found easily in everyday life and often used without our knowledge, biomimetics is a broad field with a long history. From knives and axes inspired by the dental structures of currently extinct animals to the strongest cutting-edge carbon nanomaterials, bioengineering has always evolved along with human history.
Leonardo da Vinci’s (1452–1519) work is a fundamental example of biomimicry. He designed a “flying machine” inspired by a bird. In the Far East, General Yi Sun-sin built the turtleship, a warship modeled after a turtle, to fight Japanese raiders during invasions.
The Wright brothers (1867–1948) took note of the wings of eagles and made a powered airplane that succeeded in human flight for the first time in 1903. Over the next century, the airplane became faster, more stable, and more aerodynamic.
Schmitt was the first to coin the term biomimetics in 1957, and he announced a turning point for biology and technology.
Jack E Steele of NASA, who coined the word bionics in 1960, was also the first to use the word biomimetics in a paper in 1969, which led to the addition of the term to the dictionary in 1974.
In 1997, Janine M Benyus published her book Biomimicry, which emphasizes that biomimicry is leading the path to a new age of technological development by taking lessons from nature as the groundwork for products, rather than just using it for raw materials.
Janine Benyus and others stepped further to organize a social enterprise called Biomimicry 3.8 to share ideas and concepts of biomimicry and biomimetics as well as to connect interdisciplinary researchers, scientists, artists, engineers, business leaders, and stakeholders.
Biomimicry taxonomy categorizing the research interests of biomimetics.
Research methods for biomimetics The basic research method for biomimetics has six steps, which can be used to apply biomimetics to design, product, service, and agriculture.
Like the sticky substance found in geckos’ feet, the functional possibilities of biologically inspired design should be researched rather than just applying the design as it is used by the organism. Although the discovery or fusion of innovative technology is crucial for increased profits, a simple creative design idea can provide greater convenience for human life.
The function of the organism, the principles under which that function is achieved, and the relationship between these two must be established. Knowledge and application of various materials need to be accumulated through research and database compilation. The relationship between structure and function usually comes from the surface structure, which can be observed by a scanning electron microscopy technique. These fine structures play an important role in the organism and are said to be the first step for biomimetics. The US researchers are using the Biomimicry Taxonomy as a practical database.
The greatest challenge faced by biomimetics is to determine how nano- and microstructures function in their relationship with the organism and the environment, especially if these have not been fully explored yet. Finding substantial examples through the integration of biology, natural history, and materials science is the next step in biomimetic research.
Identifying various functional and environmental adaptation mechanisms of organisms and their energy-minimizing design is the next research frontier. A successful example of this is the antireflective coating that was inspired by the 200 nm structures reflecting visible light rays from a moth’s eye. The nature of new biomimetic materials lies in discovering hierarchical structures and their corresponding functions to remodel them into something we can utilize.
The combination of newly discovered materials with biomimetics research will be a key to understanding their applications and limitations. The morphological and functional uses of the new material must first be understood along with the pros and cons of biomimetics, and the results from their combination have to be unraveled. Active research is being performed on these fronts, but making progress in these areas is realistically a difficult pursuit.
The determined biological material’s structure and the function become the source of innovation for the development of a new material while possibly providing links to other materials. The structure and function of already known materials go through tests and assessments that help them morph and evolve into new materials. By combining them with current advancements in medicine, chemistry, and nanotechnology, we may find novel utilities that may benefit human life.
Examples of biomimetics
Due to the heterogeneous nature of the cellular microenvironments, biomimetic analytical platforms conveying complex environments in vivo models have been studied to probe the characteristics of cells and their microenvironments. By engineering the microenvironments (ie, microwells), researchers mimicked the cell-to-cell interactions in lymph nodes or other tissues where two types of cells dynamically communicate upon immunological cues. As the biomimetic microenvironments become more elaborated and sophisticated, researchers preparing biomimetic cellular environments will be enlightened and find solutions to the enigmatic relationships between cells and their adjacent microenvironment.
1. Sharkskin = Swimsuit
Sharkskin-inspired swimsuits received a lot of media attention during the 2008 Summer Olympics when the spotlight was shining on Michael Phelps.
Seen under an electron microscope, sharkskin is made up of countless overlapping scales called dermal denticles (or "little skin teeth"). The denticles have grooves running down their length in alignment with water flow. These grooves disrupt the formation of eddies, or turbulent swirls of slower water, making the water pass by faster. The rough shape also discourages parasitic growth such as algae and barnacles.
Scientists have been able to replicate dermal denticles in swimsuits (which are now banned in major competition) and the bottom of boats. When cargo ships can squeeze out even a single percent in efficiency, they burn less bunker oil and don't require cleaning chemicals for their hulls. Scientists are applying the technique to create surfaces in hospitals that resist bacteria growth — the bacteria can't catch hold on the rough surface.
2. Beaver = Wetsuit
Beavers have a thick layer of blubber that keeps them warm while they're diving and swimming in their water environments. But they have another trick up their sleeves for staying toasty. Their fur is so dense that it traps warm pockets of air in between the layers, keeping these aquatic mammals not only warm, but dry.
Engineers at the Massachusetts Institute of Technology thought surfers might appreciate that same ability, and they created a rubbery, fur-like pelts they say could make "bioinspired materials," such as wetsuits.
“We are particularly interested in wetsuits for surfing, where the athlete moves frequently between air and water environments,” says Anette (Peko) Hosoi, a professor of mechanical engineering and associate head of the department at MIT. “We can control the length, spacing, and arrangement of hairs, which allows us to design textures to match certain dive speeds and maximize the wetsuit's dry region.”
3. Burr = Velcro
Velcro The name Velcro, a common hook-and-loop fastener, comes from the French words for velvet, “velour,” and hook, “crochet”. In the early 1940s, Swiss engineer George de Mastral noticed the tendency of the fruit of the burr (Xanthium strumarium) to stick to dog’s hair and used a microscope to observe the hooks on the fruit which attach to animal hair. He discovered that an elliptical fruit with a length of 1 cm had densely packed hook-like projections. These latched onto peoples’ clothing or animals’ hair, allowing seeds to be dispersed widely. Inspired by this burr, de Mastral used nylon to create velcro fasteners. To enhance adhesive abilities, velcro consists of a strip with round loops and a strip with burr-like hooks. For its small surface area, velcro has exceptional adhesive strength and is used extensively as a simple and practical substitute for buttons or hooks in clothing and shoes.
4. Whale = Turbine
Whales have been swimming around the ocean for a long time, and evolution has crafted them into a super-efficient form of life. They are able to dive hundreds of feet below the surface and stay there for hours. They sustain their massive size by feeding on animals smaller than the eye can see, and they power their movement with über-efficient fins and a tail.
Scientists at Duke University, West Chester University and the U.S. Naval Academy discovered that the bumps at the front edge of a whale fin greatly increase its efficiency, reducing drag by 32 percent and increasing lift by 8 percent. Companies are applying the idea to wind turbine blades, cooling fans, airplane wings and propellers.
5. Aircraft
The emergence of airplanes realized the age-long dream of mankind to fly, but it was also a groundbreaking form of transportation. The basic structure of the wings of airplanes consists of a differing sized curved surface on the upper and lower part of the wing that creates hydrodynamic forces explained by the Bernoulli effect. Through this hydrodynamic structure, the velocity of the airstream is faster on the upper part of the wings and slower on the bottom part of the wings. The higher pressure from the bottom of the wings and the speed of the plane enables the 100 ton airplane to fly. This was the principle that led the Wright brothers to succeed in their first flight, but it was also the result of numerous years of biomimetic research on the structure and design of birds’ wings and their feathers. Beyond individual birds, a flock of wild geese fly in a V formation, creating an ascending air current allowing those flying behind to fly with less effort. AIRBUS, a French aviation company, uses these principles to design their planes. Furthermore, birds that fly short and long distances have different feathers and shapes. These insights have been used to design airplanes that have to travel shorter and longer distances in a different manner.
6. Automobiles
Over the most recent decade, automobile design has not only had an influence on the exterior of cars, but also had an influence on their function. The economizing and energy efficient aspects of biomimetics have been adopted in cars as demonstrated by DaimlerChrysler’s prototype bionic concept car
The exterior of this car is based on the shape of the boxfish, making it stable and aerodynamic. The basic structure of this car consists of a large outward appearance and small wheels, and the design was evaluated through computer simulation to achieve a minimal stress concentration. This car has an average fuel efficiency of 70 mi/gal (23 km/L) and a maximum speed of 190 km/h, making it more fuel efficient than any existing car.
The front of the Japanese bullet train was inspired by a kingfisher’s beak, so that the sonic boom when the train exits a tunnel and air resistance can be minimized while acceleration and energy efficiency can be increased. This idea was taken from the observation that a kingfisher dives perpendicular to the surface of the water when hunting, causing minimal splashing. Since it simulated the rounded beak structure of the kingfisher, the Shinkansen also came to be known as the bullet train. Another example is SkinzWraps, a film inspired by the microprojections on shark skin to repel germs. The use of SkinzWraps in automobiles reduced car pollution and increased fuel efficiency by 18%–20%. It has also been applied to swimsuits, bringing better results for athletes.
7. Architecture
Biomimicry has the longest history of application in architecture. Previous biomimetic technologies are being used to this day and will be developed further. The most notable example of biomimetic architecture is the 6 m-tall termite’s nest in the African grasslands. These nests are built from soil, tree bark, sand, and termite saliva, yet they are firmer than concrete.
Biomimetics in biomedical engineering
With designs originating from organisms, biomimetics has facilitated and improved human life through many convenient products. In the future, biomimetics will have a greater impact through the combination of medicine, science, and biomedical engineering to treat diseases, physical disabilities, and wounds. Regenerative medicine and tissue engineering are particularly promising fields. Principles and functions of biomimetics that can be applied in biomedical engineering are derived from many sources, including how a lizard regenerates its tail and a buckhorn regenerates its horns every year, the adhesive, plegmatical, and regenerative properties of a spider web, and leukocyte adhesion/migration in inflammation.
An example would be a biocompatible medical bandage that can be made compatible with human tissue and integrated with a ubiquitous health care (U-health) system to get real time reports on the granular status of recovery or disease. A biocompatible, short-lived medical bandage or tape can be used to detect signals, allowing us to monitor heart attacks or myocardial infarction that cannot be monitored or detected using current medical devices. Such a bandage would also be compatible with our skin and result in fewer side effects and less irritation despite better attachment. Such function is derived from the foot hair of the gecko, as mentioned previously.
Next-generation biomimetics combines biology with other technology in solving problems. In particular, nanotechnology is becoming a key discipline that will be utilized to help understand the material and its structures along with accelerating development of secondary structure of proteins. Protein-functionalized nanoparticles, peptide-functionalized gold nanoparticles, and carbohydrate-functionalized nanoparticles are areas of nanotechnology that are finding biomimetic applications. Furthermore, biomimetic approaches may open up promising new fields. Various hybrid composites inspired by the nature have been fabricated and used as a template that can regulate biological processes in tissue engineering. Structural biomaterials such as bones or nacres are hierarchically constructed and organized. In order to elucidate the structural complexity of these biomaterials, studies have demonstrated the development of morphological structures of inorganic–organic hybrid materials to mimic biological and structural formations like sponge spicule formation or the nacre (brick-and-mortar) structure of mollusks.
Multifunctional fibrous scaffolds have been developed as native tissue architecture, which have high potential for bone regeneration. One group recently tested nanofibers as a scaffold made of poly D,L-lactide-co-trimethylene carbonate (PLMC). The biomimicking attributes of poly D,L-lactide-co-trimethylene carbonate nanofibers showed enhanced efficacies and efficiencies as scaffold materials for tissue repair and regeneration.
The integration of biomimetics in biomedical engineering is advancing technology in many ways. Painless syringe needles developed by Kansai University (Osaka, Japan) is one example of biomimetics meeting bioengineering to develop a new material to improve medical operations. This group modeled the structure of mosquito mouthparts that are able to extract blood from the host animal with the least amount of nerve irritation. Such needles are used to help diabetics or during surgery to help patients overcome fear of needles. They use a biodegradable polymer, polylactic acid, which makes the needles safer and more practical than traditional microsilicon needles. Such needles can be inserted at particular angles with certain sensitivity to result in painless insertion. Painless needles are a great example of significant contribution to advancement of biomimetics and biomedical engineering.
Conclusion
Biomimetics or biomimicry have been used and advanced even without formal research in many areas. Accumulating creative ideas as a foundation, mankind has accelerated the speed of development and evolution of civilization. However, such rapid industrialization has resulted in environmental pollution and a shortage of natural resources that is threatening the survival and future of humanity. As a result, it has become critical and urgent to find alternative methods to engineer materials, products, and services. Biomimetics is potentially the best method to help us cope with future development of civilization, environmental pollution, and resource shortage threats.
