Metal-based Devices Research Articles

Recent Advances in Liquid Metal-Based Flexible Devices with Highly Sensitive, Plastic and Biocompatible in Bionic Electronics

Recent Advances in Liquid Metal-Based Flexible Devices with Highly Sensitive, Plastic and Biocompatible in Bionic Electronics

Multifunctional fluorescent SPIONs display exceptional optical/magnetic contrast and enhanced photoconductivity in interdigitated electrode based photoresponsive devices

The schematic process of the fabrication of a SPION metal-based μ-IDE device.

Graphene-Assembled Film-Based Reconfigurable Filtering Antenna with Enhanced Corrosion-Resistance

Corrosion-resistance is the key to improve the reliability and service lifespan of highly integrated reconfigurable filtering antennae. However, the conventional methodology for corrosion prevention cannot achieve desired effects, due to the limited intrinsic corrosion-resistance capacity of traditional metal-based devices. Here, we developed a reconfigurable filtering antenna based on graphene assembled film (GAF), featuring significant corrosion-resistance enhancement. The GAF-based antenna exhibits comparable electrical performance when compared with a copper-based antenna, and can flexibly switch between two working modes, including ultra-wideband (UWB, 2.8–11 GHz) and narrowband filtering (NBF, 3.23–3.77 GHz). To further demonstrate the of the corrosion-resistance of GAF, a salt spray corrosion test found that the GAF-based antenna exhibits steady electrical properties after corrosion for over 336 h, while the copper-based antenna shows rapid performance degradation. The simulated and experimental results are in agreement, indicating that the proposed GAF reconfigurable filtering antenna can be applied to broader application prospects in communication systems, especially in severe environments.

Centimeter-Scale Two-Dimensional Metallenes for High-Efficiency Electrocatalysis and Sensing

Two-dimensional (2D) metals have received considerable attention in recent years because of their fascinating physical and chemical properties, as well as potential applications in electrocatalysis, sensors, plasmonics, etc. However, the fabrication of 2D metals, especially atomically thin ones with large lateral size, remains a significant challenge because of the strong and isotropic metallic bonds. Here, we use Pt as a model system and demonstrate a general way to fabricate freestanding, high-quality 2D metals with giant aspect ratios (as large as ∼107) and controllable thickness down to 1 nm via a combination of room-temperature physical deposition and chemical etching. The cool deposition could suppress the Volmer–Webber growth mode, resulting in the formation of continuous ultrathin Pt with smooth surface and high conductivity. Moreover, the ultrathin 2D Pt exhibit outstanding hydrogen evolution reaction activity with a mass activity of 8.06 mA μg–1 at 0.06 V, ∼18 times higher than that of the commercial Pt/C catalyst. Additionally, the freestanding Pt-based strain sensor exhibits a high gauge factor of up to ∼4643, which is 3 orders of magnitude higher than that of conventional constantan wire-based strain gauges. Our studies pave the way for further developing wafer-scale 2D metal-based devices for various applications.

Injectable and tissue-conformable conductive hydrogel for MRI-compatible brain-interfacing electrodes

The development of flexible and stretchable materials has led to advances in implantable bio-integrated electronic devices that can sense physiological signals or deliver electrical stimulation to various organs in the human body. Such devices are particularly useful for neural interfacing systems that monitor neurodegenerative diseases such as Parkinson’s disease or epilepsy in real time. However, coupling current brain-interfacing devices with magnetic resonance imaging (MRI) remains a practical challenge due to resonance frequency variations from inorganic metal-based devices. Thus, organic conductive materials, such as poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), have recently been considered as promising candidates. Nonetheless, their conformability on curvilinear tissues remains questionable. In this study, we developed an injectable conductive hydrogel (ICH) composed of tyramine-conjugated hyaluronic acid (HATYR) and PEDOT:PSS for MRI-compatible brain-interfacing electrodes. Our ICH produced low impedance around 5 kΩ even under 10 Hz, demonstrating high confidence volumetric capacitance. Due to HATYR’s biocompatibility, histological and cytotoxicity assays showed almost no inflammation and toxicity, respectively; in addition, ICH was able to degrade into 40% of its original volume within four weeks in vivo. An electrocorticogram (ECoG) array was also patternable by syringe injections of ICH on a stretchable and flexible elastomeric substrate layer that conformed to curvy brain tissues and successfully recorded ECoG signals under light stimulation. Furthermore, MRI imaging of implanted devices did not show any artifacts, indicating the potential of the MRI-compatible hydrogel electrodes for advanced ECoG arrays. This study provides a promising solution for MRI-compatible neural electrodes, enabling the advancement of chronic neural interfacing systems for monitoring neurodegenerative diseases.

Research Progress of Shape Memory Polymer and 4D Printing in Biomedical Application.

As a kind of smart material, shape memory polymer (SMP) shows great application potential in the biomedical field. Compared with traditional metal-based medical devices, SMP-based devices have the following characteristics: 1) The adaptive ability allows the biomedical device to better match the surrounding tissue after being implanted into the body by minimally invasive implantation; 2) it has better biocompatibility and adjustable biodegradability; 3) mechanical properties can be regulated in a large range to better match with the surrounding tissue. 4D printing technology is a comprehensive technology based on smart materials and 3D printing, which has great application value in the biomedical field. 4D printing technology breaks through the technical bottleneck of personalized customization and provides a new opportunity for the further development of the biomedical field. This paper summarizes the application of SMP and 4D printing technology in the field of bone tissue scaffolds, tracheal scaffolds, and drug release, etc. Moreover, this paper analyzes the existing problems and prospects, hoping to provide a preliminary discussion and useful reference for the application of SMP in biomedical engineering.

Controlling the oxidation and wettability of liquid metal via femtosecond laser for high-resolution flexible electronics.

Liquid metal-based electronic devices are attracting increasing attention owing to their excellent flexibility and high conductivity. However, a simple way to realize liquid metal electronics on a microscale without photolithography is still challenging. Herein, the wettability and adhesion of liquid metal are controlled by combining the stirring method, femtosecond laser microfabrication, and sacrificial layer assistant. The adhesive force of liquid metal is dramatically enhanced by adjusting its oxidation. The wetting area is limited to a micro-pattern by a femtosecond laser and sacrificial layer. On this basis, a high-resolution liquid metal printing method is proposed. The printing resolution can be controlled even less than 50 μm. The resultant liquid metal pattern is applied to electronic skin, which shows uniformity, flexibility, and stability. It is anticipated that this liquid metal printing method will hold great promise in the fields of flexible electronics.

3D Heteroatom-Doped Carbon for Lithium/Zinc Metal Anodes

With the advance of portable electronics and electric vehicles, graphite-based lithium-ion batteries with moderate energy densities can not meet the ever-increasing energy demand which calls for high-energy anode materials.[1] Among candidates, lithium metal has been regarded as the ultimate anode for rechargeable batteries because of its highest theoretical specific capacity (3860 mA h g−1) and lowest electrochemical potential (−3.040 V vs SHE).[1] Unfortunately, only primary lithium metal batteries (LMBs) but no rechargeable ones have been commercialized due to the low Coulombic efficiency (CE) and dendritic growth during Li plating/stripping, resulting in short cycle life and safety concerns. Recently, it has been clarified that LMBs failure majorly occur because of low CE, active Li consumption or electrolytes depletion and the low CE is largely caused by “dead” Li formation, which is associated with Li deposition morphology.[2] As such, it is of great significance to develop methods to regulate the Li plating/stripping behavior and minimize the generation of inactive Li deposits for practical application of LMBs. Many strategies have been proposed to improve CE, inhibit Li dendrites, and extend cycle life, including Li host design,[3] electrolyte engineering,[4] separator modification,[5] and artificial solid electrolyte interphase (SEI) construction.[6] In this work, we report the large-area coating of polymer-derived N,O-codoped vertically aligned carbon sheet arrays on commercial Cu foil current collector (NOCA@Cu) as the efficient 3D host toward safe and dendrite-free LMBs through polymer interfacial self-assembly and morphology-preserved carbonization.[7] Interestingly, it is found that the different orientation mode, vertical or horizontal, of polymer layers on the Cu surface will have a huge influence on heteroatom dopants and topological defects of derived carbon. The optimized NOCA@Cu delivers excellent performance with a high CE of 91–93% and long life up to 600 cycles in the carbonate electrolyte as well as 98.5% CE and stable cycling up to 1300 h in ether electrolyte, much better than horizontal carbon film-coated Cu and pristine Cu.On the other hand, aqueous zinc metal-based energy devices show great promise for large-scale energy storage due to the advantage of Zn metals including high theoretical capacity (gravimetric: 820 mAh g−1), suitable redox potential (−0.764 V vs. SHE), high safety, cost effectiveness, and eco-friendliness.[8] However, similar to Li metal, Zn metal also shows poor reversibility of deposition/dissolution.[9] This poor reversibility is mainly caused by the low CE and dendritic growth of Zn metal accompanied by side reactions from metal corrosion and hydrogen evolution due to water decomposition. [10] Hence, it is significant to develop dendrite-free Zn metal anodes with high CE for rechargeable devices, which unfortunately is still challenging as with Li metal anodes. Similar strategies have been proposed to tackle the issues, such as host construction,[11] interfacial protection,[12] and electrolyte engineering.[13] Despite the progress, most of reported Zn anode only experienced low depth of discharge (DOD, <1%),[14] which will considerably lower cell-level energy densities. As such, construction of Zn hosts, e.g., carbon-rich nanomaterials, to regulate the plating/stripping of Zn metal anode under high DOD is important to achieve high cell-level energy densities. As potential carbon hosts, 3D carbons with highly exposed surface area and hierarchically oriented building blocks could homogenize ionic flux, decrease local current densities, and guide Zn deposition in a unique way.[15] In this work, we firstly regulate heteroatom-doped 3D carbon host for high-DOD Zn metal chemistry, including Coulombic efficiency, deposition morphology, and full cell applications. DFT calculations reveal that among oxygen/nitrogen dopants the ether (C-O), carboxylic (-O-C=O-) and pyrrolic N groups show strong binding with Zn, making them favorable heterogeneous nucleation sites for zinc growth. Accordingly, monomers enriched with those O/N groups were rationally selected and corresponding polymers were prepared via controlled self-assembly and converted to carbon with different morphologies and sizes. Among carbon hosts, carbon flowers (Cflower) enable best performance with high CE values of 97~99% at current densities of 0.5~10 mA cm-2, surpassing other structured hosts. Reference [1] Chem. Rev. 2017, 117, 10403.[2] Nature 2019, 572, 511.[3] Carbon Energy 2021, 1.[4] Adv. Energy Mater. 2017, 7, 1602011.[5] ACS Nano 2017, 11, 6114.[6] Nat. Nanotechnol. 2014, 9, 618.[7] Adv. Funct. Mater. 2021, 31, 2102354.[8] Chem. Rev. 2020, 120, 7795.[9] Angew. Chem. Int. Ed. 2020, 59, 13180.[10] ACS Energy Lett. 2020, 5, 3569.[11] Adv. Mater. 2020, 32, 1906803.[12] Adv. Energy Mater. 2018, 8, 1801090.[13] Nat. Mater. 2018, 17, 543.[14] Adv. Mater. 2019, 0, 1900668.[15] Electrochem. Energ. Rev. 2021, 4, 269.

Plasmon-induced super-semiconductor at room temperature in nanostructured bimetallic arrays

Solid-state electrical conducting materials can be roughly categorized as superconductors, conductors, and semiconductors, depending on their conducting carriers, resistance, and band structures. This research reports the discovery of super-semiconductors, whose resistivity is 3–10 orders of magnitude lower than conventional semiconductors at room temperature. In addition, there is a transition from a metal state to a super-semiconducting state at near room temperatures, which is accompanied by an increase in hole carrier density and the mobility increase in electrons. For the first time, a hole-dominated carrier metal is observed in nanostructured bimetallic arrays near room temperature, and no other special conditions are required. Such a behavior is due to the generation of hot electrons and holes induced by metal plasmon resonance in the infrared range in the nanostructured bimetallic arrays. Our research empowers metals with semiconductor features and paves the way to realize ultra-low-power metal-based semiconductor devices.

Reactive ion etching of tantalum in silicon tetrachloride

A precise patterning of metal structures plays an essential role in the development of feasible metal-based devices. By examining the etching conditions under which a layer of material is properly etched, the etching process can be further optimised and hence controlled. This work reports on the reactive ion etching (RIE) of micrometric films of tantalum (Ta) using silicon tetrachloride (SiCl4)/Argon (Ar) plasmas. The etching characteristics have been studied with respect to SiCl4/Ar ratio, plasma power and chamber pressure. It has been found that increasing the flow rate of SiCl4 or plasma power leads to an increase in the etching rate. Moreover, the observations suggest that it is ineffective to increase the flow rate of Ar to more than 30 sccm and the plasma pressure to more than 100 mTorr. The work implemented here represents an important step for the development of tantalum-based structures that can be used in a wide range of devices.

Liquid Metal-Based Devices: Material Properties, Fabrication and Functionalities.

This paper reviews the material properties, fabrication and functionalities of liquid metal-based devices. In modern wireless communication technology, adaptability and versatility have become attractive features of any communication device. Compared with traditional conductors such as copper, the flow characteristics and lack of elastic limit of conductive fluids make them ideal alternatives for applications such as flexible circuits, soft electronic devices, wearable stretch sensors, and reconfigurable antennas. These fluid properties also allow for innovative manufacturing techniques such as 3-D printing, injecting or spraying conductive fluids on rigid/flexible substrates. Compared with traditional high-frequency switching methods, liquid metal (LM) can easily use micropumps or an electrochemically controlled capillary method to achieve reconfigurability of the device. The movement of LM over a large physical dimension enhances the reconfigurable state of the antenna, without depending on nonlinear materials or mechanisms. When LM is applied to wearable devices and sensors such as electronic skins (e-skins) and strain sensors, it consistently exhibits mechanical fatigue resistance and can maintain good electrical stability under a certain degree of stretching. When LM is used in microwave devices and paired with elastic linings such as polydimethylsiloxane (PDMS), the shape and size of the devices can be changed according to actual needs to meet the requirements of flexibility and a multistate frequency band. In this work, we discuss the material properties, fabrication and functionalities of LM.

Exploring the Effect of Ammonium Iodide Salts Employed in Multication Perovskite Solar Cells with a Carbon Electrode.

Perovskite solar cells that use carbon (C) as a replacement of the typical metal electrodes, which are most commonly employed, have received growing interest over the past years, owing to their low cost, ease of fabrication and high stability under ambient conditions. Even though Power Conversion Efficiencies (PCEs) have increased over the years, there is still room for improvement, in order to compete with metal-based devices, which exceed 25% efficiency. With the scope of increasing the PCE of Carbon based Perovskite Solar Cells (C-PSCs), in this work we have employed a series of ammonium iodides (ammonium iodide, ethylammonium iodide, tetrabutyl ammonium iodide, phenethylammonium iodide and 5-ammonium valeric acid iodide) as additives in the multiple cation-mixed halide perovskite precursor solution. This has led to a significant increase in the PCE of the corresponding devices, by having a positive impact on the photocurrent values obtained, which exhibited an increase exceeding 20%, from 19.8 mA/cm2, for the reference perovskite, to 24 mA/cm2, for the additive-based perovskite. At the same time, the ammonium iodide salts were used in a post-treatment method. By passivating the defects, which provide charge recombination centers, an improved performance of the C-PSCs has been achieved, with enhanced FF values reaching 59%, which is a promising result for C-PSCs, and Voc values up to 850 mV. By combining the results of these parallel investigations, C-PSCs of the triple mesoscopic structure with a PCE exceeding 10% have been achieved, while the in-depth investigation of the effects of ammonium iodides in this PSC structure provide a fruitful insight towards the optimum exploitation of interface and bulk engineering, for high efficiency and stable C-PSCs, with a structure that is favorable for large area applications.

IMPACT OF VENTILATIONS IN ELECTRONIC DEVICE SHIELD ON MICRO-CLIMATE DATA ACQUIRED IN A TROPICAL GREENHOUSE

The greenhouse which is a building used to manipulate the micro-climate is an essential building for plant growth. Greenhouses have one or more devices that are used to monitor their internal environments against changes in micro-climate. The problem is that some devices are metal-based devices and plastics that can be deformed, such as electronic devices, one of which is a micro-climate monitoring device, so a shield that can protect the device but does not interfere with the sensor readings is needed. The purpose of this study was to make and test a plastic-based container called Duradus Junction Box, which has six removable ventilation openings to measure the micro-climate data. This study uses five Duradus Junction Boxes with different numbers of ventilation openings, a micro-controller connected to the air temperature and relative humidity sensor, and a MicroSD module to record all micro-climate data, all devices being then tested simultaneously for 30 days. Statistically, after using One Way ANOVA, this study found that micro-climate measurements result for actual devices data can be considered similar because the P-value for temperature (0.886) and relative humidity (0.917) is greater than alpha level of 0.05. However, when reading the recorded data for both parameters, it can be seen that micro-climate data inside all shields are slightly higher than actual microclimate data ranging from 1 to 2oC for air temperature and 1 to 3% for air relative humidity.

Magnonics in collinear magnetic insulating systems

In the last decades, collinear magnetic insulating systems have emerged as promising energy-saving information carriers. Their elementary collective spin excitations, i.e., magnons, can propagate for long distances bypassing the Joule heating effects that arise from electron scattering in metal-based devices. This Tutorial article provides an introduction to theoretical and experimental advances in the study of magnonics in collinear magnetic insulating systems. We start by outlining the quantum theory of spin waves in ferromagnetic and antiferromagnetic systems, and we discuss their quantum statistics. We review the phenomenology of spin and heat transport of the coupled coherent and incoherent spin dynamics and the interplay between magnetic excitations and lattice degrees of freedom. Finally, we introduce the reader to the key ingredients of two experimental probes of magnetization dynamics, spin transport and NV-center relaxometry setups, and discuss experimental findings relevant to the outlined theory.

Charge-offset stability of single-electron devices based on single-layered Fe nanodot array

In metal-based single-electron devices (SEDs), charge-offset drift has been observed, which is a time-dependent instability caused by charge noise. This instability is an issue in the application of new information processing devices, such as neural network devices, quantum computing devices (charge sensing), and reservoir computing devices. Therefore, the charge-offset drift in metal-based SEDs needs to be suppressed. However, the charge-offset stability of metal-based SEDs has not been investigated in depth, except in the case of Al and Al2O3 SEDs. In this work, Fe-based SEDs formed by single-layer Fe nanodot arrays embedded in MgF2 were studied with regard to their charge-offset stability. Using devices that produce simple current oscillations, the charge-offset drift (ΔQ0) of Fe-based SEDs was evaluated by focusing on peak shifts of the simple current oscillation over time, despite the use of a multi-dot system. This drift (ΔQ0 ≈ 0.3e) was shown to be much lower than in SEDs with Al-dots and Al2O3 tunnel junctions. Notably, the charge-offset drift in the metal-based SEDs was suppressed using the Fe–MgF2 system. The excellent stability of these devices was attributed to the material properties of the Fe–MgF2 system. Finally, as the Fe nanodot array contained numerous dots, the effect of satellite dots acting as traps on the charge-offset instability was discussed. The findings of this study will be important in future applications of metal-based SEDs in new information processing devices.

Rewritable Nanoplasmonics through Room-Temperature Phase Manipulations of Vanadium Dioxide.

The interactions between light and plasmonic charge oscillations in conducting materials are important venues for realizing nanoscale light manipulations. Conventional metal-based plasmonic devices lack tunability due to the fixed material permittivities. Here, we show that reconfigurable plasmonic functionalities can be achieved using the spatially controlled phase transitions in strongly correlated oxide films. The experimental results discussed here are enabled by a recently developed scanning probe-based technique that allows a nonvolatile, monoclinic-metal VO2 phase to be reversibly patterned at the nanoscale in ambient conditions. Using this technique, rewritable waveguides, spatially modulated plasmonic resonators, and reconfigurable wire-grid polarizers are successfully demonstrated. These structures, effectively controlling infrared lights through spatially confined mobile carriers, showcase a great potential for building programmable nanoplasmonic devices on correlated oxide platforms.

Copper-based etalon filter using antioxidant graphene layer

Copper is a low-cost material compared to silver and gold, having high reflectivity in the near infrared spectral range as well as good electrical and thermal conductivity. Its properties make it a good candidate for metal-based low-cost multilayer thin-film devices and optical components. However, its high reflectance in the devices is reduced because copper is easily oxidized. Here, we suggest a copper-based Fabry–Perot optical filter consisting of a thin dielectric layer stacked between two copper films, which can realize low-cost production compared to a conventional silver-based etalon filter. The reduced performance due to the inherent oxidation of the copper surface can be overcome by passivating the copper films with monolayer graphene. The anti-oxidation of copper film is investigated by optical microscopy, x-ray photoelectron spectroscopy, and transmission measurement in UV–vi spectral ranges. Our results show that the graphene coating can be expanded for various metal-based optical devices in terms of anti-corrosion.

Manipulating metals for adaptive thermal camouflage.

Many species in nature have evolved remarkable strategies to visually adapt to the surroundings for the purpose of protection and predation. Similarly, acquiring the capabilities of adaptively camouflaging in the infrared (IR) spectrum has emerged as an intriguing but highly challenging technology in recent years. Here, we report adaptive thermal camouflage devices by bridging the optical and radiative properties of nanoscopic platinum (Pt) films and silver (Ag) electrodeposited Pt films. Specifically, these metal-based devices have large, uniform, and consistent IR tunabilities in mid-wave IR (MWIR) and long-wave IR (LWIR) atmospheric transmission windows (ATWs). Furthermore, these devices can be easily multiplexed, enlarged, applied to rough and flexible substrates, or colored, demonstrating their multiple adaptive camouflaging capabilities. We believe that this technology will be advantageous not only in various adaptive camouflage platforms but also in many thermal radiation management-related technologies.

Novel advances in metal-based solar absorber for photothermal vapor generation

Access to safe drinking water has become an extremely urgent research topic worldwide. In recent years, the technology of solar vapor generation has been extensively explored as a potential and effective strategy of transforming elements content in seawater. In this review, the basic concepts and theories of metal-based photothermal vapor generation device (PVGD) with excellent optical and thermal regulatory are introduced. In the view of optical regulation, how to achieve high-efficiency localized evaporation in different evaporation system (i.e., volumetric solar heating and interface solar heating) is discussed; from the aspect of thermal regulation, the importance of selective absorption surface for interfacial PVGD is analyzed. Based on the above discussion and analysis, we summarize the challenges of metal-based desalination device.

Chemical coating of crystalline-Fe/amorphous-Fe core-shell structured composites and their enhanced soft magnetic properties

New-type crystalline-Fe/amorphous-Fe core-shell structures with greatly-improved soft magnetic performance have been synthesized from coating micron-sized Fe powders with amorphous micrometer-thick Fe layers using a facile chemical coating method. Surface-oxidized amorphous Fe layers are uniformly coated upon the surfaces of high-purity Fe particles, which results in their high saturated magnetization (204.6 A m2 kg−1) and high compacted density (7.42 g/cm3) in these crystalline-Fe/amorphous-Fe composites. For metal-based soft magnetic composites used in high-power applications, it is always an important goal to accomplish increased magnetic inductions along with reduced core loss. In the present work, excellent soft magnetic performance containing high inductions, reduced core loss and desirable frequency-dependent magnetic characteristics is successfully achieved in fully compressed crystalline-Fe/amorphous-Fe composites due to higher resistivity of amorphous Fe shells, which promises their latent utilization for high-power metal-based magnetic devices.