Gallium Liquid Metal: Nanotoolbox for Antimicrobial Applications.

Gallium-based liquid metals (GLMs) are promising anode materials for lithium-ion batteries due to their low-melting point, fluidity, high-electrical and -thermal conductivity, and high-theoretical capacity for Li (769 mAh/g, Li2Ga). Notably, GLMs undergo a reversible liquid-to-solid-to-liquid transition during lithiation and delithiation, enabling a self-healing mechanism that mitigates surface defects. This mechanism extends the cycle life of anodes utilizing GLMs either as active materials( 1–6 ) or in combination with high-volume expansion materials such as silicon (~400%)( 7–9 ).Fundamental studies on the self-healing mechanism of GLMs are limited. Previous investigations have primarily relied on macroscopic characterizations such as X-ray diffraction (XRD) in bulk electrodes( 3,10 ) or in situ transmission electron microscopy (TEM) on individual GLM nanoparticles (NPs) in solid-state cells open to the environment( 6,11 ). In this work, we adopt a multi-scale approach to gain insights into the (de)lithiation mechanism. We conducted: (1) in situ TEM observations of GLM NPs on a TEM grid current collector to simultaneously track lithiation/delithiation dynamics across multiple nanoparticles; (2) cryogenic TEM where GLM NPs on a TEM grid are cycled in a lithium-ion battery electrolyte, and the grid is subsequently transferred to a cryo-TEM for high-resolution interfacial characterization of the GLM NPs; and (3) cryogenic focused-ion beam tomography to analyze structural changes in a composite electrode comprised of GLM NPs, Super P carbon, and PVDF binder on a Cu current collector over continuous cycles within a coin or pouch cell. By investigating GLMs at multiple length scales, this study advances the understanding of how the lithiation/delithiation mechanism of GLM NPs influences capacity fade in lithium-ion batteries. In a broader context, this study establishes a framework for future multi-length scale investigations into battery materials.References Jin, X. et al. Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes. Adv. Mater. 34, 2200181 (2022).Zhu, M., Li, S., Li, B. & Yang, S. A liquid metal-based self-adaptive sulfur–gallium composite for long-cycling lithium–sulfur batteries. Nanoscale 11, 412–417 (2019).Guo, X. et al. A Self-Healing Room-Temperature Liquid-Metal Anode for Alkali-Ion Batteries. Adv. Funct. Mater. 28, 1804649 (2018).Pu, J. et al. Liquid Metal-Based Stable and Stretchable Zn-Ion Battery for Electronic Textiles. Adv. Mater. 36, 2305812 (2024).Liu, G. et al. Soft, Highly Elastic, and Discharge-Current-Controllable Eutectic Gallium–Indium Liquid Metal–Air Battery Operated at Room Temperature. Adv. Energy Mater. 8, 1703652 (2018).Huang, C. et al. Alkali-ion Batteries by Carbon Encapsulation of Liquid Metal Anode. Adv. Mater. n/a, 2309732.Hapuarachchi, S. N. S. et al. Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium-Ion Batteries. Batter. Supercaps 1, 122–128 (2018).Ju, Z. et al. Assembled MXene–Liquid Metal Cages on Silicon Microparticles as Self-Healing Battery Anodes. Nano Lett. 24, 6610–6616 (2024).Zhao, Z. et al. Liquid Metal Remedies Silicon Microparticulates Toward Highly Stable and Superior Volumetric Lithium Storage. Adv. Energy Mater. 12, 2103565 (2022).Wang, K. et al. Core-shell GaSn@rGO nanoparticles as high-performance cathodes for room-temperature liquid metal batteries. Scr. Mater. 217, 114792 (2022).Liang, W. et al. Nanovoid Formation and Annihilation in Gallium Nanodroplets under Lithiation–Delithiation Cycling. Nano Lett. 13, 5212–5217 (2013).

Interfacing of surfaces with gallium-based liquid metals – approaches for mitigation and augmentation of liquid metal adhesion on surfaces

Introduction Stretchable devices have been highly demanded because of wearable devices in the IoT society. Stretchable lithium ion batteries are crucial to growth of IoT society, since the current developed devices possesses only interface part. The batteries and devices require higher stretchability and robustness to deformation. Liquid metal (LM) is one of the prominent materials for stretchable sensors(1) and wiring circuit(2). In addition, LMs have self-healing characteristics(3) and high capacity (Ga:769 mAh/g, Sn:990 mAh/g) in lithium ion batteries. Here, we investigated the electrochemical characteristics and improvement of robustness using liquid metal nano particles (LMNP) anode in stretchable lithium ion batteries. In this study, stretchable 3D porous LMNP electrodes are fabricated and assembled into stretchable batteries. The stretchable batteries consist of stretchable LMNP and LiFePO4 (LFP) electrodes based on 3D porous polydimethylsiloxane (PDMS)/Ecoflex/Super P carbon composites, stretchable separator, [Li(G4)][TFSI] electrolyte and stretchable package. The batteries have high stretchability and robustness to deformation. Experiment 3D porous PDMS/Ecoflex/Super P carbon composites were used for stretchable electrode substrates. The porous structure was prepared by sacrifice-template method using sugar(4). 3D porous PDMS/Ecoflex/Super P carbon composites was composed of PDMS, Ecoflex with the weight ratio of 6:4 and coating Super P carbon on the surface. LMNP was prepared by ultra-sonication GaSn (Ga:Sn=88:12) alloy. The LMNP alloy was used as active materials of anode. The anode slurries were prepared by mixing the LMNP, Super P carbon, poly(vinylidene fluoride) (PVDF) in N-methyl-2-pyrrolidione (NMP) solvent. LFP was used as active materials of cathode. The cathode slurries consisted of LFP, Super P carbon, PVDF. Stretchable electrodes were fabricated by drop cast method with the electrode slurries on the 3D porous substrates. [Li(G4)][TFSI] was composed of LiTFTI and Tetraethylene glycol dimethyl ether (G4). Stretchable batteries were assembled using the PDMS/Ecoflex/Super P carbon/LMNP anode, PDMS/Ecoflex/Super P carbon/LFP cathode, stretchable separator and stretchable packaging. The nickel/aluminum tabs are attached to PDMS/Ecoflex/Super P carbon/LMNP and PDMS/Ecoflex/Super P carbon/LFP electrode by using small amount of epoxy resin adhesive(Fig. 1). Results and Discussion To investigate the electrochemical characteristics of the stretchable electrode on lithium ion batteries, we respectively conducted galvanostatic tests of the stretchable LMNP anode and the stretchable LFP cathode in half-cell configurations paired with lithium metal as counter and reference electrode. The results show the electrodes can charge/discharge on lithium ion batteries at 1 C. In addition, the electrochemical performance of the stretchable LMNP electrode was investigated. The charge/discharge curves were measured after 100% strain-release cycle 50 and 100 times. The results of the stretchable LMNP electrode showed the capacity retention was higher than the stretchable Si NP (silicone nano particle) electrode. The LMNP used as active materials improve robustness to stretching were confirmed. The full cells were tested using PDMS/Ecoflex/Super P carbon/LMNP and PDMS/Ecoflex/Super P carbon/LFP electrode with charge/discharge measurement. As a result, the full battery could work. Acknowledgement This work was supported by JST CREST Grant Number JPMJCR1905, Japan, by the Japan Science and Technology Agency, PRESTO Grant Number JPMJPR18J2, and by JSPS Grant-in-Aid for Challenging Exploratory Research. References (1) Yuji Gao et al, Advanced. Materials , 2017, 1701985(2) Guangyong Li et al, Sensors and Actuators B , 2015, 221, 1114-1119(3) Yingpeng Wui et al, Energy & Environmental Science , 2017, 10, 1854-1861(4) Hongsen Li et al, Advanced. Materials , 2017, 1700898 Image Figure 1 Self-healing behavior of LMNP (left). Schematic diagram of stretchable battery (right). Figure 1

Gallium-based liquid metals (GLMs) exist as atypical liquid-phase metals at and near room temperature while being electrically and thermally conductive, enabling copious applications in soft electronics and thermal management systems. Yet, solid metals are affected by interfacing with GLMs, resulting in liquid metal embrittlement and device failure. To avert this issue, mechanically durable and electrically tunable diffusion barriers for long-term reliable liquid metal-solid metal interfacing based on the deposition of various diamond coatings are designed and synthesized, as they feature high chemical inertness and extraordinary mechanical resistance. The diamond coatings show superlyophobicity (GLM contact angle ≥ 155°) and are nonstick toward GLMs, thereby achieving high mobility of GLM droplets (sliding angle 8-12°). The excellent barrier and anti-adhesion performance of the diamond coatings are proven in long-term experiments (3 weeks) of coated titanium alloy (Ti) samples in contact with GLMs. The electrical performance of the conductive diamond coating deposited on Ti is reliable and stable over a period of 50 h. As proof-of-concept applications a switch and a thermal management device based on liquid metals are demonstrated, signifying that coating diamond films on metals is a potent means to achieve stable integration of solid metals with GLMs.

We report the fabrication and characterization of a reversible resonant frequency tunable antenna based on liquid metal actuation. The antenna is composed of a coplanar waveguide fed monopole stub printed on a copper-clad substrate, and a tunnel-shaped microfluidic channel linked to the printed metal. The gallium-based liquid metal can be injected and withdrawn from the channel in response to an applied air pressure. The gallium-based liquid metal is treated with hydrochloric acid to eliminate the oxide layer, and associated wetting/sticking problems, that arise from exposure to an ambient air environment. Elimination of the oxide layer allows for reliable actuation and repeatable and reversible tuning. By controlling the liquid metal slug on-demand with air pressure, the liquid metal can be readily controllable to connect/disconnect to the monopole antenna so that the physical length of the antenna reversibly tunes. The corresponding reversible resonant frequency changes from 4.9 GHz to 1.1 GHz. The antenna properties based on the liquid metal actuation were characterized by measuring the reflection coefficient and agreed well with simulation results. Additionally, the corresponding time-lapse images of controlling liquid metal in the channel were studied.

Conductive fabrics are promising candidates for developing flexible, lightweight, and high conductivity electromagnetic (EM) shielding materials to meet the requirements of next‐generation flexible and wearable electronics. Herein, an effective strategy to construct a conductive titanium carbide (Ti3C2Tx)/Polyaniline (PANI) composite with 3D nanoflower structure by deposition of PANI on the surface of single‐layer Ti3C2Tx nanosheets through in situ and oxidant‐free polymerization of aniline monomer to avoid the restacking/aggregation and easy oxidation of Ti3C2Tx MXene is developed. In addition, GaIn liquid metal (LM) nanoparticles are also incorporated into the Ti3C2Tx/PANI microsphere to increase conductivity and stability. This method solves the existing problems of poor connectivity between LM nanoparticles and discontinuity of the Ti3C2Tx MXene nanosheets. Eventually, by using carbon fabrics (CF) as the substrate, a flexible, stable, and efficient electromagnetic interference (EMI) shielding conductive composite fabric with an optimal EMI shielding efficiency (EMI SE) value of 52.0 dB in the range of 8.2–12.4 GHz at a thickness of 0.27 mm is developed. Meanwhile, the as‐prepared fabrics demonstrate superior Joule heating property, high mechanical flexibility, and excellent bending‐release stability. The study provides a simple and efficient method to fabricate multifunctional conductive textiles to meet the need for practical application in EMI shielding area.

Recent development and advances on fabrication and biomedical applications of Ga-based liquid metal micro/nanoparticles

Gallium-based liquid metals (LMs) are widely used for stretchable and reconfigurable electronics thanks to their fluidic nature and excellent conductivity. These LMs possess attractive optical properties for photonics applications as well. However, due to the high surface tension of the LMs, it is challenging to form LM nanostructures with arbitrary shapes using conventional nanofabrication techniques. As a result, LM-based nanophotonics has not been extensively explored. Here, a simple yet effective technique is demonstrated to deterministically fabricate LM nanopatterns with high yield over a large area. This technique demonstrates for the first time the capability to fabricate LM nanophotonic structures of various precisely defined shapes and sizes using two different LMs, that is, liquid gallium and liquid eutectic gallium-indium alloy. High-density arrays of LM nanopatterns with critical feature sizes down to ≈100nm and inter-pattern spacings down to ≈100nm are achieved, corresponding to the highest resolution of any LM fabrication technique developed to date. Additionally, the LM nanopatterns demonstrate excellent long-term stability under ambient conditions. This work paves the way toward further development of a wide range of LM nanophotonics technologies and applications.

We investigated frequency tunability of a microfluidic-based antenna using on-demand manipulation of a gallium-based liquid metal alloy. The fluidic antenna was fabricated by polydimethylsiloxane (PDMS) and filled with the gallium-based liquid metal alloy (Galinstan ® ). It is composed of a digital number “7”-shaped feedline, and a square-shaped and a digital number “6”-shaped patterns, which are all implemented with the liquid metal. The gallium-based liquid metal was adhered to the channel surface due to its viscous oxide layer originating from the gallium oxide forming when it exposed to the air environment. We treated the liquid metal with hydrochloric acid solution to remove the oxide layer on the surface resulting in easy movement of the liquid metal in the channel, as the liquid metal surface has been transformed to be non-wettable. We controlled the physical length of the liquid metal slug filled in feedline with an applied air pressure, resulting in tuning the resonant frequency ranging from 2.2 GHz to 9.3 GHz. The fluidic antenna properties using the liquid metal’s electrical conductivity and mobility were characterized by measuring the return loss (S11), and also simulated with CST Microwave Studio.

Gallium-based liquid metals (LMs) featuring both high conductivity and fluidity are ideal conductors for soft and stretchable electronics. However, their liquid nature is a double-edged sword in many key applications since LMs are inherently prone to mechanical damage. Although additional encapsulation is frequently used for the protection of delicate LM electrodes, it hinders the electrical interfacing with other objects for interconnection, sensing, and stimulation. Here, different from conventional patterning methods that deposit LM on or inside substrates, we for the first time report a simple strategy to create surface-embedded LM of eutectic gallium-indium (EGaIn) circuits with mechanical damage endurance. This was achieved by using direct magnetic printing to overcome the high surface tension of LM, allowing it to be passively filled into the laser-patterned microgrooves on soft substrates. We show that the surface-embedded LM circuits are resistant to mechanical erasure, washing, and peeling. We also show the applications of our surface-embedded LM electrodes in respiration monitoring and electrical stimulation of nerves. This work provides a simple and efficient way to create mechanically reliable LM microelectrodes, holding great promise for wearable and implantable bioelectronics.

Stretchable conductor is the key component of stretchable electronic devices which has become an important development direction of flexible electronic. Patterned stretchable conductor is one of the key technologies for successfully manufacturing stretchable electronic devices. In order to acquire stretchable conductor with good conductivity and stable mechanical stretchability, stretchable conductive ink based on liquid metal nanoparticles (LMNPs) and silver flakes was developed and printed on the modified PDMS substrate by screen printing technology. Liquid metal recovered the fluidity and connected with the silver flakes under pressure after drying. So the fluidity and conductivity of the liquid metal can be used to achieve the preparation of stretchable conductor and overcome the trade-off between conductivity and stretchability. The initial resistance of prepared stretchable conductor is 2 Ω, and the resistance change rate is 0.65 when the tensile strain is 110%. At the same time, it still has a low resistance of 42.7 Ω and resistance change rate of 20.35 when the tensile strain is 660%.KeywordsLiquid metalStretchable conductorConductivityTensile strainPrinting

Antimicrobial Resistance in the Intensive Care Unit: Mechanisms, Epidemiology, and Management of Specific Resistant Pathogens

Surface Chemistry of Gallium-Based Liquid Metals

Gallium-based liquid metal (LM) is regarded as one of the most promising candidates for the new-generation jigsaw of stretchable electronics. Nonetheless, the obstacle for the LM application lies in its high surface tension and easy fluidity which leads to great difficulty in handling and processing. Herein, a cross-mechanochemistry between liquid metal and inorganic solid, mediated via the coordination binding between the empty electronic orbits of the former and the lone electron pair of the latter is reported. The mechanism is validated via density functional theory calculation and electron energy loss spectroscopy, and experimentally proven to be universally applicable for various liquid metals and inorganic solids. With the unique mechanochemistry, simple ball milling allows on-demand transformation of the liquid metal into a low-surface-tension liquid, semi-solid paste, or even solid powder. The overcoming of the intrinsic high surface tension of the liquid metal with this approach unleashes the freedom to easily process the liquid metal composites into polymer composites or as direct molding processable paste and printable electronic ink.

We demonstrate a magnetocaloric ferrofluid based on a gadolinium saturated liquid metal matrix, using a gallium-based liquid metal alloy as the solvent and suspension medium. The material is liquid at room temperature, while exhibiting spontaneous magnetization and a large magnetocaloric effect. The magnetic properties were attributed to the formation of gadolinium nanoparticles suspended within the liquid gallium alloy, which acts as a reaction solvent during the nanoparticle synthesis. High nanoparticle weight fractions exceeding 2% could be suspended within the liquid metal matrix. The liquid metal ferrofluid shows promise for magnetocaloric cooling due to its high thermal conductivity and its liquid nature. Magnetic and thermoanalytic characterizations reveal that the developed material remains liquid within the temperature window required for domestic refrigeration purposes, which enables future fluidic magnetocaloric devices. Additionally, the observed formation of nanometer-sized metallic particles within the supersaturated liquid metal solution has general implications for chemical synthesis and provides a new synthetic pathway toward metallic nanoparticles based on highly reactive rare earth metals.