• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• 한국수소및신에너지학회논문집
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• 제27권2호
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• pp.176-181
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• 2016

Recent years, supercapacitors have been attracting a growing attention as an efficient energy storage, due to their long-lifetime, device reliability, simple device structure and operation mechanism and, most importantly, high power density. Along with the increasing interest in flexible/stretchable electronics, the supercapacitors with compatible mechanical properties have been also required. A eutectic gallium-indium (EGaIn) liquid metal could be a strong candidate as a soft electrode material of the supercapacitors because of its insulating surface oxide layer for electric double layer formation. Here, we report the electrochemical study on the charging/reaction process at the interface of EGaIn liquid metal and electrolyte. Numerical fitting of the charging current curves provides the capacitance of EGaIn/insulating layer/electrolyte (${\sim}38F/m^2$). This value is two orders of magnitude higher than a capacitance of a general metal electrode/electrolyte interface.

• 한국전자파학회논문지
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• 제27권1호
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• pp.8-13
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• 2016

본 논문에서는 잉크젯 프린팅 기술을 이용하여 종이 필름 위에 전도성 잉크를 인쇄하여 방사 패턴 변환이 가능한 종이접기 형태의 안테나를 제안한다. 제안된 안테나는 접었을 때와 펼쳤을 때 각각 다이폴 안테나와 루프 안테나로 동작하며, 종이 필름을 접고 펼치는 방식에 따라 상호 변환될 수 있다. 제안된 안테나는 다이폴 상태와 루프 상태일 때 모두 동일하게 1.85 GHz에서 동작하도록 설계되었다. 종이 필름을 접었을 때 종이 필름의 코팅과 그 위에 인쇄된 전도성 잉크가 깨짐 현상을 해결하기 위해 액체금속(liquid metal)중 하나인 EGaIn(Eutectic Gallium Indium)을 사용하였다. 제안된 안테나의 성능은 시뮬레이션과 실제 측정 결과로 확인할 수 있으며, 다이폴 상태와 루프 상태일 때 안테나 이득은 각각 -4 dBi, -5 dBi이다. 또한, 측정 결과, 다이폴 상태와 루프 상태일 때 서로의 Null 부분을 서로 상호 보완해 주는 것을 확인할 수 있다.

• ETRI Journal
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• 제44권1호
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• pp.147-154
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• 2022

We demonstrate a new double-layer structure for stretchable interconnects, where the top surface of a serpentine polyimide support is coated with a thin eutectic gallium-indium liquid metal layer. Because the liquid metal layer is constantly fixed on the solid serpentine body in this liquid-on-solid structure, the overall stretching is accomplished by widening the solid frame itself, with little variation in the total length and cross-sectional area of the current path. Therefore, we can achieve both invariant resistance and infinite fatigue life by combining the stretchable configuration of the underlying body with the freely deformable nature of the top liquid conductor. Further, we fabricated various types of double-layer interconnects as narrow as 10 ㎛ using the roll-painting and lift-off patterning technique based on conventional photolithography and quantitatively validated their beneficial properties. The new interconnecting structure is expected to be widely used in applications requiring high-performance and high-density stretchable circuits owing to its superior reliability and capability to be monolithically integrated with thin-film devices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1235-1236
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• 2015

This paper reports hyperelastically stretchable strain gauges based on liquid metal (eutectic gallium-indium;EGaIn) and a platinum-catalyzed silicone elastomer ($Ecoflex^{TM}$). A custom liquidmetal patterning setup was operated to fabricate liquidmetal straingauge on flexible substrate. The printed strain gauges were tested under cyclic uniaxial stretching, twisting, even bending of human finger. By engineering the orientation of solid wires placed over two terminals of t he printed liquid metal resistor, we stably achieved the stretchability of ~800 % which is the highest value reported so far, to the best of our knowledge.