Butterfly wings are colorless when observed under SEM, what kind of microstructure does it have?

The researchers devised an interesting experiment to observe the wings of a butterfly using a scanning electron microscope. With this microscope, which can see the three-dimensional structure of nanoscale objects, people are surprised to find:

The originally colorful butterfly wings have lost their color, revealing a wonderful uneven structure. It turns out that the wings of butterflies are colorless, and it is only because of their special microstructure that they show colorful colors under the illumination of light. Structural color is different from pigment color.

The change of pigment color is mainly due to the absorption of light of different frequencies, while the principle of structural color is to use periodic structure, that is, photonic crystals, to regulate the reflection and transmission of light. Let's talk about photonic crystals first, its biggest feature is the existence of bandgaps, that is, light cannot propagate in a specific frequency band. Therefore, this can be used to reflect light of a specific frequency for the purpose of color control.

Structural colors have a higher efficiency at regulating light than pigmented colors, which is the miraculous result of biological evolution. Generally speaking, photonic crystals can be divided into one-dimensional, two-dimensional, and three-dimensional, so these three nanoperiodic optical structures also exist in nature. See the figure below, where a, b, and c are one-dimensional photonic crystals, d, e are two-dimensional photonic crystals, and f, g are three-dimensional photonic crystals.

In fact, a one-dimensional photonic crystal is enough to simply adjust the color, but biological evolution has advanced to two- and three-dimensional photonic crystals. Scientists have not given a clear answer to this question. But two-dimensional photonic crystals have another advantage, and that is hydrophobicity.

In addition, some organisms can also change the color of their bodies, in fact, by regulating the cycles of the cyclical structure, such as fish changing color by changing the volume of cells, and small bugs in Figure B changing color by shrinking or expanding their wings. In fact, chameleons also change color based on this principle. <>

On the wings of butterflies, there is a layer of powdery scales, which are transformed from single skin cells. Scales come in a variety of shapes, and there are several different shapes of scales on the wings of a butterfly, and it is they that decorate the wings with various colors. The scales were observed under an electron microscope, and each scale had dozens to more than 1,000 ridges, and they had very good refractive properties.

There are also many parallel thin sheets, superimposed on the ridges like vertical writing. The more such ridges, the more beautiful the light will shine. The color of a butterfly is made up of a mixture of pigment and structural colors on the scales.

Pigment color, also known as chemical color, is determined by the pigment particles attached to the surface of the scales. When the chemical properties of the pigment particles are changing, the pigment will fade or even disappear completely due to chemical reactions such as oxidation or reduction. Structural color is also called physical color, which is formed by reflection and refraction of light when it hits the different structures of the butterfly scales.

This physical color does not change color due to chemical factors, so it is a permanent color. Depending on the angle of illumination or under different light sources, the scales will produce different lights and colors. When pigment and structural colors are mixed together, the colors and markings on the butterfly's wings are even more beautiful and dazzling.

The beautiful color on the wings of a butterfly is completely different from other ordinary animals, it does not come from the cells on its body but from the color of its scales. A scale is not a cell, but a so-called cell derivative that is secreted outward by the cells that make up the wing membrane. The scales are usually flattened and feathered, but at the base they are constricted into a needle-like stalk and penetrate into the wing membrane.

Usually the scales are gently attached to the wing membrane and fall off easily. If we look at the wings of a butterfly with a microscope, we will find that thousands of these scales are systematically and neatly arranged on the wing membrane, so that the whole wing takes on a certain color and color depending on the species. Some scales contain countless colors of nude-grained pigments, the color of which is the same color as the substances we see every day, and we call them chemical colors or pigment colors.

I think that actors and screenwriters can symbolize children and parents, parents sketch a blueprint for a better future for their children after the birth of their children, and hope that children can achieve it step by step, but in this process, children have their own thoughts and pursuits, and do not want to live according to the wishes of their parents, you can talk about your own feelings, the coordination of conflicts of opinions between children and parents, of course, this is guided from the point of actors and screenwriters, and can be connected more realistically.

This means that only by looking at things scientifically can we see them as they are.

Yo, I'm a college entrance examination question in Anhui.

Are butterfly wings really colorless? Of course not! The mystery of the color of a butterfly's wings stems from the countless tiny scales that cover the wings.

These scales resemble bird feathers, with an oblong shape and a small short stalk embedded in the wing membrane at the base. There are two main types of scale color, one is the pigment particles produced by its own physiological metabolism, which is called chemical color; The other is due to the principle of physical optics, i.e., structural color (physical color). The white, yellow, red, brown, and black of the scales are mostly formed by chemical colors, such as yellow and red from carotenoid pigments, while brown and black from melanin.

These are the pigment particles that butterflies are able to produce through their own physiological metabolism. Another type of pigment particles, such as flavonoid pigment granules that form white and yellow, need to be indirectly related to the accumulation of plant pigments ingested by butterflies in their larval stages. Although these pigment particles have a variety of vivid colors, they are prone to fade or even disappear due to various chemical reactions.

You can see the color on the outside, but when you touch your hand, the color will fade... It's magical.

How could there be no color?

The colors and patterns on the wings of butterflies are given by the scales.

But the color of the scales is also divided into physical and chemical colors.

On the wings of most butterflies, the scales themselves have a chemical color, that is, color, like a pigment. But the electron microscope cannot see the color of the object at all, only the microstructure of the object. Colored and colorless things look the same under the electron microscope.

However, there are a considerable number of species of butterflies in the family Flash butterfly, and the scales on the wings are colorless (chemical). However, the scales themselves have a precise microstructure, which can reflect and refract light of a specific wavelength and arrange them neatly on the wings, so that the butterfly wings have the reflection of metallic blue, green, purple and other colors. If the internal microstructure or arrangement of the scales on the wings of this type of butterfly is destroyed, the shiny metal will be destroyed.

It is a physical color (structural color).

In addition, if the scales on the wings are wiped off, a panchromatic iridescence will be generated on the transparent fin membrane body due to physical and optical effects such as film interference. This phenomenon is also seen in the butterfly genus Silky Eye Butterfly from South America, which has almost no scales on its wings (natural reasons, it has evolved transparent wings without scales, which can hide in the shadows when it travels through the forest, without being detected by enemies, reducing the rate of predation by predators), and at a certain angle you can observe blue-purple iridescent colors on the wings.

To sum up, butterfly wings are colored.

Now it's time to look at the idea of the score, but yours is really off topic. You have nothing to do with seeing the essence through the phenomenon and achieving success with the help of external forces.

You're okay, I'm running much more than you, I write about technology to create a better future.

Writing a book that I know that this matter has to be done, is it off topic???

In the Anhui college entrance examination questions, it is clearly pointed out that the butterfly wings observed by SEM are used, and the SEM imaging map is colorless.

There was a problem with the essay topic. First, many butterfly wings are pigmented, that is, colored. Second, the scanning electron microscope is black and white no matter what it takes.

The part seen has no color.