Scientists have created "photonic sunflowers" that are controlled by light

The research opens up new possibilities for developing intelligent systems that will work

reacting to light.For example,  Highly efficient, self-installing solar cells. Their peculiarity is that they automatically follow the direction and angle of the sun's light. Engineers also have the prospect of creating light-driven microfluidic valves or soft robots. Details about the creation of a “photonic sunflower”, the petals of which bend in response to light, tracking its path and angle of refraction, are described in the article for Nature Communications magazine.

Color arises from absorption andreflections of light. This process consists of a series of complex interactions. Objects absorb light of certain frequencies and reflect others. The angle at which light meets a surface affects which wavelengths are absorbed as well as the heat generated by that absorbed energy.

Photonic material developed by the teamTufts University, combines two layers. The first is an opal-like silk fibroin film doped with gold nanoparticles (AuNP), which form photonic crystals. The second is a substrate made of polydimethylsiloxane (PDMS), a silicon-based polymer. Besides its remarkable flexibility, durability and optical properties, silk fibroin is unusual in that it has a negative coefficient of thermal expansion (CTE). This means that it shrinks when heated and expands when cooled. PDMS, on the other hand, 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. Thus, the material bends as one side expands and the other contracts or expands more slowly.

Most optomechanical devices thattransform light into motion, require complex and energy-intensive manufacturing or customization. With this in mind, scientists have achieved precise control over the conversion of light energy and the generation of the macro motion of these materials without the need for electricity or wires.

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Fibroin is a fibrillar protein secreted by arachnids and some insects and forms the basis of spider webs and insect cocoons, in particular, silk of the silkworm Bombyx mori.

Alloying - adding impurities to the composition of materials to change (improve) the physical and / or chemical properties of the base material.

Polydimethylsiloxane is a viscousa substance that is in a liquid state and does not have an odor. Characteristics such as taste and color are also missing. Other fluid names are often mentioned, such as E900, silicone oil or PDMS. It is impossible to dissolve the substance in water or ethanol. For these purposes, only organic solvents are suitable.

Negative Thermal Expansion (NTE) is an unusual physicochemical process in which some materials contract when heated, rather than expanding like most other materials.