Conductive Bridge Research Articles

Double network hydrogel confined MXene/Liquid metal by dynamic hydrogen bond for high-performance wearable sensors

Double-network (DN) hydrogels, which integrate long-chain and short-chain molecular structures, exhibit significant potential in wearable sensors due to their exemplary mechanical properties. However, conventional hydrogels often suffer from poor conductivity and low sensitivity. In this study, we develop a novel DN hydrogel (comprising polyacrylamide/sodium alginate) that encapsulates MXene (Ti3C2Tx) and liquid metal (LM). This configuration leverages the conductive properties of two-dimensional MXene and zero-dimensional liquid metal embedded within the DN hydrogel networks. The Ti3C2Tx MXene sheets enhance the binding capacity with LM by serving as a conductive bridge, thereby improving interfacial interactions and reducing hysteresis. The resultant strain sensor, fabricated from this composite DN hydrogel, achieves high sensitivity (gauge factor up to 12.84), a broad detection range (0 %-1500 %), rapid response time (262 ms), and excellent repeatability and stability. We have integrated this strain sensor into wearable flexible devices, such as contact lenses, enabling real-time monitoring of human physiological pressures.

Ppulsed field ablation and ultra-high-density mapping for PVI: use of machine learning and data augmentation to guide procedure and identify recurrent tachycardia mechanisms at one-year follow-up

Abstract Background In managing atrial fibrillation (AF), radiofrequency and cryoablation have been cornerstone techniques for achieving pulmonary vein isolation (PVI). Recently, pulsed-field ablation (PFA) has introduced a novel method for PVI. There remains a gap in knowledge regarding the permanent efficacy of ablation, related explicitly to acute lesion characteristics following PVI. Purpose Our study delves into an in-depth examination of acute lesion characteristics following PFA-PVI through ultra-high-density mapping (UHDM). We aim to identify specific clinical, anatomical, and periprocedural lesion features independently related to 1) intraoperative identification of UHDM non-isolated gaps with electrical conduction after first isolation and 2) three months follow-up recurrency of specific arrhythmias. Methods Results The present study includes 204 patients submitted to PFA-PVI for AF. UHDM guided all procedures to identify non-isolated gaps with electrical conduction. Perioperative and 3-month follow-up data were collected prospectively and analyzed. To build our prediction model, avoiding biases related to the unbalanced nature of the data, data augmentation was performed with SMOTE (Synthetic Minority Over-sampling Technique). Two machine learning (ML) models have been built, using logistic regression as learner, to predict the presence of isolation gaps identified by UHDM and follow-up recurrence of arrhythmias. A 20-fold cross-validation has been performed to train and test the models. The non-isolated gap was detected and immediately corrected in 14 (6.9%) patients and was present more often in patients with larger left atria (LA) (p<0.0001) and those with persistent AF (p=0.02). The ML model achieved an AUC of 0.88 in the prediction of the non-isolated gap after PFA (Precision: 0.65; Sens.: 0.90; F1: 0.76; Spec.: 0.83; NPV: 0.96). At three months follow-up, no patient experienced recurrent AF; recurrent roof-dependent atrial tachycardia was present in 10 (4.9%). Patients with recurrent atrial tachycardia had a significantly narrower remaining atrial-roof conduction bridge (p=0.01) identified intra-procedurally by UHDM, significantly larger LA (p=0.03), and non-significant trend for older age (p=0.07). The ML model achieved an AUC of 0.86, predicting recurrent tachycardia after PFA (Precision: 0.63; Sens.: 0.86; F1: 0.72; Spec.: 0.82; NPV: 0.94). Conclusions Consistent use of UHDM can help identify non-isolated gaps with electrical conduction that may occur even after PVI with updated technologies, such as PFA. Non-isolated gaps should be expected, particularly in patients with larger LA, where UHDM could be of particular use. Moreover, UHDM can help predict the eventual recurrence of arrhythmias. Again, LA size plays an essential role in such recurrencies, together with the size of the remaining conducting tissue "bridges" within the LA roof, measure by UHDM.

High-sensitive electrochemical sensor based on Ni/NiCx-integrated functional carbon nanotubes for simultaneous determination of acetaminophen and dopamine

In complex environmental substance monitoring, the simultaneous detection of single and multiple substances with high sensitivity has been a research focus in the field of electrochemical sensors. Rational selection of appropriate dopants to optimize the electrode material is crucial in this regard. In this work, we employed a multi-doping strategy to effectively enhance the electrocatalytic performance of multi-walled carbon nanotubes (MWCNTs). By doping Ni/NiCx onto MWCNTs, we successfully constructed a heterojunction material (Ni/NiCx-N-MWCNTs). The successful doping of Ni/NiCx allows for the synergistic effects of multiple elements. Ni/NiCx serves as a conductive bridge, forming a three-dimensional network of nanotubes, which effectively reduces the aggregation of carbon nanotubes, exposes more active sites, and enhances electrocatalytic activity. The electrochemical sensor based on Ni/NiCx-N-MWCNTs demonstrated high sensitivity, selectivity, and simultaneous electrochemical detection for acetaminophen (1–150 μM, limit of detection (LOD)=0.56 μM) and dopamine (1–80.0 μM, LOD=0.19 μM). Its excellent reproducibility (relative standard deviation (RSD)=2.01 %) and interference resistance provide Ni/NiCx-N-MWCNTs with significant advantages over other electrode materials, indicating a promising application potential.

Vertical‐Switching Conductive Bridge Random Access Memory with Adjustable Tunnel Gap and Improved Switching Uniformity Using 2D Electron Gas

AbstractOwing to the high reactivity and diffusivity of Ag and Cu ions, controlling the atomic filament formation and rupture processes in conductive bridge random‐access memory (CBRAM) is challenging. In this study, it is demonstrated that by using a 2D electron gas (2DEG) as the bottom electrode (BE) in a vertical‐switching CBRAM (V‐CBRAM), filament formation and rupture can be effectively managed and the tunnel gap distance created by partial filament formation can be adjusted. The 2DEG BE induces partial filament formation by limiting the number of electrons required for this process in the V‐CBRAM device, as verified via current fitting to the quantum point contact model. Varying the electron concentration and activation energy for electrons trapped in the 2DEG, when paired with various programming voltages, leads to transitions in the device resistance state via changes in the distance of the tunnel gap. This tunnel‐gap‐tunable 2DEG V‐CBRAM device, which exhibits superior switching uniformity, can be employed for nonvolatile memory applications in the sub‐G0 conductance regime, such as 3‐bit multilevel cells and selector‐less memory.

Nanoparticle Shape Effects on the SERS Properties of Small Conductive Bridges

Nanoparticle Shape Effects on the SERS Properties of Small Conductive Bridges

Deciphering the Novel Picolinate-Mn(II)/peroxymonosulfate System for Sustainable Fenton-like Oxidation: Dominance of the Picolinate-Mn(IV)-peroxymonosulfate Complex.

A highly efficient and sustainable water treatment system was developed herein by combining Mn(II), peroxymonosulfate (PMS), and biodegradable picolinic acid (PICA). The micropollutant elimination process underwent two phases: an initial slow degradation phase (0-10 min) followed by a rapid phase (10-20 min). Multiple evidence demonstrated that a PICA-Mn(IV) complex (PICA-Mn(IV)*) was generated, acting as a conductive bridge facilitating the electron transfer between PMS and micropollutants. Quantum chemical calculations revealed that PMS readily oxidized the PICA-Mn(II)* to PICA-Mn(IV)*. This intermediate then complexed with PMS to produce PICA-Mn(IV)-PMS*, elongating the O-O bond of PMS and increasing its oxidation capacity. The primary transformation mechanisms of typical micropollutants mediated by PICA-Mn(IV)-PMS* include oxidation, ring-opening, bond cleavage, and epoxidation reactions. The toxicity assessment results showed that most products were less toxic than the parent compounds. Moreover, the Mn(II)/PICA/PMS system showed resilience to water matrices and high efficiency in real water environments. Notably, PICA-Mn(IV)* exhibited greater stability and a longer lifespan than traditional reactive oxygen species, enabling repeated utilization. Overall, this study developed an innovative, sustainable, and selective oxidation system, i.e., Mn(II)/PICA/PMS, for rapid water decontamination, highlighting the critical role of in situ generated Mn(IV).

Simulations of RF wave-induced modulation of filament growth and bipolar resistive switching in conductive bridging RAM

Simulations of RF wave-induced modulation of filament growth and bipolar resistive switching in conductive bridging RAM

Modulating conductive filaments via thermally stable bilayer organic memristor

The basic unit of information in conductive bridge random access memory based on the redox mechanism of metal ions is physically stored in a conductive filament (CF). Therefore, the overall performance of the device is indissolubly related to the properties of such CFs, as unreliable performance often originates from unstable CFs behavior. However, accurately controlling the dissolution of CFs during device operation can be challenging due to their non-uniformity. This paper proposes a type of memristor based on a solid polymer electrolyte with a polyvinylpyrrolidone/polyvinyl alcohol composite layer structure. The properties of the composite layer are employed to regulate the number of CFs and the growth/fracture location, while the damage to the device by Joule heat is prevented. The device exhibits low operating voltage (0.5 V), stable switching conditions (2000 cycles), and a long holdup time (>3 × 104 s).

Breakdown and interface dynamics of pulsed discharge plasma across air-water interface: From single to repetitive stimulation

Pulsed discharge in the vicinity of a multi-phase interface, where a discontinuity of physical properties exists, can be a joint problem of both electro- and thermo-physics. This study shows a comprehensive analysis of electric breakdown across an air-water interface and its successive multi-physical effects. The scenario is constructed via a pair of pin electrodes positioned on both sides of the interface, and the transient discharge is analyzed using high-speed backlight photography synchronized with electrical and optical diagnostics. It is observed that the corona/streamer develops from either side of the pin electrode. Electrostatic instability causes the interface to fluctuate and a water column to form above the interface. By increasing the applied voltage, discharge evolves from “dielectric barrier” mode (pin to interface) to “through breakdown” mode (pin to pin). Once the conductive channel bridges two electrodes, electric power of ∼40 kW peak and deposited energy of 100 mJ will be injected into the channel and promote the “streamer-spark” transition, resulting in a crown-like splash (100 m s-1) near the interface and cavity formation. As the quenching of diffused plasmas, the over-expanded splash (5 mm in diameter) would be re-compressed by the ambient air. Particularly, the shrinkage of the thin water film of the splash can reach a 20 mm jet near the axis and develop Rayleigh-Taylor instability, along with the formation of micro-jets eruption during the convergent collision. More sophisticated interactions will appear at higher repetitive frequency (>100 Hz), where the perturbation caused by one pulse will influence the next, namely the “memory” effect. Furthermore, periodic loading on the interface effectively changes the cavity characteristics, showing an attractive prospect in fluid control applications.

Ni3C nanosheets and PVA nanocomposite based memristor for low-cost and flexible non-volatile memory devices

Two-dimensional (2D) MXenes have gained extensive attention in the field of memristors due to their high ion mobility, chemical stability and tunable electrical and surface properties. Moreover, MXenes have tunable interlayer bonding which enables enhancement in memristor performance. In this work, we synthesize a novel nanocomposite of Ni3C nanosheets and polyvinyl alcohol (PVA) and fabricate a flexible memristor with Ag/Ni3C-PVA/ITO/PET configuration for non-volatile memory applications. Ni3C nanosheets were synthesized from Ni-MAX (Ni3AlC2) through a solvothermal etching and exfoliation process. The nanosheet like structure of Ni3C is confirmed through Scanning Electron Microscopy (SEM) and Transmission Electron microscopy (TEM). Characterization techniques like X-ray diffraction (XRD), Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) reveal the crystalline phases, surface functional groups and chemical bonds present in Ni3C nanosheets and Ni3C-PVA nanocomposite. The memristor was fabricated through a facile low cost solution processed based fabrication technique. The Ag/Ni3C-PVA/ITO/PET memristor exhibits bipolar non-volatile switching characteristics. The device with optimised mass ratio of 4:3 (Ni3C: PVA) shows a decent off/on ratio of 2.09 × 102, long retention time of 104 s, and an endurance of 102 DC cycles. The SET voltage of the as-fabricated device is 2.8 V and the RESET voltage is −5.33 V. The flexible memristor exhibits outstanding mechanical robustness over 500 bending cycles. The high charge carrier mobility of Ni3C results in lower switching voltage and the dielectric property of PVA improves data retention and off/on ratio of the memristor. The resistive switching behaviour is explained through conductive metallic bridge mechanism. The conduction mechanism follows Ohmic conduction in ON state and trap controlled space charge limited current (TCSCLC) mechanism in OFF state. The results demonstrate that the nanocomposite with its superior resistive switching effects is suitable for cost-effective, high-performance, flexible non-volatile memory devices.

Parameters Optimization of Conductive Rubber Snow-Melting Bridge Deck Pavement Based on Material-Structure Integrated Design Idea

Parameters Optimization of Conductive Rubber Snow-Melting Bridge Deck Pavement Based on Material-Structure Integrated Design Idea

(Invited) Bio-Inspired Time Varying Networks for Novel Computing Primitives

As a result of a hundred million years of evolution, living animals have adapted extremely well to their ecological niche. Such adaptation implies species-specific interactions with their immediate environment by processing sensory cues and responding with appropriate behavior. Understanding how living creatures perform pattern recognition and cognitive tasks is of particular importance for computing architectures: by studying these information pathways refined over eons of evolution, researchers may be able to streamline the process of developing more highly advanced, energy efficient autonomous systems.With the advent of novel electronic and ionic components along with a deeper understanding of information pathways in living species, a plethora of opportunities to develop completely novel information processing avenues are within reach.Basal biological principles are highlighted, including phylogenies, ontogenesis, and homeostasis, with particular emphasis on network topology and dynamics. While in machine learning, system training is performed on virgin networks without any a priori knowledge, the approach proposed here distinguishes itself unambiguously by employing growth mechanisms as a guideline to design novel computing architectures. Within this framework, experiments on low-frequency relaxation type oscillators coupled via complex time-varying networks will be presents. The spatio-temporal development of the network results from a mutual interaction between the oscillator ensemble and the network structure. The blooming and pruning of suddenly appearing conductive bridges and their relation to the synchrony state of the oscillator ensemble will be discussed.

Silver nanowires/WO3 quantum dots electrode with enhanced vertical electric field gradient for Al3+/Li+ dual-functional electrochromic supercapacitor

Dual-functional electrochromic supercapacitors (DECSs), which demonstrate the substantial potential for reversible changes in optical properties and energy storage capabilities, hold considerable promise for a wide range of applications in areas such as smart windows, displays, and wearable electronics. Nevertheless, challenges still exist in effectively optimizing their capacitance, ensuring cycling stability, and achieving cost-effective fabrication. Herein, this study explores an approach by integrating Al3+ and Li+ ions as hybrid electrolyte to enhance electrochemical activity. Utilizing WO3 quantum dots (WQDs) embedded within Ag nanowires (Ag NWs) grids offers a promising strategy to augment the vertical electric field gradient and prevent the self-agglomeration of WQDs. In addition, the integration of hybrid electrolyte comprising Al3+ and Li+ ions not only enhance electrochemical activity but also serves to mitigate the high-cost lithium sources. The resulting Ag NWs/WQDs electrode exhibits an impressive specific capacitance of 681.6 F g−1 at 0.25 mA cm−2 in Al3+/Li+ hybrid electrolyte, a notable 5-fold increase compared to the pristine WQDs electrode in Li+ electrolyte (139.3 F g−1). Simultaneously, this dual-function electrode demonstrates a large optical modulation (81.8 % at 700 nm), a fast switching-speed (tbleaching=7 s, tcoloring=5 s), and a long cycling life (maintaining 84.6 % of its original capacitance after 5000 cycles). Noteworthy insights from COMSOL simulations highlight the Ag NWs grid's "conductive bridge" function, which shows a positive attribution in optimizing the vertical electric field gradient. As a demonstration of proof-of-concept, a large-size flexible dual-functional electrochromic supercapacitor (DECS, 15 cm×10 cm) confirms energy-saving and storage dual-functionality device. Typically, the DECS-equipped inner room experiences a temperature 10°C lower than that of a room with a blank PET within 10 min, indicating the significant irradiation shielding. In addition, this device exhibits a remarkable specific capacitance of 9.25 mF cm−2 at 5 mV s−1, accompanied by an exceptional stability under simulated solar irradiation. The innovation of 0D/1D hierarchical structure of the electrodes together with the hybrid electrolyte not only reduce costs but also enhance the capacitance and cycle stability of DECSs, offering new insights for the development of next-generation flexible electronic wearables.

Reconfigurable Origami/Kirigami Metamaterial Absorbers Developed by Fast Inverse Design and Low-Concentration MXene Inks.

Reconfigurable metamaterial absorbers (MAs), consisting of tunable elements or deformable structures, are able to transform their absorbing bandwidth and amplitude in response to environmental changes. Among the options for building reconfigurable MAs, origami/kirigami structures show great potential because of their ability to combine excellent mechanical and electromagnetic (EM) properties. However, neither the trial-and-error-based design method nor the complex fabrication process can meet the requirement of developing high-performance MAs. Accordingly, this work introduces a deep-learning-based algorithm to realize the fast inverse design of origami MAs. Then, an accordion-origami coding MA is generated with reconfigurable EM responses that can be smoothly transformed between ultrabroadband absorption (5.5-20 GHz, folding angle α = 82°) and high reflection (2-20 GHz, RL > -1.5 dB, α = 0°) under y-polarized waves. However, the asymmetric coding pattern and accordion-origami deformation lead to typical polarization-sensitive absorbing performance (2-20 GHz, RL > -4 dB, α < 90°) under x-polarized waves. For the first time, a kirigami polarization rotation surface with switchable operation band is adapted to balance the absorbing performance of accordion-origami MA under orthogonal polarized waves. As a result, the stacked origami-kirigami MA maintains polarization-insensitive ultrabroadband absorption (4.4-20 GHz) at β = 0° and could be transformed into a narrowband absorber through deformation. Besides, the adapted origami/kirigami structures possess excellent mechanical properties such as low relative density, negative Poisson's ratio, and tunable specific energy absorption. Moreover, by modulating the PEDOT:PSS conductive bridges among MXene nanosheets, a series of low-concentration MXene-PEDOT:PSS inks (∼46 mg·mL-1) with adjustable square resistance (5-32.5 Ω/sq) are developed to fabricate the metamaterials via screen printing. Owing to the universal design scheme, this work supplies a promising paradigm for developing low-cost and high-performance reconfigurable EM absorbers.

In Situ TEM Investigation of Conductive Bridge RAM Devices

In Situ TEM Investigation of Conductive Bridge RAM Devices

Impact of inert electrode on the volatility and non-volatility switching behavior of SiO2-based conductive bridge random access memory devices

Impact of inert electrode on the volatility and non-volatility switching behavior of SiO2-based conductive bridge random access memory devices

Testing and Evaluation of Interlayer Shear Performance of Conductive Rubber Active Deicing Composite Bridge Deck Pavement Structure

Abstract To achieve real-time, sustainable, efficient, and environmentally friendly active deicing of bridge decks, a new active electric heating deicing technology based on conductive rubber as a heat source is proposed in this study. The conductive rubber was laid between asphalt layer and cement layer as the functional deicing layer, and the conductive rubber active deicing composite bridge deck pavement structure was established. The interlayer treatment method of conductive rubber active deicing composite structure was proposed. Styrene butadiene styrene–modified asphalt, PB-II type polymer-modified asphalt waterproof coating, and AMP-100 second-order reactive waterproofing coating were selected as waterproofing bonding layer. The interlayer shear performance of conductive rubber composite structure was tested and evaluated by 45° inclined shear test. Taking shear strength as the evaluation index of interlayer shear performance, the durability of interlayer shear performance of conductive rubber composite bridge deck pavement in complex environment was studied. Taking the fatigue life as the evaluation index, the interlayer fatigue resistance of conductive rubber composite bridge deck and traditional bridge deck under different stress ratios were analyzed. The results showed that shear strength between the layers of the conductive rubber active snow-melting bridge deck pavement structure using PB-II type waterproof bonding layer material was the highest, which was 0.584 MPa, and the optimum dosage was 1.5 kg/m2. Under the complex environment, the interlayer shear performance of conductive rubber composite bridge deck pavement decreases, which could still be maintained at about 70 % and had certain durability. Under the same interlaminar shear stress, the interlaminar shear fatigue life of the conductive rubber active snow-melting bridge deck was reduced by about 34 % compared with the traditional bridge deck. The research results can provide a theoretical basis and data support for the structural design of conductive rubber active deicing bridge deck pavement and the selection of waterproof bonding layer materials.

Artificial Multimodal Neuron with Associative Learning Capabilities: Acquisition, Extinction, and Spontaneous Recovery.

Associative multimodal artificial intelligence (AMAI) has gained significant attention across various fields, yet its implementation poses challenges due to the burden on computing and memory resources. To address these challenges, researchers have paid increasing attention to neuromorphic devices based on novel materials and structures, which can implement classical conditioning behaviors with simplified circuitry. Herein, we introduce an artificial multimodal neuron device that shows not only the acquisition behavior but also the extinction and the spontaneous recovery behaviors for the first time. Being composed of an ovonic threshold switch (OTS)-based neuron device, a conductive bridge memristor (CBM)-based synapse device, and a few passive electrical elements, such observed behaviors of this neuron device are explained in terms of the electroforming and the diffusion of metallic ions in the CBM. We believe that the proposed associative learning neuron device will shed light on the way of developing large-scale AMAI systems by providing inspiration to devise an associative learning network with improved energy efficiency.

Boosted adsorption and oxidation performances in peroxymonosulfate (PMS)-based heterogeneous fenton-like reactions via P, N co-doping strategy

The heterogeneous Fenton-like reactions (HTFR) have attracted considerable interest for their efficacy in degrading pollutants. However, the development of effective strategies for enhancing performance in HTFR remains a subject of ongoing research. Herein, a synergistic adsorption and oxidation-dominated process was developed to overcome the bottlenecks of peroxymonosulfate (PMS)-based HTFR in terms of mass transfer and catalyst reactivity. Heteroatom (P, N) co-doping for manganese (Mn) was employed to fabricate an efficient catalyst, Mn@5-NPC-800, which exhibited exceptional abilities of adsorption and PMS activation. The enhanced performance of HTFR was attributed to the increased specific surface area (SSA) and enhanced yields of graphitic-N/MnIII of the catalyst, which facilitated reactant enrichment and electron transfer in the delocalized conjugated area, respectively. The PMS-based HTFR induced by Mn@5-NPC-800 for pollutant removal was characterized by a synergistic adsorption and reactive oxygen species (ROS)-dominated oxidation process. DFT calculations revealed that the N, P co-doped carbon matrix (NPC) acted as a conductive bridge, significantly improving electron transfer between MnP and PMS molecule, which was identified as a key factor in governing the catalytic performance. The investigation presents a suggestive example of employing a doping strategy to create a synergistic effect of adsorption and oxidation, thereby strengthening the performance of Fenton-like reactions.

Facile production of graphene-based ternary composite coatings on metallic bipolar plates

Graphene-based composite coatings can be applied on metallic bipolar plates (BPs) of PEMFC for corrosion protection and electron conduction, benefited from the high electrical conductivity, chemical stability and physical barrier properties of graphene. To reach the high electrical conductivity requirement, the composite coatings shall have high graphene content, which brings challenges including dispersion, processability and interface compatibility. In this work, polyisocyanate was grafted on graphene surfaces to enhance the compatibility with polyurethane (PU). Carbon black was introduced as conductive bridging, which filled in defects of graphene/PU coatings. The corrosion current density of the ternary composite coatings with 60 % functionalized graphene, 30 % PU and 10 % carbon black was 0.43 μA·cm−2 in H2SO4 solution of pH 3 at 80 °C, while the interfacial contact resistance was 6.75 mΩ·cm2 and the in-plane conductivity was 137.4 S·cm−1. The composite coatings provided an efficient and cost-effective solution for up-scaling production of metallic BPs.