In addition to the NanoBio conference in San Francisco there is the European NanoBio Europe meeting in Grenoble. 

 As a merger of the NanoBioTec - Congress and Exhibition (Münster since 2001) and the NanoBiotechnologies X-France (Paris2001, Grenoble2003, Nice2005) we NanoBio-Europe we are proud to present the second annual international conference on Nanobiotechnology in Europe, the “NanoBio-Europe’06“.

Conference website

I am up in the air over whether this is biomimetic but it certainly is bioinspired. Mitchell Joachim of MITs Media lab leads a team that is designing a tree house. Not a house that will be put in a tree, but rather a living tree that will be sculpted into a house. Obviously a house that is also a tree will have radically innovative systems for all aspects of living. Water would be gathered in a roof-top trough and circulate by gravity through the house, where it would be used by the inhabitants, filtered through a garden, and purified in a pond containing bacteria, fish, and plants that consume organic waste. A composting system would treat human refuse. The main construction technique will be ‘pleaching’, weaving together growing branches to form various support and shelter structures. The only real drawback I see is that 10 years is the low end on an estimate for how long it will take to grow this house. Article

From the German pavilion at the 1967 Montreal Expo to swooping roofs on the Jeddah airport Frei Otto has added a new syntax to architecture. he has taken the sturdy geodesic shapes of Fuller (inspired by mathematics) and imbued them with a soaring lightness that reflects his close observation of nature. Frei wrote a book, that I cannot find, called ‘Biology and Building’ that explained his ideas on the imitation of living structure. He takes inspiration from spider webs, trabecular bone, and soap bubbles, always stretching the structure to the point where the viewer is nervous about integrity.  I like that he thinks ahead of technology and mathematics, as this quote from the liked article below illustrates. 

Article on Otto the prizewinner

The adhesive abilities of the gecko foot have long been a case study for the promise of biomimetics. Now scientists at UC Santa Barbara have taken the next step towards actually building stuff using the principles involved.

The fine hair adhesive system found in nature is capable of reversibly adhering to just about any surface. This dry adhesive, best demonstrated in the pad of the gecko, makes use of a multilevel conformal structure to greatly increase inelastic surface contact, enhancing short range interactions and producing significant amounts of attractive forces. Recent work has attempted to reproduce and test the terminal submicrometre ‘hairs’ of the system. Here we report the first batch fabricated multi-scale conformal system to mimic nature’s dry adhesive. The approach makes use of massively parallel MEMS processing technology to produce 20–150 μm platforms, supported by single slender pillars, and coated with ∼2 μm long, ∼200 nm diameter, organic looking polymer nanorods, or ‘organorods’. To characterize the structures a new mesoscale nanoindenter adhesion test technique has been developed. Experiments indicate significantly improved adhesion with the multiscale system. Additional processing caused a hydrophilic to hydrophobic transformation of the surface and testing indicated further improvement in adhesion.

I hope Adam has some more to say about the science behind this development.

The Bell Labs crew that has been looking at the optical properties of biological materials has mde an interesting observation about the skeleton of the same deep sea sponge featured in an earlier entry.  The same structural principals applied in building design seem to have shaped the sponge’s silicaeous skeleton.

For example, the fibers that comprise the sponge’s skeleton are arranged in a lattice, or open criss-cross pattern, reinforced by fibers that run diagonally in both directions inside alternate squares in the lattice. This construction technique is often found in high-rise buildings and free-standing bookshelves to counteract shear stress, which can easily collapse a non-reinforced square structure.

It is not uncommon for this story to be turned on its head - in a few months we may read that these building were inspired by the sponge skeleton.  The most interesting aspect of this story is not that the bioinspired one but rather that over a huge range of size scales (sponge to skyscraper) and in very different fluid media (water vs air) the dominant forces producing fracture lead to the same compromises and solutions. That seems unexpected.

Article

I have been looking hard for examples of actual bioinspired design with little success. This ‘green’ building in Harare, Zimbabwe, might be an example, though I would need to understand the inspirational process used by architect Mick Pearse.

Termites must maintain a very constant 87 degree F temperature in their mounds or the fungi they cultivate will not do well. They construct mounds that can tower over 10 feet in height and might contain several hundred thousand to millions of workers.  These desert insects are faced with a serious heating/cooling problem with no refuge to be found in technology.  They take advantage of the thermal inertia of their mound and the daily swing in air temperature to cool the mound 24/7.  At night, cool breezes flow in through myriad tunnel openeings to carry away heat left from the day.  As dawn breaks holes are patched in some places and open in others to ensure that the flow of air in the heat of the day follows a circuitous route from the bottom of the termitary to the top.  This allows the entering warm air to be cooled by the thermal mass of the lower quarters.  By constantly opening and closing vents to take advantage of breezes, and by maintaining a cool inner core to the mound the termites are able to keep a surprisingly even internal temperature.

The building in Harare is passively cooled: the architects saved 20% of the cost of the building by forgoing the imported A/C system.  There are few windows and the windows are well shaded from the sun, minimizing incoming radiated heat is a major design consideration.   Fans blow all the time moving air from outside to in through a carefully calibrated route that maximizes cooling of the incoming air during the day and cooling of the building by incoming air at night.  This works because of the warm/temperate climate, with 15 degree C temperature changes there is an opportunity every night to dump the heat fo the preceeding day.

So, the principals of passive heating and cooling are certainly practiced by termites, and this is the same ‘technology’ that the arcitects used..  Was the design really bioinspired? Or is it a case of a parallel drawn to the general technology of passive cooling after the fact? 

Web Site

The Molecular Motors Group at the has a really nice site (that includes the GIF above) with explanations of techniques and motivations in the world of molecular motors. The image above is remarkable because it shows single actin molecules, carrying a fluorescent tag, as they are pulled across a mat of myosin. Actin and myosin are the two molecules that interact to power muscular contraction. Actin is the passive player, being a polymeric protein with regularly spaced spots that myosin can get a grip. Myosin, which looks like a double headed golf club, grabs onto actin then changes conformation by acutely bending. Myosin then releases actin and grabs it at a site further along. It all looks rather like a frantic hand over hand tug of war. The whole reaction is powered by ATP the basic energy unit of life.

In this experiment myosin is attached to a plate and bathed in ATP rich fluid. Fluorescently labeled actin is then added and it is promptly yanked across the surface of the plate by the myosin. By measuring the speed of actin movement it is possible to learn the characteristics of different forms of myosin. When we find a few practical, interesting things to attach to these tiny motors it will be a great example of biomimetics.

Lab Website. 

While micro-electro-mechanical systems (MEMs) certainly claim some tiny motors, the really small stuff is all biological.  Motor molecules like dynein and kinesin shuttle material (proteins, vacuoles, organelles) from one place to another in the cell. At a slightly larger scale and longer distance scale actin and myosin interact to shorten muscle. I recently ran across a colleague’s website with wonderful images and explanations of some of these ‘molecular’ motors.  It is clear that this biomimetic technology in very close to paying off with product.

Steve Gross Lab Website 

Malcolm Gordon (UCLA) and Morrie Gharib (CalTech) organized a satellite symposium for the 2005 International Union of Physiological Sciences meeting on topics of interest tot he readers of this blog.  The two day meeting featured sessions on locomotion, muscle, internal flows and materials.  The diversity of presenters was quite spectacular - ranging from jellyfish swimming to spiders silk withs tops in between at robotic fish and flies.

Conference Website

One of the clearest examples of taking a biomimetic product to market is that of the ‘Lotus Effect‘ products. The basic principle as well as the fine details of design are based on the way that water rolls off the leaves of the lotus plant (Nelumbo nucifera). Pay attention to the time line, it is probably as good as it gets for moving biological understanding to commercial realization.

In the 1970’s Wilhelm Barthlott, now at the University of Bonn, Germany, noticed the dirt resistant properties of certain plant leaves. If you stop and think a moment, in spite of living in a dirt filled world, indeed, with their very roots in soil, plants seldom have much noticeable grime on their surfaces. This is a good thing since it would undoubtedly interfere with photosynthesis. This lack of dirt is not due to paucity of local grime but rather to the ease with which any water that hits the leaf washes away offending particles.

Dirt washes away because the surface of the some leaves, and the sacred lotus in particular, are very resistant to ‘wetting’. Wetting refers to the ability of a liquid droplet to spread out on a surface and depends on the properties of the substrate and the liquid. Wettability can be quantified by measuring the contact angle that a droplet forms with a surface. On a water wettable surface, say untreated wood, a droplet will lay out nearly flat with a very low contact angle. The same droplet on a newly waxed table stays drop-like and has a high contact angle. When water hits a wettable surface any dirt on the surface is jostled around then settles back on the surface. On the other hand when water hits an unwettable or hydrophobic surface the dirt becomes suspended in the water droplet and can’t get back to the surface. As the drop rolls it carries dirt with it.

Obviously this is not a completely novel idea. The reason we wax out cars is not that wax is a bullet-proof, scuff resistant coating, but rather that it makes it easier to wash dirt off and harder for dirt to stick. The secret to the lotus plant’s dirt busting is a bit more complicated than just wax, but wax is at the root of the solution. The leaves of the lotus are covered with a waxy secretion that repels water. The surface geometry of the wax further repels water. Tiny mounds of wax, on the micron size scale, serve to hold surface drops of water up above the leaf, increasing contact angle beyond that found on an unpatterned wax surface.

Barthlott patented the pattern of bumps in the hydrophobic surface and called it the Lotus Effect ™. The German paint company STO has introduced a paint with emulsified waxes that dries into a micro rough surface. This paint, Lotusan, will stay clean as long as there are regular applications of water. It is really only suitable for exterior use, but in that capacity it now has a 4 year track record. Of course the surface is subject to attack by the elements and I suspect that the oilier the local dirt the hard it is for Lotusan to stay clean. In fact, if Lotusan does get dirty it is problematic to clean it since rubbing it disturbs the micro-patterned surface ruining the self-cleaning properties.

Further products in late development or early commercialization are self cleaning roof tiles and a sprayable self cleaning coating.