Organic solar cells for indoor use to power devices from the Internet of Things

Organic solar cells that can convert ambient light into electricity have been developed by a research group consisting of Swedish and Chinese scientists.

These cells use the light from the environment (much weaker than the light that a solar cell can get if it is placed outside, of course) to produce low levels of electricity, levels that are still considered sufficient to feed millions of small devices and the ‘Internet of Things’ will come online in the coming years.

These are usually devices that act as sensors and inevitably have to work with batteries. The latter will need to be recharged or modified, which is tricky and expensive. These organic solar cells are flexible, economical to build and can adapt to different aspects of light, but they can be applied everywhere because they are very small at the expansion level.

Researchers have developed new materials that they have used as an active layer in organic cells, allowing them to absorb ambient light. Initial tests showed that a solar cell of one square centimeter, exposed to ambient light with an intensity of 1000 lux, can convert 26.1% of that energy into electricity.

A second solar cell, a little larger, of 4 cm in the square, still manages to maintain energy efficiency of 23%. According to Feng Gao, a researcher at Link√∂ping University, this is a “great promise” in the context of feeding devices for the Internet of Things.

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Researchers train artificial intelligence to recognize smells

A team of Google Brain researchers published a new study on arXiv in which they explain how they train artificial intelligence software to recognize smells. They first created a set of more than 5,000 molecules and then labeled these molecules with descriptions that identified the type of odor.

The researchers used a special artificial intelligence called graphical neural network (GNN) so that these molecules were associated with their descriptions based on their structures. This is not a software that can be compared to the sensitivity of the human sense of smell, because the latter is very difficult to define. For example, there are scents that can appear in one way for one person and in another.

Moreover, some molecules sometimes have the same atoms and the same bonds, but they are arranged as mirror images: these molecules, usually recognized by the same software as practically the same, can have completely different smells. And this without mentioning the fragrances that are the result of the fragrances combined.

Despite these undeniable difficulties, Google researchers think that this is an important first step, a step that can also be useful in the fields of chemistry, sensory neuroscience and the production of synthetic fragrances.

This is not the first team of researchers to attempt to mimic or imitate the characteristics of an olfactory system based on artificial intelligence. For example, a team of scientists from the Barbican Centre in London used machine learning techniques to “recreate” the smell of an extinct flower. In addition, IBM is conducting experiments to create new fragrances generated by artificial intelligence.

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Scientists discover how metal can become magnetic with light

A new method for making non-magnetic metals magnetic has been developed by a group of researchers from the University of Copenhagen and Nanyang Technology University, Singapore. According to the press release, the process of using laser light can also be used to equip many materials with new properties.

Researchers have discovered that when they stimulate a metal through a certain process with laser light, its structure can transform and acquire new properties. The study was explained by Mark Rudner, a researcher at the Niels Bohr Institute of the Danish University: “We have been studying for several years how to transform the properties of a substance by emitting it with certain types of light. The novelty is that not only can we change properties with the help of light, but we can also change the material from the inside out and create a new phase with completely new properties. For example, a non-magnetic metal can suddenly become a magnet.”

According to researchers, the electrical currents circulating in the metal essentially appear spontaneously when the metal itself is irradiated with linear polarised light. What changes are the plasmons, a kind of electronic wave, present in the metal that begins to rotate clockwise or counterclockwise and change the electronic structure of the material, causing instability in the direction of the autorotation that makes the metal magnetic.

The study was published in Nature Physics.

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New material made of cellulose and silk can replace plastic

A group of researchers from Aalto University and the VTT Technical Research Centre of Finland created a new biobased material made from wood pulp fibres and spider silk proteins. The end result is at the same time a strong and expandable material that, according to the press release presenting the research, could also be a replacement for plastic in the future.

Because of its intrinsic properties, the same material can also be used in medical applications, in the textile industry and in the packaging industry. The advantage of such material over plastic is clear: it would be biodegradable and would not damage nature as plastic does.

In order to carry out their experiments, the researchers used birch pulp. They converted this substance into cellulose nanofibrils and then placed it on a kind of hard scaffolding. They then placed a matrix of very soft spider silk. It is not silk of real cobwebs, but still of biological silk, because it is produced in the laboratory with the help of bacteria with synthetic DNA.

In essence, knowing the structure of silk DNA, it can be built almost from scratch. In addition to the qualities of this material, this study shows the new possibilities of protein technology.

As specified by Pezhman Mohammadi, VTT researcher and one of the authors of the study together with Markus Linder: “In the future, we could produce similar compounds with slightly different building blocks and achieve a different set of functions for different applications.” The same researchers are also working on other projects to build their own materials with similar methods.

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Scientists model new superhard materials with artificial intelligence

A group of scientists from the University of Buffalo automated 43 new forms of carbon, some of which could be even tougher than diamonds.

Each computer-modeled carbon variety is made of carbon atoms placed with a certain pattern in a kind of crystal lattice. The researchers then published the study on npj Computational Materials, a study that also confirms how artificial intelligence, and in particular the machine learning technique, can also be important for the research of new materials and in general in all fields of materials science.

Among other things, superhard materials can be very useful because they can cut, drill or even grind other materials and objects and can also be used to create scratch-resistant coatings. Currently there is no harder material than diamond, but the latter is also very expensive, as Eva Zurek, a chemist at the University of Buffalo, who was involved in the research, recalled.

Precisely for this reason, there are many laboratories around the world that try to synthesize materials, at least by modeling them, which are harder than diamonds and possibly cheaper. However, these are often long and laborious processes, and this is where the computer and the new and increasingly powerful artificial intelligence algorithms play a role.

With the computer, you can get modeled materials that can exhibit other interesting properties, such as certain interactions with heat or electricity or other properties that diamonds don’t have.
“Few superhard materials are known, so it’s interesting to find new ones,” says the researcher, who suggests that the open-source algorithm they used, called XtalOpt, to generate random and crystalline structures containing carbon, can also be used to discover new structures and new materials in an increasingly efficient and fast way and that some of them can reserve a pleasant surprise.

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MIT scientists create a system to change the colors of objects

A new way to change the colors of objects was developed by a team of scientists from the Computer Science and Artificial Intelligence Laboratory (CSAIL) at MIT.

Researchers have developed a method based on a programmable ink that allows a surface to change color when exposed to ultraviolet light or visible light rays at certain wavelengths. The system, called PhotoChromeleon, uses a certain ink made from liquid photochromatic dyes that can be sprayed or even painted. Once applied, the object can change color or colors depending on the light beam that illuminates it, a reversible process that can be repeated.

The system has already been tested on different types of objects, from smartphone cases to model cars, and the same researchers have created a video that has been published on YouTube.

And it is precisely in the area of personalization that such a system could find its best application, as Yuhua Jin, the main author of the study related to this project implies: “Users can personalize their personal effects and appearance on a daily basis, without having to buy the same object several times in different colors and styles.”

The researcher, together with his colleagues, adapted an already existing system called ColorMod, which however had to print every pixel on the object. Furthermore, the colors can only be two: the basic color of the object or transparent. This new method allows you to change all the desired colors, depending on the photochromic dye that is applied to the surface.

Each dye interacts with different wavelengths and therefore it is possible to control each “color channel” of the color, depending on the wavelength of the emitted light source, to activate or deactivate it as desired. The method involves placing the object in a box with a particular projector and an ultraviolet light that serves to “erase” the colors and start again.

The same researcher also thought of creating an interface for automatic processing of drawings and models, offering users a kind of autonomy for personalization. The coloring process takes 15 to 40 minutes, depending on the shape and size of the object.

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