Inspired by nature: How biomimicry is enabling the design of more intelligent and sustainable systems

Increasingly, though, biomimicry (a design philosophy that builds on Mother Nature's own 3.8 billion-year R&D programme) is becoming an ever stronger influence on engineering design. From imitating the way geckos stick to walls or hummingbirds hover, the process of taking nature's best ideas and adapting them for human use is becoming increasingly common practice. There are a number of different approaches to biomimicry. One is to see nature's models and emulate its forms, processes, systems and strategies to solve human problems in a sustainable way. Another is to see nature as a measure; using an ecological standard to judge and measure the sustainability of innovations. The third approach is to see nature as a mentor, focusing not on what can be extracted from the natural world, but what can be learned from it. One company taking this latter approach is Festo, which has for some years encompassed the Bionic Learning Network, a co-operation between Festo and renowned universities, institutes and development companies, that takes principles from nature to inspire technology and industrial applications. Over the years, the Network has produced a number of eyecatching initiatives that have not only garnered publicity, but have also fed back technology and techniques into industry. These include a biomechatronic handling system modelled on an elephant's trunk and a pneumatic drive inspired by the fluidic muscle in the human arm. Elias Knubben, head of corporate bionic projects at Festo, says of this initiative: "In industry, criteria such as flexibility, weight and energy efficiency are acquiring increasing significance. Optimised over billions of years, nature shows in a variety of ways how maximum performance can be achieved while using minimal energy consumption and as few materials as possible. Our aim is not to copy nature, but to learn from it and take inspiration from its vast pool of highly efficient, smart solutions." One of the Bionic Learning Network's most recent developments is an innovative assistance system inspired by the strength and flexibility of the human hand. The ExoHand concept is a solution for future human-machine co-operation in industrial environments based on 'soft robotics' – robot systems that closer reflect biological organisms. It is designed to meet the challenge of an ageing population by functioning as an assistance system for assembly tasks in production. As a force feedback system, Festo claims it can extend people's scope of action in production environments and can also be used as a platform for the development of new applications in service robotics, as well as personal assistance systems. "Worn like a glove, the ExoHand is designed to support the human hand from the outside to reproduce the physiological degrees of freedom – the scope of movement resulting from the geometry of the joints," explains Knubben. "Eight double-acting pneumatic actuators move the fingers so that they can be opened and closed. For this purpose, non-linear control algorithms are implemented on a CoDeSys-compliant controller, which allows precise orientation of the individual finger joints. The forces, angles and positions of the fingers are tracked by sensors." According to Knubben, the fingers can be actively moved and their strength amplified with the operator's hand movements transmitted to the robotic hand in real time. The objectives are to enhance the strength and endurance of the human hand, to extend scope of action and to secure an independent lifestyle for users at an advanced age. Another recent innovation is the NanoForceGripper, which uses suction components modelled on the footpads of a gecko. A key component is a foil on the underside of the gripper with 29,000 adhesive elements per square centimetre. These sucker-like elements adhere securely and permanently to the surfaces of the object to be handled. This effect is due to extremely small intermolecular forces of attraction known as 'van der Waals forces'. A counteracting force 'peels' off the gripper using Festo's Fin Ray Effect (modelled on the tailfin of a fish). When this force is applied, the flat structure is deformed into a curved surface. The effective foil-coated gripping surface becomes increasingly small, and the gripped component is gently released. According to Knubben, the NanoForceGripper can grip especially delicate objects with a smooth surface such as glass using virtually no energy. "It's another example of how Festo is transferring nature's optimisation principles to develop new technological methods and innovation processes that can be put to use in automation," he says. Designing differently Festo is far from being the only body using nature as a model, however. Researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering have developed a cheap, biodegradable, biocompatible material called Shrilk, which they believe could one day provide a more environmentally-friendly alternative to plastic. Designed to replicate the exceptional strength, toughness and versatility of insect cuticle, the material is called Shrilk because it is composed of fibroin protein from silk and from chitin, which is commonly extracted from discarded shrimp shells. It is thin, transparent, flexible, and according to postdoctoral fellow Javier Fernandez, as strong as an aluminium alloy at half the weight. "A natural insect cuticle, such as that found in the rigid exoskeleton of a housefly or grasshopper, is uniquely suited to the challenge of providing protection without adding weight or bulk," Fernandez explains. "As such, it can deflect external chemical and physical strains without damaging the insect's internal components. Also remarkable is its ability to vary its properties, from rigid along the insect's body segments and wings to elastic along its limb joints." An insect cuticle is a composite material consisting of layers of chitin, a polysaccharide polymer and protein organised in a laminar, plywood-like structure. Mechanical and chemical interactions between these materials provide the cuticle with its unique mechanical and chemical properties. By studying these complex interactions and recreating this unique chemistry and laminar design in the lab, Fernandez and Wyss Institute director Donald Ingber were able to engineer a thin, clear film that has the same composition and structure. "A major benefit of Shrilk is its biodegradability," Fernandez comments. "Plastic's toughness and mouldability represented a revolution in materials science during the 1950s and '60s. Decades later, however, the material is raising questions about how appropriate it is for one-time applications such as plastic bags. The great thing about Shrilk is that not only will it degrade in landfill, but its basic components are used as fertiliser, so it will enrich the soil." In addition, Fernandez says Shrilk can be produced at a very low cost, since chitin is readily available as a shrimp waste product. It is also easily moulded into complex shapes, such as tubes. By controlling the water content in the fabrication process, the researchers have even been able to reproduce the wide variations in stiffness. These attributes could have multiple applications. As a cheap, environmentally-safe alternative to plastic, Fernandez says Shrilk could be used to make rubbish bags, packaging and nappies that degrade quickly. As an exceptionally strong, biocompatible material, it could also be used to suture wounds that bear high loads, such as in hernia repair, or as a scaffold for tissue regeneration. "When we talk about the Wyss Institute's mission to create bio-inspired materials and products, Shrilk is an example of what we have in mind," says Fernandez. "It has the potential to be both a stepping stone toward significant medical advances and a solution to some of today's most critical environmental problems." One such environmental problem, that of getting water to crops in areas of extreme drought, was addressed recently by Australian engineer Edward Linacre, whose beetle-inspired irrigation system won the 2011 James Dyson Award. Called Airdrop, the concept is a low-cost, self-powered pump and underpipes system designed to deliver water to the roots of crops in the most arid places on Earth. To create it, Linacre studied the Namib beetle's ability to survive by consuming the dew it collects on the skin of its back in the early mornings. He says: "The concept was born out of the droughts that have blighted Australian farmers. I found the solution in an unusual source – the Namib beetle. It lives in dry deserts, but produces water to drink by condensing liquid on its hydrophilic back." The Airdrop system mimics this survival technique by harvesting moisture from the air and turning it into condensation. A turbine intake drives air underground through piping that rapidly cools the air to the temperature of the soil, where it reaches 100% humidity and produces water. The water is then stored in an underground tank and pumped through to the roots of crops via sub-surface drip irrigation hosing. However, while Linacre makes no secret of the biological inspiration behind his design, he does sound a note of caution, pointing out that biomimicry is only the first step. "The natural world doesn't engineer conventional solutions to problems," he says. "Finding inspiration from nature is a great start, but it's only one part of the process. Once you have your idea, prototype, test and redesign – improving the design by going back to the drawing board again and again." Even so, there is little doubt that nature has much to teach engineers and inventors. As Sir James Dyson concluded when giving Linacre his award: "Biomimicry is a powerful weapon in any engineer's armoury. Airdrop shows how simple, natural principles like the condensation of water can be applied to good effect through skilled design and robust engineering." Spiderbot takes on hazardous missions A computer-controlled, 3D printed bionic robot modelled on the same principle that moves spider legs has been developed by a team from the Fraunhofer Institute for Manufacturing Engineering and Automation in Germany. Designed to track and relay emergency responders in hazardous situations, the novel eight legged prototype mimics the way a spider builds up high levels of body pressure to pump fluid into their limbs to extend them. Not only does the design give it the agility and stability of real spiders when getting around on the ground, it also features hydraulically operated drive bellows that serve as joints and allow it to jump. Like its biological counterpart, the spiderbot is extremely stable, keeping four of its legs on the ground at any one time while the remaining four legs turn and ready themselves for the next step. Diagonally-opposed members can also move simultaneously and bending the front pairs of legs pulls the robot's body along, while stretching the rear legs pushes it. To get it to jump, the researchers fitted the spiderbot's 8" legs and its body with pneumatically-operated elastic drive bellows that bend and extend its legs.The components required for locomotion, such as the control unit, valves and compressor pump, are all located in the robot's body, which can also be fitted with various measuring devices and sensors, depending on the application.