{"id":14705,"date":"2017-03-24T20:59:05","date_gmt":"2017-03-24T20:59:05","guid":{"rendered":"http:\/\/www.kurzweilai.net\/?p=296436"},"modified":"2017-03-28T01:34:09","modified_gmt":"2017-03-28T01:34:09","slug":"a-printable-sensor-laden-skin-for-robots-or-an-airplane","status":"publish","type":"post","link":"https:\/\/hoo.central12.com\/fugic\/2017\/03\/24\/a-printable-sensor-laden-skin-for-robots-or-an-airplane\/","title":{"rendered":"A printable, sensor-laden ‘skin’ for robots (or an airplane)"},"content":{"rendered":"
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Illustration of 3D-printed sensory composite (credit: Subramanian Sundaram)<\/p><\/div>\n

MIT researchers have designed a radical new method of creating flexible, printable electronics that combine sensors and processing circuitry.<\/p>\n

Covering a robot — or an airplane or a bridge, for example — with sensors will require a technology that is both flexible and cost-effective to manufacture in bulk. To demonstrate the feasibility of their new method, the researchers at MIT\u2019s Computer Science and Artificial Intelligence Laboratory<\/a> have designed and built a 3D-printed device that responds to mechanical stresses by changing the color of a spot on its surface.<\/p>\n

Sensorimotor pathways<\/strong><\/p>\n

\u201cIn nature, networks of sensors and interconnects [such as the human nervous system] are called sensorimotor pathways,\u201d says Subramanian Sundaram<\/a>, an MIT graduate student in electrical engineering and computer science (EECS), who led the project. \u201cWe were trying to see whether we could replicate sensorimotor pathways inside a 3-D-printed object. So we considered the simplest organism we could find\u201d — the golden tortoise beetle, or \u201cgoldbug,\u201d an insect whose exterior usually appears golden but turns reddish orange if the insect is poked or prodded, that is, mechanically stressed.<\/p>\n

The researchers present their new design in the latest issue of the journal\u00a0Advanced Materials Technologies<\/em>.<\/p>\n

The key innovation was to 3D-print directly on the plastic substrate (support structure) instead of placing components on top. That greatly increases the range of devices that can be created; a printed substrate could consist of many materials, interlocked in intricate but regular patterns, which broadens the range of functional materials that printable electronics can use.*<\/p>\n

Printed substrates also open the possibility of devices that, although printed as flat sheets, can fold themselves up into more complex, three-dimensional shapes. Printable robots that spontaneously self-assemble when heated, for instance (see “Self-assembling printable robotic components<\/a>“), are a\u00a0 topic of\u00a0ongoing research<\/a>\u00a0at the CSAIL Distributed Robotics Laboratory, led by Daniela Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT.<\/p>\n

3D-printed sensory composite
\n<\/strong><\/p>\n

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The sensory composite is grouped into 4 sets of functional layers: a base with spatially varying mechanical stiffness and surface energy, electrical materials, electrolyte, and capping layers. All these materials are 3D-printed. (credit: Subramanian Sundaram et al.\/ Advanced Materials Technologies)<\/p><\/div>\n

The MIT researchers\u2019 new device is approximately T-shaped, but with a wide, squat base and an elongated crossbar. The crossbar is made from an elastic plastic, with a strip of silver running its length; in the researchers\u2019 experiments, electrodes were connected to the crossbar\u2019s ends. The base of the T is made from a more rigid plastic. It includes two printed transistors and what the researchers call a \u201cpixel,\u201d a circle of semiconducting polymer whose color changes when the crossbars stretch, modifying the electrical resistance of the silver strip.**<\/p>\n

A transistor consists of semiconductor channel on top of which sits a \u201cgate,\u201d a metal wire that, when charged, generates an electric field that switches the semiconductor between its electrically conductive and nonconductive states. In a standard transistor, there\u2019s an insulator between the gate and the semiconductor, to prevent the gate current from leaking into the semiconductor channel.<\/p>\n

The transistors in the MIT researchers\u2019 device instead separate the gate and the semiconductor with an electrolyte — a layer of water containing\u00a0 potassium chloride mixed with glycerol. Charging the gate drives potassium ions into the semiconductor, changing its conductivity.***<\/p>\n

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Photograph of the fully 3D-printed sensory composite shows a strain sensor (top) linked to an electrical amplifier that modulates the transparency of the electrochromic pixel (scale bar is 10mm). (credit: Subramanian Sundaram et al.\/ Advanced Materials Technologies)<\/p><\/div>\n

\u201cI am very impressed with both the concept and the realization of the system,\u201d says Hagen Klauk, who leads the Organic Electronic Research Group at the Max Planck Institute for Solid State Research, in Stuttgart, Germany. \u201cThe approach of printing an entire optoelectronic system — including the substrate and all the components — by depositing all the materials, including solids and liquids, by 3-D printing is certainly novel, interesting, and useful, and the demonstration of the functional system confirms that the approach is also doable. By fabricating the substrate on the fly, the approach is particularly useful for improvised manufacturing environments where dedicated substrate materials may not be available.\u201d<\/p>\n

The work was supported by the DARPA SIMPLEX program through SPAWAR.<\/p>\n

* To build the device, the researchers used the\u00a0MultiFab<\/a>, a custom 3-D printer developed MIT. The MultiFab already included two different \u201cprint heads,\u201d one for emitting hot materials and one for cool, and an array of ultraviolet light-emitting diodes. Using ultraviolet radiation to \u201ccure\u201d fluids deposited by the print heads produces the device\u2019s substrate.<\/em><\/p>\n

** Sundaram added a copper-and-ceramic heater, which was necessary to deposit the semiconducting plastic: The plastic is suspended in a fluid that\u2019s sprayed onto the device surface, and the heater evaporates the fluid, leaving behind a layer of plastic only 200 nanometers thick. The layer of saltwater lowers the device\u2019s operational voltage, so that it can be powered with an ordinary 1.5-volt battery. <\/em><\/p>\n

*** But it does render the device less durable. \u201cI think we can probably get it to work stably for two months, maybe,\u201d Sundaram says. \u201cOne option is to replace that liquid with something between a solid and a liquid, like a\u00a0hydrogel<\/a>, perhaps. But that\u2019s something we would work on later. This is an initial demonstration.\u201d<\/em><\/p>\n

\n

Abstract of\u00a03D-Printed Autonomous Sensory Composites<\/em><\/h4>\n

A method for 3D-printing autonomous sensory composites\u00a0requiring no external processing is presented. The composite operates at 1.5 V, locally performs active signal transduction with embedded electrical gain, and responds to stimuli, reversibly transducing mechanical strain into a transparency change. Digital assembly of spatially tailored solids and thin films, with encapsulated liquids, provides a route for realizing complex autonomous systems.<\/p>\n","protected":false},"excerpt":{"rendered":"

MIT researchers have designed a radical new method of creating flexible, printable electronics that combine sensors and processing circuitry. Covering a robot — or an airplane or a bridge, for example — with sensors will require a technology that is both flexible and cost-effective to manufacture in bulk. To demonstrate the feasibility of their new […]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48,55,43],"tags":[],"class_list":["post-14705","post","type-post","status-publish","format-standard","hentry","category-electronics","category-nanotechmaterials-science","category-news"],"_links":{"self":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14705"}],"collection":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/comments?post=14705"}],"version-history":[{"count":3,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14705\/revisions"}],"predecessor-version":[{"id":14767,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/14705\/revisions\/14767"}],"wp:attachment":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/media?parent=14705"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/categories?post=14705"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/tags?post=14705"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}