{"id":129069,"date":"2023-07-11T07:35:00","date_gmt":"2023-07-11T05:35:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=129069"},"modified":"2023-07-06T09:24:15","modified_gmt":"2023-07-06T07:24:15","slug":"the-chameleon-effect","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/the-chameleon-effect\/","title":{"rendered":"The chameleon effect"},"content":{"rendered":"\n\n\n<p><strong>Researchers from Empa&#8217;s Cellulose &amp; Wood Materials laboratory have developed a cellulose-based material that allows just that. The mixture of hydroxpropyl cellulose with water, carbon nanotubes and cellulose nanofibrils changes color when heated or stretched \u2013 without the addition of any pigments.<\/strong><\/p>\n\n\n\n<div class=\"wp-block-image is-style-default\"><figure class=\"alignleft size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17.jpeg\" alt=\"\" class=\"wp-image-129071\" width=\"330\" srcset=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17.jpeg 870w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17-300x200.jpeg 300w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17-150x100.jpeg 150w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17-768x512.jpeg 768w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-17-400x267.jpeg 400w\" sizes=\"(max-width: 870px) 100vw, 870px\" \/><figcaption><em>Colourful cellulose: The Empa logo 3D-printed from the new HPC mixture changes color when it gets warmer. <strong>\u00a9<\/strong><\/em> <em>Empa<\/em><\/figcaption><\/figure><\/div>\n\n\n\n<p>An elastic material that changes color, conducts electricity, can be 3D printed and is also biodegradable? That is not just scientific wishful thinking: Empa researchers from the Cellulose &amp; Wood Materials laboratory in D\u00fcbendorf have produced a material with these exact properties on the basis of cellulose and carbon nanotubes.<\/p>\n\n\n\n<p>The researchers started with hydroxypropyl cellulose (HPC), which is commonly used as an excipient in pharmaceuticals, cosmetics and foodstuffs, among other things. When mixed with water HPC is known to form liquid crystals. These crystals have a remarkable property: Depending on their structure \u2013 which itself depends on the concentration of HPC, among other things \u2013 they shimmer in different colors, although they themselves have no color or pigment. This phenomenon is called structural coloring and is known to occur in nature: Peacock feathers, butterfly wings and chameleon skin get all or part of their brilliant coloration not from pigments, but from microscopic structures that &#8220;split&#8221; the (white) daylight into spectral colors and reflect only the wavelengths for specific colors.<\/p>\n\n\n\n<figure class=\"wp-block-embed aligncenter is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"BorlabsCookie _brlbs-cb-youtube\"><div class=\"_brlbs-content-blocker\"> <div class=\"_brlbs-embed _brlbs-video-youtube\"> <img decoding=\"async\" class=\"_brlbs-thumbnail\" src=\"https:\/\/renewable-carbon.eu\/news\/wp-content\/plugins\/borlabs-cookie\/assets\/images\/cb-no-thumbnail.png\" alt=\"YouTube\"> <div class=\"_brlbs-caption\"> <p>By loading the video, you agree to YouTube&#8217;s privacy policy.<br><a href=\"https:\/\/policies.google.com\/privacy?hl=en&amp;gl=en\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Learn more<\/a><\/p> <p><a class=\"_brlbs-btn _brlbs-icon-play-white\" href=\"#\" data-borlabs-cookie-unblock role=\"button\">Load video<\/a><\/p> <p><label><input type=\"checkbox\" name=\"unblockAll\" value=\"1\" checked> <small>Always unblock YouTube<\/small><\/label><\/p> <\/div> <\/div> <\/div><div class=\"borlabs-hide\" data-borlabs-cookie-type=\"content-blocker\" data-borlabs-cookie-id=\"youtube\"><script type=\"text\/template\">PGlmcmFtZSB0aXRsZT0iVGhlIGNoYW1lbGVvbiBlZmZlY3Q6IElyaWRlc2NlbnQgM0QgaW5rIGZyb20gY2VsbHVsb3NlIiB3aWR0aD0iNTAwIiBoZWlnaHQ9IjI4MSIgc3JjPSJodHRwczovL3d3dy55b3V0dWJlLW5vY29va2llLmNvbS9lbWJlZC9OeHYybXNHbWU1dz9mZWF0dXJlPW9lbWJlZCIgZnJhbWVib3JkZXI9IjAiIGFsbG93PSJhY2NlbGVyb21ldGVyOyBhdXRvcGxheTsgY2xpcGJvYXJkLXdyaXRlOyBlbmNyeXB0ZWQtbWVkaWE7IGd5cm9zY29wZTsgcGljdHVyZS1pbi1waWN0dXJlOyB3ZWItc2hhcmUiIHJlZmVycmVycG9saWN5PSJzdHJpY3Qtb3JpZ2luLXdoZW4tY3Jvc3Mtb3JpZ2luIiBhbGxvd2Z1bGxzY3JlZW4+PC9pZnJhbWU+<\/script><\/div><\/div>\n<\/div><\/figure>\n\n\n\n<p>The structural coloring of HPC changes not only with concentration but also with temperature. To better exploit this property, the researchers, led by Gustav Nystr\u00f6m, added 0.1 weight percent carbon nanotubes to the mixture of HPC and water. This renders the liquid electrically conductive and allows the temperature, and thus the color of the liquid crystals, to be controlled by applying a voltage. Added bonus: The carbon acts as a broadband absorber that makes the colors deeper. By incorporating a small amount of cellulose nanofibers into the mixture, Nystr\u00f6m&#8217;s team was also able to make it 3D printable without affecting structural coloring and electrical conductivity.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Sustainable sensors and displays<\/h3>\n\n\n\n<div class=\"wp-block-image is-style-default\"><figure class=\"alignright size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-10.png\" alt=\"\" class=\"wp-image-129072\" width=\"350\" srcset=\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-10.png 435w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-10-300x152.png 300w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-10-150x76.png 150w, https:\/\/renewable-carbon.eu\/news\/media\/2023\/07\/image-10-400x202.png 400w\" sizes=\"(max-width: 435px) 100vw, 435px\" \/><figcaption><em>Biodegradable: The display consists of seven electrically conductive segments that change color when a voltage is applied. <em><strong>\u00a9<\/strong><\/em> <em>Empa<\/em><\/em><\/figcaption><\/figure><\/div>\n\n\n\n<p>The researchers used the novel cellulose mixture to 3D print various potential applications of the new technology. These included a strain sensor that changes color in response to mechanical deformation and a simple seven-segment display. <\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u201cOur lab has already developed different disposable electronic components based on cellulose, such as batteries and sensors,\u201d says Xavier Aeby, co-author of the study. \u201cThis is the first time we were able to develop a cellulose-based display.\u201d<\/p><\/blockquote>\n\n\n\n<p>In future, the cellulose-based ink could have many more applications, such as temperature and strain sensors, in food quality control or biomedical diagnostics. <\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u201cSustainable materials that can be 3D printed are of great interest, especially for applications in biodegradable electronics and the Internet of Things,\u201d says Nystr\u00f6m, head of the laboratory. \u201cThere are still many open questions about how structural coloring is generated and how it changes with different additives and environmental conditions.&#8221; <\/p><\/blockquote>\n\n\n\n<p>Nystr\u00f6m and his team aim to continue this line of work in the hope of discovering many more interesting phenomena and potential applications.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Researchers from Empa&#8217;s Cellulose &amp; Wood Materials laboratory have developed a cellulose-based material that allows just that. The mixture of hydroxpropyl cellulose with water, carbon nanotubes and cellulose nanofibrils changes color when heated or stretched \u2013 without the addition of any pigments. An elastic material that changes color, conducts electricity, can be 3D printed and [&#8230;]<\/p>\n","protected":false},"author":3,"featured_media":129071,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"Is it possible to 3D print biodegradable sensors and displays?","footnotes":""},"categories":[5572],"tags":[10588,10503,6162],"supplier":[506],"class_list":["post-129069","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bio-based","tag-3dprinting","tag-biodegradable","tag-cellulose","supplier-eidgenoessische-materialpruefungs-und-forschungsanstalt-empa"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/129069","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=129069"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/129069\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/129071"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=129069"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=129069"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=129069"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=129069"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}