Unique Landscapes And Micro-Needles Could Be Created By The Same Process

Sep 15, 2020

This false-color photograph shows a "forest" of many candy pinnacles that have been dissolved in water. The candy was initially a solid block containing pores, which the dissolving process has reshaped into a bed-of-nails formation.
Credit Courtesy of NYU's Applied Mathematics Lab

How the unique topography of places like Sinks Canyon State Park in Wyoming formed has puzzled researchers for a long time. But researchers at New York University published research last week that gave some insight into the process.

The topography is known as karst, and it's made up of caves, sinkholes, and outcrops. The researchers believe it occurs in submerged rock-usually soft rock like limestone.

"We were looking at candy dissolving, and so we used lollipop candy. So this is like hard candy that will dissolve by the same types of chemistry that rocks dissolve by, not quite as complicated but a lot of the same kind of fundamentals. But it does so faster. So you can actually see it dissolve," said principal investigator Leif Ristroph.

Ristroph said the water created flows and carvings in the candy on its own, with no current in the water or premade tracks in the candy. But if they left the candy in the water for long enough, it created a whole new structure.

"We were surprised that when you take a chunk of candy and leave it in a tank of water, which is a pretty simple thing to do, and when you do that, you come back a couple hours later, you will find a super sharp needle sitting there," Ristroph said. "So what was initially maybe a blobby shape, or a rounded shape, gets carved into this needle."

Researchers say this dissolving reaction could also provide insight into the manufacturing of sharp-tipped structures like micro-needles and probes used in scientific research and medical procedures.

Have a question about this story? Contact the reporter, Ivy Engel, at iengel@uwyo.edu.