Channel Architecture Research Articles

Graphdiyne scaffold anchored highly dispersed ruthenium nanoparticles as an efficient cathode catalyst for rechargeable Li–CO2 battery

Lithium (Li)–CO2 battery is rising as an attractive energy-storage system with the competence of CO2 conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herein, a rational design on a highly catalytic Li–CO2 battery electrode built by graphdiyne powder as a multi-functional laminar scaffold with anchored highly dispersed Ru nanoparticles is explored. The strong interaction between the abundant acetylenic bond sites of graphdiyne scaffold and Ru nanoparticles can effectively promote the electrochemical progress and reduce the voltage polarization. The unique channels architecture of the cathodic catalyst with enough space not only accelerates CO2 diffusion and electrons/Li+ transport, but also allows a large amount of accommodation for discharged product (Li2CO3) to assure an advanced capacity. The corresponding Li–CO2 battery displays an advanced discharged capacity of 15,030 mAh/g at 500 mA/g, great capacity retention of 8873 mAh/g at 2 A/g, high coulombic efficiency of 97.6% at 500 mA/g and superior life span for 120 cycles with voltage gap of 1.67 V under a restricted capacity of 1000 mAh/g at 500 mA/g. Ex/in-situ studies prove that synergy between Ru nanoparticles and acetylene bonds of GDY can boost the round-trip CO2RR and CO2ER kinetics.

Cryo-EM structures of human Cx36/GJD2 neuronal gap junction channel

Connexin 36 (Cx36) is responsible for signal transmission in electrical synapses by forming interneuronal gap junctions. Despite the critical role of Cx36 in normal brain function, the molecular architecture of the Cx36 gap junction channel (GJC) is unknown. Here, we determine cryo-electron microscopy structures of Cx36 GJC at 2.2–3.6 Å resolutions, revealing a dynamic equilibrium between its closed and open states. In the closed state, channel pores are obstructed by lipids, while N-terminal helices (NTHs) are excluded from the pore. In the open state with pore-lining NTHs, the pore is more acidic than those in Cx26 and Cx46/50 GJCs, explaining its strong cation selectivity. The conformational change during channel opening also includes the α-to-π-helix transition of the first transmembrane helix, which weakens the protomer-protomer interaction. Our structural analyses provide high resolution information on the conformational flexibility of Cx36 GJC and suggest a potential role of lipids in the channel gating.

Cryo-EM structure of human heptameric pannexin 2 channel

Pannexin 2 (Panx2) is a large-pore ATP-permeable channel with critical roles in various physiological processes, such as the inflammatory response, energy production and apoptosis. Its dysfunction is related to numerous pathological conditions including ischemic brain injury, glioma and glioblastoma multiforme. However, the working mechanism of Panx2 remains unclear. Here, we present the cryo-electron microscopy structure of human Panx2 at a resolution of 3.4 Å. Panx2 structure assembles as a heptamer, forming an exceptionally wide channel pore across the transmembrane and intracellular domains, which is compatible with ATP permeation. Comparing Panx2 with Panx1 structures in different states reveals that the Panx2 structure corresponds to an open channel state. A ring of seven arginine residues located at the extracellular entrance forms the narrowest site of the channel, which serves as the critical molecular filter controlling the permeation of substrate molecules. This is further verified by molecular dynamics simulations and ATP release assays. Our studies reveal the architecture of the Panx2 channel and provide insights into the molecular mechanism of its channel gating.

Interface Engineering of "Clickable" Organic Electrochemical Transistors toward Biosensing Devices.

"Clickable" organic electrochemical transistors (OECTs) allow the reliable and straightforward functionalization of electronic devices through the well-known click chemistry toolbox. In this work, we study various aspects of the click chemistry-based interface engineering of "clickable" OECTs. First, different channel architectures are investigated, showing that PEDOT-N3 films can properly work as a channel of the transistors. Furthermore, the Cu(I)-catalyzed click reaction of ethynyl-ferrocene is studied under different reaction conditions, endowing the spatial control of the functionalization. The strain-promoted and catalyst-free cycloaddition of a dibenzocyclooctyne-derivatized poly-l-lysine (PLL-DBCO) is also performed on the OECTs and validated by a fiber optic (FO)-SPR setup. The further immobilization of an azido-modified HD22 aptamer yields OECT-based biosensors that are employed for the recognition of thrombin. Finally, their performance is evaluated against previously reported architectures, showing higher density of the immobilized HD22 aptamer, and originating similar KD values and higher maximum signal change upon analyte recognition.

State-dependent salt bridge interaction during activation in prokaryotic cyclic nucleotide-gated channel SthK.

The cyclic nucleotide-binding domain (CNBD) family of voltage-gated ion channels are complex molecular machines regulating membrane excitability in many cell types. While the protein structures of many CNBD channel family members have provided considerable insights into channel architecture, the mechanism of how cyclic nucleotide binding modulates channel opening is still unknown. The prokaryotic cyclic nucleotide-gated (CNG) channel, SthK, from Spirochaeta thermophila, has considerable structural and functional similarity to eukaryotic CNG channels. SthK can be readily expressed in E. coli spheroplasts and its response to ligand activation recorded with inside-out patch-clamp electrophysiology to test the functionality of various mutations. Using thermodynamic mutant cycle analysis, we have shown that there is a stabilizing interaction between arginine R125 at the end of the S4 voltage sensor helix and aspartate D261 in the B’ helix of the C-linker when the channel is in the presence of cyclic adenosine monophosphate (cAMP). Furthermore, when these residues (R125 and D261) were both mutated to cysteines, we were able to create a spontaneous disulfide bridge between these residues and lock the channel in the open, activated state, even in the absence of cAMP. These results indicate that we have identified an important state-dependent salt bridge between the C-linker domain and voltage sensor domain of this channel. Both charged residues are conserved in the eukaryotic CNGA1 channel structure, where it seems likely they play a similar role in state-dependent stabilization of the open state of these channels. Additionally, the aspartate residue is conserved across all CNG and HCN channels, further highlighting the potential significance of this C-linker residue. These new results help to better characterize the ligand-activated allosteric pathway in CNBD channels.

Kv1.3-dependent immune system activation is regulated by KCNE4.

Kv1.3 is a voltage-gated potassium channel that regulates leukocyte physiology. The association of Kv1.3 with the regulatory subunit KCNE4 fine-tunes the channel's activity. KCNE4 is a transmembrane protein that interacts with Kv1.3 through both of their cytoplasmic C-terminal ends. The protein regulates the membrane trafficking of the channel, affecting the magnitude of the currents and the C-type inactivation. Anomalies in Kv1.3 activity cause several autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, or multiple sclerosis. Therefore, the therapeutic relevance of Kv1.3 postulates KCNE4 as a potential modulator of the immune system physiology. In this study, we investigated the effect of KCNE4 on the activity of Kv1.3 in different leukocyte cell lines. We analyzed the expression of KCNE4 in a model of Jurkat T-lymphocytes and in CY15 dendritic antigen-presenting cells. Dendritic cells exhibit a high expression of the ancillary peptide. Manipulation of KCNE4 abundance affected the Kv1.3-dependent T cell physiology, having an impact on the channel's translocation to the immunological synapse (IS) and IL-2 production. In CY15 cells, activation with LPS increased the Kv1.3/KCNE4 ratio and the current density of the cells. The oligomeric Kv1.3-KCNE4 channel has a variable stoichiometry as demonstrated by single fluorescence bleaching steps. Each tetramer can bind up to four molecules of KCNE4, affecting plasma membrane trafficking and current density of Kv1.3 in a progressive manner. Contrarily, a single KCNE4 subunit was able to enhance the C-type inactivation of the channel. Our results prove that KCNE4 acts as a regulatory element in Kv1.3-dependent immune system physiology. Kv1.3 is differentially modulated by the KCNE4 availability influencing the Kv1.3/KCNE4 architecture of the oligomeric channel and its physiological function. Supported by the Ministerio de Ciencia e Innovación (MICINN/AEI), Spain (PID2020-112647RB-I00 and 10.13039/501100011033) and European Regional Development Fund (FEDER).

Architectural complexities and morphological variations of the indus fan and its elements: Understanding of the turbidite system through seismic characterization

The investigations of the processes occurring in submarine fans improve the understanding of intricacies of deepwater turbidity system and their associated developed architectural elements. The seismic patterns and depositional geometries of the channel levee complexes of the Indus fan have been studied using 2D/3D seismic and well data. The Indus fan is the second largest submarine fan in the world, with a horizontal extent of some 1500 km and a thickness of approx. 9 km. The development source of the Indus fan is divided into two units primarily based on their stratigraphic architecture and depositional characteristics. Firstly, the Eocene-Oligocene to Miocene lower unit that is built of channel lobes, and regionally developed large mass-transport deposits including megaturbidites. The other unit is Miocene and the Quaternary upper part that constitute major channel levee complexes with minor intercalations of locally developed mass transport deposits. The former progressively increase in thickness and width upwards the Eocene-Oligocene to Quaternary. This gave rise to symmetrical and asymmetrical growth patterns as a result of multiple phases of erosion and deposition. Such an architecture is present at an extensive scale primarily in the Plio-Pleistocene channels where the vertical to lateral growth ratio is higher than the channels. A single episode of thick MTDs is recognized by seismic reflection geometries suggesting sea level fluctuations that occurred between the Eocene-Oligocene and the Miocene, and from the Pliocene and the Quaternary channels. Regional confinements drastically affected the development of the Indus fan from the Eocene-Oligocene to Miocene, diminishing from the Pliocene-Quaternary. Sediment zonation occurred owing to the presence of structural confinements that controlled the growth of channel levee complexes and in general the entire Indus fan. Our results based on seismic reflection data of channel levee complexes suggest that increasing but alternating sediment supply from Eocene till Plio-Pleistocene, assisted the active channels and levee growth. Continuous increase in turbidity current size and energy along with sedimentation rates modified (i.e., increased the channel aspect ratio) the channel architecture of the Indus Fan.

Input-Reflectionless Quasi-Elliptic-Type Single- and Dual-Band Bandpass Filters Based on Passive Channelized Principles

An approach to design quasi-elliptic-type planar filters with single- and dual-band bandpass transfer functions and input-absorptive capabilities is presented. Two-branch channelized passive circuit configurations are exploited for this purpose, in which the low-order reflective-type filtering profile of their branches is converted into the desired sharp-rejection input-reflectionless filtering action in the overall circuit. This is achieved by means of fully-destructive and frequency-selective transversal signal-interference effects at the total input and output accesses of the channelized filter, respectively. The theoretical operational principles of the proposed concept of single/dual-passband input-reflectionless two-branch channelized filter are detailed, along with design considerations for their RF transmission-line-based implementation. Besides, its generalization to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {N}$ </tex-math></inline-formula> -channel architectures is also analyzed. Furthermore, as the fundamental elements of the devised channelized filtering philosophy to increase selectivity, alternative solutions to realize their output phase-delay sections for a more-flexible control of the transmission zeros in the overall transfer function are discussed. For experimental-demonstration purposes, two microstrip proof-of-concept prototypes are developed and measured. They consist of 3-GHz single-band and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.58/3.43$ </tex-math></inline-formula> -GHz dual-band designs with input-quasi-reflectionless spectral ratio above 2.5:1 and 3:1, respectively.

Beamforming Technologies for Ultra-Massive MIMO in Terahertz Communications

Terahertz (THz) communications with a frequency band 0.1-10 THz are envisioned as a promising solution to future high-speed wireless communication. Although with tens of gigahertz available bandwidth, THz signals suffer from severe free-spreading loss and molecular-absorption loss, which limit the wireless transmission distance. To compensate for the propagation loss, the ultra-massive multiple-input-multiple-output (UM-MIMO) can be applied to generate a high-gain directional beam by beamforming technologies. In this paper, a review of beamforming technologies for THz UM-MIMO systems is provided. Specifically, we first present the system model of THz UM-MIMO and identify its channel parameters and architecture types. Then, we illustrate the basic principles of beamforming via UM-MIMO and discuss the far-field and near-field assumptions in THz UM-MIMO. Moreover, an important beamforming strategy in THz band, i.e., beam training, is introduced wherein the beam training protocol and codebook design approaches are summarized. The intelligent-reflecting-surface (IRS)-assisted joint beamforming and multi-user beamforming in THz UM-MIMO systems are studied, respectively. The spatial-wideband effect and frequency-wideband effect in the THz beamforming are analyzed and the corresponding solutions are provided. Further, we present the corresponding fabrication techniques and illuminate the emerging applications benefiting from THz beamforming. Open challenges and future research directions on THz UM-MIMO systems are finally highlighted.

Broadband Connectivity for Handheld Devices via LEO Satellites: Is Distributed Massive MIMO the Answer?

Significant efforts are being made to integrate satellite and terrestrial networks into a unified wireless network. One major aspect of such an integration is the use of unified user terminals (UTs), which work for both networks and can switch seamlessly between them. However, supporting broadband connectivity for handheld UTs directly from low Earth orbit (LEO) satellite networks is very challenging due to link budget reasons. This paper proposes using distributed massive multiple-input multiple-output (DM-MIMO) techniques to improve the data rates of handheld devices with a view to supporting their broadband connectivity by exploiting the ultra-dense deployment of LEO satellites and high-speed inter-satellite links. In this regard, we discuss DM-MIMO-based satellite networks from different perspectives, including the channel model, network management, and architecture. In addition, we evaluate the performance of such networks theoretically by deriving closed-form expressions for spectral efficiency and using extensive simulations based on actual data from a Starlink constellation. The performance is compared with that of collocated massive MIMO connectivity (CMMC) and single-satellite connectivity (SSC) scenarios. The simulation results validate the analytical results and show the superior performance of DM-MIMO-based techniques compared to CMMC and SSC modes for improving the data rates of individual users.

Heat transfer of thin flat heat pipes with gradually varied vapor–liquid channels

The heat flow density is constantly increasing due to the growing demand for the integration and compaction of electronic devices. A sintered thin flat heat pipe (TFHP) is a typical device for managing the heat flux of highly integrated electronic circuits. Four different structures of the vapor–liquid flow channel architecture are designed in this work. Heat transfer performance tests of different TFHPs are carried out for different thermal powers. The surface temperature distribution and thermal resistance of the TFHP under different operating conditions are investigated. The experimental results show that the design of the vapor–liquid flow channel significantly impacts the TFHP’s heat transfer performance and that the wedge-shaped wick is better suited to the flow channel. The wedge-shaped wick has the lowest thermal resistance of 0.28 °C/W and the most elevated maximum thermal power of 22 W. The heat dispatch performance of the sintered wick TFHP is improved.

Three Different Interaction Patterns between MCM-41 and Proteins.

As one of the most studied mesoporous silica nanoparticles (MSNs) in drug delivery systems, Mobil Composition of Matter No. 41 (MCM-41) possesses unique properties including perfect channel architecture, excellent load capacity, and good biocompatibility. However, the applications of MCM-41 nanoparticles in drug delivery have not yet been industrialized, due to the interaction between MCM-41 and biomolecules (especially proteins) that affect their in vivo behaviors after dosing. To investigate the interactions between MCM-41 and proteins, this study selected bovine serum albumin (BSA), lysozyme (Lyso), and bovine hemoglobin (BHb) as model proteins and characterized the ultraviolet-visible, fluorescence, circular dichroism spectra and the protein adsorption of MCM-41-protein complex. The UV-Vis spectra exhibited the different absorption increment degrees of three proteins. The fluorescence spectra showed that the fluorescence intensity of proteins changed by different trends. The CD spectra indicated that the secondary structure changes were ranked as BSA &gt; Lyso &gt; BHb, which is consistent with the protein's adsorption capability on MCM-41. It was shown that there were three different patterns of MCM-41-proteins interactions. The hydrophilic and low-charged BSA followed the strong interaction pattern, the hydrophilic but heavily charged Lyso followed the moderate interaction pattern, and the hydrophobic BHb followed the weak interaction pattern. Different interaction patterns would lead to different effects on the structural properties of proteins, the surface chemistry of MCM-41, and the absorption capability of proteins on MCM-41. We believe our study will provide a better insight into the application of MCM-41 nanoparticles in drug delivery systems.

Disulfide bond and crosslinking analyses reveal inter-domain interactions that contribute to the rigidity of placental malaria VAR2CSA structure and formation of CSA binding channel

VAR2CSA, a multidomain Plasmodium falciparum protein, mediates the adherence of parasite-infected red blood cells to chondroitin 4-sulfate (C4S) in the placenta, contributing to placental malaria. Therefore, detailed understanding of VAR2CSA structure likely help developing strategies to treat placental malaria. The VAR2CSA ectodomain consists of an N-terminal segment (NTS), six Duffy binding-like (DBL) domains, and three interdomains (IDs) present in sequence NTS-DBL1x-ID1-DBL2x-ID2-DBL3x-DBL4ε-ID3-DBL5ε-DBL6ε. Recent electron microscopy studies showed that VAR2CSA is compactly organized into a globular structure containing C4S-binding channel, and that DBL5ε-DBL6ε arm is attached to the NTS-ID3 core structure. However, the structural elements involved in inter-domain interactions that stabilize the VAR2CSA structure remain largely not understood. Here, limited proteolysis and peptide mapping by mass spectrometry showed that VAR2CSA contains several inter-domain disulfide bonds that stabilize its compact structure. Chemical crosslinking-mass spectrometry showed that all IDs interact with DBL4ε; additionally, IDs interact with other DBL domains, demonstrating that IDs are the key structural scaffolds that shape the functional NTS-ID3 core. Ligand binding analysis suggested that NTS considerably restricts the C4S binding. Overall, our study revealed that inter-domain disulfide bonds and interactions between IDs and DBL domains contribute to the stability of VAR2CSA structural architecture and formation of C4S-binding channel.

Multi-Channel LSTM-Capsule Autoencoder Network for Anomaly Detection on Multivariate Data

Deep learning techniques have recently shown promise in the field of anomaly detection, providing a flexible and effective method of modelling systems in comparison to traditional statistical modelling and signal processing-based methods. However, there are a few issues that Neural Networks (NN)s face, such as generalisation ability, requiring large volumes of labelled data to train effectively, and understanding spatial context in data. This paper introduces a novel NN architecture to tackle these problems, which utilises a Long-Short-Term-Memory (LSTM) encoder and Capsule decoder in a multi-channel input Autoencoder architecture for use on multivariate time series data. Experimental results show that using Capsule decoders increases the resilience of the model to overfitting and improves training efficiency, which is shown by the improvement of Mean Squared Error (MSE) on unseen data from an average of 10.61 to 2.08 for single channel architectures, and 10.08 to 2.05 for multi-channel architectures. Additionally, results also show that the proposed model can learn multivariate data more consistently, and was not affected by outliers in the training data. The proposed architecture was also tested on an open-source benchmark, where it achieved state-of-the-art performance in outlier detection, and performs best overall with a total accuracy of 0.494 over the metrics tested.

Artificial Water Channels—Progress Innovations and Prospects

Artificial Water Channels—Progress Innovations and Prospects

Structural controls on the pathways and sedimentary architecture of submarine channels: New constraints from the Niger Delta

AbstractIn submarine settings, the growth of structurally influenced topography can play a decisive role in controlling the routing of sediments from shelf‐edge to deep water, and can determine depositional architectures and sediment characteristics. Here we use well‐constrained examples from the deep water Niger Delta, where gravity‐driven deformation has resulted in the development of a large fold and thrust belt, to illustrate how spatial and temporal variations in the rate of deformation have controlled the nature and locus of contrasting depositional styles. Published work in the study area using 3D seismic data has quantified the growth history of the thrust‐related folds at multiple locations using line‐length‐balancing, enabling cumulative strain for individual structures over time and along‐strike to be obtained. We integrate this information with seismic interpretation and facies analysis, focusing on the interval of maximum deformation (15 to 3.7 Ma), where maximum strain rates reached 7%/Ma. Within this interval, we observe a vertical change in depositional architecture where: (1) leveed‐confined and linear channels pass upward in to (2) ponded lobes with erosionally confined channels and finally (3) channelised sheets. Our analysis demonstrate that this change is tectonically induced and diachronous across the fault array, and we characterise the extent to which structural growth controls both the distribution and the architecture of the turbidite deposits in such settings. In particular, we show that leveed‐confined channels exist when they can exploit strain minima between growing faults or at their lateral tips. Conversely, as a result of fault linkage and increased strain rates submarine channels become erosional and may be forced to cross folds at their strain maxima (crests), where their pathways are influenced by across‐strike variations in shortening for individual structures. Our results enable us to propose new conceptual models of submarine channel deposition in structurally complex margins, and provide new insights into the magnitude of fault interaction needed to alter depositional style from leveed to erosionally confined channels, or to deflect seabed systems around growing structures.

Cover Feature: Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane (ChemElectroChem 20/2022)

Cover Feature: Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane (ChemElectroChem 20/2022)

Evolution of submarine channel morphology in intra-slope mini-basins: 3D-seismic interpretation from offshore Niger delta

The morphological characteristics of a submarine channel system, within buried intra-slope mini-basins in the offshore Niger Delta have been investigated on 3D seismic data. The studied submarine channel named Amaku Channel Levee System (ACLS) initiated after avulsion of a feeder channel called Amaku Major System (AMS). The ACLS runs across three folds (A, B, and C), related to mobile shale deformation, being underlain by mass transport complexes (MTCs), lobes, and levees. From three defined channel reaches (upper, middle, and lower reaches), we have used seismic facies description, channel architecture characterization and quantitative analyses to decipher the spatial and temporal evolution of the channel levee system. Our results reveal that the western channel margin was controlled by structural barriers associated with mobile shale deformation, while the eastern channel margin was influenced by depositional barriers linked to levees and mass transport complexes (MTCs). We argue that the depositional barriers are in some cases more efficient than the structural barriers in controlling channel pathways, since pre-channel sediments confine the channel elements and divert them against positive reliefs. Seismic observations show that channels migrate from folds to structural lows causing flow stripping processes. Downstream variations of morphological parameters (such as sinuosity, width, and levee width), indicate that pre-existing deposits prevented these basin-ward migrations, driving straightening and narrowing of the channel system. This study reveals that submarine channels can undergo dramatic morphological and stratigraphic changes in structurally complex areas because of the configuration of sidewall reliefs, which is controlled, in turn, by the interplay between structural deformation and pre-channel deposition.

Effects of fractal network channel on heat and mass transfer in methanol steam reforming

Hydrogen production by methanol steam reforming is one of the best choices for portable proton exchange membrane fuel cells (PEMFC). The channel is a dominant role in hydrogen production performance as the main reaction site. In this study, a fractal network channel architecture was designed and a three-dimensional (3D) numerical simulation was conducted in accordance with the Uniform Latin Hypercube design simulation scheme to explore the influence mechanism of branch grade (m), branch angle (θ), branch length ratio (α) and branch width ratio (β) on hydrogen production performance. Furthermore, four factors (m, θ, α, β) for the hydrogen production performance of fractal network channel were optimized by combining response surface method and non dominated sorting genetic algorithm II. The results showed that the hydrogen production performance is most sensitive to changes in β with the growth of the fractal network, followed by m, α, and θ. And the optimum parameter combination in terms of yield hydrogen is m of 3, θ of 134°, α of 0.88, and β of 0.85. The mechanism of the influence of fractal network structure parameters on the methanol reforming reaction as revealed in this study may provide a workable guideline for effective heat and mass transfer in new fractal reaction channel.

Flow Channel Architecture and Diffusion Characteristics of Nonenzymatic Electrochemical Glucose Fuel Cells with Proton Exchange Membrane

A nonenzymatic glucose fuel cell directly oxidizes glucose to gluconic acid as a Pt-based abiotic catalyst in a proton exchange membrane environment and has various advantages (e.g., biocompatibility, chemical stability, high ionic conductivity). We report the permeability of a less hydrophobic diffusion layer for three flow-field designs (serpentine, interdigitated, and parallel). In all cases, as the channel width of the flow path increases, the power density increases and the Ohmic resistance decreases. The serpentine shape (channel and rib widths: 1.5 and 0.5 mm, respectively) exhibits remarkable maximum power and current densities (cell voltage: 60 mV) of 103.4 μW cm -2 and 1,273 μA cm -2 compared to those of the parallel (46.5 μW cm -2 , 683 μA cm -2 ) and interdigitated (74.0 μW cm -2 , 878 μA cm -2 ) shapes, respectively. Furthermore, permeability and performance analyses according to the single-cell temperature, glucose concentration, and flow rate changes provide various perspectives on glucose fuel cells.