The ice that makes up glaciers isn't 100% solid – it's actually full of air bubbles, some of which formed centuries ago. Inspired by this fact, scientists have developed a method of using bubbles to store coded data in ice. The technology could actually have some practical applications.
As we all know, liquid water solidifies as it freezes. In the process, it squeezes out and pushes together dissolved gases, which form trapped air pockets … aka bubbles.
Because water freezes in stacked successive layers, those bubbles end up being suspended throughout the depth of the ice. Additionally, the rate at which water freezes affects the shape and size in which bubbles form, in a predictable manner.
With these phenomena in mind, Mengjie Song, Keke Shao and colleagues at the Beijing Institute of Technology went about developing their experimental data storage system. The scientists set up what is known as a Hele-Shaw cell, in which a thin rectangular column of deionized liquid water was sandwiched between two vertically-oriented clear acrylic sheets.
A cold plate at the bottom of the cell was used to chill and freeze the water, forming a slab of ice. The rate at which it froze could be manually controlled by adjusting the plate's temperature, over a range of -15 ºC to -35 ºC (5 ºF to -31 ºF).
It was found that as the freezing rate was decreased, any one ice layer would contain either egg-shaped bubbles, a mix of egg- and needle-shaped bubbles, needle-shaped bubbles only, or no bubbles at all. The scientists thus proceeded to assign different combinations of bubble shape, size and depth to different English letters and Arabic numerals in Morse, binary, and ternary codes.
In order to read the resulting messages, a camera was utilized to take a photo of a bubble-coded ice slab prepared by someone using the Hele-Shaw cell. That photo was then converted to a grayscale image, which was analyzed by a computer running custom decoding software.
While that software could decipher messages delivered in all three types of code, binary was found to be the most effective, as the messages could be about 10 times longer for a given amount of ice space.
The researchers envision the technology being used to record, store and read messages in very cold, remote regions such Antarctica, the Arctic, or even other planets, where electricity and electronic equipment would be in short supply. Although some power would be required to record the messages, none would subsequently be necessary as long as the ambient temperature stayed below freezing.
Looking beyond its data storage applications, the bubble-manipulating tech might also be useful for tweaking the strength of ice structures, developing aircraft de-icing systems, or studying how bubbles form in harder-to-image materials such as aluminum.
"Our findings can be widely applied in many areas," says Song. "We can manipulate bubbles to efficiently produce ice with different bubble contents."
A paper on the study – which also involved scientists from Hanyang University in South Korea and The Hong Kong Polytechnic University – was recently published in the journal Cell Reports Physical Science.
Source: Cell Press via EurekAlert
