New smart materials controlled only by light twist, bend and move

The flower-shaped photonic material moves in response to light, closely tracking the maximum exposure angle.Credits: Fio Omenetto, Tufts University

Researchers at Tufts University’s Faculty of Engineering have created a photoactivation composite device that can perform accurate and visible movements and form complex three-dimensional shapes without the need for wires or other working materials or energy sources. .. This design combines a programmable photonic crystal with an elastomeric composite that can be designed on a macro and nanoscale to respond to illumination.

This research focuses on smart optical drive systems such as highly efficient self-aligning solar cells that automatically follow the direction of the sun and the angle of light, microfluidic bulbs that operate with light, and soft robots that move with light on demand. It provides a new path for development. .. “Photonic Sunflower,” which tracks the path and angle of light as its petals curl toward or away from the light, demonstrates its technology in a paper published March 12, 2021. Nature Communications..

Color results from the absorption and reflection of light. Behind all the flashes of iridescent butterfly wings and opal gemstones, natural photonic crystals embedded in wings and stones absorb light of a particular frequency and reflect other frequencies in a complex mutual. It has an effect. The angle at which light meets the crystal surface can affect which wavelengths are absorbed and the heat generated from the absorbed energy.

Designed by Tufts Team, the photonic material combines the two layers. An opal-like film made of silk fibroin doped with gold nanoparticles (AuNP) that forms photonic crystals. Silk fibroin is unusual for its excellent flexibility, durability, and optical properties, as well as its negative coefficient of thermal expansion (CTE), which shrinks when heated and expands when cooled. In contrast, PDMS has a high CTE and expands rapidly when heated. As a result, when the new material is exposed to light, one layer heats up much faster than the other, causing one side to expand and the other layer to contract or expand more slowly. , The material bends.

Solar cells mounted on light-powered materials can move and track light sources without wires, gears, or motors.Credits: Fio Omenetto, Tufts University

“Our approach allows us to design how these opal-like films can be patterned on multiple scales to absorb and reflect light. As light travels and the amount of energy absorbed changes, The material folds and behaves differently as a function of it. Its position relative to the light. ” Fiorenzo Omenet, the corresponding author of the study and Frank C. Doble Engineering Professor at Tufts University, said.

Most optomechanical devices that convert light into motion involve complex, energy-intensive manufacturing or setup, but “realize exquisite control of light energy conversion without the need for electricity or wires, these. You can generate a “macro motion” of the material. “Omenet said.

Researchers programmed photonic crystal films by applying stencils and exposing them to water vapor to produce specific patterns. The surface water pattern changes the wavelengths of absorbed and reflected light from the film, and when exposed to laser light, the material bends, folds, and twists in different ways, depending on the shape of the pattern. I will.

In their study, the authors demonstrated a “photonic sunflower” that incorporates a solar cell into a bilayer membrane so that cells track a light source. The photonic sunflower keeps the angle between the solar cell and the laser beam nearly constant, maximizing the efficiency of the cell as the light travels. This system works with white light as well as with laser light. Such wireless, photoresponsive heliotropic (solar tracking) systems have the potential to increase the efficiency of light-to-energy conversion in the photovoltaic industry. The team’s material demonstration also included a butterfly that opens and closes in response to light and an auto-folding box.

Brighten perovskite LEDs with photonic crystals

For more information:
Nature Communications (2021). DOI: 10.1038 / s41467-021-21764-6

Courtesy of Tufts University

Quote: Light-only, twisting, bending and movement of new smart materials (2021, March 12) from https: // March 2021 Obtained on the 12th.

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New smart materials controlled only by light twist, bend and move

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