A researcher at AIST has developed a technology to improve the photovoltaic efficiency of wide-bandgap CIS-type thin-film solar cells that do not contain the rare metal indium.
For tandem-type solar cells, which are expected to achieve even higher performance than the solar cells currently in widespread use, the development of top cell materials for short-wavelength light absorption that satisfy all the elements of "low cost," "high performance," and "high reliability (stability)" has been a challenge. In this study, we developed a technology to improve the quality of photo-absorber layers with a wide bandgap energy, which is particularly suitable as a top cell among CIS-type compounds, a promising material group that satisfies these elements. The newly developed photo-absorber layer has excellent stability and is expected to be applied to inexpensive, high-performance, and flexible tandem-type solar cells in the future.

A researcher in AIST, in collaboration with the Japan Medical Startup Incubation Program (JMPR) and N.B. Medical Corporation, has developed a novel anti-thrombogenic coating for stents used in the treatment of intracranial aneurysms.
In medical devices that come into contact with blood, the control of thrombus formation is an important factor in avoiding serious complications. Because of the placement of foreign bodies in blood vessels, patients with stents are always at risk for thrombotic complications. Therefore, antiplatelet medication is mandatory. Many antithrombotic coatings have been investigated to reduce the risk of thrombus formation. The principle of conventional coatings is that they exhibit antithrombotic properties by inhibiting nonspecific adsorption of plasma proteins. However, the inhibition of protein adsorption also means inhibition of cell adhesion. Therefore, although the antithrombogenicity is improved, the cell adhesiveness is accordingly decreased in conventional coating technology.
Recently, we have found an anti-thrombogenic coating with a new principle. This technology preferentially captures non-coagulant proteins in the blood, thereby inhibiting the blood coagulation reaction from the stent surface due to the blocking effect. This technology, which controls rather than inhibits the protein adsorption, provides anti-thrombogenic properties while simultaneously is able to improve the cell adhesion. The improved cell adhesion can accelerate the coverage of the stent with the vessel. The early coverage of the stent with the vessel means earlier completion of the stent therapy.
This technology reduces the occurrence of thrombotic complications, which have been an issue with stent therapy. Furthermore, it enables reduction of the treatment period, and thereby, the amount of antiplatelet drug use can be lower, which not only reduces the burden on patients, but also contributes to the medical cost cut.
The details of this technology were published in Scientific Reports on July 10, 2024.

Jun Sugawara, Leader of the Physiological System Research Group, at the Human Information Interaction Research Group, National Institute of Advanced Industrial Science and Technology (AIST), in collaboration with Professor Hiroshi Tomiyama and Senior Professor Akira Yamashina (at the time of the research) of the Department of Cardiovascular Medicine, Tokyo Medical University, and Professor Hirofumi Tanaka of the University of Texas at Austin (UT), U.S.A, have developed the pulse wave velocity (PWV; baPWV, hbPWV, and CAVI are also classified as PWV).
Cardiovascular disease (CVD) is a major cause of death and a significant healthcare burden in Japan. Measuring and evaluating arterial stiffness, a key contributing factor to CVD, can help prevent the onset of such diseases. Brachial-ankle pulse wave velocity (baPWV), a widely used systemic index of arterial stiffness in Japan and abroad, increases significantly after middle age (around the 50s). To measure baPWV, patients must lie down with blood pressure cuffs wrapped around their upper arms and ankles.
In contrast, heart-brachial pulse wave velocity (hbPWV), which was investigated for its usefulness in this study, reflects the stiffness of the proximal aorta. Since proximal aortic stiffness increases linearly with age, starting as early as the 30s, evaluating hbPWV may allow for earlier and more accurate detection of CVD risk than baPWV. Additionally, hbPWV, which is calculated from simultaneous measurements of heart sounds and brachial pulse waveforms, can be measured in a sitting position, similar to how brachial blood pressure is measured, thereby reducing the burden on both the patient and the healthcare professional.
The algorithm for hbPWV measurement could be integrated into spot arm sphygmomanometers and even home blood pressure monitors. This would increase the opportunities to measure arterial stiffness indices and provide more chances for early detection of CVD risk.
Details of this technology were published in Hypertension Research on August 1, 2024.

A researcher at AIST, in collaboration with the University of Tsukuba, has developed a highly efficient method for the direct formic acid synthesis from carbon dioxide and hydrogen.
Formic acid has attracted significant attention as one of the promising hydrogen carriers. In the conventional method, formic acid is first produced from carbon dioxide and hydrogen as a stable “formate salt" under basic conditions and later, the “formate salt” is converted to formic acid through acid treatment. However, these methods involve multiple steps to manage the generated heat and to remove by-products, leading to high production costs, which complicates the cost-effective supply of hydrogen.
In this study, we have developed a simple and efficient method for the direct synthesis of formic acid from carbon dioxide and hydrogen using the iridium catalyst in hexafluoroisopropanol (HFIP). Until now, direct synthesis with iridium catalysts faced challenges due to the rapid decomposition of formic acid into hydrogen and carbon dioxide in water. In contrast, we discovered that HFIP inhibits the formic acid decomposition and increases the formation rate of iridium hydride complexes, the key intermediates in the synthesis, by more than four times compared to that of water.
This breakthrough enables the direct, efficient production of formic acid without the need for formate intermediates. Furthermore, this achievement paves the way for formic acid to be used as a sustainable hydrogen source. By integrating it with AIST’s flow-based power generation system (please refer to the previous press release), this innovation could accelerate the development of carbon-neutral hydrogen storage and production solutions.

Researchers at AIST, in collaboration with Sakamoto Lime Industry Co., Ltd. have developed a method to detect trace amounts of mercury in the soil.
Environmental pollution by Hg and other heavy metals is strictly controlled worldwide. In Japan, numerous standard values have been established for a range of Hg-related parameters, including soil Hg levels and waste management. These measures are aimed at mitigating the health risks associated with Hg exposure. This newly developed technology enables the detection of mercury in solution without complicated procedures using an easily portable device by means of an electrochemical mercury measurement technique. Although electrochemical measurement is easily affected by impurities in the solution (hereafter referred to as "foreign substances") that interfere with the measurement, the unique data processing and analysis enables the determination of whether mercury is contained at a concentration of 0.5 ppb (ppb is one billionth) or higher even in soil test solutions containing a large amount of foreign substances. In the future, we expect to develop a soil analysis system that can be used by anyone on the spot.
Details of this technology were published in Nanomaterials on June 5, 2024.

In 2020, AIST researchers estimated the microbially mediated methane consumption rate by chemical and microbiological analyses coupled with stable isotope tracer experiments of sediments collected from the seafloor off Sakata City, Yamagata Prefecture, where methane hydrates are distributed. They also discovered that in the redox transition zone below the seafloor, methane-oxidizing microorganisms that require oxygen for growth (aerobic methanotrophs) and those that do not (anaerobic methanotrophs) are metabolically active and consume methane. These findings contribute to an accurate understanding of the seafloor budget of methane.

The National Institute of Advanced Industrial Science and Technology (AIST) and Nichia Corporation have developed a light source with light-emitting diodes (LEDs) that replaces existing luminous intensity standard lamps by reproducing the standard spectrum of incandescent lamps as defined by the International Commission on Illumination (CIE).
The comfortable lighting level in living and working spaces is evaluated by an illuminance meter. Illuminance meters (illuminance sensors) are familiar measuring instruments that are incorporated into smartphones and used for dimming displays, etc. It is mandatory for new automobiles sold after April 2020 to have automatic headlights in order to avoid no lights at dusk hours for a safety reason. The system is equipped with a function that automatically turns on the headlights when the ambient light level is less than 1 000 lx. In order to properly use illuminance meters from the viewpoint of safety management, it is important to measure and control illuminance accurately, for example, by having them calibrated traceable to the national measurement standards.
Manufacturers and testing laboratories calibrate illuminance meters using "luminous intensity standard lamps," which are incandescent lamps calibrated to be traceable to national measurement standards. However, incandescent lamps are no longer produced worldwide, and as a result of this phase-out, the discontinued luminous intensity standard lamps have become a global concern.
In response, AIST and Nichia Corporation have developed a light source (Illuminant A standard LED) that provides the standard spectrum (CIE standard illuminant A) using LEDs. The Illuminant A standard LED not only meets the specifications for spectrum and illuminance values required for calibration of illuminance meters, but also improves the aging rate to about 1/20 of a luminous intensity standard lamp by an appropriate seasoning process of the LED package. As a result, it is expected to extend the recalibration periods and improve the measurement uncertainty in manufacturers and testing laboratories.
Details of this technology were published in Measurement on August 16, 2024.

In support of the development of large-scale superconducting quantum computers, researchers with the National Institute of Advanced Industrial Science and Technology (AIST), one of the largest public research organizations in Japan, in collaboration with Yokohama National University, Tohoku University, and NEC Corporation, proposed and successfully demonstrated a superconducting circuit that can control many qubits at low temperature.
To realize a practical quantum computer, it is necessary to control the state of a huge number of qubits (as many as one million) operating at low temperature. In conventional quantum computers, microwave signals for controlling qubits are generated at room temperature and are individually transmitted to qubits at low temperature via different cables. This results in numerous cables between room and low temperature and limits the number of controllable qubits to approximately 1,000.
In this study, a superconducting circuit that can control multiple qubits via a single cable using microwave multiplexing was successfully demonstrated in proof-of-concept experiments at 4.2 K in liquid helium. This circuit has the potential of increasing the density of microwave signals per cable by approximately 1,000 times, thereby increasing the number of controllable qubits significantly and contributing to the development of large-scale quantum computers.
The above results will be published in “npj Quantum Information” on June 3 at 10 a.m. London time.