Arbitrary Geometry Research Articles

A bionic self-driven retinomorphic eye with ionogel photosynaptic retina.

Bioinspired bionic eyes should be self-driving, repairable and conformal to arbitrary geometries. Such eye would enable wide-field detection and efficient visual signal processing without requiring external energy, along with retinal transplantation by replacing dysfunctional photoreceptors with healthy ones for vision restoration. A variety of artificial eyes have been constructed with hemispherical silicon, perovskite and heterostructure photoreceptors, but creating zero-powered retinomorphic system with transplantable conformal features remains elusive. By combining neuromorphic principle with retinal and ionoelastomer engineering, we demonstrate a self-driven hemispherical retinomorphic eye with elastomeric retina made of ionogel heterojunction as photoreceptors. The receptor driven by photothermoelectric effect shows photoperception with broadband light detection (365 to 970 nm), wide field-of-view (180°) and photosynaptic (paired-pulse facilitation index, 153%) behaviors for biosimilar visual learning. The retinal photoreceptors are transplantable and conformal to any complex surface, enabling visual restoration for dynamic optical imaging and motion tracking.

SHORYUKEN: An open-source software package for calculating nonlocal exchange interactions in nanowires

We present the open-source software package, SHORYUKEN (Streamlined High-level Operations in Real-space to Yield, Understand, and Keep Exchange in Nanowires), for calculating nonlocal exchange interactions in nanowires with arbitrary geometries, sizes, doping densities, and compositions. In addition to enabling new calculations of nonlocal exchange, the SHORYUKEN software package is a significant enhancement of our previous HADOKEN code and includes new algorithmic improvements as well as an improved treatment of surface states for nanowires with intrinsic polarization. Our calculations show that the inclusion of nonlocal exchange can have significant effects on the eigenenergy spectrum, number of occupied states, and distribution of electrons within these nanosystems. The SHORYUKEN software package is the first open-source code for calculating nonlocal exchange to predict electron gas formation in nanowire systems with arbitrary cross-sectional geometries. Program summaryProgram Title: SHORYUKENCPC Library link to program files:https://doi.org/10.17632/f77p84pbcv.1Licensing provisions: GNU General Public License 3Programming language: MATLABNature of problem: The SHORYUKEN code calculates nonlocal exchange interactions of electrons in nanowires by solving modified nonlocal exchange and Poisson-like equations self-consistently on a finite element grid. The software package is capable of performing calculations for core-multishell nanowires with arbitrary cross-sectional shapes.Solution method: iterative solution of the Schrödinger-Poisson equations with nonlocal exchange using finite element methods and sparse matrix linear algebra

SPRAY: A smoothed particle radiation hydrodynamics code for modeling high intensity laser-plasma interactions

Here we report the development of SPRAY, a massively parallel GPU accelerated, smoothed particle hydrodynamics (SPH)-based, radiation hydrodynamics (RHD) code designed specifically for simulating high intensity laser-plasma interactions. When a target is irradiated by an intense laser, highly complex fluid deformation occurs due to instabilities, which is challenging to study numerically. SPRAY is particle-based, mesh-free, and Lagrangian, which addresses numerical issues that posed difficulties to existing methods. Its SPH formulations for RHD governing equations are tailored toward accurate and reliable simulations of laser-target irradiation phenomena, and are solved via a time-dependent, flux-limited diffusion method. A new laser energy coupling module, which is based on the Wentzel-Kramers-Brillouin (WKB) approximation, is implemented with a totally mesh-free ray-tracing scheme that is applicable for arbitrary geometry and dimensions. The accuracy and reliability of the code are demonstrated with a series of benchmark problems. To the authors' knowledge, this is the first attempt to employ SPH method for simulations of laser-plasma interactions in high energy density physics research. Possible expansions to the code, such as laser beam-beam interaction modeling and more sophisticated multi-group radiation transport are left for future development.

The time-domain Cartesian multipole expansion of electromagnetic fields

Time-domain solutions of Maxwell’s equations in homogeneous and isotropic media are paramount to studying transient or broadband phenomena. However, analytical solutions are generally unavailable for practical applications, while numerical solutions are computationally intensive and require significant memory. Semi-analytical solutions (e.g., series expansion), such as those provided by the current theoretical framework of the multipole expansion, can be discouraging for practical case studies. This paper shows how sophisticated mathematical tools standard in modern physics can be leveraged to find semi-analytical solutions for arbitrary localized time-varying current distributions thanks to the novel time-domain Cartesian multipole expansion. We present the theory, apply it to a concrete application involving the imaging of an intricate current distribution, verify our results with an existing analytical approach, and compare the proposed method to a finite-difference time-domain numerical simulation. Thanks to the concept of current “pixels” introduced in this paper, we derive time-domain semi-analytical solutions of Maxwell’s equations for arbitrary planar geometries.

Optimisation of Supports’ Position for a Reinforced Concrete Slab of Arbitrary Geometry

Introduction. A number of research held in recent years on rational design of buildings and structures built for different purposes study the rational position of the vertical members — columns or supports. However, the majority of up-to-date research and publications focus on elucidating the rational position of the supports in the context of improving the efficiency of the beams. Whereas the behaviour of the reinforced concrete slabs affected by changing the position of the supports is not covered well enough in the modern research. The present study is targeted exactly at revealing the behaviour of the reinforced concrete slab structures of a building in case of varying position of the main supports.Materials and methods. During the present numerical experiment, a reinforced concrete slab of arbitrary geometry with the given thickness h, the concrete grade with the respective properties and the reinforcement possessing the properties according to its class, has been investigated. Additionally, it was decided to set the distance magnitudes from the centers of gravity of the upper and lower row of reinforcement to the bottom and top surface of the slab 𝑎𝑥, 𝑎′𝑥, 𝑎𝑦, 𝑎′𝑦. The number of columns n was set for the slab. It was considered that the number of columns was known, but their position could change. Moreover, among the total number of columns, there were distinguished the certain ones having the definite (constant) position, whereas the remaining supports could change their position within the slab area. Bearing in mind the above, the researchers were to solve the problem of rational position of the moveable columns.Results. This paper presents the results of the numerical experiment on identifying the most optimal (rational) position of the reinforced concrete columns supporting a slab of the arbitrary geometry. Based on the several parameters at once, such as deflection, potential strain energy and consumption of the reinforcement products, the analysis of the rational position of the supports under the slab was made and functional dependences on changing the above mentioned parameters have been presented in the work.Discussion and conclusion. Based on the results obtained in the numerical experiment, the analysis of the behaviour of the reinforced concrete slabs of a set thickness upon changing the position of the supports under the slab was made and the changes of the slab operational parameters were analysed and compiled into the functional dependences.

Predicting lift and drag coefficients during hypersonic Mars reentry using hyStrath

During hypersonic reentry, a spacecraft experiences several different fluid flow regimes, which usually require the application of different software frameworks to simulate the respective regimes. This study aims to evaluate the hyStrath library for predicting aerodynamic lift and drag coefficients of complex three-dimensional (3D) geometries during hypersonic Mars reentry, using flight data of the Viking 1 mission as reference. A range of altitudes (h=30−140 km) and Mach numbers (M=13−24) where flight data is available is considered, covering the rarefied, transitional, and continuum fluid flow regimes. The hyStrath library contains a set of modified solvers and state-of-the-art thermophysical and chemistry models within the framework of OpenFOAM, dedicated to modeling high-enthalpy hypersonic flow problems. Depending on the flow regime, the computational fluid dynamics solver hy2Foam or direct-simulation Monte Carlo solver dsmcFoam+ are employed in the study. Because hyStrath is based on OpenFOAM, it allows the use of an unstructured adaptive mesh refinement approach for arbitrary geometries. We obtain excellent results throughout all investigated flow regimes and Mach numbers with an average deviation of 1.5% and 2% from the measured lift and drag coefficients, respectively. The applicability of the framework for accurately modeling both rarefied and continuum Mars reentry problems of complex 3D geometries such as the Viking capsule is demonstrated.

A large-scale traffic signal control algorithm based on multi-layer graph deep reinforcement learning

Due to its capability in handling complex urban intersection environments, deep reinforcement learning (DRL) has been widely applied in Adaptive Traffic Signal Control (ATSC). However, most existing algorithms are designed for specific road networks or traffic conditions, making it difficult to transfer them to new environments. Moreover, current graph-based algorithms do not fully capture the geometric and spatial features of intersections, leading to incomplete embedding of the agent's environment depiction. Additionally, the actions adopted by these algorithms are inherently based on fixed-cycle phases, limiting the flexibility of traffic signal control. To address the aforementioned issues, this paper proposes a Multi-layer Graph Mask Q-Learning (MGMQ) algorithm for multi-intersection ATSC to optimize traffic and reduce delay. Unlike previous graph-based algorithms, this paper introduces a method for computing multi-layer graphs, dividing the traffic environment into upper-level traffic network-layer graphs and lower-level intersection-layer graphs, and employs the graph attention algorithm and an improved GraphSAGE algorithm for computation. This method not only enables the generation of embedded state for intersections that include geometric and spatial features, but also allows the algorithm to adapt to different traffic conditions and road networks. Additionally, we introduce an action masking mechanism, allowing this algorithm can be adapted to different action spaces. As a result, the algorithm uses arbitrary signal phases as actions to achieve flexible traffic flow control, and can be directly applied to intersections with arbitrary geometry. The final test results demonstrate that a model trained solely on synthetic road networks can be directly transferred to other synthetic network configurations or real-world urban road networks, outperforming current state-of-the-art algorithms.

A T-splines-oriented isogeometric topology optimization for plate and shell structures with arbitrary geometries using Bézier extraction

Recently, the non-uniform rational B-splines (NURBS) have been considerably employed in modeling plate and shell structures, or developing the related size, shape or topology optimization methods for their design. However, the NURBS with the tensor product feature strongly hinders the effectiveness of the optimization on complex structures. The primary intention of the current research is to propose a new T-splines-oriented Isogeometric Topology Optimization (T-ITO) method and then address the critical design problem of plate and shell structures with arbitrary shapes in practical applications. Firstly, the Bézier extraction is utilized in the T-splines to map the geometrical model into a family of Bézier elements, each of which is presented by a local Density Distribution Function (DDF) for elementary topology. A global DDF is constructed by an assembly of all local DDFs with a natural connection to the present structural topology. Secondly, the T-splines-based IsoGeometric Analysis (T-IGA) formulation with the Bézier extraction for complex plate and shell structures is developed using the Kirchhoff-Love theory, where a universal numerical implementation framework is constructed, including the Rhino, MATLAB, export modules with all geometric information and import modules for the analysis. Thirdly, a mathematical formulation for plate and shell structures with arbitrary geometries is developed using the T-ITO method to improve structural loading-capability, and the sensitivity analysis with respect to design variables is rigorously derived in detail. Finally, several numerical examples of plate and shell structures with both regular and elaborate geometries are tested to demonstrate the validity, effectiveness, superiorities and indispensability of the T-ITO method.

Progress in 3D printing of recycled PET

Filaments from blends of post-industrial, low-quality recycled poly(ethylene terephthalate) (RPET) and ethylene-butyl-acrylate-glycidyl-methacrylate (EBA-GMA) were extruded with different EBA-GMA contents, then specimens were 3D-printed by fused filament fabrication technology. It has been demonstrated that, when 0–90° layer order is applied, at 15 wt% EBA-GMA content the unnotched impact strength increases by two and a half times and the notched impact strength by nine times compared to samples printed from elastomer-free RPET. DSC and DMA measurements proved that EBA-GMA reactively bonds to PET molecules, which is indicated by the increment of rigid amorphous phase and glass transition temperature and the reduction of crystallinity. The co-polymer molecules formed in-situ during compounding create a Toughening Enhancer Interphase (TEI), which also remains after 3D printing and effectively enhances impact strength. The strain at break and tensile strength of the filaments are substantially higher than that of 3D-printed specimens due to the increasing shrinkage and the resulting increased porosity of the printed specimens with higher EBA-GMA content. However, the Young-modulus values are quite similar. The flexural strength of the 3D-printed specimens reaches 40–60% of the values of injection moulded samples. The proposed method enables the production of parts with arbitrary geometry and balanced mechanical properties from RPET, which may substitute acrylonitrile butadiene styrene.

3D Numerical Cross-Section Analysis of a Tapered Beam Slice

Cross-section analysis is an important tool used to recover stresses and strains in a structure at specific cross-sections of arbitrary geometries, without the need for a full 3D model. This is particularly essential for large-scale structures such as aircrafts, wind turbine blades, etc. where making a full model can be computationally very expensive or impractical. The majority of currently available cross-section analysis frameworks are based on stepwise prismatic assumptions, which are hardly suited for the analysis of tapered beams. In fact, high-fidelity stress analysis obtained from analytical and full 3D models shows that predictions of stepwise prismatic approximations can significantly deviate from the correct solution of tapered beams. In this work, a prismatic 3D cross-section analysis method is extended to analyze a symmetrically tapered finite cross-section slice. In this study, the cross-section slice is discretized with 8-node and 20-node solid elements. The boundary conditions are applied as six constraint equations via the Lagrange multiplier method. The external nodal forces acting on the cross-section faces are obtained from the equivalent tractions induced by the cross-section forces. The developed numerical model is validated against the exact analytical solutions of a wedge as well as commercial finite element (FE) software COMSOL and it is shown that the numerically predicted displacement and stress fields agree well with those provided by the wedge’s analytical solution and the FE COMSOL results. This work contributes to the advancement of high-fidelity numerical tapered cross-section analysis methods with an application for many engineering structures.

Version [formula omitted]- [MaSMaker: An open-source, portable software to create and integrate maze-like surfaces into arbitrary geometries]

MaSMaker 2.0 aims to contribute to the computational design and fabrication of Triply Periodic Minimal Surface (TPMS) structures. This updated version expands the capabilities of the software in three aspects: (1) the repertoire of available TPMS structures, (2) the possibility of generating graded and hybrid TPMS prisms was added as a basic exploration tool, looking for more complex applications, and (3) introduces the functionality for recommending the resolution to build the TPMS structure depending on the Additive Manufacturing (AM) process to be used. The “isovalue” request has been replaced with a “Volume Fraction” request as a design variable, employing polynomial models derived from wide-ranging characterizations. AM recommendations come from analyzing ratios that consider cell size, cell type, and AM technology limitations to propose a design resolution. MaSMaker 2.0 combines mathematical precision and fabrication feasibility, empowering designers to seamlessly create and manufacture intricate TPMS structures.

A reduced-order computational homogenization framework for locally resonant metamaterial structures

A computational homogenization framework is presented to study the dynamics of locally resonant acoustic metamaterial structures. Modelling the resonant units at the microscale as representative volume elements and building on well-established scale transition relations, the framework brings as a main novelty a reduced-order macroscopic homogenized continuum whose governing equations involve no additional variables to describe the microscale dynamics unlike micromorphic homogenized continua obtained by alternative computational homogenization approaches. This model-order reduction is obtained by formulating the governing equations of the micro- and macroscale problems in the frequency domain, introducing a finite-element discretization of the two problems and performing an exact dynamic condensation of all the degrees of freedom at the microscale. An appropriate inverse Fourier transform approach is implemented on the frequency-domain equations to capture transient dynamics as well; notably, the implementation involves the Exponential Window Method, here applied for the first time to calculate the time-domain response of undamped locally resonant acoustic metamaterial structures. The framework may handle arbitrary geometries of micro- and macro-structures, any transient excitations and any boundary conditions on the macroscopic domain.

A physics-based tessellation algorithm for particle assemblies on arbitrary surfaces

Interacting particle assemblies embedded on a surface are often used to model biophysical systems and to study new colloidal materials. The configurations resulting from the particles interacting with each other and with their substrate affect the system's physical properties, which depend on local symmetries and defects. It is therefore important to identify the nature and location of defects in the particle assembly. This task is often achieved using either the Voronoi tessellation algorithm or order parameters. Although very useful, they present limitations, especially when the particle assemblies are embedded on irregular or highly deformed 3D surfaces. In this work, we present a novel algorithm to generate the tessellation of particle assemblies on 3D surfaces of arbitrary geometry. The algorithm is based on the particles' physical interactions and does not require a priori information on the surface geometry. The resulting cells in the tessellation represent each particle's interactions with its first ring of neighboring particles. The algorithm is tested using 2D and 3D surfaces, with or without periodic boundary conditions, with holes or fully covered by particles, of regular geometry or highly deformed shape, and in the presence of positive, zero, and negative Gaussian curvature. In all cases, the presented algorithm is capable of generating a tessellation representing the particle interactions and highlighting the location and nature of the assembly defects. Finally, the proposed algorithm is compared with both Voronoi and hexatic order parameters in several representative cases to highlight similarities with existing methods as well as the advantages of the newly proposed algorithm.

Adjoint-based shape optimization for radiative transfer in porous structure for volumetric solar receiver

Due to their large surface areas, porous structures are often used for volumetric solar receivers for efficient utilization of the solar energy. However, the precise simulation and optimization of radiative heat transfer inside porous structures are still challenging due to their complex geometries. In the present study, an adjoint-based shape optimization framework for radiative transfer in porous structures is first proposed. Specifically, an arbitrary complex geometry of a porous structure is represented by a level-set function embedded in a Cartesian grid system. The volume penalization method combined with the discrete ordinate method is employed to simulate a forward radiative transfer problem in a porous structure. Then, a cost functional for an adjoint analysis is defined by the volume average of the divergence of the radiative heat flux, which corresponds to the total heat absorbed by the porous structure with a negative sign. The adjoint equations for minimizing the cost functional, and the corresponding shape update formula are derived and implemented in an open-source software, OpenFOAM. The developed adjoint-based shape optimization framework is applied to three types of initial porous structures, i.e., SC Kelvin, BCC Kelvin, and square honeycomb models. For all the initial porous models, the front surface commonly extends towards the direction of the incident radiation, and consequently notable improvements of the absorption efficiency can be achieved through the optimization. In addition, a systematic parametric survey for the initial shape of the SC Kelvin model is conducted to reveal the impacts of the number of unit cells, the solid emissivity, and the solid temperature on the optimal shapes and the resulting absorption efficiencies.

General acoustic Willis media modeled as conventional materials with embedded sources

Willis coupling vectors provide additional degrees of freedom to manipulate acoustic waves unavailable in conventional materials, but the additional material properties make it difficult to simulate the interaction between sound and Willis media especially when inhomogeneous media with arbitrary geometries are involved. To address this challenge, we establish the equivalence between the wave equation inside a three-dimensional, inhomogeneous, and anisotropic Willis medium to the well-known acoustic wave equation in conventional materials with embedded continuous distributions of monopole and dipole sources. We validate the equivalence in numerical simulations showing that conventional materials with embedded sources replace physical Willis metamaterials anisotropic in the Willis and mass density tensors without modifying the scattered sound distribution. Moreover, the equivalence offers insights into the physics of Willis materials. For example, it shows that various combinations of Willis coupling vectors can generate identical sound scattering for any excitation. It also shows whether effective material parameters extracted from single Willis cell simulations remain valid in bulk metamaterials obtained by replicating periodically that cell. These results suggest that the equivalence model can advance the design of Willis metamaterials and provide a tool to better understand the physics of Willis media.

Variational construction of tubular and toroidal streamsurfaces for flow visualization

Approximate streamsurfaces of a three-dimensional velocity field have recently been constructed as isosurfaces of the closest first integral of the velocity field. Such approximate streamsurfaces enable effective and efficient visualization of vortical regions in three-dimensional flows. Here we propose a variational construction of these approximate streamsurfaces to remove the limitation of Fourier series representation of the first integral in earlier work. Specifically, we use finite-element methods to solve a partial differential equation that describes the best approximate first integral for a given velocity field. We use several examples to demonstrate the power of our approach for three-dimensional flows in domains with arbitrary geometries and boundary conditions. These include generalized axisymmetric flows in the domains of a sphere (spherical vortex), a cylinder (cylindrical vortex) and a hollow cylinder (Taylor–Couette flow) as benchmark studies for various computational domains, non-integrable periodic flows (ABC and Euler flows) and Rayleigh–Bénard convection flows. We also illustrate the use of the variational construction in extracting momentum barriers in Rayleigh–Bénard convection.

Numerical extraction of three-dimensional acoustic polarizabilities for acoustically small scatterers

Polarizability is a convenient descriptor for scattering from low-ka inhomogeneities in both electromagnetism, where it originated, and in acoustics, where it is increasingly used in the design of metamaterial elements. In two or three dimensions, the polarizability is represented by a block matrix that couples the local pressure and particle velocity fields to the lowest-order components of the multipole expansion, usually truncated to dipole order. A fully dense acoustic polarizability matrix has components that couple spatially uniform pressure and velocity oscillations to dipole and monopole scattering, respectively. This unique coupling leads to acoustic bianisotropy, also known as Willis coupling, for a collection of scatterers. The design of Willis materials necessitates computationally efficient methods to extract all components of the polarizability matrix and, at present, only two-dimensional analytical extraction methods are found in the literature. In this work, we present an algorithm to extract all components of the three-dimensional polarizability matrix from a scatterer with arbitrary geometry and composition. The method presented here is numerically efficient and yields results that are in agreement with an analytically obtained benchmark polarizability, providing a useful tool for acoustic metamaterial design.

Active acoustic metamaterials with independently programmable bulk modulus and full mass density tensor

Active acoustic metamaterials consist of unit cells with sensor-driver pairs that produce a coherent response to incident waves. The effective acoustic properties of the metamaterials depend on the gains programmed between the sensing and driving components. The strength of the monopole response to the local pressure determines the effective bulk modulus and the dipole response to the local particle velocity determines the effective mass density. The unit cells are controlled individually, so in theory the metamaterials can be scaled to an arbitrary size and geometry, but prior realizations were limited to only a few cells with 1D operation. Here, we present an active acoustic metamaterial of nine cells in 2D with programmable bulk modulus and mass density tensor. We demonstrate the ability to independently program the property components (bulk modulus and four mass density elements) for any desired set within stable limits, including previously unattainable acoustic properties necessary for the fabrication of transformation acoustics devices. We also demonstrate complex effective properties, specifically a lossy layer with impedance matched to the background, such that incident waves are absorbed with no reflection. The effective properties of the active metamaterial are validated by comparing the experimental total and scattered fields to ideal simulation results.

Improving Fabrication and Performance of Additively Manufactured RF Cavities by Employing Co-Printed Support Structures and Their Subsequent Removal

The enormous potential of additive manufacturing (AM), particularly laser powder bed fusion (L-PBF), to produce radiofrequency cavities (cavities) has already been demonstrated. However, the required geometrical accuracy for GHz TM010 cavities is currently only achieved by (a) avoiding downskin angles <40∘, which in turn leads to a cavity geometry with reduced performance, or (b) co-printed support structures, which are difficult to remove for small GHz cavities. We have developed an L-PBF-based manufacturing routine to overcome this limitation. To enable arbitrary geometries, co-printed support structures are used that are designed in such a way that they can be removed after printing by electrochemical post-processing, which simultaneously reduces the surface roughness and thus maximizes the quality factor Q0. The manufacturing approach is evaluated on two TM010 single cavities printed entirely from high-purity copper. Both cavities achieve the desired resonance frequency and a Q0 of approximately 8300.

Custom-form iron trifluoride Li-batteries using material extrusion and electrolyte exchanged ionogels

Custom-form factor batteries fabricated in non-conventional shapes can maximize the overall energy density of the systems they power, particularly when used in conjunction with energy dense materials (e.g., Li metal anodes and conversion cathodes). Additive manufacturing (AM), and specifically material extrusion (ME), have been shown as effective methods for producing custom-form cell components, particularly electrodes. However, the AM of several promising energy dense materials (conversion electrodes such as iron trifluoride) have yet to be demonstrated or optimized. Furthermore, the integration of multiple AM produced cell components, such as electrodes and separators, along with a custom package remains largely unexplored. In this work, iron trifluoride (FeF3) and ionogel (IG) separators are conformally printed using ME onto non-planar surfaces to enable the fabrication of custom-form Li-FeF3 batteries. To demonstrate printing on non-planar surfaces, cathodes and separators were deposited onto cylindrical rods using a 5-axis ME printer. ME printed FeF3 was shown to have performance commensurate with FeF3 cast using conventional means, both in coin cell and cylindrical rod formats, with capacities exceeding 700 mAh/g on the first cycle and ranging between 600 and 400 mAh/g over the next 50 cycles. Additionally, a ME process for printing polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) based IGs directly onto FeF3 is developed and enabled using an electrolyte exchange process. In coin cells, this process is shown to produce cells with similar capacity to cells built with Celgard separators out to 50 cycles, with the exception that cycling instabilities are observed during cycles 8–20. When using printed and exchanged IGs in a custom cylindrical cell package, 6 stable high-capacity cycles are achieved. Overall, this work demonstrates approaches for producing high-energy-density Li-FeF3 cells in coin and cylindrical rod formats, which are translatable to customized, arbitrary geometries compatible with ME printing and electrolyte exchange.