Characterization of liquid-metal Galinstan® for droplet applications

We report our characterization of nontoxic liquid-metal alloy Galinstan
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on its potential for substituting mercury droplets in miniature devices. To combat the super fast oxidation, which has been hindering the studies of Galinstan
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our entire experiments are performed in a nitrogen-filled glove box. Galinstan
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droplets are found to behave like a true liquid, indicating a good liquid-air interface, only if the oxygen traces stay below 1 ppm. Surface tension of Galinstan
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is measured to be 534.6±±10.7 mN/m in nitrogen at 28°C using a pendant drop method. Advancing/receding contact angles on glass and Teflon surfaces are found to be 146.8°/121.5° and 161.2°/144.4°, respectively. The electrowetting on dielectric (EWOD) mechanism of Galinstan
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is also demonstrated.