Don't just be inspired. Be bio-inspired

Human ingenuity has brought advances that have changed our lives immeasurably - but don’t let that fool you; we don’t know it all just yet

By mimicking the nano-structure of the lotus, we now have self-cleaning paints and sprays

If there is one defining feature of human kind, it is the unswerving confidence in the ingenuity of their own species. The almost universal belief that if there is a problem, then it will be us who are best suited to solve it. This is perhaps understandable - but ultimately, completely incorrect.

Technological leaps like the development of the steam engine, home computers and space travel undoubtedly bolstered our collective self confidence, but are we really the be all and end all of innovation? Can scientists and engineers solve any problem in a closed environment whilst ignoring processes that occur elsewhere?

The answer it seems is increasingly - no. Often, to best solve an engineering or scientific problem we need a little help from a technologist that has been in the game a lot longer than us. Mother Nature.

This is why the field of bio-inspiration is emerging as one of the most innovative areas of science today. Researchers and engineers in this field set out to harvest nature of its novel design solutions, and use its principles to engineer technical breakthroughs. And the approach is working. Self cleaning surfaces, powerful LEDs, adhesive tape and even novel computer algorithms are just some of the spoils of this research partnership with the natural world.

However, the solutions don’t always come easily. Often Nature’s answers are hidden out of sight in the nano-realm - a realm that scientists have had access to only relatively recently with the invention of the electron microscope and the subsequent advent of nanotechnology. It was this extra level of insight into the natural world that caused many to look to nature for solutions that were proving elusive.

Once natures underlying nano-structures started to become clear, this connection was perhaps inevitable explains Peter Forbes, author of The Gecko’s Foot – a look at bio-inspired materials. “Nature and technology have been seen as polar opposites by many, with nature as a comforting balm for gritty hard-edged city technology. But nature at the nano-level looks like…well, contemporary high technology and architecture!”

The advent of bio-inspiration has not only brought nature closer to high technology engineering, but it has also brought together scientists of differing specialties. Forbes explained to Laboratory News: “It is definitely a coming together of disciplines. Indeed that is the key. I visited a physicist in Exeter who had a lab full of butterflies!” He added: “You have to look beyond your own discipline to get the advantage. Good bio-inspirationists need to look everywhere.”

Perhaps the highest profile source of bio-inspiration is the humble gecko. For

The humble gecko could give us a spiderman suit

centuries people looked in wonder at the impressive ability of this reptile to walk upside down on almost any surface. But it wasn’t until 2000 that researchers in the US learned that, surprisingly, the gecko’s secret lay in one of the weakest forces in nature. A gecko’s foot is covered in around half a million minute hairs known as setae which can deform to fit a surface so exactly that contact is close enough for a molecular attraction known as the van der Waals force to come into play. Once the mechanism was uncovered, it seemed an ideal target for bio-inspirationists, especially since life wasn’t a pre-requisite for it to work. Kellar Autumn of Lewis and Clark College in the US, one of the principle researchers working on the gecko question, points out that a dead gecko will stay stuck to the wall for as long as you like. This is because the mechanism will work whenever you have enough fine hairs per unit area. With this discovery, geckos had given up nature’s sticky secret, and the mechanism for a super-adhesive material was in place, but to make it work scientists now needed a material that could act just like the gecko’s minute hairs. Enter nanotechnology.

Carbon nanotubes have been one of the hottest topics in nano-science in recent years, attracting the attention of scientists across many disciplines. So it wasn’t long before researchers realised that they would be ideal as artificial gecko hairs. And recent research indicates that they work like a charm, even outdoing the ability of the ever sticky gecko. A team at the University of Akron in the US used carbon nanotubes 10-20nm in diameter and 65μm in length deposited onto a quartz and silicon substrate and claim that the structure creates adhesion forces 200 times greater than gecko foot-hairs.

Despite this, super-adhesive suits allowing its wearers to climb any surface are not with us just yet. “This is a good example of actual benefits as a result of bioinspiration, but it does take a long time to develop technologies,” explains Forbes. “There was a lot of hype when the work on the gecko’s foot came out, with the media predicting Spiderman gloves for all. But of course things take time.”

In many ways the use of the gecko method sums up bio-inspiration perfectly. By understanding a natural solution to a problem, researchers were able not only to mimic that solution, but push it further and actually improve it. As Forbes puts it, “Bio-inspiration seeks to use nature’s principles to create things that evolution never achieved.”

A long standing debate has often raised the question as to who is the better technologist, nature or us. One unique ability that mankind can bring to the table is the ability to conceptualise a problem and envisage different solutions. Evolution proceeds as variations on a theme and must progress through incipient stages before a functional structure is complete. Human innovation can take leaps that are not bound by the small steps of natural selection and, importantly, can start from scratch if an idea is not working – a case of revolution rather than evolution. “We have the advantage in many ways. If a development is not working we can just stop and immediately redesign it,” explains Forbes.   

But solutions arrived at by natural selection are often more than just a good starting point in the search for answers to scientific problems. Nature has some tricks up its sleeve that just don’t need improving.

One of the clearest examples of taking a bio-inspired product to market is that of the ‘Lotus effect’. Lotus plants - flowering wetland plants native to Asia - have superhydrophobic surfaces, meaning that water droplets falling onto them bead up and roll off. These rolling droplets pick up small particles of dirt so that the lotus leaves are self cleaning - preventing the build up of dirt which would prevent efficient photosynthesis.
Wilhelm Barthlott, a botanist from the University of Bonn in Germany, first discovered that the effect arises because lotus leaves have a very fine surface structure and are coated with hydrophobic wax crystals of around 1nm in diameter. Surfaces that are rough on a nanoscale tend to be more hydrophobic than smooth surfaces because of the reduced contact area between the water and solid. In the lotus plant, the actual contact area is only 2-3% of the droplet-covered surface.
This nanostructure is essential to the self-cleaning effect - on a smooth hydrophobic surface, water droplets slide rather than roll and do not pick up dirt particles to the same extent.
Once this was understood, bio-inspired minds began twitching and soon a raft of self cleaning products boasted the ‘Lotus effect’ as their mode of operation. BASF's lotus-effect aerosol spray, for example, combines nanoparticles with hydrophobic polymers so that as it dries the coating develops a nanostructure – mimicking that of the lotus leaf - through self-assembly.
So, bio-inspired solutions can bring together millennia of natural selection and the power of the human mind, meaning perfectly suited solutions to specific problems can be found. But can it really be considered a discipline in its own right?
Well, the signs of a burgeoning academic growth area are certainly there. Several departments specialising in the subject have sprung up. The Poly-PEDAL lab at Berkeley University of California aims to understand the complete movement of an animal in order to construct ever more able robots. The BIRG (Biologically Inspired Robotics Group) at the Swiss Federal Institute of Technology has a similar goal but are hoping that the central nervous system will give them clues as to the best way to produce a robot that can effectively adapt to changing environments. There are also successful bioinspiration groups based at Reading and Leeds universities.
Perhaps the best marker for a new discipline is the presence of a peer reviewed journal. March this year saw the first issue of Bioinspiration & Biomimetics so all the signs are that bioinspiration is a subject in its own right. However, as Forbes points out, it really doesn’t matter what label the work is given as long as it is done.
“Really, weather the scientists working together are called a ‘bio-inspiration department’ or not is of no matter, as long as they are working together.”      
That, of course, is the crux of bio-inspiration. Not only must scientists and engineers look to nature, but also to experts in other fields. As is true for so many aspects of science and technology - collaboration really is the key.   

 

By Phil Prime, assistant editor, Laboratory News
Phil holds a degree in Neuroscience from Nottingham University and an NCTJ in journalism from City College, Brighton.