1. Introduction
Like the ability of electron regulation of electronic semiconductors, the photonic analogs usually considered as photonic structure materials are regarded as essential for light manipulation [1, 2]. With particular designs of photonic structures, they are expected to achieve different far-field and near-field optical features and thus lead to a perspective in all-optical circuit [3]. Though humankind has entered the nano-scale realm several decades ago, it is still a hard task for engineers to explore novel optical functional devices due to the limited experiences and originalities on artificial photonic structures design and the desired optical features. Additionally, it is also great challenges to fabricate photonic structures, owing to their sub-optical-wavelength to sub-micron featured sizes, especially in a high dimensional way by nano-fabrication technologies today.
By contrast, nature are found to develop photonic structures millions of years before our initial attempts. Diversified photonic structures, most of which are sophisticated and hierarchic, are revealed in beetles, butterflies, sea animals and even plants in recent surveys [4–10]. The exhibited optical features are regarded to have particular biological functions such as signal communications, conspecific recognition, and camouflage, which are optimized under selection pressure. Naturally, the occurring photonic structures provide us ideal ‘blueprints’ on design and stimulate similar optical functional devices. Various fabrication methods of bio-inspired photonic structures are explored [11–16]. By chemical methods (e.g. Sol-Gel, colloidal crystallization, chemical systhesis), nanoimprint lithography and nanocasting, physical layer deposition (PLD), atomic layer deposition (ALD), and etc., bio-inspired photonic structures, their reverse counterparts, and applications are achieving greater success than ever before.
This Chapter will review the typical bio-inspired photonic structures and focus on the biomimetic fabrications, the corresponding optical functions and the prototypes of optical devices. It is organized as follows: four subsections are introduced in Section 2, in which each describes one catagory of bio-inspired optical functional devices. In every subsection, the nature prototype is introduced first, then followed by biomimetic fabrication methods and optical features of artificial analogs, finally closed on the bio-inspired optical devices. A brief perspective is given in Section 3.
2. Bio-inspired optical functional devices
2.1. Anti-reflection devices
2.1.1. Prototypes
In arthropodal animals such as butterflies, nipple arrays with typical spacing of optical wavelength or subwavelength are commonly found on surfaces of their compound eyes, which are believed helpful to the light-harvest efficiency of the biological visual system [17]. With optical impedance matching to the ambience, the light transmission are enhanced. Another analogous examples are the transparent wings of some lepidoptera insects like hawkmoths [18] and cicada [19] (Fig.1 (a)). The tapered pillars lead to gradual changes of refraction index in view of effective medium theory (Fig.1 (b)) and therefore play a key role in minimizing the reflection over broadband and large view angles. In order to physically explain the anti-reflection origin, the Fresnel equations are given as follows.
where
2.1.2. Bio-inspired fabrications
Inspired by nature, many efforts are made in exploring techniques for fabricating the anti-reflection nanostructures and a variety of methods, e.g., conformal evaporated-film-by-rotation (CEFR), colloidal lithography, self-masked dry etching, nanoimprint lithography (NIL), ALD and other approaches, are realized [16].
Oblique angle deposition (OAD) is usually employed to fabricate anisotropic film which is originated from the oblique growth of contained nanorods with a tilted angle to the substrate surface normal. The so-called CEFR method, which rotates the substrates at a high speed under OAD, leads to the straight growth of a dense array columns to substrate surface rather than helical structures which are formed under low rotation rate. That is, CEFR method is suitable for conformal replication of the photonic structure with a curved surface even under thick film deposition. With compound eyes of the fruit fly as bio-templates, it is reported artificial replica is successfully fabricated and hence similar optical features are inherited, respectively [22].
Many lithography techniques are applied for fabricating antireflection structures, among which colloidal lithography is amuch simpler approach [23]. With colloidal crystals asmasks, the silicon substrate is etched by reaction ion etching (RIE). During the fabrication duration, the colloidal spheres are etched by RIE gradually firstly, leading to a reduced transverse cross section of the spheres and thus an increasing exposure of the substrate. Attributed to the features of RIE, the etching rates of the apex and the junction parts of the spheres are not uniform, resulting in the etching morphology modification from frustum to cone arrays on the substrate finally [24].
Electron cyclotron resonance (ECR) plasma etching technique is employed by researchers to fabricate antireflection structures with much higher aspect ratio surfaces [25–27]. With the selected gas-mixture consisting of SiH4, CH4, Ar, and H2, one step and self-masked dry etching are realized for fabricating high density nanotip arrays on a 6-inch silicon wafer. The fabrication progress is illustrated in the schematic diagram of Fig. 2(a). In brief, SiC clusters, which size and density can be tuned via process temperature, gas pressure, and composition, are formed on surfaces of the silicon substrate due to the reaction of SiH4 and CH4 plasma. Ar and H2 are responsible for the dry etching process. The SiC clusters then act as nanomasks or nanocaps to protect the underlying substrate frometching, thus forming an aperiodic array of silicon nanotips with their lengths varying from ∼1000 nm to ∼ 16
Avoiding time-consuming and complicated mask fabrication, scientists also attempt to directly use cicada wings or insect eyes as bio-templates [19, 28, 29]. For example, the nipple arrays on wing surfaces are stamped under certain pressure on glass-phase PMMA, which is at higher degree than its glass-transition temperature, supported by silicon wafer. A release process makes the polymer reverse nanostructures of the bio-templates. With the patterned PMMA as a mask or a mold, inverse or similar structures of the cicada wing are achieved by RIE or thermodeposition. A schematic diagram of the NIL, the fabricated structures, and the natural templates for comparison are illustrated in Fig. 3(a), Fig. 3(b), and Fig. 3(c), respectively. It is also worthy to note that an extra advantage of using bio-templates in NIL process is the notable low-surface-tension, which is vital for the release process, due to the wax layer commonly found on surfaces of plants and insects.
Taking advantages of accurate thickness control and three-dimensional (3D) fabrication of ALD, conformal replica is accomplished after ALD growth and sintering the hybrid structures with fly eyes as bio-templates, achieving similar anti-reflective features in the artificial analog finally [29].
2.1.3. Potential applications
Due to the high reflectance of silicon solar cells (more than 30%) induced by the high index contrast of silicon and air according to the Fresnel equations, scientists are already aware of the vital roles of high-quality antireflection coatings at early ages of solar cell fabrications [30]. Inspired by antireflection structures found in moth eyes, nanodomes or similar architectures are reproduced on surfaces of solar cells, leading to a dramatic light absorption increase and therefore a superior efficiency improvements than that of quarter-wavelength antireflection coating [31–33], as shown in Fig. 4(a) -(d). The recent theoretical investigations even report a high light trapping close to the Yablonovitch limit in the silicon solar cell by optimizing a double-sided antireflection structure design (Fig. 4(e) and (f))[34].
The biomimetic antireflection structures can also play a key role in light extraction of light-emitting devices (LEDs) [35–37]. Because of the total internal reflection and the waveguiding modes in the glass substrate, only about 20% amount of the generated light can irradiate from the LEDs. By fabricating silica cone arrays on the surfaces of the ITO glass substrate to modulate the above two bottleneck factors, the light luminance efficiency of white LEDs is significantly improved by a factor of 1.4 in the normal direction and even larger enhancement for large viewing angles.
Another fascinating application of the inspired antireflection structures is the use in the micro Sun sensor for Mars rovers [38]. On the basis of the recorded image by an active pixel sensor, the location coordinates of the rover can be calculated. However, the ghost image originating from the multiple internal reflection of the optical system leads to severe limitation of the accuracy. By fabricating dense nanotip arrays on the surfaces of the sensor, the internal reflection is minimized to be nearly 3 orders of magnitude lower than that of no treatments, resulting in a more reliable three-axis attitude information.
2.2. Color-tunable devices
2.2.1. Prototypes
Besides the well known coloration change strategy via migrations and volumes change of pigment granules such as chameleons, nature develops a second approach which is known as structural coloration change (SCC). By varying photonic structure characterizations, incident light angle, or the refraction index contrast of the color-produced optical system via the environmental stimuli, reversible coloration changes, which are basically passive, are revealed in fishes, beetles, and birds [39–46]. Most structural basis of SCC are attributed to the one-dimensional (1D) reflectors. For example, the damselfish
where
In biological system, high-dimensional photonic structures responsible for the coloration change are also discovered, though they are rare. An intriguing example is hercules beetles
2.2.2. Bio-inspired fabrications and applications
Due to the obvious appearance changes which are easy to be picked up with the naked eye, color-tunable devices are explored to identify the status changes by temperature, vapor, solvent, humidity in ambience, the applied mechanical force, electric field, magnetic field and etc. Besides the sensors, some novel writing system (’paper and ink’) are developed. The key idea is to modify period (
2.2.2.1.
Because of relatively simple control by the environmental stimuli and large spectral variation which can be recognized by the naked eye, approaches on the modulation of photonic structure period are always of scientist interests in obtaining tunable color applications.
’M-Ink’ is a mixture of colloidal nanocrystal clusters (CNCs), solvent and photocurable resin (Fig. 6(a)). With the superparamagnetic Fe3O4 nanocrystals encapsulated by silica shell, ’M-Ink’ can response to external magnetic fields. The role of the resin is to provide repulsive force which balances the attractive force of the CNCs. Without external magnetic fields, CNCs are randomly dispersed (infinite period) in liquid resin. The exhibited coloration is consistent with the magnetite, to be brown. After applying magnetic fields, the CNCs are assembled to form chain-like structures along the magnetic field lines (Fig. 6(b)). The additional magnetic force, the intrinsic force among the CNCs, and the repulsive force by resin establish dynamic balance with variation of the external magnetic fields, tuning the distance between the neighboring CNC (finite period). The switchable period then determines the color of the light diffracted from the CNC chain, leading to a full color show (Fig. 6(c)). The final step is to fix the desired coloration. After exposure to ultraviolet (UV) light at different exerted magnetic fields locations, the chain-like CNCs can be frozen in the solidified resin instantaneously, remaining the periods of the chains undistorted and accomplishing high-resolution color pattern fabrication (Fig. 6(d)) [57].
With similar principle, the electric field-driven tunable color sensor is also realized by highly charged polystyrene (PS) colloids which form non-close-packed face-centered cubic (fcc) lattice [58]. Tuning the period along [111] direction by the balance of the exerted electrostatic force and the repulsive force, the exhibited coloration changes as a result of the applied electric field. The so-called ’P-Ink’ is an electroactive material which consists of inverse opal inside polyferrocenylsilane (PFS) derivatives matrix. Such ink fabrication includes 3 primary steps: An opal film made of silica spheres is deposited onto glass substrate first by self-assembly; UV light is exposed to the sample in order to solidify the matrix and then form a stable PFS/silica composite; With diluted HF, inverse opal structure are realized in the elastomeric polymer matrix. By applying tunable voltage, macroscopic swelling and shrinking of the polymer matrix and microscopic Bravais lattice change responsible for the reverse coloration occur [59]. Stimulated by electrical forces, quite a few switchable coloration devices or sensors based on other materials or circumstances can be found elsewhere [60–62].
Many pressure-based photonic and even laser devices are reported [63–66]. Using monodispersed PS spheres to form cubic close packing (ccp) structures which are embedded in polydimethylsiloxane (PDMS) matrix, reverse colors are observed simply by stretching and releasing the rubber sheet. Upon mechanical stress, the lattice is elongated along the applied force direction, while the interplanar spacing in the perpendicular direction (i.e. distance between the (111) planes) decreases because of the nearly invariance volume of the rubber. The compressed distance leads to a blue-shift, e.g., from red to green [63]. Such opal rubber is believed to have practical applications such as a color indicator, tension meter or elongation strain sensor. The inverse opal structures (filled by air voids) in elastomer network are also synthesized [64, 67] (Fig. 7(a)). The porous elastomeric photonic crystals (EPCs) show highly reversible optical response to compressive force, e.g., 60 nm spectral blue-shift under a compressive pressure of ∼ 15 kPa in the structures having 350-nm void size. Although the coloration change can be attributed to the Bravais lattice deformability, like the mechanism mentioned before. However, it is especially noteworthy that porous EPCs remain nearly undeformed in orthogonal directions when an external pressure is exerted in one direction, which can be ascribed to the high filling factor of air voids. The air voids enable the distortion of the cross-sectional void spaces from roughly circular to elliptical shape and a reduction of the air volume fraction under pressure. The elastic deformation feature of such structures helps to reduce the redistribution of stress along lateral directions when compressed by a patterned surface, leading to novel biometric applications such as the fingerprint recognition devices, as shown in Fig. 7(b). Additionally, air voids of porous EPCs provide a platform to incorporate with other functional materials for us to explore new applications. For instance, filling PbS quantum dots in the air voids, the photoluminescence (PL) emission, which leads to many potential applications in the near-infrared region, can be modified by overlapping with the forbidden bandgap of the inverse opal structures (Fig. 7(c)).
The chemical solvents are also used to be as stimuli. An interesting example is invention of new type ’photonic paper/ink’ system [68, 69]. With novel soft materials consisting of closely packed PS and polymer elastomer (colloids and PDMS), the exhibited coloration can be altered reversely by immersing the materials into silicone liquid (’writing process’) and an evaporation process (‘erasing process’). The spacing between the (111) planes is adjusted by the strength of interaction between PDMS matrix and the contained silicone oligomers with different molecule weight in the liquid. With different solvents (’ink’), the swelling and shrinkage of the matrix showa featured reversible shift of Bragg diffraction peak. Amultilayer based on alternating Teflon-like layer and Au nanoparticle/Teflon-like layer composite layer operates not in visible but optical telecommunication wavelength range [70]. When the structure is exposed to different organic solvent vapor (e.g. acetone, ethanol, methanol, water, chloroform, and etc.), the molecules enter the metal/polymer composite inside the holes and microvoids in its structure, resulting in the swelling up, e.g., for acetone vapors at a molar fraction of 0.25, with an relative increase of 12.5% in thickness to an equilibrium state while leaving the Teflon-like layer unchanged due to its inert chemical features. The measured reflectance show a large variation of 0.2
Other external stimuli such as UV light, heat, or chemical reaction are applied to trigger and fabricate coloration sensitive materials as well by reversely controlling the spacing of the responsible photonic structures. Detailed information can be found in some references and recent reviews [14, 15, 61, 71–74].
2.2.2.2.
Besides
Besides infiltration, phase-transition materials can also induce refraction index variation and switchable coloration, providing the transition conditions are satisfied. The best-known phase-transition material maybe is liquid crystals (LCs). Above the phase-transition temperature of 34°, LCs change their nematic phase which is anisotropic to isotropic phase, leading to a significant change of refraction index and coloration, e.g., in inverse opal structures. By mixing the active material into LCs, sensitive reflection and polarization triggered by UV light are reported by a series of subsequent researches [77–79]. Besides LCs, various sensitive materials, including Ag2Se, W
2.2.2.3.
Iridescence is a characteristic of structural coloration, which is determined by band dispersions of photonic structures. With various incident angle or observation direction, the perceived coloration is changing. Hence, it is feasible to explore novel tunable color devices by tuning orientations of the photonic structures [84–86]. Just like the fish neon tetra
2.3. Structural color mixing and applications
2.3.1. Prototypes
Structural coloration results fromthe interaction of light and photonic structureswith featured size of visible wavelengths. It is even more widespread than pigmentary coloration in animal world. Some literatures have well reviewed the field comprehensively. In the Chapter, we do not plan to pay attention to the overall structural coloration but only focus on a specific subject ’structural color mixing’ [87–92]. In tiger beetles
2.3.2. Bio-inspired fabrications and applications
Structural coloration may be especially crucial for future color and related industry because of the non-fading feature (if the photonic structures are undeformed) [93, 94] and environmental friendliness. Naturally, structural coloration mixing inherits the advantages. Mimicking the nature, mixed structural color and its application can be obtained. For example, PS colloids with a diameter of 5
2.4. Other bio-inspired fabrications and applications
Besides the main categories, some other bio-inspired photonic applications are also reported [96–100]. For examples, the natural scales of
3. Perspectives
In the Chapter, several important kinds of bio-inspired photonic applications are reviewed, including antireflection devices, color-tunable sensors, structural color mixing applications and etc. The nature nourishes scientists the functional optical applications either the blueprints of photonic architecture or directly the bio-templates. Due to the higher index of inorganic materials used, the mimicking photonic structures even show better optical performances as well as enhanced mechanical properties of high temperature tolerance, stability and infrangibility. The biomimetic applications are anticipated to help our life better in the near future. However, complicated photonic structures (e.g. those of high-dimensional, hierarchic, amorphous features in nature) still remains hardly reproduced or, if they are fabricated successfully, the efforts involved are so great using the traditional fabrication ways that optical devices can not commercially explored. Thorough physical mechanism understanding as well as better fabrication approach explorations may help to simply the structure fabrications, achieve similar optical functions and realize commercial applications. In addition, adding substances such as functional chemical groups, fluorescence particles, metal, or other active materials, the mimicking photonic structures allow the properties of interest to be augmented, which may open a new window of novel optical device exploration. Although the photonic biomimicry is in its infancy, we believe that the bio-inspired optical device would surely have profound impacts on our modern society.
References
- 1.
Yablonovitch E. 1987 Inhibited Spontaneous Emission in Solid-State Physics and Electronics Phys. Rev. Lett.,58 - 2.
John S. 1987 Strong localization of photons in certain disordered dielectric superlattices Phys. Rev. Lett.,58 - 3.
Joannopoulos J. D. Johnson S. G. Winn J. N. Meade R. D. 2008 Photonic Crystals: Molding the Flow of Light, nd Ed. Princeton University Press, Princeton and Oxford, USA. - 4.
(Fox D. L. 1976 ). Animal Biochromes and Structural Colours, University of California Press, Berkeley, USA. - 5.
Srinivasarao M. 1999 Nano-Optics in the biological world: beetles, butterflies, birds, and moths Chem. Rev.,99 1935 EOF - 6.
Vukusic P. Sambles J. R. 2003 Photonic structures in biology. 424 852 EOF 5 EOF - 7.
Parker A. R. 2005 A geological history of reflecting optics J. R. Soc. Interface,2 - 8.
Seago A. Brady P. Vigneron-P J. Schultz T. D. 2009 Gold bugs and beyond: a review of iridescence and structural colour mechanisms in beetles (Coleoptera) J. R. Soc. Interface,6 S165-S184. - 9.
Shawkey M. D. Morehouse N. I. Vukusic P. 2009 A protean palette: colourmaterials and mixing in birds and butterflies. J. R. Soc. Interface,6 S221-S231. - 10.
Kinoshita S. Yoshioka S. 2005 Structural colors in nature: the role of regularity and irregularity in the structure. ChemPhysChem,6 1442 EOF 59 EOF - 11.
Parker A. R. Townley H. E. 2007 Biomimetics of photonic nanostructures. Nat. Nanotech.,2 347 EOF 53 EOF - 12.
Pulsifer D. P. Lakhtakia A. 2011 Background and survey of bioreplication techniques. Bioinsp. Biomim.,031001 - 13.
Chung-J W. Oh-W J. Kwak K. Lee B. Y. Meyer J. Wang E. Hexemer A. Lee-W S. 2011 Biomimetic self-templating supramolecular structures. 478 364 EOF 8 EOF - 14.
Fudouzi S. 2011 Tunable structural color in organisms and photonic materials for design of bioinspiredmaterials. Sci. Technol. Adv. Mater.,064704 - 15.
Zhao Y. Xie Z. Gu H. Zhu C. Gu Z. 2012 Bio-inspired variable structural color materials Chem. Soc. Rev.,41 3297 EOF 3317 EOF - 16.
(b Li. Y. Zhang J. Yang B. 2010 Antireflective surfaces based on biomimetic nanopillared arrays 5 117 EOF 127 EOF - 17.
Land M. F. Nilsson D. E. 2001 Animal Eyes Oxford University Press, Oxford, UK. - 18.
Yoshida A. Motoyama M. Kosaku A. Miyamoto K. 1997 Antireflective nanoproturberance array in the transparent wing of a hawkmoth Cephanodes hylas. Zool. Sci.,14 - 19.
Zhang G. Zhang J. Xie G. Liu Z. Shao H. 2006 Cicada wings: a stamp fromnature for nanoimprint lithography. Small,12 - 20.
(Born M. Wolf E. 1999 ). Principles of Optics, 7th Ed. Cambridge University Press, Cambridge, UK. - 21.
Xi J. Schubert Q. Kim M. F. Schubert J. H. Chen E. F. Lin M. Liu S. W. Smart J. A. 2007 Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection. Nat. Photon.,1 - 22.
Martín-Palma R. J. Pantano C. G. Lakhtakia A. 2008 Replication of fly eyes by the conformal-evaporated-film-by-rotation technique. 355704 - 23.
Yang-M S. 2006 Nanomachining by colloidal lithography. Small,4 458 EOF 75 EOF - 24.
Pearton S. J. Norton D. P. 2005 Dry etching of electronic oxides, polymers, and semiconductors. Plasma Process. Polym.,2 - 25.
Hsu C. Lo H. Chen C. Wu C. T. Hwang J. Das D. Tsai J. Chen L. Chen K. 2004 Generally applicable self-masked dry etching technique for nanotip arrayfabrication. Nano Lett.,3 - 26.
Hsu C. Huang Y. F. Chen L. C. Chattopadhyay S. Chen K. H. Lo H. C. Chen C. F. 2006 Morphology control of silicon nanotips fabricated by electron cyclotron resonanceplasma etching. J. Vac. Sci. Technol. B,1 - 27.
Huang Y. Huang Chattopadhyay. S. Jen Y. Peng C. Liu T. Hsu Y. Pan C. Lo H. Hsu C. Chang Y. Lee C. Chen K. Chen L. 2007 Improved broadband and quasi-omnidirectional anti-reflection propertieswith biomimetic silicon nanostructures. Nat. Nanotech.,2 - 28.
Gao H. Liu Z. Zhang J. Zhang G. Xie G. 2007 Precise replication of antireflective nanostructures from biotemplates. Appl. Ph ys. Lett.,12 - 29.
Huang J. Wang X. Wang Z. L. 2008 Bio-inspired fabrication of antireflection nanostructures by replicating fly eyes. 025602 - 30.
Green M. A. 1987 Higher Efficiency Silicon Solar Cells, Trans Tech Pub, Aedermannsdorf, Switzerland. - 31.
Zhao J. Green M. A. 1991 Optimized antireflection coatings for high-efficiency silicon solar cells IEEE Trans. Electron Devices,8 1925 EOF 1934 EOF - 32.
Zhu J. Hsu C. Yu Z. Fan S. Cui Y. 2010 Nanodome Solar Cells with Efficient Light Management and Self-Cleaning Nano Lett.,6 1979 EOF 1984 EOF - 33.
Chen H. L. Chuang S. Y. Lin C. H. Lin Y. H. 2007 Using colloidal lithography to fabricate and optimize sub-wavelength pyramidal and honeycomb structures in solar cells. Opt. Express,15 14793 EOF 803 EOF - 34.
Wang K. X. Yu Z. Liu V. Cui Y. Fan S. 2012 Absorption enhancement in ultrathin crystalline silicon solar cells with antireflection and light-trapping nanocone gratings Nano Lett.,3 1616 EOF 1619 EOF - 35.
Ishimori M. Kanamori Y. Sasaki M. Hane K. Xie G. 2002 Subwavelength antireflection gratings for light emitting diodes and photodiodes fabricated by fast atom beam etching Jpn. J. Appl. Phys.,41 4346 EOF 4349 EOF - 36.
(a Li. Y. Li F. Zhang J. Wang C. Zhu S. Yu H. Wang Z. Yang B. 2010 Improved light extraction efficiency of white organic light-emitting devices by biomimetic antireflective surfaces Appl. Phys. Lett.,153305 - 37.
Song Y. M. Choi E. S. Park G. C. Park C. Y. Jang S. J. Lee Y. T. 2010 Disordered antireflective nanostructures on GaN-based light-emitting diodes using Ag nanoparticles for improved light extraction efficiency Appl. Phys. Lett.,093110 - 38.
Lee C. Bae S. Y. Mobasser S. Manohara H. 2005 A novel silicon nanotips antireflection surface for the micro Sun sensor. Nano Lett.,12 2438 EOF 42 EOF - 39.
Cong H. Yu B. Zhao X. S. 2011 Imitation of variable structural color in paracheirodon innesi using colloidal crystal films. Opt. Express,13 12799 EOF 808 EOF - 40.
Hadley N. F. 1979 Wax secretion and color phases of the desert Tenebrionid beetle Cryptoglossa verrucosa (LeConte). Science,203 367 EOF 9 EOF - 41.
Mäthger L. M. Land M. F. Siebeck U. E. . Marshall N. J. 2003 Rapid colour changes in multilayer reflecting stripes in the paradise whiptail, Pentapodus paradiseus J. Exp. Biol.,206 - 42.
Mc Clain E. Seely M. K. Hadley N. F. Fray V. 1985 Wax blooms in Tenebrionid beetles of the Namib desert: correlations with environment 66 112 EOF - 43.
Jolivet P. 1994 Phsiological colour changes in tortoise beetles, In: Novel Aspect of the Biology of Chrysomelidae, Cox, M.L. & Petitpierre, E., (Eds.), page numbers (331-335), Kluwer Academic, Netherland. - 44.
Vigneron J. P. Pasteels J. M. Windsor D. M. Vertésy Z. Rassart M. Seldrum T. Dumont J. Deparis O. Lousse V. Biró L. P. Ertz D. . Welch V. 2007 Switchable reflector in the Panamanian tortoise beetle Charidotella egregia (Chrysomelidae: Cassidinae) Phys. Rev. E.,031907 - 45.
Mason C. W. 1929 Transient color changes in the tortoise beetles (Coleoptera: Chrysomelidae). Entomol. News,45 - 46.
Eliason C. M. Shawkey M. D. 2010 Rapid, reversible response of iridescent feather color to ambient humidity. Opt. Express,20 - 47.
Kasukawa H. Oshima N. Fujii R. 83 1 EOF 7 EOF - 48.
Kasukawa H. Oshima N. Fujii R. 1987 Mechanism of light reflection in blue damselfish motile iridophore. Zool. Sci.,4 - 49.
Oshima N. Fujii R. (1987 1987 Mobilemechanisms of blue damselfish (Chrysiptera cyanea) iridophores Cell Motil. Cytoskel.,8 - 50.
Liu F. Bong B. Q. Liu X. H. Zheng Y. M. Zi J. 2009 Structural color change in longhorn beetles Tmesisternus isabellae. Opt. Express,18 16183 EOF 91 EOF - 51.
Lythgoe J. N. Shand J. 1982 Changes in spectral reflexions from the iridophores of the neon tetra. J. Physiol.,325 - 52.
Oshima N. 2005 Light reflection in motile iridophores of Fish, In: Structural Colors in Biological Systemsa˛łPrinciples and Applications, Kinoshita, S. & Yoshioka, S., (Eds.), page numbers (211), Osaka University Press, Japan. - 53.
Yoshioka S. Matsuhana B. Tanaka S. Inouye Y. Oshima N. Kinoshita S. 2011 Mechanism of variable structural colour in the neon tetra: quantitative evaluation of the Venetian blind model J. R. Soc. Interface,8 56 EOF 66 EOF - 54.
Hinton H. E. Jarman G. M. 1972 Physiological colour change in the Hercules beetle 238 160 EOF 161 EOF - 55.
Hinton H. E. Jarman G. M. 1973 Physiological colour changes in the elytra of the Hercules beetles, Dynastes hercul es. J. Insect Physiol.,19 533 EOF 549 EOF - 56.
Rassart M. Colomer-F J. Tabarrant T. Vigneron J. P. 2008 Diffractive hygrochromic effect in the cuticle of the hercules beetle Dynastes hercules New J. Phys.,033014 - 57.
Kim H. Ge J. Kim J. Choi S. Lee H. Lee H. Park W. Yin Y. Kwon S. 2009 Structural colour printing using a magnetically tunable and lithographically fixable photonic crystal Nat. photon.,3 534 EOF 540 EOF - 58.
Shim T. S. Kim-H S. Sim J. Y. Lim-M J. Yang-M S. 2010 Dynamic Modulation of Photonic Bandgaps in Crystalline Colloidal Arrays Under Electric Field Adv. Mater.,22 4494 EOF 4498 EOF - 59.
Puzzo D. P. Arsenault A. C. Manners I. Ozin G. A. 2009 Electroactive Inverse Opal: A Single Material for All Colors. Angew. Chem., Int. Ed.,47 943 EOF 7 EOF - 60.
Arsenault A. C. Puzzo D. P. Manners I. Ozin G. A. 2007 Photonic-crystal full-colour displays. Nat. Photon.,1 - 61.
Walish J. J. Kang Y. Mickiewicz A. Thomas E. L. 2009 Bioinspired electrochemically tunable block copolymer full color pixels Adv. Mater.,21 3078 EOF 3081 EOF - 62.
Hwang K. Kwak D. Kang C. Kim D. Ahn Y. Kang Y. 2011 Electrically tunable hysteretic photonic gels for nonvolatile display pixels Angew. Chem., Int. Ed.,50 6311 EOF 6314 EOF - 63.
Fudouzi H. Sawada T. 2006 Photonic rubber sheets with tunable color by elastic defornmation. Langmuir,3 - 64.
Sumioka K. Kayashima H. Tsutsui T. 2002 Tuning the Optical Properties of Inverse Opal Photonic Crystals by Deformation Adv. Mater.,18 1284 EOF 1286 EOF - 65.
Fudouzi S. Kanai T. Sawada T. (2011 2011 Widely tunable lasing in a colloidal crystal gel film permanently stabilized by an ionic liquid. Adv. Mater.,33 - 66.
Arsenault A. C. Kitaev V. Manners I. Ozin G. A. Mihi A. Míguez H. 2005 Vapor swellable colloidal photonic crystals with pressure tunability J. Mater. Chem.,15 133 EOF 138 EOF - 67.
Arsenault A. C. Clark T. J. Freymann G. V. Cademartiri L. Sapienza R. Bertolotti J. Vekris E. Wong S. Kitaev V. Manners I. Wang R. Z. John S. Wiersma D. Ozin G. A. 2006 From colour fingerprinting to the control of photoluminescence in elastic photonic crystals Nat. Mater.,5 179 EOF 184 EOF - 68.
(a Fudouzi. H. Xia Y. 2003 Photonic papers and inks: color writing with colorless materials Adv. Mater.,11 892 EOF - 69.
(b Fudouzi. H. Xia Y. 2003 Colloidal crystals with tunable colors and their use as photonic papers Langmuir,23 9653 EOF - 70.
Convertino A. Capobianchi A. Valentini A. Emilio N. M. C. 2003 A new approach to organic solvent detection: high-reflectivity Bragg reflectors based on a gold nanoparticle/Teflon-like composite material Adv. Mater.,13 1103 EOF - 71.
Weissman J. M. Sunkara H. B. Tse A. S. Asher S. A. 1996 Thermally Switchable Periodicities and Diffraction from Mesoscopically Ordered Materials 5289 959 EOF - 72.
Holtz J. H. Asher S. A. 1997 Polymerized colloidal crystal hydrogel films as intelligent chemical sensing materials. 389 829 EOF 32 EOF - 73.
Hu Z. Lu X. Gao J. 2001 Hydrogel opals. Adv. Mater.,22 - 74.
Gates B. Park S. H. Xia Y. 2000 Tuning the photonic bandgap properties of crystalline arrays of polystyrene beads by annealing at elevated temperatures Adv. Mater.,9 653 EOF 656 EOF - 75.
Kim J. H. Moon J. H. Lee-Y S. Park J. 2010 Biologically inspired humidity sensor based on three-dimensional photonic crystals Appl. Phys. Lett.,103701 - 76.
Burgess I. B. Mishchenko L. Hatton B. D. Kolle M. Loncar M. Aizenberg J. 2011 Encoding complex wettability patterns in chemically functionalized 3D photonic crystals J. Am. Chem. Soc.,133 12430 EOF 12432 EOF - 77.
Kubo S. Gu Z. Z. Takahashi K. Ohko Y. Sato O. Fujishima A. 2002 Control of the optical band structure of liquid crystal infiltrated inverse opal by a photoinduced nematic-isotropic phase transition. J. Am. Chem. Soc.,124 10950 EOF 1 EOF - 78.
Kubo S. Gu Z. Z. Takahashi K. Fujishima A. Segawa H. Sato O. 2004 Tunable photonic band Gap crystals based on a liquid crystal-infiltrated inverse opal structure. J. Am. Chem. Soc.,126 8314 EOF 9 EOF - 79.
Kubo S. Gu Z. Z. Takahashi K. Fujishima A. Segawa H. Sato O. 2005 Control of the optical properties of liquid crystal-infiltrated inverse opal structures using photo irradiation and/or an electric field Chem. Mater.,17 2298 EOF 2309 EOF - 80.
Jeong U. Xia Y. N. 2005 Photonic crystals with thermally switchable stop bands fabricated from Se@Ag2Se spherical colloids. Angew. Chem., Int. Ed.,44 3099 EOF 103 EOF - 81.
Li B. Zhou J. Li L. Wang J. Liu X. H. Zi J. 2003 Ferroelectric inverse opals with electrically tunable photonic band gap. Appl. Phys. Lett.,83 - 82.
Kuai-L S. Bader G. Ashrit P. V. 2005 Tunable electrochromic photonic crystals.Appl. Phys. Lett.,221110 - 83.
Khalack J. Ashrit P. V. 2006 Tunable pseudogaps in electrochromic WO3 inverted opal photonic crystals. Appl. Phy s. Lett.,211112 - 84.
Kim S. Jeon S. Jeong W. C. Pank H. S. Yang S. 2008 Optofluidic Synthesis of Electroresponsive Photonic Janus Balls with Isotropic Structural Colors Adv. Mater.,21 4129 EOF 4134 EOF - 85.
Ge J. Lee H. He L. Kim J. Lu Z. Kim H. Goebl J. Kwon S. Yin Y. 2009 Magnetochromatic microspheres: rotating photonic crystals. J. Am. Chem. Soc.,43 - 86.
Kim J. Song Y. He L. Kim H. Lee H. Park W. Yin Y. Kwon S. 2011 Real-time optofluidic synthesis of magnetochromatic microspheres for reversible structural color patterning. Small,7 1163 EOF 8 EOF - 87.
Schultz T. D. Rankin M. A. 1985 The ultrastructure of the epicuticular interference reflectors of tiger beetles(Cicindela). J. Exp. Biol., 117 - 88.
Schultz T. D. Rankin M. A. (1989 1989 Schultz, T.D. & Bernard, G.D. (1989). Pointillistic mixing of interference colours in cryptic tiger beetles. Nature,337 - 89.
Berthier J. Boulenguez J. Balint Z. 2007 Multiscaled polarization effects in Suneve coronata (Lepidoptera) and other insects: application to anti-counterfeiting of banknotes Appl. Phys. A,1 123 EOF 130 EOF - 90.
Vukusic P. Sambles J. R. Lawrence C. R. 2000 Colour mixing in wing scales of a butterfly. 404 457 EOF - 91.
Liu F. Yin H. W. Dong B. Q. Qing Y. H. Zhao L. Meyer S. Liu X. H. Zi J. Chen B. 2008 Inconspicuous structural coloration in the elytra of beetles Chlorophila obscuripennis (Coleoptera). Phys. Rev. E,012901 - 92.
Liu F. Wang G. Jiang L. P. Dong B. Q. 2010 Structural colouration and optical effects in the wings of Papilio peranthus J. Opt.,065301 - 93.
Vinther J. Briggs D. E. G. Clarke J. Mayr G. Prum R. O. 2010 Structural coloration in a fossil feather Biol. Lett.,6 - 94.
Parker A. R. 2000 515 million years of structural colour J. Opt. A: Pure Appl. Opt.,2 R15 EOF R28 EOF - 95.
Kolle M. Salgard-Cunha P. M. Scherer M. Huang F. M. Vukusic P. Mahajan S. Baumberg J. J. Steiner U. (2010 2010 Mimicking the colourful wing scale structure of the Papilio blumei butterfly. Nat. Nanotechnol.,5 - 96.
Vukusic P. Kelly R. Hooper I. 2009 A biological sub-micron thickness optical broadband reflector characterized using both light and microwaves J. R. Soc. Interface,6 S193 EOF S201 EOF - 97.
Huang J. Wang X. Wang Z. L. 2008 Controlled replicaton of butterfly wings for achieving tunable photonic properties. Nano Lett.,10 - 98.
Biro L. P. Kertesz K. Horvath E. Mark G. I. Molnar G. Vertesy Z. Tsai J. Kun F. Bailint A. Z. Vigneron J. P. 2009 Bioinspired artificial photonic nanoarchitecture using the elytron of the beetle Trigonophorus rothschildi varians as a ‘blueprint’ J. R. Soc. Interface,47 - 99.
Liu F. Shi W. Z. Hu X. H. Dong B. Q. 2012 Hybrid structures and the optical effects in Morpho scales with thin and thick coatings using an atomic layer deposition method. Unpublished data. - 100.
Zhang W. Zhang D. Fan T. X. Gu J. J. Ding J. Wang H. Guo Q. Ogawa H. 2009 Novel Photoanode Srucure Templated from Butterfly Wing Scales. Chem. Mater.,1 - 101.
Potyrailo R. A. Ghiradella H. Vertiatchikh A. Dovidenko K. Cournoyer J. R. Olson E. 2007 Morpho butterfly wing scales demonstrate highly selective vapour response Nat. photon.,1 123 EOF 128 EOF - 102.
Liu F. Dong B. Q. Zhao F. Hu X. Liu X. Zi J. 2011 Ultranegative angular dispersion of diffraction in quasiordered biophotonic structures Opt. Express,8