{"id":197130,"date":"2015-07-15T17:55:16","date_gmt":"2015-07-15T20:55:16","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=197130"},"modified":"2015-09-11T18:11:37","modified_gmt":"2015-09-11T21:11:37","slug":"unexpected-filaments","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/unexpected-filaments\/","title":{"rendered":"Unexpected filaments"},"content":{"rendered":"
\"Microtubes

UFABC<\/span>Microtubes covered with nanowires…UFABC<\/span><\/p><\/div>\n

In scientific research, the search for one result often leads, fortuitously, to a different, even more important result. This is what happened to physicist Jos\u00e9 Ant\u00f4nio Souza when advising master’s student Cynthia G\u00f3mez, both at the Federal University of the ABC (UFABC). She developed coaxial microcables that can be used in telecommunications in order to understand how electric current flows through them. That was when she observed the formation of unexpected structures, namely microtubes covered by nanowires with a diameter equivalent to 1 millimeter divided by one million. The study led Souza to envision future technological applications for the discovery, from its use in nanoelectronics and microelectronics to drug delivery systems in which microtubes carry drugs to the location in the body where they should act. In order to ensure their rights to possible financial exploitation of the discovery, the pair filed for a patent related to the new material with the Brazilian Industrial Property Institute (INPI). Once protected, the results were published in the journal Applied Physics Letters<\/em>, together with professors Jeroen Schoenmaker, Alejandro Z\u00fa\u00f1iga and Denise Criado, all at UFABC.<\/p>\n

The coaxial microcables with which they worked consisted of metallic zinc (Zn) wires with a diameter between 30 and 120 micrometers, covered with a nanometric layer of zinc oxide \u00a0(ZnO). “Our objective was to study the electrical resistance\u2014or its inverse, conductivity\u2014of these microwires, with increases in temperature and the presence of magnetic fields, and infer the formation of nanostructures on their surface,” says Souza. “The intention was to manufacture magnetic coaxial cables, because it is believed that all nanostructured materials exhibit magnetic properties.”<\/p>\n

For the study, Souza and G\u00f3mez heated the metal microwires made of zinc in a special chamber with atmosphere and temperature control. Next, the nanowires grew on the microlayer of zinc oxide via a physical mechanism involving the diffusion of ions (electrically charged atoms) from the metal. In the next step, they passed an electric current through the coaxial microcables. What happened surprised the researchers. “The electricity had a colossal effect on the structure,” recounts the physicist from UFABC. “When the temperature reached 600\u00b0C, the metallic zinc nucleus evaporated completely, leaving only a hollow microwire, covered with nanowires.<\/p>\n

Integrating features<\/strong>
\nThe temperature at which this process occurred also surprised the researchers. Normally, zinc evaporates at 1,000\u00b0C. “The electric current greatly increased the vapor pressure, leading to total evaporation of the metal,” explains Souza. “Our discovery opens the way to obtaining microtubes of other materials such as tin and aluminum, for example.” Structures like that discovered by the UFABC researchers are called hierarchical, and are composed of two or more different shapes, such as wires and tubes. Sometimes they also have different sizes, such as in the case of the experiment by Souza and G\u00f3mez.<\/p>\n

\"...appeared

UFABC<\/span>…appeared on solid coaxial microcables after a process involving electrical current and heatUFABC<\/span><\/p><\/div>\n

The technological possibilities of the discovery, according to the researcher, lie in the fact that one can combine the applications of nanowires with those of microtubes in a single device because they can be manufactured together in the same structure. Nanowires, alone, can be used in sensors and to build electron microscopes and in computer circuits smaller that current ones. Microtubes, in turn, are used to transport nanofluids, such as ferrofluids, that contain magnetic nanoparticles.\u00a0 “A combination of these features is very important in the field of microelectronics,” says Souza. “In addition, one can imagine, for example, a microtube filled with a drug and nanowires of a biocompatible material, which would allow development of devices for drug delivery.”<\/p>\n

Physicist F\u00e1bio Coral Fonseca, of the Nuclear and Energy Research Institute (IPEN) in S\u00e3o Paulo, who studies materials for energy conversion and magnetism, mentions other possible applications of the discovery by the UFABC researchers. “These structures can be exploited in lab-on-a-chip devices [a sort of miniature laboratory that enables testing and biological analysis on a chip] if they demonstrate the necessary properties,” he says. “Another application that can be imagined is in catalysis [acceleration of chemical reactions] if, for example, nanowires can be obtained from metals or alloys with good catalytic properties.”<\/p>\n

Fonseca believes the UFABC work is important because of these technological application possibilities. “I think that the processing and phenomena involved in manufacturing these structures are important,” he says. “It is interesting to note the simplicity of the method and the use of electric current in the process, which seems to play an important role in obtaining the structures.” He recalls, however, that discovering how to combine these more specific properties and applications of nanowires and microtubes still depends on future research.<\/p>\n

Project<\/strong>
\nSynthesis and characterization of physical properties of nanosized materials (n\u00ba 2013\/16172-5<\/a>); Grant Mechanism:<\/strong> Regular Research Grant; Principal Investigator:<\/strong> Jos\u00e9 Ant\u00f4nio Souza (UFABC); Investment:<\/strong> R$75,905.92 and $59,151.64 (FAPESP).<\/p>\n

Scientific article
\n<\/em>G\u00f3mez, C. M. R. et al<\/em>.\u00a0Microtubes decorated with nanowires<\/a>.\u00a0Applied Physics Letters<\/strong>. V. 106, May 2015 (on-line).<\/p>\n","protected":false},"excerpt":{"rendered":"Microtube in nanowires could have applications in nano and microelectronics ","protected":false},"author":20,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[169],"tags":[249],"coauthors":[112],"class_list":["post-197130","post","type-post","status-publish","format-standard","hentry","category-technology","tag-nanotechnology"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/197130","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=197130"}],"version-history":[{"count":0,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/197130\/revisions"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=197130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=197130"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=197130"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=197130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}