Researchers at AIST, in collaboration with Shimane University, have succeeded in developing a unique thermoelectric material (goniopolar material) that can orthogonalize temperature differences and current direction.
Most primary energy is discharged as heat, and to make effective use of this unused heat (waste heat), development of thermoelectric materials that convert heat into electricity is underway worldwide. In recent years, new materials with high performance have been reported one after another, but only Bi₂Te₃ based materials, which were discovered more than half a century ago and operate near room temperature, have been put to practical use. The lack of practical thermoelectric modules that can operate at temperatures higher than room temperature has hindered progress in power generation using waste heat. In particular, conventional thermoelectric modules have a "longitudinal" configuration in which the heat flow and the power generation direction are the same, which causes elemental diffusion and other reactions at the electrode interface in contact with the high-temperature heat source during power generation, leading to degradation, which poses a durability challenge. The research group fabricated single crystals of Mg₃Sb₂ and Mg₃Bi₂ with precisely controlled carrier density and discovered an extremely unique property (goniopolarity) that leads to the realization of "transverse" thermoelectric modules in which the heat flow and power generation direction are orthogonal. The transverse thermoelectric module does not require electrodes at the high-temperature side of the module, which prevents thermal degradation, and is expected to drastically solve the durability issue that has been the bottleneck of conventional thermoelectric modules.
First-principles calculations were performed to elucidate the origin of the goniopolarity, and it was found that the sign of charge carriers differs depending on the crystallographic direction due to the anisotropy of the electronic structure. Since there are many materials with similar characteristics, the application of the method used in this study is expected to lead to the development of thermoelectric modules with higher performance.

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.

AIST proposed the general requirements of an international standard for dynamic signs with Mitsubishi Electric Corporation, and the proposal was adopted as ISO 23456-1:2021.
The more effective sign system will be established by developing individual standards under this international standard. We are expecting for the society sharing with various age groups, cultures, and perceptual and physical characteristics, such as the elderly and wheelchair users under the concept of accessibility for all people.

AIST researchers have developed highly active and selective metal nanoparticle catalysts, and have achieved an environmentally friendly organic synthesis method with these heterogeneous catalysts using continuous production flow process technology.
This technology is a method for synthesizing functional materials by direct flow of hydrogen and substrates using a newly developed heterogeneous catalyst and newly designed continuous-flow synthesis equipment or continuous separation and purification modules. This time, leuco-quinizarins, which are key intermediate to be converted to various functional materials such as pigment dyes, pharmaceuticals, and energy materials, were successfully synthesized catalytically using hydrogen as a reducing agent in highly selective manner for the first time in the world.
Conventional leuco-quinizarin synthesis methods consume stoichiometric amounts of inorganic reagents and generate potentially hazardous waste. The newly developed method, on the other hand, is characterized by a heterogeneous catalyst that can be used over a long period of time under continuous-flow conditions, and by the fact that it only consumes hydrogen, an environmentally friendly reductant, and produces no waste, thus realizing an environmentally friendly organic synthesis. Furthermore, we have newly developed a continuous separation and recovery module unified with function of a batch reactor that can not only separate and recover solvents and hydrogen but also can convert in-situ generated leuco-quinizarin to various anthraquinone derivatives. By coupling this continuous separation and recovery module unified with function of a batch reactor with a continuous-flow hydrogenation system for synthesis of leuco-quinizarin, we have succeeded in continuous production of anthraquinone derivatives as a functional material from inexpensive raw materials. The newly developed continuous-flow synthesis technology will contribute to the development of continuous synthesis processes for functional materials with complex structures, since it can be coupled with other continuous synthesis equipment to realize further multi-step continuous synthesis methods.

A researcher at AIST, in collaboration with Aichi Steel Corporation, has developed a highly sensitive magnetic sensor that can automatically compensate for fluctuations in detection sensitivity due to manufacturing variations and environmental changes.
Compact, highly sensitive magnetic sensors are needed in a wide variety of applications, including industrial and biological measurement. To apply them to fields such as IoT, their sensitivity must be maintained at a constant level. The cost of manually adjusting sensitivity has hindered the expansion of applications for small, high-sensitivity magnetic sensors.
By combining an application-specific integrated circuit (hereinafter referred to as "ASIC") with an automatic correction function originally designed by AIST and a magnetic impedance element (hereinafter referred to as "MI element") developed by Aichi Steel Corporation, the fluctuation of the magnetic detection sensitivity was reduced to 1/3 of its original level. This automatic calibration technique does not require a special test mode for the process, and can be performed in the background during normal sensing operation. The digital-output architecture achieves both easy handling of output signals and low power consumption. This approach is expected to expand the range of applications for compact, high-sensitivity magnetic sensors.

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.

Researchers at AIST, in collaboration with researchers at Yokohama National University, have succeeded in generating a highly accurate time scale for 230 consecutive days by using an optical lattice clock.
Currently, a redefinition of the second is being discussed so that the optical frequency obtained using an optical clock will be used as the standard. Once the second is redefined, it is expected that a "graduated scale" tens of thousands of times finer than the current definition will be established, and that highly accurate time and frequency can be supplied to society. Many issues remain to be addressed in order to redefine the second, such as ensuring that the new definition is accurate and realized robustly over a long period compared with the current definition. Among them, the generation of a highly accurate and stable time scale by adjusting the frequency of an atomic clock based on an optical clock is considered as one of the conditions that are desired to be achieved for the redefinition of the second, and so research to incorporate an optical clock into a time scale is underway in many countries. AIST has been generating a time scale by manually adjusting the frequency of a hydrogen maser atomic clock, which is an atomic clock capable of continuous operation, but an even more accurate time scale can be expected to be generated by using an optical lattice clock. However, it has been difficult to accurately adjust the frequency of the atomic clock during the shutdown period of the optical lattice clock because the optical lattice clock could only be operated at a low uptime.
Using previously obtained data from an optical lattice clock that had been successfully operated at high uptime, the frequency of the hydrogen maser atomic clock was adjusted in a postprocessing analysis to generate a time scale based on the optical lattice clock. This time scale achieved the world's highest level of synchronization accuracy of within ±1 ns (one billionth of a second) from UTC, the international time standard, over a 230-day period. This achievement is expected to accelerate the consideration of the redefinition of the second.
Details of this technology have been published in Physical Review Applied on June 7, 2024 (EST).

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.