{"46258":{"#nid":"46258","#data":{"type":"news","title":"Scientists Unlock Optical \u0026 Chemical Secrets of Jeweled Beetles","body":[{"value":"\u003Cp\u003EA small green beetle may have some interesting lessons to teach scientists about optics and liquid crystals -- complex mechanisms the insect uses to create a shell so strikingly beautiful that for centuries it was used in jewelry.\u003C\/p\u003E\n\u003Cp\u003EIn an article published in the July 24 issue of the journal \u003Cem\u003EScience\u003C\/em\u003E, researchers provide a detailed analysis of how the jeweled beetle \u003Cem\u003EChrysina gloriosa \u003C\/em\u003Ecreates the striking colors using a unique helical structure that reflects light of two specific colors -- and of only one polarization: left circular polarization.  The reflecting structures used by the beetle consist predominately of three different polygonal shapes whose percentages vary with the curvature of the insect\u0027s shell.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022Iridescent beetles, butterflies, certain sea organisms and many birds derive their unique colors from the interaction of light with physical structures on their external surfaces,\u0022 said Mohan Srinivasarao, a professor in the School of Polymer, Textile and Fiber Engineering at the Georgia Institute of Technology.  \u0022Understanding how these structures give rise to the stunning colors we see in nature could benefit the quest for miniature optical devices and photonics.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EWith support from the National Science Foundation, Srinivasarao and colleagues Vivek Sharma, Matija Crne and Jung Ok Park used two different microscopy techniques to study the surface structures on the shell of the beetle.  What they found confirmed earlier suggestions that the colors are produced from liquid crystalline material, which self-assembles into a complex arrangement of polygonal shapes each less than 10 microns in size.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022When we looked at the beetle\u0027s surface, we found tiles in the shapes mostly of hexagons, pentagons and heptagons,\u0022 Srinivasarao said.  \u0022These patterns arise, we think, because of the nature of the cholesteric liquid crystal and how the liquid crystal phase structures itself at the interface between air and fluid.  We think these patterns result because the liquid crystal must have defects on the surface when exposed to air, and those defects create the patterns in the beetle\u0027s shell or exoskeleton.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EBecause of simple geometric restrictions, the percentage of each shape depends on the curvature of that particular section of the shell.  \u0022This is really a pattern formation issue,\u0022 said Srinivasarao.  \u0022It is difficult to pack only hexagons onto a curved surface.  On flat surfaces, there are fewer defects in the form of five- and seven-sided cells.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EIn addition, the five- and seven-sided cells normally appear in pairs, an issue also dictated by the geometric difficulties of packing the shapes onto curved surfaces.  The researchers found very similar structures in the ten different beetles purchased from an insect supply house.\n\u003C\/p\u003E\n\u003Cp\u003ELiquid crystalline materials are valuable industrially, used in displays for laptop computers, portable music players and other devices.  They are also used in children\u0027s thermometers, where temperature affects the color of light reflected from the material, indicating whether or not a child has a fever.\n\u003C\/p\u003E\n\u003Cp\u003EWhile the structures are determined genetically, their final form depends on the living conditions the beetle experiences during its growth and development, Srinivasarao noted.\n\u003C\/p\u003E\n\u003Cp\u003EThe fact that these jeweled beetles reflect circular polarization was identified in the early 1900s by a Nobel Prize-winning physicist, A.A. Michelson, who hypothesized that the circular polarization might result from a \u0022screw structure\u0022 within the insect\u0027s cuticle, but he did not elaborate on it further.  The solidified structures produced from a cholesteric liquid crystal and its defects on the beetle\u0027s shell reflect bright green light with a wavelength of 530 nanometers mixed with yellow light in a wavelength of 580 nanometers.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022The most dramatic way to get saturated color is through what this beetle does with the circularly-polarized light,\u0022 Srinivasarao said.  \u0022The reflection is very metallic and angle-dependent, and this is due to the helical pitch of the cholesteric liquid crystal.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ESunlight normally contains light in equal quantities with a left circular polarization and a right circular polarization.  The jewel beetle\u0027s exoskeleton, however, reflects only light with a left circular polarization.  Only a few members of the scarab family of beetles reflect both polarizations.\n\u003C\/p\u003E\n\u003Cp\u003EHow the beetles benefit from the specific color and polarization isn\u0027t known for sure, but scientists speculate that the optical properties may confuse predators, causing them to misjudge the location of the insects -- or suggest that they may not be good to eat.  The colors may also help the insects find mates. \n\u003C\/p\u003E\n\u003Cp\u003EIn future research, Srinivasarao hopes to study other insects that use complex structures to create unique colors.  He believes that scientists still have a lot to learn by studying the optical structures of beetles and other insects.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022We are just now starting to catch up with what these beetles have been doing for many, many years,\u0022 he said.  \u0022There are hundreds of thousand of species, and the way they generate color is just stunning -- especially since it is all done with water-based systems, mostly based on the biopolymer chitin.  This is self-assembly at several levels, and we need to learn a lot more to duplicate what these insects do.\u0022\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Assistance\u003C\/strong\u003E: John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Abby Vogel (404-385-3364); E-mail: (\u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Assistance\u003C\/strong\u003E: Mohan Srinivasarao (404-894-9348); E-mail: (\u003Ca href=\u0022mailto:mohan.srinivasarao@ptfe.gatech.edu\u0022\u003Emohan.srinivasarao@ptfe.gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Research has applications in optics, liquid crystal displays"}],"field_summary":[{"value":"A small green beetle may have some interesting lessons to teach scientists about optics and liquid crystals -- complex mechanisms the insect uses to create a shell so strikingly beautiful that for centuries it was used in jewelry.","format":"limited_html"}],"field_summary_sentence":[{"value":"Scientists are learning the optical secrets of a small beetle"}],"uid":"27303","created_gmt":"2009-07-23 00:00:00","changed_gmt":"2016-10-08 03:03:14","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2009-07-23T00:00:00-04:00","iso_date":"2009-07-23T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"46259":{"id":"46259","type":"image","title":"Jeweled beetle","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Jeweled beetle","file":{"fid":"101050","name":"twq78748.jpg","image_path":"\/sites\/default\/files\/images\/twq78748.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/twq78748.jpg","mime":"image\/jpeg","size":932318,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/twq78748.jpg?itok=2z083pTI"}},"46260":{"id":"46260","type":"image","title":"Mohan Srinivasarao","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Mohan Srinivasarao","file":{"fid":"101051","name":"tlq78748.jpg","image_path":"\/sites\/default\/files\/images\/tlq78748.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tlq78748.jpg","mime":"image\/jpeg","size":1397177,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tlq78748.jpg?itok=d4QXF_uU"}},"46261":{"id":"46261","type":"image","title":"Jung Ok Park","body":null,"created":"1449174375","gmt_created":"2015-12-03 20:26:15","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Jung Ok Park","file":{"fid":"101052","name":"tqd78748.jpg","image_path":"\/sites\/default\/files\/images\/tqd78748.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tqd78748.jpg","mime":"image\/jpeg","size":1358978,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tqd78748.jpg?itok=hZl0XO23"}}},"media_ids":["46259","46260","46261"],"related_links":[{"url":"http:\/\/www.ptfe.gatech.edu\/directory\/faculty\/index.php?id=ms308","title":"Mohan Srinivasarao"},{"url":"http:\/\/www.ptfe.gatech.edu\/","title":"Georgia Tech"},{"url":"http:\/\/www.nsf.gov\/news\/newsmedia\/beetles\/","title":"National Science Foundation slideshow on beetles"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"141","name":"Chemistry and Chemical Engineering"},{"id":"145","name":"Engineering"},{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"7065","name":"beetle"},{"id":"3248","name":"crystals"},{"id":"7064","name":"iridescent"},{"id":"2768","name":"optics"},{"id":"7066","name":"polarize"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}