Liquid metals have high potential to mount electronic components at room temperature, but their electrical nature has not been clarified. In this paper, the effect of two factors on contact resistivity were identified: (1) formation of metal oxide layers, and (2) surface wettability of the metal. We compared three different methods to form electrical connections between liquid metals and solid metals. When two copper films were connected using galinstan that was pre-deposited, the contact resistivity was1.21 × 10^-6 Ω m². Alternatively, the same connection was made by placing copper films first, followed by the placement of galinstan. The contact resistivity in this method was 4.08 × 10^-8 Ω m². Application of the vacuum to the assembly further reduced the contact resistivity down to 2.30 × 10^-8 Ω m². These results suggest that placing liquid metals after solid metals and applying vacuum can reduce the contact resistivity.

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This paper demonstrates the development of a strain gauge using an electronic tattoo for measuring facial expression. In recent years, research on emotion estimation by facial expression analysis has attracted attention. In general, analyzing facial images is used to measure facial expressions. However, this method cannot measure when the subject is moving. To solve this problem, we developed electronic tattoos. Since electronic tattoos are flexible and can be attached to the skin, they are considered to be useful for facial expression detection for all movements in daily life. Therefore, we fabricated strain gauges using electronic tattoos and evaluated its effectiveness.

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Until now, a lot of stretchable device is proposed. In this study, a highly stretchable vibrating element was developed by mounting a planar coil of liquid metal on a magnetic elastomer with oriented magnetic particles. The planar coil of liquid metal was fabricated by photolithography and showed a stable resistance value. The device was able to generate a peak sound pressure in the frequency range of 500 Hz to 20,000 Hz, which is the audible frequency range of humans. Furthermore, a cartilaginous conduction device was realized by molding magnetic elastomers into the form of ear shapes and achieved the functionality of a speaker with high adhesion to ears.

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To provide tactile feedback to human’s palm, the palm-based devices has been developed, which is equipped with tactile sensors. Currently, soft actuators are used to drive the artificial muscles in this device, but the presence of electrical wiring makes it difficult to achieve complex motions and make the device wearable. However, it is difficult to make the device wearable. Thus, we aimed to invent a palm-type device that does not require wiring by mounting an actuator and a tactile sensor in a palm-type device using liquid metal as the working fluid. As a first step, we have developed a palm-type device with a tactile sensor in the palm of hand.

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Liquid-state electronics utilizing functional liquids confined in soft templates as the sensing and actuating component present the ideal platform for enabling conformal coverage of electronic systems on curved and soft surfaces. However, to date, optoelectronic devices based on functional liquid materials as represented by photodetectors and optical memories still have not been proposed; this advancement is crucial to scaling up current liquid-state devices to a system level. Here, this study proposes optoelectronic devices based on liquid metal and photo-switchable ionic liquid with liquid-liquid heterojunction technology. The sensing and memory schemes we present are generic for different liquid-state devices, enabling different functionality to be added to the liquid-state electronics. As a proof of concept, we demonstrate a light sensor composed of the ionic liquid, and an optical memory using a composite of the ionic liquid and polypropylene glycol. These devices are important advancements towards the realization of liquid-state electronic systems.

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磁界に対して垂直に置かれた導線に電流を流すと，磁界と電流に垂直な向きにアンペール力が作用する．本研究では，このアンペール力を利用した軸受の開発を目的としている．軸受の周囲に磁石を配置し，その中に置かれた軸に電流を流すことによって軸にアンペール力を作用させる．これによって軸を浮上させ，軸と軸受の固体接触を避けることができる．この軸受を試作した．

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Until now, a lot of wearable devices which have stretchability have been developed. However, the devices have stretchability only in a sensor part, not circuit part or entire device. In this study, stretchable system which is composed of hard and soft hetero-polymer substrate and liquid metal electrodes was developed. The substrate consists of three layers, epoxy, PDMS and Eco-Flex. The electric components were mounted on the epoxy substrate, which prevent the deformation of a circuit. The circuit based on liquid metal electrodes was constructed on the PDMS and Eco-Flex parts. We succeeded in the development of the system and demonstrated the functionality of the system in this study.

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マイクロインジェクション法は狙った細胞に目的の物質を導入できることから，細胞生物学においてポピュラーな手法として用いられてきた．しかし，主に動物細胞で用いられてきた技術であるために，高い膨圧を持つ植物細胞では原形質が針内部に流入してしまい針が詰まってしまうことが問題であった．我々が開発したレーザー熱膨張式マイクロインジェクション（Laser-assisted Thermal-expansion Microinjection，LTM法）は，針内部のレーザー吸収剤の熱膨張圧によって原形質の流入を防ぐことができるために，針が詰まることなく1本の針で連続してインジェクションすることが可能となった．また，従来の方法では十分な圧力が得られないために扱うことができなかった，先端径が0.1 μm程度の針を用いることもできるため，細胞へのダメージも少なくなった．使用用途は植物細胞に限らず，出芽酵母のような微小細胞や細胞核・オルガネラなどにもインジェクションが可能である．本稿ではLTM法の原理とともに，これまでの利用例についてもご紹介したい．

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Recently, soft robots have attracted interest of researchers. The advantages of the soft robots are the flexibility and simplicity of the structure. However, in order to implement complex motions with the robots, sensors and wires are required to measure the condition of the robots. In this study, we propose a method to actuate soft robots with pressurized liquid metal. The method enables the robots to provide both electrical signal and force. We prototyped a McKibben artificial muscle actuator and evaluated the mechanical properties and electrical properties to verify the proposed concept.

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Very high temperature and high pressure conditions are expected inside a acoustic bubble at collapse in a low-vapor pressure liquid as mercury. We measured multi-bubble sonoluminescence from mercury with varying saturation rare gas, input power and frequency. The results showed no clear difference in MBSL spectrum with the rare gas. The results suggested that a bremsstrahlung from mercury is the main light-emitting source, because the ionization energy of mercury is smaller than that of any rare gas.

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An innovative coaxial MHD power generator using low-melting point alloy has been proposed for efficient wind power generation. MHD power generation is a kind of the direct-electricity-generation method. In order to develop the generator, three dimensional MHD Taylor Couette flow is simulated using lattice Boltzmann method for MHD based on Dellar 's model. In this study, the coaxial MHD power generation characteristic using the low-melting-point-alloy is investigated at low Reynolds numbers. As the obtained results, the velocity profile is changed due to the effect of the Lorentz force. And output voltage increases linearly with the Reynolds number while sticking Hartmann number to 4.

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グラファイト粉末と低粘度流動パラフィン等のバインダー液体を混合して調製した液状炭素を電極として用い，ポーラログラフィーを行った．液状炭素はシリンジポンプにより送液し，炭素滴をキャピラリーの先端から水溶液中へ吐出させた．これを作用電極とし，フェロセンカルボン酸（FcCOO⁻）についてポーラログラフィーを行った結果，明瞭な限界電流をもつFcCOO⁻の1電子酸化波が観察された．対数プロット解析を行うと，炭素滴が小さいときほどオーム降下の影響が小さくなり，傾きが可逆波の理論値に近づいた．限界電流値の濃度依存性からIlkovic式に基づいて求められたFcCOO⁻の拡散係数は，白金ディスク電極でのサイクリックボルタンメトリーから求められたそれとほぼ同程度であり，Ilkovic式が炭素滴電極にも近似的に適用可能であることが示された．正側及び負側の電位窓，ならびにゼロ電荷電位についても検討した．

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