3D Electrode Research Articles

Rapid Differentiation between Microplastic Particles Using Integrated Microwave Cytometry with 3D Electrodes.

Rapid identification of microparticles in liquid is an important problem in environmental and biomedical applications such as microplastic detection in water sources and physiological fluids. Existing spectroscopic techniques are usually slow and not compatible with flow-through systems. Here we analyze single microparticles in the 10-24 μm range using a combination of two electronic sensors in the same microfluidic system: a microwave capacitive sensor and a resistive pulse sensor. Together, this integrated sensor system yields an electrical signature of the analyte particles for their differentiation. To simplify data analysis, 3D electrode arrangements were used instead of planar electrodes so that the generated signal is unaffected by the height of the particle in the microfluidic channel. With this platform, we were able to distinguish between polystyrene (PS) and polyethylene (PE) microparticles. We showcase the sensitivity and speed of this technique and discuss the implications for the future application of microwave cytometry technology in the environmental and biomedical fields.

Optimal placement of high-channel visual prostheses in human retinotopic visual cortex

Objective.Recent strides in neurotechnology show potential to restore vision in individuals with visual impairments due to early visual pathway damage. As neuroprostheses mature and become available to a larger population, manual placement and evaluation of electrode designs become costly and impractical. An automatic method to simulate and optimize the implantation process of electrode arrays at large-scale is currently lacking.Approach.Here, we present a comprehensive method to automatically optimize electrode placement for visual prostheses, with the objective of matching predefined phosphene distributions. Our approach makes use of retinotopic predictions combined with individual anatomy data to minimize discrepancies between simulated and target phosphene patterns. While demonstrated with a 1000-channel 3D electrode array in V1, our simulation pipeline is versatile, potentially accommodating any electrode design and allowing for design evaluation.Main results.Notably, our results show that individually optimized placements in 362 brain hemispheres outperform average brain solutions, underscoring the significance of anatomical specificity. We further show how virtual implantation of multiple individual brains highlights the challenges of achieving full visual field coverage owing to single electrode constraints, which may be overcome by introducing multiple arrays of electrodes. Including additional surgical considerations, such as intracranial vasculature, in future iterations could refine the optimization process.Significance.Our open-source software streamlines the refinement of surgical procedures and facilitates simulation studies, offering a realistic exploration of electrode configuration possibilities.

3D Soft Liquid Metal Electrodes for High‐Resolution and Long‐Term Electromyography in Muscle Trauma Assessment

AbstractElectromyography (EMG) is a widely used diagnostic technique for evaluating the electrical activity of muscles and their controlling nerves. However, conventional surface electrodes with planar structures often suffer from low spatial resolution and suboptimal signal quality. Here, 3D‐shaped, substrate‐free, soft, and biocompatible liquid metal electrodes (LMe) are presented as a wearable interface for neuromuscular signal recording. These electrodes enable the acquisition of high‐quality EMG signals while their intrinsic mechanical softness supports long‐term use in clinical settings. In a human pilot study, continuous, high‐spatial‐resolution EMG monitoring of musculoskeletal activity over 25 days is achieved. Furthermore, in vivo EMG monitoring in mouse models of ischemia and volumetric muscle loss demonstrated the therapeutic effects of extracellular muscle‐rehabilitative drugs. This work highlights the potential of LMe for advanced drug screening and long‐term clinical diagnostics.

Imaging local pH in boundary layers at 3D electrodes in electrochemical flow systems

Imaging local pH in boundary layers at 3D electrodes in electrochemical flow systems

3D layer shape electrode of NiS in-situ growth on shaddock peel derived carbon for high-performance supercapacitors

3D layer shape electrode of NiS in-situ growth on shaddock peel derived carbon for high-performance supercapacitors

High‐Performance Three‐Dimensional Go‐Frame Electrode Design for Capacitive Humidity Sensors in Real‐Time Human Respiration Monitoring

AbstractThe increasing need of environmental and physiological monitoring propels the development of humidity sensors, especially for applications aimed at personal health detection. Among the various types of humidity sensors, capacitive humidity sensors are particularly noted for their rapid response, low power consumption, and high sensitivity. However, conventional capacitive humidity sensors, including widely used planar interdigitated electrodes (IDE) and parallel plate (PP) structures, face challenges with achieving high sensitivity and producing stable output signals. Thus, this work introduces a novel 3D electrode configuration called the “Go‐frame (GF),” designed to surmount these limitations by enhancing linearity, sensitivity, and stability. The GF humidity sensor consists of a pin structure on the bottom electrode, which is coated with a sensing material, and capped with a grid‐shaped top electrode. The experimental findings demonstrate that the GF humidity sensor outperforms both IDE and PP structures, achieving a sensitivity of 65.27 fF/%RH, low hysteresis of 4.06%, and enhanced signal stability. Additionally, the 3D‐structured humidity sensor exhibits high repeatability and long‐term stability over a week. This advancement in electrode design represents a significant innovation in capacitive humidity sensing technology, promising widespread adoption in critical applications, including real‐time human respiration monitoring.

A 3D porous electrode for real-time monitoring of microalgal growth and exopolysaccharides yields using Electrochemical Impedance Spectroscopy.

A 3D porous electrode for real-time monitoring of microalgal growth and exopolysaccharides yields using Electrochemical Impedance Spectroscopy.

Electrical stimulation of neuroretinas with 3D pyrolytic carbon electrodes

Retinal prosthesis has been one of the medical strategies aimed at restoring some degree of vision for patients affected by retinal degenerative diseases, such as Retinitis Pigmentosa (RP) and age-related macular degeneration (AMD), which are leading causes of irreversible visual loss. In retinal prosthesis, electrical pulses are typically delivered to the retinal neurons via electrodes on the surface of the implant. In this work, we fabricated 3D carbon pillar electrodes by pyrolysis of SU-8 structures defined photolithographically on Si wafers. We then measured compound action potentials induced in porcine neuroretinas stimulated with electrical pulses. The recorded spikes were validated to be biological in origin by adding the voltage-gated sodium-channel blocking agent tetrodotoxin. The minimum threshold voltage needed to effectively stimulate retinal cells, such as retinal ganglion cells, with 3D electrodes was analyzed through systematic investigation of the spike rate and amplitudes as a function of stimulation voltage. 3D electrodes significantly increased spike rate and amplitudes above spontaneous activity in the tissue during stimulation and outperformed the 2D counterpart, both in terms of spike rate and amplitude. Our results indicate a threshold voltage range of 500-600 mV for 1 ms pulses at a frequency of 10 Hz above which a significant increase in spike count was observed. Furthermore, we report an order of magnitude increase in peak-to-peak amplitude for evoked spikes (> 3 mV), compared to spontaneous spikes (∼ 200 µV). Based on numerical integration, we estimate the area under the curve to be ~14 times larger in evoked compound action potentials compared to spontaneous activity. This indicates the relative increase in number of contributing cells to the compound action potential. At a stimulation voltage of 600 mV the spike rate for 3D electrodes was above 10 spikes/channel/s. We hypothesize that the significant difference between 2D and 3D electrodes is not only caused by the higher active electrode surface area of the 3D micropillar electrodes, but also by more intricate contact and interaction with the inner cell layers of the retinal tissue. Our findings indicate that 3D carbon micropillar electrodes are promising for electrical stimulation of the retina.

Recent Advances in 3D Printed Electrodes - Bridging the Nano to Mesoscale.

3D architected electrodes offer inherent physicochemical advantages for energy storage, conversion, and sensing. 3D printing methods such as stereolithography and two photon polymerization are uniquely capable of fabricating these architected electrodes with a high degree of geometric complexity impossible to achieve with other methods at the mesoscale (10 µm-1mm). The material set for 3D printing traditionally is focused on structural materials rather than functional materials suitable for electronic and electrochemical applications. In this review the fundamental challenges are considered for transforming 3D printed materials into conductive, multifunctional electrodes suitable for electrical and electrochemical devices by printing nanocomposites, infusing molecular precursors and post-processing these structures via carbonization. To understand the design of 3D electrodes toward their use in both sensors and electrochemical devices such as catalysts, this review summarizes recent advances in hierarchical design of porous metastructures, the engineering of mass transport and electronic transport in 3D structures, and the application of high-throughput materials design by machine learning and artificial intelligence. These emerging approaches to 3D electrode design and architecture promise to expand the capabilities of additive manufacturing beyond structural materials and bring its advantages to bear on modern devices such as sensors, batteries, supercapacitors, and electrocatalysts.

An In‐Depth Study of the Fe−Se System at the Nanoscale Reveals Remarkable Results on the Electrocatalytic Oxygen Evolution Reaction

AbstractA catalyst for an electrocatalytic oxygen evolution reaction (OER) is a key component of the large‐scale storage of renewable energy through the conversion of water into oxygen and hydrogen. Iron‐based selenide materials are currently being considered as potential options for electrocatalytic oxygen evolution reaction (OER) because of their, widespread availability, low cost, and outstanding performance. In this study, we employed a thermal decomposition method to synthesize all stable phases of the Fe−Se system, including Fe7Se8, Fe3Se4, FeSe2, and FeSe. Additionally, we slurry‐coated these phases onto a three‐dimensional (3D) nickel foam substrate. The prepared 3D electrodes of Fe7Se8, Fe3Se4, FeSe2, and FeSe exhibit remarkably low overpotentials of 270, 276, 299, and 289 mV at a current density of 50 mA/cm2 for OER. In addition, the catalytic activity for OER is also tested on glassy carbon electrodes to compare its performance with the Ni‐foam 3D substrate. The Fe7Se8 phase in the Fe−Se system exhibits the highest catalytic activity towards OER on both substrates due to variations in the Fe2+/Fe3+ ratio and the presence of Fe vacancies (cation vacancies) within the crystal lattice. Moreover, a faradaic efficiency of 98 % was exhibited by Fe7Se8 for the oxygen evolution reaction (OER).

High performance Mg–Li dual metal-ion batteries based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres cathodes

Although Mg-Li dual metal-ion batteries are proposed as a superior system that unite safety of Mg-batteries and performance of Li-ion based systems, its practical implantation is limited due to the lack of reliable high-performance cathodes. Herein, we report a high-performance Mg-Li dual metal-ion battery system based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres (NS) cathode. This 2D cathode displayed exceptional pseudocapacitance (a maximum of 93%) specific capacity (303 mAh g-1at 25 mA g-1), rate performance (210 mAh g-1at 1 A g-1), consistent cycling (retain ∼100% capacity for 3000 cycles at 1 A g-1), Coulombic efficiency (nearly 100%) and fast-charging (∼12.1 min). These properties are remarkably dominant to the existing Mg-Li dual metal-ion battery cathodes. Spectroscopic and microscopic mechanistic studies confirmed negligible structural changes during charge-discharge cycles of the TiO2-B nanosheet assembled spheres electrodes. Exceptional electrochemical properties of the 2D electrode is ascribed to remarkable pseudocapacitive Mg-Li dual metal-ion diffusion via the numerous nanointerfaces of TiO2-B caused by its hierarchical microstrucrure. Large surface area, nanosheet morphology, mesoporous structure and ultrathin nature also acted as secondary factors facilitating improved electrode-electrolyte contact. Demonstrated approach of pseudocapacitive type Mg-Li dual metal-ion intercalation through hierarchical nanointerfaces may be further utilized for the designing of numerous top-notch electrode materials for futuristic Mg-Li dual metal-ion batteries.

High-Energy Aqueous Sodium-Ion Batteries Using Water-in-Salt Electrolytes and 3D Structured Electrodes.

Aqueous sodium-ion batteries (SIBs) are gradually being recognized as viable solutions for large-scale energy storage because of their inherent safety as well as low cost. However, despite recent advancements in water-in-salt electrolyte technologies, the challenge of identifying anode materials with sufficient specific capacity persists, complicating the wider adoption of these batteries. This study introduces an innovative and straightforward approach for synthesizing vanadium oxide laser-scribed graphene (VOx-LSG) composites, which function as effective anode materials in aqueous sodium-ion batteries. By combining a rapid laser-scribing technique with precise thermal control, the method not only allows for changing the morphology of the vanadium oxide, but also tuning its oxidation state. This is achieved while embedding these electrochemically active particles within a highly conductive graphene scaffold. When paired with a Prussian blue-based cathode (Na1.88Mn[Fe(CN)6]0.97) in a concentrated NaClO4-based aqueous electrolyte, the battery's charge storage mechanism is found to be largely surface-controlled, leading to exceptional rate performance. The full cell demonstrates specific capacities of 128 mA h/g@0.05 A/g and 65.6 mA h/g@1 A/g, with an energy density of 47.7 W h/kg, outperforming many existing aqueous sodium-ion batteries. This strategy offers a promising path forward for integrating efficient, eco-friendly, and low-cost anode materials into large energy storage devices and systems.

Self-Potential Inversion for Regularly Polarized Ore Deposits Anomalies in Different Models Based on Quantum Genetic Algorithm

The self-potential (SP) method is widely used in mineral exploration for its simplicity and cost-effectiveness. Traditional inversion approaches often face challenges with local optima and computational inefficiency in complex models. A quantum genetic algorithm (QGA) for SP data inversion is introduced, combining quantum computation principles with genetic algorithms. Modal analysis and parameters analysis of inversion in different physical models are conducted to determine parameter sensitivity and the optimal parameter range. The proposed optimizer is applied on synthetic data generated from diverse geological models. Gaussian noise is added to test robustness. Indoor experiments, using a controlled environment with a 2D electrode grid, validate QGA's effectiveness in layered models. The impact of data density on the algorithm's performance is evaluated by reducing the number of measurement points. Different field cases from Turkey, Germany and USA further confirmed QGA's practical applicability, with inversion results closely matching drilling data or research published before. Uncertainty appraisal analyses show the validity of the model parameter estimations. In summary, QGA significantly improves SP data inversion, offering better accuracy, efficiency, and robustness, making it a promising tool for complex geological conditions.

Enhanced treatment of multiphase extraction wastewater from contaminated sites with Cu-Ce modified GAC three-dimensional electrodes.

Enhanced treatment of multiphase extraction wastewater from contaminated sites with Cu-Ce modified GAC three-dimensional electrodes.

Synthesis of Nickel-Based Electrocatalysts on Carbon Fiber for Maximum Active Sites Exposed: An Efficient Hydrogen Evolution 3D Electrode

Synthesis of Nickel-Based Electrocatalysts on Carbon Fiber for Maximum Active Sites Exposed: An Efficient Hydrogen Evolution 3D Electrode

Direct Fabrication of 3D Electrodes Based on Graphene and Conducting Polymers for Supercapacitor Applications (Adv. Funct. Mater. 4/2025)

Direct Fabrication of 3D Electrodes Based on Graphene and Conducting Polymers for Supercapacitor Applications (Adv. Funct. Mater. 4/2025)

Novel 3D composite for efficient photocatalysis in environmental remediation

AbstractHighly porous, self-supported 3D interconnected network-based nanomaterials hold immense promise in revolutionizing the field of catalysis. These materials combine two critical features; a large accessible surface and an overall active surface that leads to substantial catalytic effects. In this study, we developed a novel class of 3D composite material composed of zinc oxide tetrapods (ZOT) and polyethylene glycol (PEG) polymer, specifically designed for photocatalysis. A polymer composite of ZOT with PEG has been synthesized with 2.5 wt.% ZOT powder mixed with a PEG solution forming a 3D electrode. A consistent composite solution was obtained using probe-sonication and its thick layers were deposited on various substrates using the spin coating technique which were subsequently characterized for optical, morphological, and structural properties. The catalytic response of the fabricated 3D composite was evaluated both in solution and thin film forms under UV exposure. The surface-engineered ZOT-PEG composites showed an excellent capability to degrade the methylene blue (MB) dye in different forms under UV and normal light, opening their potential scopes in environmental remediation.

Charge Storage Mechanisms in Batteries and Capacitors: A Perspective of the Electrochemical Interface

AbstractResearchers developing the next generation of energy storage systems are challenged to understand and analyze the different charge storage mechanisms, and subsequently use this understanding to design and control materials and devices that bridge the gap between high specific energy and power at a target cycle life. Correctly identifying and quantifying the prominent charge storage mechanism is of the utmost importance for understanding how the system functions and tuning material properties for specific applications. The different charge storage mechanisms are defined by a characteristic current‐time scaling that has been defined for electrochemical interfaces with faradaic diffusion‐limited charge storage. However, the characteristic current‐time scaling for faradaic non‐diffusion‐limited (or pseudocapacitive) charge storage remains unelucidated despite to date many battery types, particularly those having 2D electrode materials and electrolytes with ionic liquids, deep eutectic solvents, or highly concentrated electrolytes, exhibit electrochemical interfaces with pseudocapacitive charge storage. This perspective discusses the necessary mathematical expressions and theoretical frameworks for all charge storage mechanisms which are corroborated with experimental data. This perspective can be used as a guide to quantitatively disentangle and correctly identify charge storage mechanisms and to design electrochemical interfaces and materials with targeted performance metrics for a multitude of electrochemical devices.

3D Printing of Graphene Aerogel Microspheres to Architect High-Performance Electrodes for Hydrogen Evolution Reaction.

The hydrogen evolution reaction (HER) efficiency is highly dependent on the electrocatalysts microstructure and the macrostructure of the electrodes. Herein, the graphene aerogel microspheres loaded with well-dispersed ultrafine Ni/Co nanoparticles catalyst is prepared through electro-spraying, in-situ crosslinking, freeze-drying, and pyrolysis, and then is utilized to print the HER electrode via direct ink writing (DIW). The obtained graphene-based aerogel microspheres possess peculiar cabbage-like mesoporous structures which allow ready access of reaction species to active sites, optimal mass transfer, and proton diffusion within the microspheres. DIW 3D printing achieves the ordered control on the periodic lattice macro-geometry and thus facilitates the fast gas bubble evolution and release from the electrode surface. The as-fabricated 3D electrode possesses a low overpotential of 341 mV at 10 mA cm-2, a decrease by 31.5% compared to 3D printed electrode directly from 2D graphene, and a low Tafel slope of 119.1 mV dec-1, 40% lower than that of the electrodes fabricated via directly casting the aerogel microspheres. Furthermore, the 3D-printed electrode of aerogel microspheres displays good HER stability. This work provides a good approach for constructing high-performance HER electrodes through 3D printing of graphene aerogel microspheres.

Single-Ion-Conducting Polymer Electrolytes for Rechargeable Alkaline Ag-Zn Batteries.

Recently, we reported on the synthesis and performance of a cross-linked single-anion-conducting solid-state electrolyte (SSE) based on quaternized poly(dimethylaminomethylstyrene) (pDMAMS+) via initiated chemical vapor deposition (iCVD). In the homopolymer pDMAMS+-based SSE, the cross-linking occurs at the positively charged ammonium cation sites, hindering ion transport and conductivity. To improve ionic conductivity, we now report on a copolymer system, comprising DMAMS and divinylbenzene (DVB). Incorporating DVB moves the cross-links to the polymer backbone leaving the quaternary ammonium cation and its paired anion with maximal dynamic freedom. We evaluate the structure-transport relationships of a series of p[DVB-DMAMS] copolymers with varying DVB content using electrochemical impedance spectroscopy, nuclear magnetic resonance spectroscopy, and small- and wide-angle X-ray scattering. Our best composition containing 2.5 wt % DVB provides 1 mS cm-1 single-ion OH- conductivity under hydrated conditions, a significant improvement over the 0.01 mS cm-1 of the hydrated homopolymer pDMAMS+ SSE. All copolymer compositions support Zn-ZnO and Ag-Zn electrochemical reduction-oxidation (redox) chemistry, which demonstrates the feasibility of a Ag-Zn battery using an alkaline single-ion-conducting SSE. Galvanostatic cycling shows some transport of Ag through the polymer electrolyte, however the deleterious effects of Ag migration can be partially mitigated by transitioning from a two-dimensional (2D) planar electrode to a 3D sponge electrode. With these promising results, the foundation is laid for using single-anion-conducting SSEs within alkaline Zn batteries.