3D Electrode Research Articles

Initiated Chemical Vapor Deposited Anion-Conducting Solid-State Polymeric Electrolytes for All Solid-State Batteries: Impacts of Deposition Conditions and Polymer Composition on Performance Metrics

Achieving both high energy and power density, two traditionally opposed battery metrics, requires moving away from the 200+ years-old 2D layered battery configuration to a three-dimensional all solid-state battery (3D SSB) configuration. The enhanced power and energy benefits bestowed by a 3D SSB design have been demonstrated in the Li-ion 3D SSB literature.1 However, due to limitations in thermal and electronic conductivity of Li-Ion active materials, 3D Li-ion SSBs are limited to microscale dimensions. A potential means around this limitation is to switch to conductive metal electrodes such as Zn and Ag, for which 3D architectures have been demonstrated.2 In such a case, the remaining roadblock to a macroscale 3D SSB is the submicron-thick solid-state electrolyte, which requires a non-line-of-sight deposition method for incorporation into the complex 3D base electrode. Initiated chemical vapor deposition (iCVD) is a non–line-of-sight method that is ideal for generating conformal polymer coatings on complex 3D architectures. We focus on polymers amenable to iCVD protocols that can be modified post-deposition to introduce anion conduction pathways that can facilitate Ag and Zn redox. Submicron-thick coatings of poly-dimethylaminomethylstyrene (pDMAMS) that are pinhole-free and electronically insulating on both 2D planar and complex 3D electrode architectures are prepared via iCVD. The pDMAMS coatings are rendered anion-conducting through a vapor-phase methylation process and subsequent ion exchange to yield desirable anion species (e.g., OH–, Br–, or HCO3 –). X-ray photoelectron spectroscopy, ATR-IR spectroscopy, and solid-state magic-angle spinning NMR spectroscopy confirm the structure of the pDMAMS film before and after quaternization, while atomic force microscopy and cyclic voltammetry with redox probes confirm conformality and absence of pinholes in the submicron film. With the use of cyclic voltammetry and AC electrochemical impedance spectroscopy, the electronic and ionic conductivities of the polymer films are measured before and after quaternization. Molecular dynamics simulations of pDMAMS as a function of anion and H2O content in the film are used to generate computational results (e.g., glass-transition temperature Tg, anion conductivity) for comparison to experimental results.1. Long, J.W.; Dunn, B.; Rolison, D.R.; White, H.S. Chem. Rev. 2004, 104, 10, 4463–4492.2. Parker, J.F.; Chervin, C.N.; Nelson, E.S.; Rolison, D.R.; Long, J.W. Energy Environ Sci. 2014, 7, 1117-1124.

Preliminary Evaluation of a System with On-Body and Aerial Sensors for Monitoring Working Dogs.

This paper presents a system for behavioral, environmental, and physiological monitoring of working dogs using on-body and aerial sensors. The proof of concept study presented here includes two trained dogs performing nine scent detection tasks in an uncontrolled environment encompassing approximately two acres. The dogs were outfitted with a custom designed wearable harness to monitor their heart rate, activity levels and skin temperature. We utilized a commercially available micro-air vehicle to perform aerial sensing by tracking the terrain and movement of the dog in the outdoor space. The dogs were free to explore the space working at maximal speeds to complete a scent-based search-and-retrieval task. Throughout the experiment, the harness data was transferred to a base station via Wi-Fi in real-time. In this work, we also focused on testing the performance of a custom 3D electrode with application specific ergonomic improvements and adaptive filter processing techniques to recover as much electrocardiography data as possible during high intensity motion activity. We were able to recover and use 84% of the collected data where we observed a trend of heart rate generally increasing immediately after successful target localization. For tracking the dogs in the aerial video footage, we applied a state-of-the-art deep learning algorithm designed for online object tracking. Both qualitative and quantitative tracking results are very promising. This study presents an initial effort towards deployment of on-body and aerial sensors to monitor the working dogs and their environments during scent detection and search and rescue tasks in order to ensure their welfare, enable novel dog-machine interfaces, and allow for higher success rate of remote and automated task performance.

Atrial tattoos lines: a new method to terminate atrial fibrillation

Abstract Introduction Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting more than 4% of the world's population. Furthermore, the vulnerable substrate underlying atrial cardiomyopathy remains far from being understood. Atrial cardiomyopathy is a highly complex and heterogeneous disease that occurs in the context of various clinical backgrounds, which explains the heterogenous success of established atrial ablation strategies such as pulmonary vein isolation. Here we developed a new interventional method for the treatment of AF using a tattooing procedure of silver nanowires in the atria to create circular lines of increased conductivity to prevent irregular electrical propagation. Purpose In a translational study, we tested a newly developed interventional method to terminate AF by injecting lines of silver nanowires to increase tissue conductivity. Methods The developed tattoo method was tested in vivo using an established large animal AF model of the domestic pig. Pigs (n=10) with atrial fibrillation were either treated with right atrial tattoo lines using a transmural injection procedure of silver nanowires as closed lines in the atrium or got a sham treatment with saline injections. Over 21 days, AF was induced and monitored (AF burden) by an intracardiac dual-chamber device with a biofeedback induction algorithm. Initially and before final termination, conventional electrophysiological investigation and atrial 3D mapping, echocardiography and epicardial multi electrode array (MEA) measurements were performed. Following the 21 days observation period, the heart was extracted and freshly isolated atrial cardiomyocytes were subjected to cellular electrophysiological, molecular and histochemical characterization. Electrophysiological data was used for in silico modelling of arrhythmia termination and wave propagation. The study protocol was approved by the animal ethics committee. Results The AF burden was significantly reduced (AF burden <10%) in the group treated with the new atrial tattoo line method compared to sham treated pigs. The bi-atrial diameters, quantified by echocardiography, were significantly smaller in the treatment group. Atrial refractory period was significantly shorter in the sham treated pigs. A significant increase of connexin 43 was observed in the injection area of silver nanowires in the myocardium. Measurements with MEA demonstrated increased conduction velocity by a factor of 1.5–2.0 in the areas of silver nanowire injections. Additionally, in silico modelling showed the termination of AF via the created conduction lines. Conclusion The newly developed interventional method of the creation of atrial lines with increased tissue conductivity using silver nanowires could successfully terminate AF in pigs. Perspectively, this new myocardial tattooing technique may be a promising treatment strategy for patients with complex atrial cardiomyopathies to terminate atrial arrhythmias. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Else Kröner Fresenius Foundation

In Situ Grown CoMn-Based Metal–Organic Framework on Nickel Foam as Efficient and Robust Electrodes for Electrochemical Oxygen Evolution Reaction

Abstract It is of great significance to develop efficient and robust oxygen evolution reaction (OER) electrocatalysts based on inexpensive and earth-abundant materials to enable water splitting as a future renewable energy source. Herein, the in situ grown CoMn-MOF-74 on nickel foam and their use as active electrodes for high-performance water-oxidation catalysis are reported. In alkaline media, the binder-free three-dimensional (3D) electrode shows superior OER activity with a current density of 10 mA cm−2 at a small overpotential of 260 mV, a Tafel slope of 58.2 mV dec−1, as well as excellent stability, making it one of the most active OER catalyst. Such high performance is attributed to increased electrochemically active areas, accelerated electron transport capability and the synergy between metal–organic framework (MOFs) and Ni substrate. This work elucidates a promising electrode for electrochemical water oxidation and enriches the direct application of MOF materials for future clean energy conversion and storage systems.

Fabrication and evaluation of a self-standing reduced graphene-tungsten oxides hybrid electrode for acidic water splitting

Efficient and sustained hydrogen production via acidic water splitting is of great importance in the electrolyzer industry. Here, we have designed and synthesized a self-assembled, freestanding, three dimensional (3D) reduced graphene-non-noble tungsten oxide (SA-GWO) electrode with high comprehensive acidic electrolysis performance. Adsorption isotherm suggested the formation of mesoporous structural design within a 3D self-assembled SA-GWO architecture electrode. Bi-functional (HER and OER) activity has been displayed by SA-GWO electrodes at the combined full potential of 1.9 V and attains the standard 10 mA/cm2 (1 M H2SO4, 28 °C). Remarkably, it exhibits OER activity in the acidic medium, which is so far very limited. The tafel slope and the exchange current density for the HER process are observed to be 117 mV/decade and 1.73 × 10−3 mA/cm2, respectively, at 28 °C. Importantly, the production rate of hydrogen is found to increase with increasing temperature. HER is highly dominated by the Volmer route. Gas liberated at the respective electrode has been tested via gas chromatography (GC) analysis. SA-GWO supports the faradaic efficiency of 73 and 52% for HER and OER, respectively. Tafel slope for OER appeared to be very high owing to its complex mechanistic pathway. Disintegration of 3D monoclinic WO3 and the formation of 2D nanochannels like nanostructure have been distinctly observed in SEM micro images, when the electrode is subjected to cathodic HER reaction (−0.5 V, 1 M H2SO4). Most importantly, the WO3 polymorph typically responsible for the distinct mechanism of HER and OER action in 1 M H2SO4 has been identified and proven. Moreover, the 3D SA-GWO electrode as HER possesses great endurance and incomparable stability in acidic media.

Facile Electrodeposition and Aging to Generate 3-Dimensional α-MnO2 Battery Cathodes

Conventional tape casting forms 2-dimensional (2D) electrodes containing active material, conductive additive, and binder with restricted ion access as electrodes increase in thickness. To improve the transport properties, 3D architectures were developed using electrodeposition to ensure contact between the active material with the substrate, and provide enhanced electrolyte access. This paper investigates electrodeposition of cryptomelane (α-MnO2) as a model cathode material to efficiently accommodate (de)lithation and increase areal capacity vs conventional 2D coatings. Electodeposited samples on titantium (Ti) foil substrates were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) and show a linear increase of the average oxidation of Mn (3.5–3.8) and active mass loading (1.27–9.9 mg) with deposition and aging times (0–120 min). The initial deposition is amorphous and forms the crystalline material during the elevated temperature aging step. The active material, α-MnO2, was also deposited on C-cloth and these cathodes at deposition times of 3, 6, and 9 min deliver 9, 36, and 69% higher areal capacities, respectively, at 0.2 mA cm−2 compared to conventional 2D electrodes with a mass loading equal to the 3 min sample. These results demonstrate the benefit of α-MnO2 within a porous architecture providing enhanced transport properties.

Structural changes in the retina after implantation of subretinal three-dimensional implants in mini pigs.

The retinal structural changes after subretinal implantation of three-dimensional (3D) microelectrodes were investigated in a mini pig. Three types of electrode were implanted into the subretinal spaces of nine mini pigs: 75-μm-high 3D electrodes on a 200-μm-thick right-angled polydimethylsiloxane (PDMS) substrate (group 1); a 140-μm-thick sloped PDMS substrate without electrodes (group 2); and a 140-μm-thick sloped PDMS substrate with 20-μm-high 3D electrodes (group 3). One mini pig was used as a control. Spectral domain–optical coherence tomography (SD–OCT) images were obtained at baseline and 2, 6, and 12 weeks post-surgery. Retinal specimens were immunostained using a tissue-clearing method 3 months post-implantation. The 75-μm-high 3D electrodes progressively penetrated the inner nuclear layer (INL) and touched the inner plexiform layer (IPL) 2 weeks post-surgery. At 6 weeks post-operatively, the electrodes were in contact with the nerve-fiber layer, accompanied by a severe fibrous reaction. In the other groups, the implants remained in place without subretinal migration. Immunostaining showed that retinal ganglion and bipolar cells were preserved without fibrosis over the retinal implants in groups 2 and 3 during the 12-week implantation period. In summary, SD–OCT and immunohistology results showed differences in the extent of reactions, such as fibrosis over the implants and penetration of the electrodes into the inner retinal layer depending on different types of electrodes. A sloped substrate performed better than a right-angled substrate in terms of retinal preservation over the implanted electrodes. The 20-μm-high electrodes showed better structural compatibility than the 75-μm-high 3D electrodes. There was no significant difference between the results of sloped implants without electrodes and 20-μm-high 3D electrodes, indicating that the latter had no adverse effects on retinal tissue.

Separation of microalgae cells in a microfluidic chip based on AC Dielectrophoresis

AbstractBACKGROUNDMicroalgae is an important natural resource with extensive applications in various fields, such as health products, animal feed, biopharmaceuticals, and clean energy. However, before the research and utilization of microalgae resources, the microalgae cells of interest must be separated from hybrid strains and bacteria. The traditional method of microalgae separation requires manual labor under the microscope that is time‐consuming and labor‐intensive.RESULTSHerein, a novel microalgae cell separation method based on the dielectrophoresis (DEP) technique was proposed. A unique DEP separation chip with a 3D electrode was designed. Chlorella and Closterium were used as the experimental samples to verify the effectiveness of the proposed method because they have similar volumes and very different electrical properties. Within a certain frequency range, Chlorella suffers from negative dielectrophoresis (nDEP) force and Closterium suffers from positive dielectrophoresis (pDEP) force, so their separation can be achieved. The separation efficiency exceeded 90%. In addition, the DEP response of the Chlorella and Closterium were studied, and the DEP spectra of the two microalgae cells were obtained. Moreover, the effects of DEP force on cell viability under different voltages and frequencies were experimentally analyzed.CONCLUSIONThese findings will contribute to DEP technology, to the portable and harmless separation of microalgae, and to research on the dielectric properties of microalgae cells. © 2022 Society of Chemical Industry (SCI).

Controllable dealloying of a Cu-Ga alloy and its application as an anode material for lithium-ion batteries

Abstract Porous metallic materials are widely used for lithium-ion battery (LIB) electrodes because of their low density, efficient ionic/electron pathways, and high specific surface area. In this study, we fabricate nanoporous Cu using chemical and electrochemical dealloying methods based on a Cu-Ga alloy. The effects of the dealloying conditions on the derived microstructure of the nanoporous metal and its evolution mechanisms are discussed. Analysis and control of the electrochemical dealloying process reveal that the sample morphology can be adjusted and the phase component can be controlled. Accordingly, a 3D CuGa2 electrode with a nanoporous structure is controllable synthesized, and it exhibits a higher specific capacity and cyclic stability than a 2D CuGa2 electrode when used as a LIB anode.

Effects of Structured 3D Electrodes on the Performance of Redox Flow Batteries

AbstractIn recent years, the interest in redox flow batteries as stationary energy storage devices is growing, for which disordered three‐dimensional electrodes such as felts have been the state‐of‐the‐art due to their large surface area and improved mass transfer properties. However, such electrodes present a high pressure drop and operating cost. In this work, the performance of structured three‐dimensional electrodes in a redox flow battery was studied. Compared to the carbon felt electrode similar electrochemical behaviour was demonstrated with these structured electrodes, which were based on the most common static mixer designs, but at a power consumption that was two to three orders of magnitude lower. Moreover, due to its ordered electrode design unwanted side reactions were suppressed. Consequently, these results demonstrate the influence of structured static mixer based three‐dimensional electrodes in redox flow batteries and the opportunities they hold to surpass the current state‐of‐the‐art.

A green route for lignin-derived graphene electrodes: A disposable platform for electrochemical biosensors

The tremendous growth of disposable electrode-based portable devices for point-of-care testing requires mass production of disposable electrodes in a low-cost and sustainable manner. Here, we demonstrate a green route for the conversion of biomass lignin, patterning, and reduction of the lignin-derived graphene electrodes by sequential laser lithography, water lift-off and sodium borohydride (NaBH4) treatment, and their use for electrochemical lactate biosensors. Energy-saving and localized laser lithography converted the aromatic ring-rich lignin into porous laser-induced graphene (LIG). The conductivity and attachment of the LIG to the substrate were optimized in a factorial experiment with laser power and scan speed as variables. Characterization results revealed the conversion of partial heteroatoms (e.g., Na, S, O) into granular inorganic compounds on the LIG surface under laser treatment. Water was used as an eco-friendly solvent for the patterning of the LIG (P-LIG) by a lift-off process, where the inorganic residues and un-reacted lignin were dissolved, exposing the macro-/micro-pores in the P-LIG. NaBH4 induced a reduction of the P-LIG (P-rLIG) resulting in improved electrochemical kinetics with lower charge transfer resistance (27.3 Ω) compared to the LIG (248.1 Ω) and the P-LIG (61.4 Ω). The porous P-rLIG served as a 3D electrode for the deposition of Prussian blue and lactate oxidase for disposable electrochemical lactate biosensors, delivering a good analytical performance towards lactate detection with a linear range up to 16 mM and a high sensitivity (1.21 μA mM−1). These lignin-derived disposable electrodes, utilizing renewable resources together with low-energy consumption fabrication and patterning, may contribute to the sustainable manufacturing of biosensors for point-of-care and point-of-use applications.

Three-dimensional topology optimization of Ni-YSZ anode for solid oxide fuel cells via multiphase level-set method

In the present study, numerical model is developed to optimize the 3D multiphase electrode microstructure for SOFC, e.g. nickel-yttria-stabilized zirconia (Ni-YSZ) anode. During the optimization, Ni-YSZ microstructure is deformed in order to maximize the total reaction current. Multiphase level-set (MLS) model is applied to represent the Ni-YSZ anode microstructure, and adjoint method is applied for the sensitivity analysis. In addition, in order to improve the computational accuracy and to make the optimized microstructure manufacturable, a radius constraint is imposed to ensure that the local particle radii are kept larger than a target value (Rtarget), where the interface is updated only when the local radius value is larger than Rtarget. It is also confirmed that the optimized microstructure and performance of the Ni-YSZ anode are independent of the initial structures and the phase division schemes. According to the optimization results, the optimized electrochemical performances are improved, and the particle and pore radii of the microstructure successfully remained larger than the target values. The optimized Ni-YSZ microstructures are composed of Ni particles embedded into a YSZ scaffold which has a pillar-like shape along the anode thickness direction.

Remarkable gas bubble transport driven by capillary pressure in 3D printing-enabled anisotropic structures for efficient hydrogen evolution electrocatalysts

Additive manufacturing technologies have been proved as a promising method to achieve electrocatalysts with periodic micro-size pores, while the nano-sized interspace of the material structures and their corresponding gas bubbles transfer process are not explored in detail. Herein, we employ the shear force alignment in additive manufacturing to design NiMo-based structures with anisotropic porous channels as electrocatalysts for hydrogen evolution reaction (HER) in seawater. Based on the complementary experimental and theoretical investigation, the unique anisotropic structure not only fully exposes the active sites in the electrolyte, but also facilitates the rapid electrolyte-hydrogen phase conversion during electrochemical reactions. In this case, the obtained 3D electrode exhibits superior electrocatalytic performance and excellent long-term operational stability with an extremely low overpotential of ∼150 mV at a current density of 500 mA/cm2 in 1 M KOH seawater. This work will provide a practical scenario for designing highly-efficient HER electrocatalysts.

Tailoring 3D-Printed Electrodes for Enhanced Water Splitting.

Alkaline water electrolysis, a promising technology for clean energy storage, is constrained by extrinsic factors in addition to intrinsic electrocatalytic activity. To begin to compare between catalytic materials for electrolysis applications, these extrinsic factors must first be understood and controlled. Here, we modify extrinsic electrode properties and study the effects of bubble release to examine how the electrode and surface design impact the performance of water electrolysis. We fabricate robust and cost-effective electrodes through a sequential three-dimensional (3D) printing and metal deposition procedure. Through a systematic assessment of the deposition procedure, we confirm the close relationship between extrinsic electrode properties (i.e., wettability, surface roughness, and electrochemically active surface area) and electrochemical performance. Modifying the electrode geometry, size, and electrolyte flow rate results in an overpotential decrease and different bubble diameters and lifetimes for the hydrogen (HER) and oxygen evolution reactions (OER). Hence, we demonstrate the essential role of the electrode architecture and forced electrolyte convection on bubble release. Additionally, we confirm the suitability of ordered, Ni-coated 3D porous structures by evaluating the HER/OER performance, bubble dissipation, and long-term stability. Finally, we utilize the 3D porous electrode as a support for studying a benchmark NiFe electrocatalyst, confirming the robustness and effectiveness of 3D-printed electrodes for testing electrocatalytic materials while extrinsic properties are precisely controlled. Overall, we demonstrate that tailoring electrode architectures and surface properties result in precise tuning of extrinsic electrode properties, providing more reproducible and comparable conditions for testing the efficiency of electrode materials for water electrolysis.

Wood-Based Self-Supporting Nanoporous Three-Dimensional Electrode for High-Efficiency Battery Deionization.

Developing highly efficient advanced battery deionization (BDI) electrode materials at a low cost is vital for seawater desalination. Herein, a high-efficiency wood-based BDI electrode has been fabricated for seawater desalination, benefiting from the self-supporting three-dimensional (3D) nanoporous structure and rich redox-active sites. The finely tuned rich electrochemical redox active C═O groups on the surface of the wood electrode derived from the facile thermochemical conversion of lignin play a crucial role in the Faradaic cation removal dynamics of BDI. Coupling the 3D wood electrode and a polyaniline-modified wood electrode as the cathode and anode, an all-wood-electrode-based deionization battery has been successfully assembled with a state-of-the-art ion removal capacity of up to 164 mg g-1 in seawater. Our work reported an example of utilizing wood as the BDI electrode via fine-tuning the redox-active sites, demonstrating a novel resource utilization pathway of converting cheap biomass into BDI electrodes for highly efficient seawater desalination.

Two-dimensional redox polydopamine with in-plane cylindrical mesochannels on graphene for high-energy and high-power lithium-ion capacitors

Lithium-ion capacitors (LICs) are distinguished for bridging the gap of energy and power densities between lithium-ion batteries and supercapacitors. However, the kinetic mismatch between the slow diffusion and fast adsorption/desorption of lithium ions usually leads to the sacrifice of high power density or high energy density. Here, we report a general “one-for-two” strategy for controllable construction of 2D mesoporous polydopamine/reduced-graphene-oxide heterostructure (mPDA/rGO) with ordered in-plane cylindrical mesochannels as cathode and mPDA/rGO derived nitrogen-doped carbon nanosheets (mNC/rGO) as anode of LIC to achieve fast electrochemical kinetics. The in-plane cylindrical mesochannels and surface redox reactions of 2D mPDA/rGO and mNC/rGO ensure rapid reaction kinetics in both cathode and anode. As a result, mPDA/rGO shows remarkable specific capacity of 133 mAh/g, and excellent rate capability of 94 mAh/g even at 5 A/g. Meanwhile, 2D mNC/rGO exhibits high capacitance of 550 mAh/g at 0.1 A/g and 225 mAh/g at 5 A/g. The as-assembled LIC with these two electrodes offers a high energy density of 208 Wh kg−1 at a power density of 176 W kg−1, which can retain as high as 102.2 Wh kg−1 at 8.8 kW kg−1. This study demonstrates the control of porosity and morphology as an appealing strategy for rational construction of 2D electrode materials to boost high-energy and high-power LICs.

Nanochannel array modified three-dimensional graphene electrode for sensitive electrochemical detection of 2,4,6-trichlorophenol and prochloraz.

Convenient, and sensitive detection of pesticides and their metabolites in environmental or food samples is critical for assessing potential environmental and health risks. Here, a three-dimensional (3D) electrochemical sensing platform is proposed based on the integration of nanochannel array on pre-activated 3D graphene (p-3DG) electrodes with no need of additional adhesive layers, which enables sensitive detection of prochloraz and 2,4,6-trichlorophenol (TCP) in environmental and food samples. Through two-step electrochemical polarization, organic phase anodic oxidation, and aqueous phase cathodic reduction, p-3DG electrodes with high active area and excellent electrocatalytic performance were obtained. Vertically-ordered mesoporous silica-nanochannel film (VMSF) can be rapidly grown on the surface of p-3DG by an electrochemical-assisted self-assembly (EASA) method. Taking advantage of the high electrocatalytic activity of p-3DG and the ability of nanochannels to enrich TCP through hydrogen bonding, the VMSF/p-3DG sensor can sensitively detect TCP in the range of 10 nM to 0.1 μM and 0.1–15 μM with a low limit of detection (LOD) of 2.4 nM. Compared with p-3DG and VMSF-modified 2D electrodes, the fabricated sensor has a wide detection linear range and low LOD. The coexistence of model interferents such as protein, surfactant, and humic acid did not affect the electrochemical response of TCP, confirming the high anti-fouling ability of the VMSF/p-3DG sensor. In addition, prochloraz in vegetable and fruit samples was indirectly determined because TCP was the metabolite of prochloraz.

A new current injection and voltage measurement strategy of 3D electrical impedance tomography based on scanning electrode.

Electrical impedance tomography (EIT) technology is an important imaging approach to show the conductivity distribution of the area noninvasively. Recently, 3D EIT has been extensively studied for its more comprehensive display of electrical properties. Nonetheless, most 3D EIT electrode models are based on multilayer ring electrodes and only suitable for specific scenarios. In order to overcome its limitations and alleviate the ill-condition of 3D EIT, we propose a new current injection and voltage measurement strategy based on scanning row electrodes (SRE) called the back electrode excitation (BEEM) strategy and select the optimal number of excitation electrodes according to different imaging effects. A 3D electrical impedance imaging system based on SRE is designed. Then, the traditional excitation measurement strategy is introduced, and the two strategies are compared through simulation and actual experiments. The results show that the BEEM strategy with SRE can not only obtain rich potential information in the finite field but also significantly improve the imaging detection depth, accuracy, and noise immunity compared with the flat electrode array.

Identification of Different Shallow Foundations Using 3D Electrical Resistivity Modeling

The electrical resistivity method has been successfully used to detect shallow buried foundations, almost, by using 2D electrode arrays. Basic geometry foundations (e.g., buried walls) have been investigated, although, more complicated foundation designs (e.g., stepped footing, pile group with a pile cap) are widely used in the construction industry. Investigation of these complicated foundation types, and engaging 3D surveys, therefore, are required. Multiple 3D electrical resistivity forward modeling was used to simulate different foundations (isolated simple footing, isolated stepped footing, combined simple footings, and pile group with a pile cap). The generated data sets then inverted using a robust inversion algorithm where RES3DINVx64 was used to perform the inversion process for the 3D models. The results from the 3D inverse modeling, suggest the pole-dipole and dipole-dipole arrays for all the investigated foundations.

Three-dimensional flexible and stretchable gold foam scaffold for real-time electrochemical sensing in cells and in vivo

Compared with typical two-dimensional electrodes, the three-dimensional (3D) cell culture platform can simulate the real cell survival environment for cell growth to accurately reproduce cell functions. Moreover, considering that living cells are exposed to various of mechanical force in the microenvironment, the construction of 3D electrodes with excellent flexible, stretchable, and biocompatibility is of great significance to real-time monitor mechanically evoked biomolecule release from cells. Herein, we demonstrated a straightforward and effective three-step approach to fabricate three-dimensional flexible and stretchable gold foam scaffold (3D Au foam scaffold) for construction of 3D cell culture integrated electrochemical sensing platform. The excellent biological and electrical properties of Au nanostructures and porous networks of the 3D scaffold endow the platform with desirable biocompatibility and sensitive electrochemical sensing performance. As a proof of concept, the 3D Au foam scaffold functionalized with cobalt based nanocubes (Co NCs/Au foam scaffold) was validated to provide 3D culture for human umbilical vein endothelial cells (HUVECs), and synchronously real-time monitor superoxide anion (O2•-) released by HUVECs under mechanical stretching. Furthermore, 3-mercaptopropionic acid (3-MPA) modified 3D Au foam (3-MPA/Au foam scaffold) was successfully used for real-time monitoring of catecholamines in rat brain. The results demonstrate the great potential of this 3D Au foam scaffold for real-time electrochemical monitoring biomolecules in vitro and in vivo, providing convenience for future research on mechanotransduction relevant processes.