Growing artificial cells that change color like an octopus

A team of scientists at the University of Pennsylvania has developed an artificial version of a cell type that allows octopuses and squid to change colors and patterns according to their surroundings, thereby hiding in a blink of an eye. news.

They believe this could lead to new camouflage applications in the areas of robotics, architecture, cryptography and optics. The new study was published in the journal Nature Materials.

Each artificial chromatophore acts like a pixel on the screen to match the surrounding textures and colors.

Chromatophores are special cells in squids and octopuses that can expand or contract their internal reflex plates in response to external stimuli, allowing mollusks to This species blends into its surroundings, while transmitting signs of anger or readiness to mate.

In the new study, the team of scientists used thin, flexible films made from a polymer network of liquid crystals, to create artificial pigment cells that can instantly change color from near-infrared to visible ant and ultraviolet on request. These membranes are covered with tiny holes arranged in a network, each of which can be pumped to a certain pressure. When the hole is inflated, the film is stretched, decreasing in thickness and changing color.

Previously, color-changing materials using a similar mechanism needed to deform 75% to go from red to blue. However, the new film only requires pressure equivalent to a light touch to change to any color in the visible light spectrum.

Older materials that incorporate this mechanism cannot be used for things with fixed dimensions, such as screens or windows. Meanwhile, the new artificial pigment cells need only to deform less than 20%, the team believes that it can be lined up like pixels in an LCD screen.

"When we looked at how some animals evolved structural color, we realized they have stretchy cells that behave like pixels on a screen, and we were able to take a similar approach," said the author. Lead author of the study, Shu Yang, said.

The new technology is based on the phenomenon that makes butterfly wings and peacock feathers more iridescent than pigments or dyes give. This structural color phenomenon occurs when light interacts with microscopic elements on the surface and was reproduced in the study by the team of scientists using liquid crystals.

When a pore in the screen is inflated, the membrane expands. This reduces the density of liquid crystals in the film and changes the wavelength of light that is reflected to the viewer. By recording exactly the pressure needed to make each artificial pigment cell turn into the desired color, experts can program them to look like pixels on a screen.

"I wanted to create red, green and blue in the same time, so I connected holes of different widths into the same air channel. This means that, despite the same pressure, the distortion and the colors of the pixels will be different, which reduces the complexity of the overall device," explains co-author Kim Se-Um. In the study, the prototype was able to create a checkered pattern that matched the color and texture of the surrounding surface.