{"144381":{"#nid":"144381","#data":{"type":"news","title":"Micron-Scale Swimming Robots Could Deliver Drugs \u0026 Carry Cargo Using Simple Motion","body":[{"value":"\u003Cp\u003EWhen you\u2019re just a few microns long, swimming can be difficult. At that size scale, the viscosity of water is more like that of honey, and momentum can\u2019t be relied upon to maintain forward motion.\u003C\/p\u003E\u003Cp\u003EMicroorganisms, of course, have evolved ways to swim in spite of these challenges, but tiny robots haven\u2019t quite caught up. Now a team of researchers at the Georgia Institute of Technology has used complex computational models to design swimming micro-robots that could overcome these challenges to carry cargo and navigate in response to stimuli such as light.\u003C\/p\u003E\u003Cp\u003EWhen they\u2019re actually built some day, these simple micro-swimmers could rely on volume changes in unique materials known as hydrogels to move tiny flaps that will propel the robots. The micro-devices could be used in drug delivery, lab-on-a-chip microfluidic systems \u2013 and even as micro-construction robots working in swarms.\u003C\/p\u003E\u003Cp\u003EThe simple micro-swimmers were described July 23 in the online advance edition of the journal \u003Cem\u003ESoft Matter\u003C\/em\u003E, published by the Royal Society of Chemistry in the United Kingdom.\u003C\/p\u003E\u003Cp\u003E\u201cWe believe that our simulations will give experimentalists a reason to pursue development of these micro-swimmers to go beyond what is available now,\u201d said \u003Ca href=\u0022http:\/\/www.me.gatech.edu\/faculty\/alexeev\u0022\u003EAlexander Alexeev\u003C\/a\u003E, an assistant professor in the \u003Ca href=\u0022http:\/\/www.me.gatech.edu\/\u0022\u003EGeorge W. Woodruff School of Mechanical Engineering\u003C\/a\u003E at Georgia Tech. \u201cWe wanted to demonstrate the principle of how robots this small could move by determining what is important and what would need to be used to build a real system.\u201d\u003C\/p\u003E\u003Cp\u003EThe simple swimmer designed by Alexeev and collaborators Hassan Masoud and Benjamin Bingham consists of a responsive gel body about ten microns long with two propulsive flaps attached to opposite sides. A steering flap sensitive to specific stimuli would be located at the front of the swimmer.\u003C\/p\u003E\u003Cp\u003EThe responsive gel body would undergo periodic expansions and contractions triggered by oscillatory chemical reactions, oscillating magnetic or electric fields, or by cycles of temperature change. These expansions and contractions \u2013 the chemical swelling and de-swelling of the material \u2013 would create a beating motion in the rigid propulsive flaps attached to each side of the micro-swimmer. Combined with the movement of the gel body, the beating motion would move the micro-swimmer forward.\u003C\/p\u003E\u003Cp\u003EThe trajectory of the micro-swimmer would be controlled by a flexible steering flap on its front. The flap would be made of a material that deforms based on changes in light intensity, temperature or magnetic field.\u003C\/p\u003E\u003Cp\u003E\u201cThe combination of these flaps and the oscillating body creates a very nice motion that we believe can be used to propel the swimmer,\u201d said Alexeev. \u201cTo build a device that is autonomous and self-propelling at the micron-scale, we cannot build a tiny submarine. We have to keep it simple.\u201d\u003C\/p\u003E\u003Cp\u003EKey to the operation of the micro-swimmer would be the latest generation of hydrogels, materials whose volume changes in a cyclical way. The hydrogels would serve as \u201cchemical engines\u201d to provide the motion needed to move the device\u2019s propulsive flaps. Such materials currently exist and are being improved upon for other applications.\u003C\/p\u003E\u003Cp\u003E\u201cWe are using the state-of-the art in materials science, changing the properties of the material,\u201d explained Masoud, a Ph.D. candidate in the School of Mechanical Engineering. \u201cWe have combined the materials with the principles of hydrodynamics at the small scale to develop this new swimmer.\u201d\u003C\/p\u003E\u003Cp\u003EAs part of their modeling, the researchers examined the effects of flaps of different sizes and properties. They also studied how flexible the micro-swimmer\u2019s body needed to be to produce the kind of movement needed for swimming.\u003C\/p\u003E\u003Cp\u003E\u201cYou can\u2019t swim at the small scale in the same way you swim at the large scale,\u201d Alexeev said. \u201cThere is no inertia, which is how you keep moving at the large scale. What happens at the small scale is counterintuitive to what you expect at the large scale.\u201d\u003C\/p\u003E\u003Cp\u003EThe computational fluid modeling the researchers used allowed them to study a wide range of parameters in materials, oscillation rates and flexibility. What they learned, Alexeev said, will give experimentalists a starting point for actually building prototypes of the flexible gel robots.\u003C\/p\u003E\u003Cp\u003E\u201cWe have captured the solid mechanics of the periodically-oscillating body, the fluid dynamics of moving through the viscous liquid, and the coupling between the two,\u201d he said. \u201cFrom a computational fluid dynamics standpoint, it\u2019s not an easy problem to model at this scale.\u201d\u003C\/p\u003E\u003Cp\u003EUltimately, the researchers hope to work with an experimental team to actually build the micro-swimmers. Combining their theoretical work with actual experiments could be a powerful approach to building robots on this size scale.\u003C\/p\u003E\u003Cp\u003E\u201cThis is a simulation that we hope to see in real life one day,\u201d Alexeev said. \u201cWe have learned how experimentalists can pursue fabrication of these devices without extensive trial-and-error. We can use the simulations to look inside what will happen by using the laws of physics to explain it.\u201d\u003C\/p\u003E\u003Cp\u003EThe researchers envision groups of micro-swimmers carrying cargo through microfluidic chips or other devices. Swarms of them could one day work together as tiny construction robots moving materials to desired locations for assembly.\u003C\/p\u003E\u003Cp\u003EBut the micro-swimmers won\u2019t win any Olympic competitions. Alexeev estimates that their top speed could be on the order of a few micrometers per second \u2013 which should be enough to accomplish their mission.\u003C\/p\u003E\u003Cp\u003E\u201cIf your body is micrometers in size, that kind of speed is really not too bad,\u201d he said. \u201cThe swimming speed will be rather slow, but at that size scale, you don\u2019t really need to go very fast since you only need to go short distances.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECitation\u003C\/strong\u003E: Hassan Masoud, Benjamin I. Bingham and Alexander Alexeev, Soft Matter, 2012, Advance Article. DOI: 10.1039\/C2SM25898F.\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E75 Fifth Street, N.W., Suite 309\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30308\u0026nbsp; USA\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EResearchers have used complex computational models to design micro-swimmers that could overcome the challenges of swimming at the micron scale. These autonomous micro-robots could carry cargo and navigate in response to stimuli such as light.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Computational modeling shows how micro-swimmers could overcome the challenges of swimming at the micron scale."}],"uid":"27303","created_gmt":"2012-08-05 22:17:18","changed_gmt":"2016-10-08 03:12:36","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2012-08-05T00:00:00-04:00","iso_date":"2012-08-05T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"144371":{"id":"144371","type":"image","title":"Image of Simulated Micro-Swimmer","body":null,"created":"1449178739","gmt_created":"2015-12-03 21:38:59","changed":"1475894777","gmt_changed":"2016-10-08 02:46:17","alt":"Image of Simulated Micro-Swimmer","file":{"fid":"195034","name":"microswimmer.jpg","image_path":"\/sites\/default\/files\/images\/microswimmer_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/microswimmer_0.jpg","mime":"image\/jpeg","size":572475,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/microswimmer_0.jpg?itok=NuXeZORt"}}},"media_ids":["144371"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"145","name":"Engineering"},{"id":"152","name":"Robotics"}],"keywords":[{"id":"39581","name":"Alexander Alexeev"},{"id":"39591","name":"computational modeling"},{"id":"3356","name":"hydrogel"},{"id":"39571","name":"micro-robot"},{"id":"39561","name":"micro-swimmer"},{"id":"1356","name":"robot"},{"id":"167377","name":"School of Mechanical Engineering"}],"core_research_areas":[{"id":"39471","name":"Materials"},{"id":"39521","name":"Robotics"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News \u0026amp; Publications Office\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}