Editing Biomimetics (section)

=== Optics ===
{{Further|Structural coloration|Patterns in nature|Bio-inspired photonics}}

[[Biomimetic material]]s are gaining increasing attention in the field of [[optics]] and [[photonics]]. There are still little known [[Bio-inspired photonics|bioinspired or biomimetic products]] involving the photonic properties of plants or animals. However, understanding how nature designed such optical materials from biological resources is a current field of research.

[[File:Macroscopic picture of a film of cellulose nanocrystal suspension cast on a Petri dish (diameter 3.5cm)..jpg|right|thumb|Macroscopic picture of a film of cellulose nanocrystal suspension cast on a [[Petri dish]] (diameter: 3.5cm)]]

==== Inspiration from fruits and plants ====
One source of biomimetic inspiration is from [[plant]]s. Plants have proven to be concept generations for the following functions; re(action)-coupling, self (adaptability), self-repair, and energy-autonomy. As plants do not have a centralized decision making unit (i.e. a brain), most plants have a decentralized autonomous system in various organs and tissues of the plant. Therefore, they react to multiple stimulus such as light, heat, and humidity.<ref name="journals.sagepub.com">{{Cite journal |last1=Speck |first1=Thomas |last2=Poppinga |first2=Simon |last3=Speck |first3=Olga |last4=Tauber |first4=Falk |date=2021-09-23 |title=Bio-inspired life-like motile materials systems: Changing the boundaries between living and technical systems in the Anthropocene |journal=The Anthropocene Review |volume=9 |issue=2 |language=en |pages=237–256 |doi=10.1177/20530196211039275 |s2cid=244195957 |issn=2053-0196|doi-access=free }}</ref>

One example is the carnivorous plant species ''[[Dionaea muscipula]]'' (Venus flytrap). For the last 25 years, there has been research focus on the motion principles of the plant to develop AVFT (artificial Venus flytrap robots). Through the movement during prey capture, the plant inspired soft robotic motion systems. The fast snap buckling (within 100&ndash;300&nbsp;ms) of the trap closure movement is initiated when prey triggers the hairs of the plant within a certain time (twice within 20&nbsp;s). AVFT systems exist, in which the trap closure movements are actuated via magnetism, electricity, pressurized air, and temperature changes.<ref name="journals.sagepub.com"/>

Another example of mimicking plants, is the ''[[Pollia condensata]],'' also known as the marble berry. The chiral [[self-assembly]] of cellulose inspired by the ''[[Pollia condensata]]'' berry has been exploited to make optically active films.<ref>{{Cite journal|last1=Vignolini|first1=Silvia|last2=Rudall|first2=Paula J.|last3=Rowland|first3=Alice V.|last4=Reed|first4=Alison|last5=Moyroud|first5=Edwige|last6=Faden|first6=Robert B.|last7=Baumberg|first7=Jeremy J.|last8=Glover|first8=Beverley J.|last9=Steiner|first9=Ullrich|date=2012-09-25|title=Pointillist structural color in Pollia fruit|journal=Proceedings of the National Academy of Sciences|volume=109|issue=39|pages=15712–15715|doi=10.1073/pnas.1210105109|issn=0027-8424|pmc=3465391|pmid=23019355|bibcode=2012PNAS..10915712V|doi-access=free}}</ref><ref>{{cite journal|last1=Dumanli|first1=A. G.|last2=van der Kooij|first2=H. M.|last3=Reisner|first3=E.|last4=Baumberg|first4=J.J.|last5=Steiner|first5=U.|last6=Vignolini|first6=Silvia|date=2014|title=Digital color in cellulose nanocrystal films|journal=ACS Applied Materials & Interfaces|volume=7|issue=15|pages=12302–12306|doi=10.1021/am501995e|pmid=25007291|pmc=4251880}}</ref> Such films are made from cellulose which is a biodegradable and biobased resource obtained from wood or cotton. The structural colours can potentially be everlasting and have more vibrant colour than the ones obtained from chemical absorption of light. ''[[Pollia condensata]]'' is not the only fruit showing a structural coloured skin; iridescence is also found in berries of other species such as ''[[Margaritaria nobilis]]''.<ref>{{Cite journal|last1=Vignolini|first1=Silvia|last2=Gregory|first2=Thomas|last3=Kolle|first3=Mathias|last4=Lethbridge|first4=Alfie|last5=Moyroud|first5=Edwige|last6=Steiner|first6=Ullrich|last7=Glover|first7=Beverley J.|last8=Vukusic|first8=Peter|last9=Rudall|first9=Paula J.|date=2016-11-01|title=Structural colour from helicoidal cell-wall architecture in fruits of Margaritaria nobilis|journal=Journal of the Royal Society Interface|volume=13|issue=124|pages=20160645|doi=10.1098/rsif.2016.0645|issn=1742-5689|pmc=5134016|pmid=28334698}}</ref> These fruits show [[Iridescence|iridescent]] colors in the blue-green region of the visible spectrum which gives the fruit a strong metallic and shiny visual appearance.<ref name=":0">{{Cite journal|last1=Vignolini|first1=Silvia|last2=Moyroud|first2=Edwige|last3=Glover|first3=Beverley J.|last4=Steiner|first4=Ullrich|date=2013-10-06|title=Analysing photonic structures in plants|journal=Journal of the Royal Society Interface|volume=10|issue=87|pages=20130394|doi=10.1098/rsif.2013.0394|issn=1742-5689|pmc=3758000|pmid=23883949}}</ref> The structural colours come from the organisation of cellulose chains in the fruit's [[Fruit anatomy|epicarp]], a part of the fruit skin.<ref name=":0" /> Each cell of the epicarp is made of a multilayered envelope that behaves like a [[Bragg reflector]]. However, the light which is reflected from the skin of these fruits is not polarised unlike the one arising from man-made replicates obtained from the self-assembly of cellulose nanocrystals into helicoids, which only reflect left-handed [[Circular polarization|circularly polarised light]].<ref>{{Cite journal|last1=Parker|first1=Richard M.|last2=Guidetti|first2=Giulia|last3=Williams|first3=Cyan A.|last4=Zhao|first4=Tianheng|last5=Narkevicius|first5=Aurimas|last6=Vignolini|first6=Silvia|last7=Frka-Petesic|first7=Bruno|date=2017-12-18|title=The Self-Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance|journal=Advanced Materials|volume=30|issue=19|pages=1704477|doi=10.1002/adma.201704477|pmid=29250832|issn=0935-9648|url=https://www.repository.cam.ac.uk/bitstream/1810/275165/1/Accepted%20Manuscript.pdf|doi-access=free}}</ref>

The fruit of ''[[Elaeocarpus angustifolius]]'' also show structural colour that come arises from the presence of specialised cells called iridosomes which have layered structures.<ref name=":0" /> Similar iridosomes have also been found in ''[[Delarbrea]] michieana'' fruits.<ref name=":0" />

In plants, multi layer structures can be found either at the surface of the leaves (on top of the epidermis), such as in ''[[Selaginella willdenowii]]''<ref name=":0" /> or within specialized intra-cellular [[organelle]]s, the so-called iridoplasts, which are located inside the cells of the upper epidermis.<ref name=":0" /> For instance, the rain forest plants Begonia pavonina have iridoplasts located inside the epidermal cells.<ref name=":0" />

Structural colours have also been found in several algae, such as in the red alga ''[[Chondrus crispus]]'' (Irish Moss).<ref>{{Cite journal|last1=Chandler|first1=Chris J.|last2=Wilts|first2=Bodo D.|last3=Vignolini|first3=Silvia|last4=Brodie|first4=Juliet|last5=Steiner|first5=Ullrich|last6=Rudall|first6=Paula J.|last7=Glover|first7=Beverley J.|last8=Gregory|first8=Thomas|last9=Walker|first9=Rachel H.|date=2015-07-03|title=Structural colour in Chondrus crispus|journal=Scientific Reports|volume=5|issue=1|pages=11645|doi=10.1038/srep11645|pmid=26139470|pmc=5155586|issn=2045-2322|bibcode=2015NatSR...511645C}}</ref>

==== Inspiration from animals ====
[[File:Morpho didius Male Dos MHNT.jpg|thumb|alt=Morpho butterfly.|The vibrant blue color of ''[[Morpho (genus)|Morpho]]'' butterfly due to [[structural coloration]] has been mimicked by a variety of technologies.]]

[[Structural coloration]] produces the rainbow colours of [[soap bubble]]s, butterfly wings and many beetle scales.<ref>{{Cite journal |last1=Schroeder |first1=Thomas B. H. |last2=Houghtaling |first2=Jared |last3=Wilts |first3=Bodo D. |last4=Mayer |first4=Michael |date=March 2018 |title=It's Not a Bug, It's a Feature: Functional Materials in Insects |journal=Advanced Materials |volume=30 |issue=19 |pages=1705322 |doi=10.1002/adma.201705322 |pmid=29517829|bibcode=2018AdM....3005322S |doi-access=free |hdl=2027.42/143760 |hdl-access=free }}</ref><ref>{{Cite journal|last1=Schenk |first1=Franziska |last2=Wilts |first2=Bodo D. |last3=Stavenga |first3=Doekele G|date=November 2013 |title=The Japanese jewel beetle: a painter's challenge|journal=Bioinspiration & Biomimetics |volume=8 |issue=4 |pages=045002 |doi=10.1088/1748-3182/8/4/045002 |pmid=24262911|bibcode=2013BiBi....8d5002S |s2cid=41654298 }}</ref> Phase-separation has been used to fabricate ultra-[[white]] [[scattering]] membranes from [[polymethylmethacrylate]], mimicking the [[beetle]] ''[[Cyphochilus]]''.<ref>{{cite journal |last1=Syurik |first1=Julia |last2=Jacucci |first2=Gianni |last3=Onelli |first3=Olimpia D.<!--self-citing author-->|last4=Holscher |first4=Hendrik |last5=Vignolini |first5=Silvia |date=22 February 2018 |title=Bio-inspired Highly Scattering Networks via Polymer Phase Separation |journal=Advanced Functional Materials |volume=28|issue=24 |pages=1706901 |doi=10.1002/adfm.201706901|doi-access=free }}</ref> [[light-emitting diode|LED]] lights can be designed to mimic the patterns of scales on [[firefly|fireflies]]' abdomens, improving their efficiency.<ref>{{cite web |url=https://cleantechnica.com/2013/01/09/brighter-leds-inspired-by-fireflies-efficiency-increased-by-55-percent/ |title=Brighter LEDs Inspired By Fireflies, Efficiency Increased By 55% |website=[[CleanTechnica]] |date=January 9, 2013 |first=James |last=Ayre |access-date=June 4, 2019}}</ref>

''[[Morpho (genus)|Morpho]]'' butterfly wings are structurally coloured to produce a vibrant blue that does not vary with angle.<ref name="Ball">{{cite journal |url=http://www.nature.com/scientificamerican/journal/v306/n5/full/scientificamerican0512-74.html |journal=Scientific American |author=Ball, Philip |date=May 2012 |title=Nature's Color Tricks |volume=306 |issue=5 |pages=74–79 |doi=10.1038/scientificamerican0512-74|doi-broken-date=1 November 2024 |pmid=22550931 |bibcode=2012SciAm.306e..74B }}</ref> This effect can be mimicked by a variety of technologies.<ref>{{Cite journal |last1=Song |first1=Bokwang |last2=Johansen |first2=Villads Egede |last3=Sigmund |first3=Ole |last4=Shin |first4=Jung H. |date=April 2017 |title=Reproducing the hierarchy of disorder for Morpho-inspired, broad-angle color reflection |journal=Scientific Reports |volume=7 |issue=1 |pages=46023 |doi=10.1038/srep46023 |pmid=28387328 |pmc=5384085|bibcode=2017NatSR...746023S }}</ref> [[Lotus Cars]] claim to have developed a paint that mimics the ''Morpho'' butterfly's structural blue colour.<ref>{{Cite web|url=https://discoverlexus.com/highlights/structural-blue-color-reimagined|title=Structural Blue: Color Reimagined / Discover the Global World of Lexus|website=discoverlexus.com|access-date=25 September 2018}}</ref> In 2007, [[Qualcomm]] commercialised an [[interferometric modulator display]] technology, "Mirasol", using ''Morpho''-like optical interference.<ref>{{cite web |url=https://www.qualcomm.com/blog/2010/01/07/nature-knows-best |title=Nature Knows Best: What Burrs, Geckos and Termites Teach Us About Design |last1=Cathey |first1=Jim |date=7 January 2010 |publisher=Qualcomm |access-date=24 August 2015}}</ref> In 2010, the dressmaker Donna Sgro made a dress from [[Teijin|Teijin Fibers]]' [[Morphotex]], an undyed fabric woven from structurally coloured fibres, mimicking the microstructure of ''Morpho'' butterfly wing scales.<ref>{{cite news |last1=Cherny-Scanlon |first1=Xenya |title=Seven fabrics inspired by nature: from the lotus leaf to butterflies and sharks |url=https://www.theguardian.com/sustainable-business/sustainable-fashion-blog/nature-fabrics-fashion-industry-biomimicry |access-date=23 November 2018 |work=The Guardian |date=29 July 2014}}</ref><ref>{{cite web |last1=Sgro |first1=Donna |title=About |url=https://donnasgro.com/Morphotex-Dress |publisher=Donna Sgro |access-date=23 November 2018}}</ref><ref>{{cite web |last1=Sgro |first1=Donna |title=Biomimicry + Fashion Practice |url=https://docs.google.com/file/d/0B6_GqbK7TV1pSXp4Q3MweUcwbUE/edit |publisher=Fashionably Early Forum, National Gallery Canberra |access-date=23 November 2018 |pages=61–70 |date=9 August 2012}}</ref><ref>{{cite web |website=Teijin Japan |title=Annual Report 2006 |url=https://www.teijin.com/ir/library/annual_report/pdf/ar_06_all.pdf |archive-url=https://web.archive.org/web/20181123154355/https://www.teijin.com/ir/library/annual_report/pdf/ar_06_all.pdf |archive-date=2018-11-23 |access-date=23 November 2018 |date=July 2006 |quote=MORPHOTEX, the world's first structurally colored fiber, features a stack structure with several tens of nano-order layers of polyester and nylon fibers with different refractive indexes, facilitating control of color using optical coherence tomography. Structural control means that a single fiber will always show the same colors regardless of its location.}}</ref><ref>{{cite news |title=Morphotex |url=http://transmaterial.net/morphotex/ |website=Transmaterial |access-date=23 November 2018 |date=12 October 2010}}</ref>

[[Canon Inc.]]'s SubWavelength structure Coating uses wedge-shaped structures the size of the wavelength of visible light. The wedge-shaped structures cause a continuously changing refractive index as light travels through the coating, significantly reducing [[lens flare]]. This imitates the structure of a moth's eye.<ref>{{Cite web|url=https://cpn.canon-europe.com/content/education/technical/subwavelength_coating.do|title=SubWavelength Structure Coating|first=Canon Europa N. V. and Canon Europe|last=Ltd 2002-2017|website=Canon Professional Network|access-date=2019-07-24|archive-date=2020-07-30|archive-url=https://web.archive.org/web/20200730125716/https://cpn.canon-europe.com/content/education/technical/subwavelength_coating.do|url-status=dead}}</ref><ref>{{Cite web|url=https://cpn.canon-europe.com/content/education/infobank/lenses/subwavelength_coating.do|title=SubWavelength structure Coating|first=Canon Europa N. V. and Canon Europe|last=Ltd 2002-2017|website=Canon Professional Network|access-date=2019-07-24|archive-date=2020-07-30|archive-url=https://web.archive.org/web/20200730080939/https://cpn.canon-europe.com/content/education/infobank/lenses/subwavelength_coating.do|url-status=dead}}</ref> Notable figures such as the Wright Brothers and Leonardo da Vinci attempted to replicate the flight observed in birds.<ref>{{Cite book|last1=Kulkarni|first1=Amogh|last2=Saraf|first2=Chinmay|title=2019 IEEE Pune Section International Conference (PuneCon) |chapter=Learning from Nature: Applications of Biomimicry in Technology |date=December 2019|pages=1–6|publisher=IEEE|doi=10.1109/punecon46936.2019.9105797|isbn=978-1-7281-1924-3|s2cid=219316015}}</ref> In an effort to reduce aircraft noise researchers have looked to the leading edge of owl feathers, which have an array of small finlets or [[rachis]] adapted to disperse aerodynamic pressure and provide nearly silent flight to the bird.<ref>{{Cite news|last=Stevenson|first=John|date=November 18, 2020|title=Small finlets on owl feathers point the way to less aircraft noise|work=[[Phys.org]]|url=https://phys.org/news/2020-11-small-finlets-owl-feathers-aircraft.html|access-date=November 20, 2020}}</ref>