This highlight overviews state-of-the-art methods to pattern liquid metals for use in microfluidics and electronic components that are soft, stretchable, shape reconfigurable.

Liquid metal co-injected with electrolyte through a microfluidic flow-focusing orifice forms droplets diameters and production frequencies controlled in real time by voltage. Applying voltage to the liquid controls interfacial tension via combination of electrochemistry electrocapillarity. This simple effective method can instantaneously tune size microdroplets, which has applications composites, catalysts, microsystems.

Abstract Conventional machines rely on rigid, centralized electronic components to make decisions, which limits complexity and scaling. Here, we show that decision making can be realized the material-level without relying semiconductor-based logic. Inspired by distributed exists in arms of an octopus, present a completely soft, stretchable silicone composite doped with thermochromic pigments innervated liquid metal. The ability deform metal couples geometric changes Joule heating, thus...

This work reports a simple approach to form, study, and utilize rough coatings that prevent the adhesion of gallium-based liquid metal alloys. Typically, liquids with large interfacial tension do not wet nonreactive surfaces, regardless surface topography. However, these alloys form oxide "skin" adheres many substrates, even those low energy. render closed channels including soft materials, be "oxide-phobic" via spray-coating (NeverWet, which is commercially available inexpensive). Surface...

Abstract Herein, elastomeric fibers that have shape memory properties due to the presence of a gallium core can undergo phase transition from solid liquid in response mild heating are described. The is injected into hollow fiber formed by melt processing. This approach provides straightforward method create any elastic fiber. Solidifying changes effective modulus 4 1253 MPa. increase stiffness preserve deformed shape. energy stored polymer shell during deformation drives relax back its...

This work establishes that static contact angles for gallium-based liquid metals have no utility despite the continued and common use of such in literature. In presence oxygen, these rapidly form a thin (∼1–3 nm) surface oxide "skin" adheres to many surfaces mechanically impedes its flow. property is problematic angle measurements, which presume ability liquids flow freely adopt shapes minimize interfacial energy. We show here advancing metal are always high (>140°)—even on substrates it...

Liquid metals based on gallium, such as eutectic gallium indium (EGaIn) and Galinstan, have been integrated static components in microfluidic systems for a wide range of applications including soft electrodes, pumps, stretchable electronics. However, there is also possibility to continuously pump liquid metal into microchannels create shape reconfigurable metallic structures. Enabling this concept necessitates simple method control dynamically the path takes through branched with multiple...

Stretchable fibers dissipate energy via the sequential fracturing of a metallic core held together by an elastomeric shell.

Metals tend to supercool-that is, they freeze at temperatures below their melting points. In general, supercooling is less favorable when liquids are in contact with nucleation sites such as rough surfaces. Interestingly, bulk gallium (Ga) can significantly supercool, even it heterogeneous surfaces that could provide sites. We hypothesized the native oxide on Ga provides an atomically smooth interface prevents from directly contacting surfaces, and thereby promotes supercooling. Although...

Liquid metals have long been treated as Newtonian liquids, but several researchers recently indicated that some may shear thin. While apparent thinning can be caused by surface oxidation, the reports of shear-thinning were investigated using cup and bob type rheometers, which are expected to only weakly impacted contamination effects. We show here even small amounts oxide on liquid cause dramatic changes measured viscosity sample. Using a Searle-type rotational rheometer, we eutectic gallium...

Liquid metals adhere to most surfaces despite their high surface tension due the presence of a native gallium oxide layer. The ability change shape functional fluids within three-dimensional (3D) printed part with respect time is type four-dimensional printing, yet adhesion limits pump liquid in and out cavities channels without leaving residue. Rough prevent adhesion, but methods roughen are difficult or impossible apply on interior parts. Here, we show that silica particles suspended an...

Abstract Many applications of terahertz (THz) technology require the ability to actively manipulate a free space THz beam. Yet, although there have been many reports on development devices for signal processing, few these include possibility electrical control functionality, and novel ideas are needed active reconfigurable devices. Here, we introduce new approach, based integration electrically actuated liquid metal components in waveguides. This versatile platform offers possibilities...

Abstract Electroadhesion is an attractive mechanism to electrically modulate adhesion surfaces. arises from the interaction of electric fields with conductive or dielectric materials. devices consist in‐plane, interdigitated electrodes that generate out‐of‐plane fields, which increase target To date, these have predominantly been composed carbonaceous Here, liquid metal utilized create in silicone substrates. Liquid can be patterned a variety unique ways, including microfluidic injection,...

Abstract Opportunities to improve thermal management in electronic devices are currently hindered by processing constraints that limit conductivity polymer‐matrix composites. Active patterning of filler particles is a promising route while retaining processability improving particle contact density and directing heat along optimized pathways. This study employs acoustic align compact into stripes during stereolithographic 3D printing. approach produces polymer‐based composite materials with...

Electrowetting uses voltage to manipulate small volumes of fluid for applications including lab-on-a-chip and optical devices. To avoid electrochemical reactions, a dielectric often separates the from electrode, which has undesired effect adding processing steps while increasing necessary electrowetting. We present new method dramatically reduce complexity electrode fabrication enabling multiple performance advances. This relies on self-oxidizing paint-on liquid-metal that can be fabricated...

Liquid metal-based reconfigurable antennas typically must be flushed with an electrolyte to remove the nanometer-thick oxide skin of EGaln that adheres walls microchannels. The residue prevents repeatable actuation, but presence introduces other challenges owing its often corrosive and electrically conductive nature. To overcome this issue, we present a technique for enabling reversible infusion withdrawal into acrylic micro-channels wide planar cavities by coating surfaces silica-particle...

Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text K. S. Reichel, N. Lozada-Smith, R. Mendis, I. Joshipura, M. D. Dickey, and Mittleman, "Active THz Waveguides Enabled by Liquid Metal Actuation," in Conference Lasers Electro-Optics, OSA Technical Digest (online) (Optica Publishing Group, 2017), paper SM3J.3. Export BibTex Endnote (RIS) HTML Plain alert Save article

This work characterizes the behavior of a eutectic alloy gallium and indium (75% Ga, 25% In, by weight, ‘EGaIn’) in response to electric fields. The metal is liquid at room temperature (M.P., 15.5 °C) exhibits low toxicity. These fluidic metals may be injected into microfluidic systems, fibers, capillary networks form soft electronic devices that are compliant. Once injected, remains its place because adhesive nature thin native oxide. Preventing oxide adhesion within microchannels enables...

We demonstrate an active tunable filter with channel add-drop functionality by employing electronically reconfigurable liquid metals in the gap between two waveguides to dynamically modify coupling.

We characterize the THz properties of liquid metals in conductive fluids. These results will inform design future reconfigurable signal processing components based on incorporated into waveguides.