Printing Microchip Patterns on Curvy Surfaces

National Institute of Standards, Gaithersburg, MD

Using sugar and corn syrup (i.e., candy), researcher Gary Zabow transferred the word “NIST” onto a human hair in gold letters, shown in false color in this grayscale microscope image. (Image: G. Zabow/NIST)

Semiconductor chips, micropatterned surfaces, and electronics all rely on microprinting, the process of putting precise but minuscule patterns millionths to billionths of a meter wide onto surfaces to give them new properties. Traditionally, these tiny mazes of metals and other materials are printed on flat wafers of silicon. But as the possibilities for semiconductor chips and smart materials expand, these intricate, tiny patterns need to be printed on new, unconventional, non-flat surfaces.

Directly printing these patterns on such surfaces is tricky, so scientists transfer prints. There are also liquid techniques, where the transfer material is floated on the surface of water and the target surface is pushed through it. But that can be tricky too; with a freely flowing liquid it can be hard to place the print precisely where you want it on a new surface. Gary Zabow, Scientist, NIST, has discovered that a simple combination of caramelized sugar and corn syrup can do the trick.

When dissolved in a small amount of water, this sugar mixture can be poured over micropatterns on a flat surface. Once the water evaporates, the candy hardens and can be lifted away with the pattern embedded. The candy with the print is then placed over the new surface and melted. The sugar/corn syrup combination maintains a high viscosity as it melts, letting the pattern maintain its arrangement as it flows over curves and edges. Then, using water, the sugar can be washed away, leaving just the pattern behind.

The REFLEX process transferred 1-micron disk arrays onto the sharp point of a pin. (Image: G. Zabow/NIST)

Using this technique, called REFLEX (REflow-driven FLExible Xfer), microcircuit patterns could be transferred like a stencil to allow scientists or manufacturers to etch and fill the materials they need in the right places. Patterned materials could also be transferred from their original chip onto fibers or microbeads for potential biomedical or microrobotics studies, or over sharp or curved surfaces within new devices.

The technique proved successful for a large range of surfaces, including printing onto the sharp point of a pin, and writing the word “NIST” in microscale gold lettering onto a single strand of human hair. In another example, 1-micrometer-diameter magnetic disks were successfully transferred onto a floss fiber of a milkweed seed. In the presence of a magnet, the magnetically printed fiber reacted, showing the transfer had worked.

There’s still more to explore with REFLEX, but this process could open new possibilities for new materials and microstructures across fields from electronics to optics to biomedical engineering.

For more information, contact Rebecca Jacobson at This email address is being protected from spambots. You need JavaScript enabled to view it.; 303-497-4789.