Nearer to manufacture circuits nanoparticles

Julian Gargiulo, Ianina Fernando L. Violi and Stefani in the laboratory CIBION.

Photos: CONICET Photography. Veronica Tello.

CONICET scientists achieved a major breakthrough in optical manipulation of nanometric particles.

In the Research Center Bionanociencias "Elizabeth Jares Erijman" (CIBION-CONICET) researchers found the key to print nanoparticles 60 nanometers (one nm is 10 million times smaller than one centimeter) to less than 300 nm away, and even they managed to connect, as you can see in the example of a dimer consisting of a gold nanoparticle and a silver (see Figure 1).

The results of this study, whose lead author is Julian Gargiulo, CONICET doctoral fellow of the CIBION, was published in the journal Nano Letters, the Chemical Society of the United States.

The use of nanoparticles is widespread and, for example, are used in optical biosensors for measuring physicochemical variables which determine the presence of pathogens, enzymes, viruses or other microorganisms.

They have also been used in pregnancy test strips: red banditas gold nanoparticles are surface-modified.

"The colloidal nanoparticles are suspended in a liquid such as flotando-, and optical printing technique that we developed in CIBION can 'grab' a nanoparticle from the liquid and place it in a certain position on a surface," explains Fernando Stefani , independent researcher of CONICET and associate director CIBION.

The method works by optical forces on the nanoparticles with focused lasers.

The light applied on the nanoparticles generates a force that attracts them towards the center of the light beam and pushes against a substrate to be glued.

"The laser captures and transfers them to the substrate," sums Stefani.

Image: Map of Argentina individual gold nanoparticles 60nm. (Left) and heterodimer individual particles 60nm. Silver and gold (right).

The understanding and the ability to master the manipulation of particles as small dimensions, he explains, is a challenge that will be useful for making, for example, "devices which nanoparticles of different kinds are arranged on a surface for a particular function together .

Colloidal nanoparticles offer a variety of physical and chemical properties unique to this "lists.

Exceed the limit

The lead author, Gargiullo, had set out to investigate what prevented printing phenomenon nanoparticles separation distances of less than 300 nm, and eventually lay the groundwork for connecting nanoparticles by optical forces.

In this way he found to bring the laser to the already printed nanoparticles on the surface, they absorb light, heat and generate a temperature gradient that repels other nanoparticles.

"A temperature difference of several degrees over a distance of centimeters or meters such as between two persons not generate any appreciable phenomenon.

But if that same temperature difference occurs over a distance of only several nanometers, for example between two nanoparticles, or may push the movement generating liquid flows in turn mobilize nanoparticles ", Stefani explained.

"What we discovered Julian enables us to design strategies to prevent this warming and enables the manufacture of circuits nanoparticles.

Is the first step toward making circuits and devices based on colloidal nanoparticles and defines a way to deepen the knowledge of the physico-chemical phenomena occurring, "he explains and adds:

"When we know in detail, the we can control and be closer to harness the huge properties of colloidal nanoparticles in new devices."

By Maria Bocconi

Research:

Julian Gargiulo. doctoral fellow. CIBION.
Santiago Cerrota. CIBION.
Emiliano Cortes. CIBION.
Ianina L. Violi. postdoctoral fellow. CIBION.
Fernando D. Stefani. Independent researcher. CIBION and Physics Department, Faculty of Natural Sciences of the UBA.

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