Oxidation-Mediated Fingering in Liquid Metals

Eaker, Collin B.; Hight, David; O'Regan, John; Dickey, Michael D.; Daniels, Karen E.

doi:10.1103/physrevlett.119.174502

Cited by 90 publications

(114 citation statements)

References 34 publications

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“…LMP metals have also garnered attention in other areas because of their good electrical properties. Some researchers have been able to manipulate some metals via electric fields . The study of wetting characteristics of room temperature liquid metals is not novel .…”

Section: Introductionmentioning

confidence: 99%

On the Wetting States of Low Melting Point Metal Galinstan® on Silicon Microstructured Surfaces

Davis

Ndao

2017

Adv Eng Mater

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The primary goal of this article is to measure the wetting characteristics of a low melting point metal to determine the efficacy of this type of material for possible use in thermal energy storage applications. Galinstan 1 , a commercially available alloy consisting of Gallium, Indium, and Tin is subjected to contact angle measurements on various silicon surfaces at varying temperatures. Due to the oxidation characteristics of Galinstan, all experiments are conducted in an inert nitrogen environment (<0.5 ppm oxygen) to maintain fluid-like properties. This work finds that although contact angle changes with substrate and surface structure, temperature has no observable effect on contact angle. Contact angles range from 141 on smooth silicon to greater than 160 on silicon micropillars. Although a temperature dependence is not observed over the range of temperatures studied, having wetting properties of Galinstan on various surfaces is a step toward better understanding the capabilities of this and similar materials in energy management.

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Section: Introductionmentioning

confidence: 99%

On the Wetting States of Low Melting Point Metal Galinstan® on Silicon Microstructured Surfaces

Davis

Ndao

2017

Adv Eng Mater

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“…(4) The electrochemistry-assisted sorting process was later adopted to remove the solid shell for obtaining the FLM, as illustrated in Figure 1d,e. [36][37][38] Therefore, this may generate a Marangoni flow travelling towards the area with a higher interfacial tension (cathodic pole) to drag the liquid metal toward the cathode. When the liquid metal stopped flowing, a syringe was used to collect the liquid metal, which is termed as the functional liquid metal, into a container for further experiments.…”

Section: Wwwadvmattechnoldementioning

confidence: 99%

Magnetically‐ and Electrically‐Controllable Functional Liquid Metal Droplets

Kuang

et al. 2019

Adv Materials Technologies

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including microelectromechanical (MEMS) actuators, [8][9][10][11][12] microscale heat exchangers, [13,14] soft and wearable electronics, [15][16][17][18][19] and reconfigurable structures. [20,21] Several techniques have been developed to control the motion and deformation of liquid metal droplets. Applying an external potential gradient is the most commonly used method to drive and deform liquid metal within electrolytes. [8,9,12,22] Other approaches for driving liquid metal droplets by inducing chemical reactions, [23,24] and ionic imbalance [25] have also been demonstrated. Recently, the actuation of liquid metal droplets using external magnetic fields has been explored through the modification of liquid metal surface with ferromagnetic materials. For example, liquid metal coated with iron (Fe) nanoparticles (NPs) can be manipulated, merged, and separated in microfluidic channels with various angles in discretionary direction using an external magnetic field. [26] Other ferromagnetic materials such as nickel can be electroplated on the surface of liquid metal to form a motor. [27] The liquid metal motor can be controlled using both magnetic and electric fields, and also can achieve autonomous locomotion by reacting with aluminum foil. Similarly, porous structure of liquid metal can be obtained by mixing liquid metal and iron NPs in hydrochloric acid. [28] Such a porous mix can expand when subjected to heating to control its density. However, the above-mentioned approaches using electroplating or NP coating/mixing significantly affect the intrinsic properties of liquid metal and may sacrifice the surface fluidity, deformability, and flexibility of the material.Gallium-based room temperature liquid metal alloys have recently been explored to be an emerging functional material. They have attracted particular attentions in a variety of applications due to their unique properties. Many of the applications are based on the precise control over the motion of liquid metal, and yet, the fact that currently lacking the advanced and reliable controlling methods greatly hinders the potential of liquid metal to be applied in a wider range of fields. In this study, an innovative approach is developed to obtain functional liquid metal (FLM) by modifying it with copper-iron magnetic nanoparticles (Cu-Fe NPs). The magnetic modification process enables the Cu-Fe NPs to be suspended within the liquid metal and form the FLM. The FLM exhibits similar appearance, actuating behaviors, and deformability in alkaline solutions to those of pure liquid metal alloys. Meanwhile, the magnetic modification enables the precise and rapid manipulation of the liquid metal using a magnetic field. Most importantly, for the first time, the precise control and climbing locomotion of the FLM is demonstrated with the interworking of both electric and magnetic fields simultaneously. The remarkable features of the FLM may represent vast potentials toward the development of future intelligent soft robots.

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“…Recent studies have proven that the electrochemical oxidation in gallium greatly enhances the response compared to the standard electrocapillary effect known in mercury [19]. This allows gallium liquid metals to deform [19,25], self-actuate [3,26], self-propel [27], solidify [28], mimic the stretching motion of a biological body [29], move directionally or rotationally [5,30,31], and trace a voltage through a maze [32]. Achieving self-regulating control over oscillatory fluid dynamics for gallium remains attractive for a range of environments where its low toxicity is advantageous [33][34][35].…”

Section: Discovery Of a Voltage-stimulated Heartbeat Effect In Droplementioning

confidence: 99%

“…The newly formed metal oxide behaves like a surfactant [19]. It is now well established that this leads to significant change in the surface tension from ∼500 mJ=m 2 to almost 0 [7,25]. Consequently, the droplet begins to spread into a filmlike form [see Fig.…”

Section: Discovery Of a Voltage-stimulated Heartbeat Effect In Droplementioning

confidence: 99%

Discovery of a Voltage-Stimulated Heartbeat Effect in Droplets of Liquid Gallium

Chen

Yun

et al. 2018

Phys. Rev. Lett.

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Chemomechanical effects are known to initiate fluid oscillations in certain liquid metals; however, they typically produce an irregular motion that is difficult to deactivate or control. Here we show that stimulating liquid gallium with electrochemistry can cause a metal drop to exhibit a heart beating effect by shape shifting at a telltale frequency. Unlike the effects reported in the past for mercury, the symmetry-breaking forces generated by using gallium propel the drop several millimeters with velocities of the order of 1 cm per second. We demonstrate pulsating dynamics between 0 and 610 beats per minute for 50-150 μL droplets in a NaOH electrolyte at 34 °C. The underlying mechanism is a self-regulating cycle initiated by fast electrochemical oxidation that adjusts the drop's surface tension and causes a transformation from spherical to pancake form, followed by detachment from the circular electrode. As the beat frequency can be activated and controlled using a dc voltage, the electrochemical mechanism opens the way for fluid-based timers and actuators.

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Oxidation-Mediated Fingering in Liquid Metals

Cited by 90 publications

References 34 publications

On the Wetting States of Low Melting Point Metal Galinstan® on Silicon Microstructured Surfaces

On the Wetting States of Low Melting Point Metal Galinstan® on Silicon Microstructured Surfaces

Magnetically‐ and Electrically‐Controllable Functional Liquid Metal Droplets

Discovery of a Voltage-Stimulated Heartbeat Effect in Droplets of Liquid Gallium

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