Room‐Temperature Liquid Metals as Functional Liquids

Song, Min Seok; Dickey, Michael D.

doi:10.1002/9783527804948.ch13

Cited by 9 publications

(8 citation statements)

References 140 publications

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“…and NaOH solution forms sodium tetrahydroxogallate (III) (Na[Ga(OH)4]) [57]. Upon removing the oxide, liquid gallium alloys bead up into spherical shapes due to their large interfacial tension.…”

Section: Electrochemical Oxidation Mechanismmentioning

confidence: 99%

Interfacial Tension Modulation of Liquid Metal via Electrochemical Oxidation

Song

Daniels

Kiani

et al. 2021

Advanced Intelligent Systems

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Among all of the elements in the periodic table, there are only five metals that are liquid near room temperature: francium (Fr), cesium (Cs), rubidium (Rb), mercury (Hg), and gallium (Ga).The first three elements, however, are not practical for applications because they are either radioactive (Fr, Cs) or explosively reactive with air (Rb). Mercury was widely used in the past but is now avoided due to its toxicity. [1,2] By process of elimination, therefore, gallium and gallium-based alloys are the safest liquid metals at or near room temperature. [3] Gallium, discovered in 1875, has an extremely low vapor pressure even at high temperatures (effectively zero at room temperature and only 1 kPa at 1037 C; [4] by comparison, water has a vapor pressure of 1 kPa at 7 C). This low vapor pressure keeps the liquid from evaporating and eliminates the danger of vapor inhalation. While gallium should be found as solid at room temperature, because its melting point is 30 C, it is often liquid due to its ability to supercool. To assure a roomtemperature liquid phase, eutectic alloys containing at least one additional metal are commonly used to lower the melting point below room temperature. Two popular commercial alloys are Galinstan (68.5 wt% Ga, 21.5 wt% In, and 10.0 wt% Sn) and eutectic gallium indium (EGaIn, 75.5 wt% Ga and 24.5 wt% In), for which the melting point is 10.7 and 15.5 C, respectively. [5] In air, these alloys all form surface oxides within microseconds due to a high reactivity of gallium with oxygen. Because Ga oxidizes more readily than other components in these alloys, the surface oxides are dominated by gallium oxide species. These alloys thereby exhibit similar interfacial behavior to gallium in air. [6] Thus, we discuss these gallium-based alloys without distinguishing them by their bulk composition, except where warranted. Interfacial Tension ModulationMetals have significantly larger surface tension (>400 mN m À1 depending on the liquid metal [7] ) than common fluids such as water (72 mN m À1 ), as shown in Figure 1a. The large surface tension of metals is due to the metallic bonds. [4] Gallium is notable for having the highest surface tension (708 mN m À1 ) of any liquid in air near room temperature [8,9] and alloys of Ga, such as EGaIn, also have enormous surface tension (624 mN m À1 ). [10] We note the term "surface tension" refers to the tension of fluid interfaces in contact only with a vapor phase, whereas "interfacial tension" refers more broadly to the tension of fluids

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Section: Electrochemical Oxidation Mechanismmentioning

confidence: 99%

Interfacial Tension Modulation of Liquid Metal via Electrochemical Oxidation

Song

Daniels

Kiani

et al. 2021

Advanced Intelligent Systems

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“…However, the native oxide on the surface of LMs passivates the surface and prevents the redox reactions from efficiently occurring on the LMs surface. Moreover, the redox peaks of surface oxide can itself interfere with the electrochemical measurements . Surface coating of LMs and adjusting the electrolytes composition are among the possible approaches to overcome this challenge.…”

Section: Challenges Of Lm-based Sensorsmentioning

confidence: 99%

“…Moreover, the redox peaks of surface oxide can itself interfere with the electrochemical measurements. 175 Surface coating of LMs 126 and adjusting the electrolytes composition are among the possible approaches to overcome this challenge. Optical sensing based on LMs have been mostly carried out through SPR and SERS platforms owing to the tunable and powerful SPR effects of LMs.…”

mentioning

confidence: 99%

Emerging Role of Liquid Metals in Sensing

Baharfar

Kalantar‐zadeh

2022

ACS Sens.

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Low melting point metals and alloys are the group of materials that combine metallic and liquid properties, simultaneously. The fascinating characteristics of liquid metals (LMs) including softness and high electrical and thermal conductivity, as well as their unique interfacial chemistry, have started to dominate various research disciplines. Utilization of LMs as responsive interfaces, enabling sensing in a flexible and versatile manner, is one of the most promising traits demonstrated for LMs. In the context of LMs-enabled sensors, gallium (Ga) and its alloys have emerged as multipurpose functional materials with many compelling physical and chemical properties. Responsiveness to different stimuli and easy-to-functionalize interfaces of Ga-based LMs make them ideal candidates for a variety of sensing applications. However, despite the vast capabilities of Ga-based LMs in sensing, applications of these materials for developing different sensors have not been fully explored. In the present review, we provide a comprehensive overview regarding the applications of Ga-based LMs in a wide range of sensing approaches that cover different physical and chemical sensors. The unique features of Ga-based LMs, which make them promising materials for sensing, are discussed in subsections followed by relevant case studies. Finally, challenges as well as the prospected future and developing motifs are highlighted for each type of LM-based sensors.

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“…The commercially available Galinstan is yet another liquid metal alloy widely used as the antenna-radiating element [30][31][32]. It comprises of 68.5% gallium, 21.5% indium and 10% tin with an electrical conductivity similar to EGaIn [33,34]. Galinstan also benefits from the thin surface oxide skin formed when in contact with oxygen, similar to other LM alloys.…”

Section: Conductive Fluidsmentioning

confidence: 99%

Liquid Metal Antennas: Materials, Fabrication and Applications

Paracha

Butt

Alghamdi

et al. 2019

Sensors

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This work reviews design aspects of liquid metal antennas and their corresponding applications. In the age of modern wireless communication technologies, adaptability and versatility have become highly attractive features of any communication device. Compared to traditional conductors like copper, the flow property and lack of elasticity limit of conductive fluids, makes them an ideal alternative for applications demanding mechanically flexible antennas. These fluidic properties also allow innovative antenna fabrication techniques like 3D printing, injecting, or spraying the conductive fluid on rigid/flexible substrates. Such fluids can also be easily manipulated to implement reconfigurability in liquid antennas using methods like micro pumping or electrochemically controlled capillary action as compared to traditional approaches like high-frequency switching. In this work, we discuss attributes of widely used conductive fluids, their novel patterning/fabrication techniques, and their corresponding state-of-the-art applications.Most of the conventional antennas are fabricated by etching the copper cladding on the rigid substrates to form static conductor shapes. Such antennas are highly efficient but suffer from irreversible structure deformation and even damage when being bent or stretched beyond certain limits [3]. As alternatives, several types of copper-coated polymer substrates such as Kapton, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN) films have been investigated to accommodate the need in flexible applications such as antennas. Similar to conventional substrates, the electrical properties of these substrates also degrade after severe bending/stretching, which in turn reduces antenna efficiency. Another option is polymer-based materials such as polydimethylsiloxane (PDMS), which has been typically used in combination with copper foils to realize highly flexible antennas. However, the semi-rigid copper foils may potentially suffer from irreversible deformation after certain bending cycles. Alternatively, liquid metals can be injected into microfluidic channels to fabricate highly flexible and mechanically stable antennas without compromising their electrical properties [4].In [5], a broader review of fluidics-based tuning methods for the development of microwave components was presented. Although, this included a review of antennas based on dielectric/conductive fluids, it primarily covered flexible and frequency-tunable antenna/arrays and lacked depth on polarization/pattern reconfigurability techniques. Additionally, discussion of recent advancements in state-of-the-art liquid metal applications was also missing in [5]. In [6], a mini review of flexible and stretchable antennas based on textile materials was discussed. Here, the focus was on the benefits of conductive filler-based elastomers used in antennas for bio-integrated electronics applications and the trade-off between antenna stretchability and its performance. However, a detailed review of materials, novel fabrication te...

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Room‐Temperature Liquid Metals as Functional Liquids

Cited by 9 publications

References 140 publications

Interfacial Tension Modulation of Liquid Metal via Electrochemical Oxidation

Interfacial Tension Modulation of Liquid Metal via Electrochemical Oxidation

Emerging Role of Liquid Metals in Sensing

Liquid Metal Antennas: Materials, Fabrication and Applications

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