Real-time wearable human emotion recognition technology developed

A groundbreaking technology that can recognize human emotions in real time has been developed by Professor Jiyun Kim and his research team in the Department of Material Science and Engineering at UNIST. This innovative technology is poised to revolutionize various industries, including next-generation wearable systems that provide services based on emotions.

Understanding and accurately extracting emotional information has long been a challenge due to the abstract and ambiguous nature of human affects such as emotions, moods, and feelings.

To address this, the research team has developed a multi-modal human emotion recognition system that combines verbal and non-verbal expression data to efficiently utilize comprehensive emotional information.

At the core of this system is the personalized skin-integrated facial interface (PSiFI) system, which is self-powered, facile, stretchable, and transparent.

It features a first-of-its-kind bidirectional triboelectric strain and vibration sensor that enables the simultaneous sensing and integration of verbal and non-verbal expression data.

The system is fully integrated with a data processing circuit for wireless data transfer, enabling real-time emotion recognition.

Utilizing machine learning algorithms, the developed technology demonstrates accurate and real-time human emotion recognition tasks, even when individuals are wearing masks.

The system has also been successfully applied in a digital concierge application within a virtual reality (VR) environment.

The technology is based on the phenomenon of "friction charging," where objects separate into positive and negative charges upon friction.

Notably, the system is self-generating, requiring no external power source or complex measuring devices for data recognition.

Professor Kim commented, "Based on these technologies, we have developed a skin-integrated face interface (PSiFI) system that can be customized for individuals." The team utilized a semi-curing technique to manufacture a transparent conductor for the friction charging electrodes.

Additionally, a personalized mask was created using a multi-angle shooting technique, combining flexibility, elasticity, and transparency.

The research team successfully integrated the detection of facial muscle deformation and vocal cord vibrations, enabling real-time emotion recognition.

The system's capabilities were demonstrated in a virtual reality "digital concierge" application, where customized services based on users' emotions were provided.

Jin Pyo Lee, the first author of the study, stated, "With this developed system, it is possible to implement real-time emotion recognition with just a few learning steps and without complex measurement equipment. This opens up possibilities for portable emotion recognition devices and next-generation emotion-based digital platform services in the future."

The research team conducted real-time emotion recognition experiments, collecting multimodal data such as facial muscle deformation and voice.

The system exhibited high emotional recognition accuracy with minimal training.

Its wireless and customizable nature ensures wearability and convenience.

Furthermore, the team applied the system to VR environments, utilizing it as a "digital concierge" for various settings, including smart homes, private movie theaters, and smart offices.

The system's ability to identify individual emotions in different situations enables the provision of personalized recommendations for music, movies, and books.

Professor Kim emphasized, "For effective interaction between humans and machines, human-machine interface (HMI) devices must be capable of collecting diverse data types and handling complex integrated information. This study exemplifies the potential of using emotions, which are complex forms of human information, in next-generation wearable systems."

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Solar-powered device produces clean water and clean fuel at the same time

A floating, solar-powered device that can turn contaminated water or seawater into clean hydrogen fuel and purified water, anywhere in the world, has been developed by researchers.

The device, developed by researchers at the University of Cambridge, could be useful in resource-limited or off-grid environments, since it works with any open water source and does not require any outside power.

It takes its inspiration from photosynthesis, the process by which plants convert sunlight into food. However, unlike earlier versions of the 'artificial leaf', which could produce green hydrogen fuel from clean water sources, this new device operates from polluted or seawater sources and can produce clean drinking water at the same time.

Tests of the device showed it was able to produce clean water from highly polluted water, seawater, and even from the River Cam in central Cambridge. The results are reported in the journal Nature Water.

"Bringing together solar fuels production and water purification in a single device is tricky," said Dr Chanon Pornrungroj from Cambridge's Yusuf Hamied Department of Chemistry, the paper's co-lead author. "Solar-driven water splitting, where water molecules are broken down into hydrogen and oxygen, need to start with totally pure water because any contaminants can poison the catalyst or cause unwanted chemical side-reactions."

"In remote or developing regions, where clean water is relatively scarce and the infrastructure necessary for water purification is not readily available, water splitting is extremely difficult," said co-lead author Ariffin Mohamad Annuar. "A device that could work using contaminated water could solve two problems at once: it could split water to make clean fuel, and it could make clean drinking water."

Pornrungroj and Mohamad Annuar, who are both members of Professor Erwin Reisner's research group, came up with a design that did just that. They deposited a photocatalyst on a nanostructured carbon mesh that is a good absorber of both light and heat, generating the water vapour used by the photocatalyst to create hydrogen. The porous carbon mesh, treated to repel water, served both to help the photocatalyst float and to keep it away from the water below, so that contaminants do not interfere with its functionality.

In addition, the new device uses more of the Sun's energy. "The light-driven process for making solar fuels only uses a small portion of the solar spectrum -- there's a whole lot of the spectrum that goes unused," said Mohamad Annuar.

The team used a white, UV-absorbing layer on top of the floating device for hydrogen production via water splitting. The rest of the light in the solar spectrum is transmitted to the bottom of the device, which vaporises the water.

"This way, we're making better use of the light -- we get the vapour for hydrogen production, and the rest is water vapour," said Pornrungroj. "This way, we're truly mimicking a real leaf, since we've now been able to incorporate the process of transpiration."

A device that can make clean fuel and clean water at once using solar power alone could help address the energy and the water crises facing so many parts of the world. For example, the indoor air pollution caused by cooking with 'dirty' fuels, such as kerosene, is responsible for more than three million deaths annually, according to the World Health Organization. Cooking with green hydrogen instead could help reduce that number significantly. And 1.8 billion people worldwide still lack safe drinking water at home.

"It's such a simple design as well: in just a few steps, we can build a device that works well on water from a wide variety of sources," said Mohamad Annuar.

"It's so tolerant of pollutants, and the floating design allows the substrate to work in very cloudy or muddy water," said Pornrungroj. "It's a highly versatile system."

"Our device is still a proof of principle, but these are the sorts of solutions we will need if we're going to develop a truly circular economy and sustainable future," said Reisner, who led the research. "The climate crisis and issues around pollution and health are closely related, and developing an approach that could help address both would be a game-changer for so many people."

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Record 19.31% efficiency with organic solar cells

Researchers from The Hong Kong Polytechnic University (PolyU) have achieved a breakthrough power-conversion efficiency (PCE) of 19.31% with organic solar cells (OSCs), also known as polymer solar cells. This remarkable binary OSC efficiency will help enhance applications of these advanced solar energy devices.

The PCE (Power-conversion efficiency), a measure of the power generated from a given solar irradiation, is considered a significant benchmark for the performance of photovoltaics (PVs), or solar panels, in power generation. The improved efficiency of over 19% that was achieved by the PolyU researchers constitutes a record for binary OSCs, which have one donor and one acceptor in the photo-active layer.

Led by Prof. LI Gang, Chair Professor of Energy Conversion Technology and Sir Sze-Yen Chung Endowed Professor in Renewable Energy at PolyU, the research team invented a novel OSC morphology-regulating technique by using 1,3,5-trichlorobenzene as a crystallisation regulator. This new technique boosts OSC efficiency and stability.

The team developed a non-monotonic intermediated state manipulation (ISM) strategy to manipulate the bulk-heterojunction (BHJ) OSC morphology, which simultaneously optimises crystallisation dynamics and energy loss of non-fullerene OSCs. Unlike the strategy of using traditional solvent additives, which is based on excessive molecular aggregation in films, the ISM strategy promotes the formation of more ordered molecular stacking and favourable molecular aggregation. As a result, the PCE was considerably increased and the undesirable non-radiative recombination loss was reduced. Notably, non-radiative recombination lowers the light generation efficiency and increases the heat loss.

The research team's findings are described in the study "19.3% Binary Organic Solar Cell and Low Non-Radiative Recombination Enabled by Non-Monotonic Intermediate State Transition" published in Nature Communications . The conversion of solar energy to electricity is an essential technology for achieving a sustainable environment. Although OSCs are promising devices that harness solar energy cost-effectively, their efficiency must be improved if they are to be used widely in practical applications.

Non-fullerene acceptors based organic solar cells represent the frontier of research in the field of organic photovoltaics due to both the materials and morphology manipulation innovations. Nevertheless, non-radiative recombination loss suppress and performance boosting are in the centre of organic cell research.

Prof. Li said, "Challenges in research came from the existing additive-based benchmark morphology control methods, which suffer from non-radiative recombination loss, thus lowering the open-circuit voltage due to excessive aggregation." The research team took about two years to devise a non-monotonic ISM strategy for increasing the OSC efficiency and lowering the non-radiative recombination loss. The publication of the study promises to galvanise OSC research.

Prof. Li said, "The new finding will make OSC research an exciting field, and this will likely create tremendous opportunities in applications like portable electronics and building-integrated PVs." The new door will open when low cost single-junction OSCs can achieve a PCE of over 20%, along with more stable performance and other unique advantages such as flexibility, transparency, stretchability, low weight and tuneable colour.

Prof. Li has been recognised as a Highly Cited Researcher 9 years in a row since 2014, which testifies to his significant impact on global research. His pioneering contributions to research on polymer solar cells since 2005 have brought sustainable influence on printable solar energy development with global recognition.

Underpinning the research on OPV field, Prof LI's study titled, "High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends," was published on Nature Materials in 2005. This represented OPV's first generation research breakthrough which has fuelled solar technology from this frontier study.

In 2010, Prof LI's study titled "For the Bright Future -- Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%" was published on Advanced Materials.

Prof. Li said, "The latest study shows a record low non-radiative recombination loss of 0.168 eV in a binary OSC with a PCE of over 19%. This is a very encouraging result for the long-standing research on OSCs that I have conducted over the past two decades. We have already achieved better OSC efficiency, and this will subsequently help accelerate the applications of solar energy."

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