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Professor:Kohei Soga
Assistant professor:Hiroshi Hyodo

The “OTN-NIR fluorescence bioimaging” developed in the Soga laboratory is a unique and innovative biomedical imaging technology based on the studies of fluorescent inorganic nanoparticles which can achieve much deeper observation depth compared to conventional ones. The fluorescent nanoparticles are also applied for devices such as flexible and transparent display. Beside those application researches, we study on the fundamental physical properties of icosahedral cluster solids for discovering new materials for thermoelectric converters or super conducting devices.


Example study

Development of OTN-NIR Fluorescence Bioimaging System
– from materials to systems –

1000 nmを超える(OTN: over 1000 nm)近赤外光の波長域では現在バイオメディカルイメージングに用いられている波長域よりも約10倍の透明度が実現します。OTN近赤外蛍光バイオイメージングは曽我研究室が世界に先駆けて取り組む技術開発として、生命現象の解明から医療における診断・治療まで幅広い分野における応用に期待が集まっています。材料工学としては、発光スキーム設計、無機ナノ粒子合成、生体機能分子・高分子とのコンジュゲートが出発点となります。目標は「がん」を小さく見つける、小動物の中でのナノ物質の挙動を追う、細胞の中でのナノ物質の振る舞いを明らかにすることです。国立がんセンター東病院、本学部生物工学科、電子応用工学科、本学生命医科学研究所、理化学研究所、東北大学、大阪大学、名古屋造形大学、島津製作所などとの共同研究により希土類含有セラミックナノ粒子、量子ドットを蛍光体とした蛍光体プローブ開発の材料工学を、細胞、小動物、ヒトの臨床手術のためのデバイスやシステムに至るユーザーに直結した幅広い開発プロジェクトに展開し、「使える工学」の創出を目指しています。


Development of Display Devices by Compositing RED-CNP and Polymers.

Rare-earth doped ceramics nanophosphors (RED-CNP) are known to emit “upconversion” emission, where stepwise excitation scheme can convert near-infrared light source into visible light. The upconversion emission by the RED-CNP has been applied for fluoresce bioimging by a near infrared excitation. On the other hand, Soga laboratory has developed a transparent and flexible upconversion display by compositing the RED-CNP and a flexible polymer. For making it transparent, refractive indices are matched between them. By using the RED-CNP, RGB visible emission can be obtained by invisible near infrared excitation light. By using two near infrared, invisible excitation lights with different wavelength, we are attempting to develop an 3D, color and transparent display. Currently, we are studying to from waveguide structure in the materials for easier excitation scheme. RED-CNP has a potential to emit unique fluorescence as upconversion emission. However, its application is limited as a powder or particle form. By compositing the RED-CNP with a polymer with transparency, formability and flexibility, we are attempting to develop displays with unique styles.


Structure and Properties of Boron Icosahedral Cluster Solids

Most general form of pure boron as a solid is β-rhombohedral boron (β-B). The structure of β-B naturally involves icosahedral cluster with 12 boron atoms. Due to the 5 outermost electrons, the boron can get along with a structure with 5-fold symmetry as that of the icosahedral cluster. The pure boron is a semiconductor. However, the structure and physical properties are different from famous semiconductors such as silicon or germanium. The 5-fold symmetry of the icosahedral cluster does not allow closely-packed arrangement in a periodical structure of crystals. Accordingly, the structure of the pure boron contains many vacant spaces in the crystalline structure. By doping metal dopants with several % concentration, the conducting property can be gradually controlled from that of semiconductor into metal one. In the solid, metallic bonding and covalent bonding can coexist. A lot of things are unknown for the pure and doped boron solids including the complicated band structure and the above mentioned unique structure and electric properties. The solid state physics for the icosahedral cluster solids as the physics for the cluster solids is essentially different from the popular physics for semiconductors, which is based on the periodic structure of crystalline solids. Soga laboratory is challenging to clarify the structure and physical properties of the group of these unique solids. The unique structure and properties of these solids are the seeds for finding new superconducting or thermoelectric materials.