This PDF file contains the front matter associated with SPIE
Proceedings Volume 7401, including the Title Page, Copyright
information, Table of Contents, Introduction (if any), and the
Conference Committee listing.
Humans have always sought to imitate the human appearance, functions and intelligence. Human-like robots, which
for many years have been a science fiction, are increasingly becoming an engineering reality resulting from the
many advances in biologically inspired technologies. These biomimetic technologies include artificial intelligence,
artificial vision and hearing as well as artificial muscles, also known as electroactive polymers (EAP). Robots, such
as the vacuum cleaner Rumba and the robotic lawnmower, that don't have human shape, are already finding
growing use in homes worldwide. As opposed to other human-made machines and devices, this technology raises
also various questions and concerns and they need to be addressed as the technology advances. These include the
need to prevent accidents, deliberate harm, or their use in crime. In this paper the state-of-the-art of the ultimate
goal of biomimetics, the development of humanlike robots, the potentials and the challenges are reviewed.
Bio-Mimicking/Bio-Inspiration: How can we not be inspired by Nature? Life has evolved on earth over the last 3.5 to
4 billion years. Materials formed during this time were not toxic; they were created at low temperatures and low
pressures unlike many of the materials developed today. The natural materials formed are self-assembled,
multifunctional, nonlinear, complex, adaptive, self-repairing and biodegradable. The designs that failed are fossils.
Those that survived are the success stories. Natural materials are mostly formed from organics, inorganic crystals and
amorphous phases. The materials make economic sense by optimizing the design of the structures or systems to meet
multiple needs. We constantly "see" many similar strategies in approaches, between man and nature, but we seldom
look at the details of natures approaches. The power of image processing, in many of natures creatures, is a detail that is
often overlooked. Seldon does the engineer interact with the biologist and learn what nature has to teach us. The variety
and complexity of biological materials and the optical systems formed should inspire us.
Plants have evolved unusual tissue optical properties, not surprising as creatures of light. These are
astonishingly sophisticated, involving both micro- and nanostructures. Microstructures refract, scatter, and
channel light in plant tissues, to produce concentrations and gradients of light within, and to remove undesired
portions of the electromagnetic spectrum. Nanostructures use the different refractive indices of both cellulosic
walls and bi-lipid membranes to interfere with light, multiple layers producing intense constructive coloration
and reduced fluxes within tissues. In a tropical sedge now under analysis, structures may include silica.
Recently discovered surface diffraction gratings produce strong directionally sensitive coloration that assist in
pollinator visitation. Although some of these properties have obvious applications, most await appreciation by
creative scientists to produce new useful devices.
Multilayer interference phenomenon has been widely applied to various optical components that have highly
wavelength-selective properties in reflection and transmission. In nature, some animals also take advantage of
a similar mechanism for the coloration of their brilliant bodies. However, natural examples of multilayer thin-film
structure are often modified in some structural aspects, and the modifications have been found to cause
interesting optical effects. Recently, we found such an example, highly curved multilayer structure, in the wing
scale of the Madagascan sunset moth. In this paper, we report the extended study of this subject. First, we will
review the structural characteristics and various optical phenomena that occur on the wing of the moth. Second,
inspired by the coloration mechanism of the moth wing, we newly consider multilayer designs for the color plates
that change their colors depending on the analyzing direction of polarization.
Structural colors are non-pigment colors that originate from the scattering of light from ordered microstructures,
thin films, and even irregular arrays of scatterers. Examples include the flashing sparks of colors in opals and
the brilliant hues of some butterflies such as Morpho rhetenor. Structural colors arise in nature from one or more
of a palette of physical mechanisms that are now understood quite well and can be implemented industrially to
produce structurally colored paints, fabrics, and cosmetics.
A range of different beetles exhibits brilliant colours and metallic sheen. One of the most spectacular species is the
Plusiotis resplendens from Central America with gold metal appearance. The beetle shells are made from chitin and have
a number of unique properties that apart from spectacular aesthetic effects include metal sheen from non-metal surfaces
combined with electric and thermal insulation. The reflection mechanism has been studied by a number of authors and is
well understood. Basically there are 2 different reflection principles. One is the multilayer reflector where alternating
layers have high and low refractive index. The other is the Bouligand structure where birefringent chiral nanofibres are
organised in spiral structures. The paper describes work done to explore different approaches to mimic these structures
using polymer based materials and production methods that are suitable for more complex double curved geometry. One
approach is to use alternating layers of 2 different polymers applied by dipping and another is applying cholesteric liquid
crystals in paint. However, none of them can yet make the desired metal-looking free-form surfaces.
A variety of animals emit light, either for intraspecific signalling, for predator repulsion or for using their own
vision system in total darkness. As the design of light-emitting diodes has revealed, light extraction from a
high refractive index medium is difficult because transmission is limited by total internal reflection. Surface
roughness is needed to attempt avoiding this limitation. The optical structure of the bioluminescent organs
of fireflies is investigated and the possible role of inhomogeneities for improving the efficiency of the radiative
emission is considered. This analysis shows that the light extraction in this complex structure is essentially
doubled, compared to the extraction in a reference system consisting of an homogeneous chitinous medium
terminated by a flat surface. The inequal fitting of the scales and the lowering of the average refractive index in
the photocytes accounts for most of the improvement.
The biomimetic approach seeks to incorporate designs based on biological organisms into engineered technologies.
Biomimetics can be used to engineer machines that emulate the performance of organisms, particularly in instances
where the organism's performance exceeds current mechanical technology or provides new directions to solve existing
problems. For biologists, an adaptationist program has allowed for the identification of novel features of organisms
based on engineering principles; whereas for engineers, identification of such novel features is necessary to exploit them
for biomimetic development. Adaptations (leading edge tubercles to passively modify flow and high efficiency
oscillatory propulsive systems) from marine animals demonstrate potential utility in the development of biomimetic
products. Nature retains a store of untouched knowledge, which would be beneficial in advancing technology.
Viscous coupling between filiform hair sensors of insects and arthropods has gained considerable interest recently. Study
of viscous coupling between hairs at micro scale with current technologies is proving difficult and hence the hair system
has been physically scaled up by a factor of 100. For instance, a typical filiform hair of 10 μm diameter and 1000 μm
length has been physically scaled up to 1 mm in diameter and 100mm in length. At the base, a rotational spring with a
bonded strain gauge provides the restoring force and measures the angle of deflection of the model hair. These model
hairs were used in a glycerol-filled aquarium where the velocity of flow and the fluid properties were determined by
imposing the Reynolds numbers compatible with biological system. Experiments have been conducted by varying the
separation distance and the relative position between the moveable model hairs, of different lengths and between the
movable and rigid hairs of different lengths for the steady velocity flow with Reynolds numbers of 0.02 and 0.05. In this
study, the viscous coupling between hairs has been characterised. The effect of the distance from the physical
boundaries, such as tank walls has also been quantified (wall effect). The purpose of this investigation is to provide
relevant information for the design of MEMS systems mimicking the cricket's hair array.
The male of the beetle Hoplia coerulea is known for its spectacular blue-violet iridescence. The blue coloration
is caused by the presence of an interesting photonic structure inside the scales which cover the dorsal parts of
the insect's body. This structure can be described as the stacking of chitin plates supporting arrays of parallel
rods. The change of colour of this structure with humidity is investigated, as well as its response to some other
external conditions, such as mechanical strain.
The tissue engineering focuses on synthesis or regeneration of tissues and organs. The hierarchical structure of nearly all
porous scaffolds on the macro, micro- and nanometer scales resembles that of engineering foams dedicated for technical
applications, but differ from the complex architecture of long bone. A major obstacle of scaffold architecture in tissue
regeneration is the limited cell infiltration as the result of the engineering approaches. The biological cells seeded on the
three-dimensional constructs are finally only located on the scaffold's periphery. This paper reports on the successful
realization of calcium phosphate scaffolds with an anatomical architecture similar to long bones. Two base materials,
namely nano-porous spray-dried hydroxyapatite hollow spheres and tri-calcium phosphate powder, were used to
manufacture cylindrically shaped, 3D-printed scaffolds with micro-passages and one central macro-canal following the
general architecture of long bones. The macro-canal is built for the surgical placement of nerves or larger blood vessels.
The micro-passages allow for cell migration and capillary formation through the entire scaffold. Finally, the nanoporosity
is essential for the molecule transport crucial for signaling, any cell nutrition and waste removal.
Human teeth are anisotropic composites. Dentin as the core material of the tooth consists of nanometer-sized calcium
phosphate crystallites embedded in collagen fiber networks. It shows its anisotropy on the micrometer scale by its well-oriented
microtubules. The detailed three-dimensional nanostructure of the hard tissues namely dentin and enamel,
however, is not understood, although numerous studies on the anisotropic mechanical properties have been performed
and evaluated to explain the tooth function including the enamel-dentin junction acting as effective crack barrier. Small
angle X-ray scattering (SAXS) with a spatial resolution in the 10 μm range allows determining the size and orientation of
the constituents on the nanometer scale with reasonable precision. So far, only some dental materials, i.e. the fiber
reinforced posts exhibit anisotropic properties related to the micrometer-size glass fibers. Dental fillings, composed of
nanostructures oriented similar to the natural hard tissues of teeth, however, do not exist at all. The current X-ray-based
investigations of extracted human teeth provide evidence for oriented micro- and nanostructures in dentin and enamel.
These fundamental quantitative findings result in profound knowledge to develop biologically inspired dental fillings
with superior resistance to thermal and mechanical shocks.
In this paper we explore the issue of fire and explosion in natural phenomena with a view to biomimetic applications. We
study two examples. One area is the area of trees which use fire to propagate their seeds - the Monterey, Bishop and
Knobcone pine (all in the US Pacific Northwest) have this ability which means that the cones remain closed for long
periods of time. Some, such as the Knobcone will only open under high temperature such as in a fire. There are other
pines such as the Banksia (Australia) which also operate in the same way. It is possible that these material features could
have benefit to the community in developing fire proof materials.
Another example of fire and explosion in nature is the bombardier beetle. This insect has the remarkable ability that it
can resist an attacker with a powerful jet of hot, toxic fluid. It reacts small amounts of hydroquinone with hydrogen
peroxide in the presence of the catalysts catalase and peroxidase and the spray is then ejected from combustion chambers
in its rear end.
Recent work has demonstrated that certain parts of the anatomy are in fact inlet and outlet valves and that the intake and
exhaust valve mechanism involves a repeated (pulsating) steam explosion. The research has shown the characteristics of
these ejections and an experimental rig mimicking the major physics of the beetle ejection system has been built which
shows clearly the importance of the valve system for getting good spray characteristics.
Biological systems such as butterflies and beetles have developed highly elaborate photonic crystals to create their
striking coloration. Especially, examples of the weevil and longhorn families (Curculionidae and Cerambycidae,
respectively) possess a range of interesting three-dimensional photonic crystal structures operating at visible
wavelengths, including non-close-packed lattices of cuticular spheres and diamond-based architectures. A low-temperature
sol-gel bio-templating method was developed, to transform bio-polymeric photonic crystals into heat and
photo-stable silica and titania inorganic structures. The fabricated oxide-based structures display good structural and
The characteristic brilliant green iridescence of beetles of the species Lamprocyphus augustus arises from the elaborate
multidomain photonic structure of its exoskeleton. The conformal-evaporated-film-by-rotation (CEFR) technique was
used to conformally coat the exoskeletons of L. augustus specimen with GeOx thin films. The exoskeletal surface
structure was found to be accurately replicated at the micro-scale by the coatings. Moreover, the reflectance spectrums of
an uncoated exoskeleton and a conformally coated exoskeleton turned out to display comparable overall characteristics
in the visible and the near-infrared regimes, confirming that the structure of the exoskeleton was replicated with high
fidelity by the coating, thus preserving its optical functionality. An attempt to fabricate a freestanding replica of an
exoskeleton by immersion of a coated exoskeleton in an aqueous solution of orthophosphoric acid yielded encouraging
The eyes and wings of some species of moth are covered in arrays of subwavelength pillars that have been tuned
over millions of years of evolution to reflect as little sunlight as possible. We are investigating ways of exploiting
this to reduce reflection from the surfaces of silicon solar cells. Here, we report on the experimental realization
of biomimetic antireflective moth-eye arrays in silicon using a technique based on nanoimprint lithography and
dry etching. Areas of 1cm x 1cm have been patterned and analysis of reflectance measurements predicts a loss
in the performance of a solar cell of only 6.5% compared to an ideal antireflective coating. This compares well
with an optimized single layer Si3N4 antireflective coating, for which an 8% loss is predicted.
While technology relies on components defined in a fixed position on a rigid substrate, nature prefers soft substrates, and
allows components to move significantly during morphogenesis. Taking inspiration from biological fabrication, we have
developed a technique, called active polymer nanofabrication, which utilizes thermally active polymers to create
complex nanoplasmonic substrates designed for molecular detection. We demonstrate the ability of active polymer
nanofabrication to create ultra-dense nanoplasmonic prism arrays (plasmonic nanoflowers), and correlate changes in
array morphology with optical properties. We investigate the associated changes in local electromagnetic fields with
finite element analysis. Finally, we demonstrate the ability of active polymers to deform macroscopically while retaining
nanostructure morphology. We expect these properties will make active polymer nanofabrication useful for a wide range
of nanoplasmonic devices.