Researcher finds a candy new strategy to print microchip patterns on curvy surfaces

NIST scientist Gary Zabow had by no means supposed to make use of sweet in his lab. It was solely as a final resort that he had even tried burying microscopic magnetic dots in hardened chunks of sugar—laborious sweet, principally—and sending these candy packages to colleagues in a biomedical lab. The sugar dissolves simply in water, liberating the magnetic dots for his or her research with out leaving any dangerous plastics or chemical compounds behind.

By likelihood, Zabow had left one among these sugar items, embedded with arrays of micromagnetic dots, in a beaker, and it did what sugar does with time and warmth—it melted, coating the underside of the beaker in a gooey mess.

“No problem,” he thought. He would simply dissolve away the sugar, as regular. Except this time when he rinsed out the beaker, the microdots have been gone. But they weren’t actually lacking; as an alternative of releasing into the water, that they had been transferred onto the underside of the glass the place they have been casting a rainbow reflection.

“It was those rainbow colors that really surprised me,” Zabow remembers. The colours indicated that the arrays of microdots had retained their distinctive sample.

This candy mess gave him an thought. Could common desk sugar be used to carry the facility of microchips to new and unconventional surfaces? Zabow’s findings on this potential switch printing course of have been revealed in Science on Nov. 25.

Semiconductor chips, micropatterned surfaces, and electronics all depend on microprinting, the method of placing exact however minuscule patterns millionths to billionths of a meter vast onto surfaces to offer them new properties. Traditionally, these tiny mazes of metals and different supplies are printed on flat wafers of silicon. But as the chances for semiconductor chips and sensible supplies broaden, these intricate, tiny patterns should be printed on new, unconventional, non-flat surfaces.

Directly printing these patterns on such surfaces is difficult, so scientists switch prints. There are versatile tapes and plastics that may do the job (like utilizing putty to select up newsprint), however these solids can nonetheless have bother conforming to sharp curves and corners when the print is laid again down. They may additionally depart behind plastics or different chemical compounds that could possibly be laborious to take away or be unsafe for biomedical makes use of.

There are liquid methods, the place the switch materials is floated on the surface of water and the goal floor is pushed via it. But that may be tough too; with a freely flowing liquid it may be laborious to position the print exactly the place you need it on a brand new floor.

But, as Zabow found to his shock, a easy mixture of caramelized sugar and corn syrup can do the trick.

When dissolved in a small quantity of water, this sugar combination may be poured over micropatterns on a flat floor. Once the water evaporates, the sweet hardens and may be lifted away with the sample embedded. The sweet with the print is then positioned over the brand new floor and melted. The sugar/corn syrup mixture maintains a excessive viscosity because it melts, letting the sample preserve its association because it flows over curves and edges. Then, utilizing water, the sugar may be washed away, leaving simply the sample behind.

Using this system, known as REFLEX (REflow-driven FLExible Xfer), microcircuit patterns could possibly be transferred like a stencil to permit scientists or producers to etch and fill the supplies they want in the suitable locations. Alternatively, patterned supplies could possibly be transferred from their unique chip onto fibers or microbeads for potential biomedical or microrobotics research, or over sharp or curved surfaces inside new units.

The method proved profitable for a wide range of surfaces, together with printing onto the sharp level of a pin, and writing the phrase “NIST” in microscale gold lettering onto a single strand of human hair. In one other instance, 1-micrometer-diameter magnetic disks have been efficiently transferred onto a floss fiber of a milkweed seed. In the presence of a magnet, the magnetically printed fiber reacted, exhibiting the switch had labored.

There’s nonetheless extra to discover with REFLEX, however this course of may open new potentialities for brand spanking new supplies and microstructures throughout fields from electronics to optics to biomedical engineering.

“The semiconductor industry has spent billions of {dollars} perfecting the printing techniques to create chips we depend on,” Zabow says. “Wouldn’t it be nice if we could leverage some of those technologies, expanding the reach of those prints with something as simple and inexpensive as a piece of candy?”