Serpentine Patterns Research Articles

A cross-cultural perspective on ornamental serpentine patterns along the Great Silk Road

This article explores the Silk Road, one of history’s most significant trade networks that bridged China and the West. The route fostered a vibrant cultural exchange, visible in the art and ornamental patterns that developed along its path. This study provides a cross-cultural perspective on ornamentation within the Great Steppe, particularly focusing on Kazakh baskur—a decorative band traditionally used in nomadic dwellings. Examining the symbolic and functional roles of baskur, the paper highlights both its artistic legacy and its broader cultural impact across the Silk Road region.

Analysis of Covarine Particle in Toothpaste Through Microfluidic Simulation, Experimental Validation, and Electrical Impedance Spectroscopy.

Covarine, copper phthalocyanine, a novel tooth whitening ingredient, has been incorporated into various toothpaste formulations using diverse technologies such as larger flakes, two-phase pastes, and microbeads. In this study, we investigated the behavior of covarine microbeads (200 μm) in Colgate advanced white toothpaste when mixed with artificial and real saliva. Our analysis utilized a custom-designed microfluidic mixer with 400 μm wide channels arranged in serpentine patterns, featuring a Y-shaped design for saliva and toothpaste flow. The mixer, fabricated using stereolithography 3D printing technology, incorporated a flexible transparent resin (Formlabs' Flexible 80A resin) and PMMA layers. COMSOL simulations were performed by utilizing parameters extracted from toothpaste and saliva datasheets, supplemented by laboratory measurements, to enhance simulation accuracy. Experimental assessments encompassing the behavior of covarine particles were conducted using an optical profilometer. Viscosity tests and electrical impedance spectroscopy employing recently developed all-carbon electrodes were employed to analyze different toothpaste dilutions. The integration of experimental data from microfluidic chips with computational simulations offers thorough insights into the interactions of covarine particles with saliva and the formation of microfilms on enamel surfaces.

Experimental study on the effect of new anode flow field designs on the performance of direct methanol fuel cells

Enhancing the performance of direct methanol fuel cells (DMFCs) through developing novel designs of anode flow field is significant. Thus, three new anode flow field designs (design-2, design-3, and design-4) are developed. The proposed designs combined all the advantages of serpentine, multi-zone, tapering and zigzag patterns into specific flow fields. In addition to reducing the path length of the bubbles, they accelerate their removal from the flow channels. To assess the cell’s performance, an experimental study was conducted to determine the effect of the new anode flow field designs along with methanol flowrates and methanol concentrations. Optical observations and electrochemical characterization methods are used to track the bubbles’ behavior and measure the power density of the new fabricated transparent DMFC. Experimental measurements indicate that the new flow fields significantly boost the cell’s performance at almost all operating conditions. A comparison between the output power of the new flow field designs and the reference serpentine design (design-1) showed that the new flow field designs attained a percentage enhancement of the maximum peak power density of 133%, 75% and 103%, by design-2, −3 and −4, respectively. The highest limiting current density and peak power density achieved by the new designs were 566.5mA/cm2 and 56.25mW/cm2, respectively compared with the 257.25mA/cm2 and 24.18mW/cm2 of the reference design. Moreover, a general trend indicates that a 3.0mol/L concentration performed the highest followed by 2.0mol/L and finally, 1.0mol/L. However, a lower methanol flowrate performed better than higher flowrate in the order of 2,5 and 8mL/min. The new designs are also able to evacuate the CO2 gas bubbles better than the reference design. The present findings encourage the fuel cell designers to critically think about enhancing the fuel cell performance via developing new flow field designs.

Characteristics of different flow patterns for proton exchange membrane water electrolysis with circular geometry

This study comprehensively analyzes five circular-shaped flow field configurations (one-path, two-path, two-channel, two-segment, and four-segment serpentine), using membrane electrode assembly (MEA) area of 38.5 cm2. Here, it aims to identify the optimal pattern in terms of velocity, pressure, liquid saturation, temperature, and current density distribution. Further, a comparison is conducted between the uniformity index, polarization curves, and average membrane temperature curves of various cases. Using a finite element method, a three-dimensional, non-isothermal, two-phase model is developed based on the conservation equations of mass, momentum, electric charge, energy, and species. To confirm modelling reliability, the numerical results have been validated and demonstrated a strong match with the experimental data. Findings indicate that the one-path, followed by the two-path serpentine pattern, yield the most favorable flow distribution and temperature uniformity within the PEMWE. Conversely, the four-segment serpentine flow pattern results in the least desirable outcomes. At a cell voltage of 2.1 V, the uniformity index of liquid saturation, temperature and current density and average membrane temperature for one-path and two-path serpentine patterns exhibit reductions of 70 and 29 %, 95.5 and 95.2 %, 33 and 31 %, and 9.1 and 6 K, respectively, compared to four-segment serpentine design. Moreover, the four-segment, two-segment, and two-path serpentine flow patterns exhibit optimal performance in terms of polarization curves.

Modular design of curved beam-based recyclable architected materials

Advances in manufacturing technologies have enabled architected materials with unprecedented properties. These materials are typically irreversibly designed and fabricated with characteristic geometries and specific mechanical properties, thus rendering them suitable for pre-specified requests. However, these materials cannot be recycled or reconstructed into different shapes and functionalities to economically adapt to various environments. Hence, we present a modular design strategy to create a category of recyclable architected materials comprising elastic initially curved beams and rigid cylindrical magnets. Based on numerical analyses and physical prototypes, we introduce an arc-serpentine curved beam (ASCB) and systematically investigate its mechanical properties. Subsequently, we develop two sets of hierarchical modules for the ASCB, thus expanding the constructable shape of architected materials from regular cuboids to complex curved surfaces. Furthermore, we demonstrate that the magnets attached to the centers of specific serpentine patterns of the modules allows the effective in-situ recycling of the designed materials, including sheet materials for non-damage storage, bulk materials for tunable stiffness, and protective package boxes for reshaping into decorative lampshades. We expect our approach to improve the flexibility of architected materials for multifunctional implementation in resource-limited scenarios.

Fabrication of Graphene Optical Devices for Endoscope Calibration

Endoscopic devices used in the clinical examination of pathologies such as glottic tumors can record real-time images of the vocal cords during vibration. Quantitative analysis of the glottic surface requires the metric system to obtain the absolute dimensions of the larynx in a series of acquired images. However, so far, there is no effectively automated and stable calibration method for clinical use. Therefore, most metrics used by professionals are invasive and subjective. Thus, this study reports the microfabrication of a diffractive optical element (DOE) that could potentially quantify cancer cells from the glottic surface of patients. It has been observed that the image of the glottis seen through an endoscope is shaped by its geometric properties and by the shading of color and brightness. Therefore, tumor location and size can be quantified by overlaying the DOE metric with light spots on images that include the glottic region. DOE was developed from processes used in the fabrication of integrated circuits and MEMS, already quite mature. To obtain high-quality images from optical reconstruction of the glottis, the use of graphene monolayers grown by chemical vapor deposition (CVD) on copper (Cu) foil was investigated. This was transferred to a glass substrate by wet method (Fishing method) and the etching steps of the Cu substrate were carried out. In this method, polymethylmethacrylate (PMMA) was used as the supporting polymer through the spinner. Two lithographs were made under the glass substrate with different approaches (using a Karl Suss MJB3 mask aligner system with a maximum resolution of 1 µm). The first, which preceded the thin-film transfer, aimed to delineate the graphene transfer area using an aluminum (Al) deposition technique by sputtering. The second lithography, linked to oxygen Ashing plasma corrosion, made it possible to study the modulation of a microrelief containing parallel and serpentine patterns, of amplitude and phase, spaced from 1 to 10 μm. An optical system containing an EOD and a Fourier lens was attached to the endoscope end to project a laser line parallel to the vocal cords. Image processing methods automatically identify pixels in the image data that belong to the projected laser line. Thus, the detection of the diffractive pattern was based on segmentation of endoscopic images centered on Sobel filtering and on the method with active boundary regions of the watershed. These use successively robust temporal and spatial characteristics of the laser lines projected onto the endoscopic image sequence. In short, the combination of laser projection device and image processing allows calibration of endoscopic images and can provide quantitative metric data for tumors on the surface of the vocal cords. Therefore, the proposed calibration method can be considered a powerful tool to aid in the prognosis of laryngeal pathologies. Figure 1

Spatiotemporal pattern of periodic rhythms in delayed Van der Pol oscillators for the CPG-based locomotion of snake-like robot

This is the further research on the delayed half-center oscillator (DHCO) neural system presented in our previous paper (Song and Xu in Nonlinear Dyn 108:2595–2609, 2022. https://doi.org/10.1007/s11071-022-07222-y). The DHCO is used to construct a CPG (central pattern generator) neural system to control locomotion of a snake-like robot with pitch-yaw connecting configuration. To this end, we firstly give an improved model of the VDP (Van der Pol) oscillator. Employing mutually coupled delay, a pair of VDP oscillator is connected to produce an half-center oscillator (HCO) module with time delay that is called as a DHCO (delayed HCO) model. Based on the analysis of the Hopf bifurcation, periodic rhythm and their spatiotemporal patterns of the DHCO are illustrated in the different regions of parameters. The DHCO presents periodic rhythms with synchronous and anti-synchronous patterns, which is to control joint actuators combined in snake-like robot with pitch-yaw connecting configuration. To realize a backward propulsive wave to promote snake-like robotic locomotion, based on the DHCOs, we construct a chain type of the CPG neural system combined with a new unidirectional delay in which phase difference can be regulated. Numerical simulations are illustrated that the CPG neural system can control snake-like robot to move with serpentine, rectilinear, and side-winding patterns in the forward and backward directions. The results show that the snake-like robot can be controlled in expected locomotion patterns for a region but not a fixed value of the controlling parameters. Further, the corresponding regions of the parameters are obtained by using theoretical dynamical analysis but not a trial-and-error method. The snake-like robot gets smooth and stable gait transition with parameter changing.

Additive ram material extrusion and diddling of fully compounded thermoset nitrile rubber

AbstractA ram extruder is described for high‐pressure extrusion of fully compounded thermoset rubber to achieve additive manufacturing. The extruder uses a piston driven by a geared stepper motor to provide volumetric displacement of the rubber charge residing in a temperature‐controlled barrel. Along with activators, accelerators, and a vulcanizing agent, the rubber compound is a formulation of 30 parts carbon black per hundred parts nitrile rubber. Sets of serpentine patterns are printed in parallel and transverse orientations relative to the load direction. From printing to post‐cure, the printed specimens exhibited linear shrinkage of 65% in the print direction. Although printed samples had relatively low void content compared with typical additively manufactured parts by material extrusion, significant decreases in the tensile properties were observed relative to compression‐molded specimens of the same rubber compound. The mean strain to failure was observed as 462% for compression‐molded samples, compared with 347% and 183% for printed specimens with parallel and transverse orientations. To reduce the shrinkage and increase the interfacial area between extruded roads, backstitch and sinewave diddling patterns were implemented to superimpose oscillatory motions along the print path with a periodicity of 1 mm. The specimens printed with the diddling patterns were observed to provide less shrinkage and improved properties compared to the regular serpentine patterns. The mean strain to failure in the transverse orientation, respectively, increased to 218% and 265% for the backstitch and sinewave patterns. Suggested future research is discussed, and the diddling program is provided in the appendix.

Definition of CVD Graphene Micro Ribbons with Lithography and Oxygen Plasma Ashing

This work presents the definition of CVD (Chemical Vapor Deposition) Graphene Micro Ribbons (GMRs) with traditional Photolithography and Oxygen Plasma Ashing, where: (i) CVD Graphene Micro Ribbons were defined in parallel and serpentine patterns; (ii) The defined width dimensions of GMRs are between 0.23 µm and 10 µm; (iii) The empirical calibration curve between physical and mask widths of GMRs was obtained; (iv) With our method, Graphene Field-Effect Transistors, GFETs, can be fabricated with parallel GMRs as conduction channel between source and drain. It is important to notice that parallel channels are used in Silicon Nano Wires 3D Transistors, such as FinFETs. Our method is based on low-cost lithography, compared to commonly found in the literature, based on the definition of graphene patterns by Electron Beam Lithography (high cost and low repeatability techniques). Also, graphene's good quality characteristics remain after GMRs fabrication, as proven by Raman spectroscopy. In conclusion, our method to define the GMRs is suitable for GFET technology.

Unveiling water drainage through microporous layer with laser-ablated open furrows in proton exchange membrane fuel cells

The microporous layer (MPL) in proton exchange membrane fuel cells (PEMFCs) improves the fuel cell performance remarkably. However, PEMFCs suffer from local oxygen starvation at high current densities because of the accumulation of water at the cathode. This paper presents a novel water management technique that uses open furrows with serpentine patterns in the MPL. The laser ablation technique is used to carve open furrows in the MPL, and the various properties of the furrowed MPL are characterized. To examine the effects of the furrowed MPL on water management, the polarization behavior, impedance response, and potential variation under dynamic load tests are studied experimentally and theoretically for PEMFCs with three different gas diffusion layers. The results indicate that open furrows in the MPL reduce the water saturation in the catalyst layer and increase the water discharge to the gas flow channel, thereby promoting oxygen transport to the catalyst sites.

Vertically Aligned 2D MoS2 Layers with Strain-Engineered Serpentine Patterns for High-Performance Stretchable Gas Sensors: Experimental and Theoretical Demonstration.

Two-dimensional (2D) molybdenum disulfide (MoS2) with vertically aligned (VA) layers exhibits significantly enriched surface-exposed edge sites with an abundance of dangling bonds owing to its intrinsic crystallographic anisotropy. Such structural variation renders the material with exceptionally high chemical reactivity and chemisorption ability, making it particularly attractive for high-performance electrochemical sensing. This superior property can be further promoted as far as it is integrated on mechanically stretchable substrates well retaining its surface-exposed defective edges, projecting opportunities for a wide range of applications utilizing its structural uniqueness and mechanical flexibility. In this work, we explored VA-2D MoS2 layers configured in laterally stretchable forms for multifunctional nitrogen dioxide (NO2) gas sensors. Large-area (>cm2) VA-2D MoS2 layers grown by a chemical vapor deposition (CVD) method were directly integrated onto a variety of flexible substrates with serpentine patterns judiciously designed to accommodate a large degree of tensile strain. These uniquely structured VA-2D MoS2 layers were demonstrated to be highly sensitive to NO2 gas of controlled concentration preserving their intrinsic structural and chemical integrity, e.g., significant current response ratios of ∼160-380% upon the introduction of NO2 at a level of 5-30 ppm. Remarkably, they exhibited such a high sensitivity even under lateral stretching up to 40% strain, significantly outperforming previously reported 2D MoS2 layer-based NO2 gas sensors of any structural forms. Underlying principles for the experimentally observed superiority were theoretically unveiled by density functional theory (DFT) calculation and finite element method (FEM) analysis. The intrinsic high sensitivity and large stretchability of VA-2D MoS2 layers confirmed in this study are believed to be applicable in sensing diverse gas species, greatly broadening their versatility in stretchable and wearable technologies.

3D-Printed Strain Sensors: Electro-Mechanical Simulation and Design Analysis Using Nonlinear Material Model and Experimental Investigation

This work is driven by the continuous improvement in additive manufacturing and the growing interest in developing flexible strain sensors with complex designs and structures. Characterization and analysis require not only understanding the mechanical behavior of the sensor but also the electrical behavior and the coupled electromechanical behavior. Traditionally, this coupled electromechanical behavior is determined using simplified approaches to establish a relationship between the electrical domain and mechanical domain. This work presents an experimental and numerical platform to characterize strain sensors and serves as a tool for design guidelines for these sensors. A nonlinear finite element COMSOL model is developed and validated against experiment. At 38% strain level the sensitivity is increased by 7% when the thickness,t, of the sensor decreased from t = 1.4 mm to t = 0.6 mm. A sensor with triangular embedded channels exhibits improved performance compared to square, hexagonal, and octagonal cross-sectional shapes. Three common channel patterns are examined including spiral, vertical serpentine, and horizontal serpentine patterns. Three commonly used materials for fabricating strain sensors are investigated including PDMS, EcoFlex, and NinjaFlex. At 35% strain level, a sensor with NinjaFlex substrate exhibits, approximately, 6% improvement in sensitivity, compared to a sensor with EcoFlex substrate.

Fiber Lithography: A Facile Lithography Platform Based on Electromagnetic Phase Modulation Using a Highly Birefringent Electrospun Fiber.

Lithography plays a key role in advancing manufacturing as well as the semiconductor industry. However, the currently available state-of-the-art lithography methods still require access to expensive tools and facilities. Herein, we suggest a novel lithography method based on electromagnetic phase modulation of ultraviolet using a highly birefringent electrospun fiber to overcome such limitations. The optical birefringent effect, by which the phase of incident ultraviolet electromagnetic fields is retarded when passing through optically anisotropic media, is combined with semicrystalline poly(ethylene oxide) (PEO)-poly(ethylene glycol) (PEG) polymeric microfibers patterned in a programmable form using near-field electrospinning. By positioning the mask between two linear polarizers that are perpendicular to each other, only the UV waves that are passing through the fibers can be selectively utilized to exhibit lithographic property. Therefore, the UV intensity on the photoresist (PR) surface follows the shape of the fiber pattern, enabling precisely controlled patterning of the photoresist. Zero- to two-dimensional key features of lithography are achieved, including straight, curved, array, and isolated patterns. Facile optical alignments without using dedicated alignment marks are successfully demonstrated, as well as various applications including micro- to macroscale serpentine, tree, and antenna circuit patterns on a flexible substrate. The presented approach, packed in a table-top scale, is expected to provide a practical and affordable lithography solution by leveraging the direct-writing capability and tunable optical functionality of polymers, scalability, and the simple optical alignment method.

Information hiding in geometric patterns and its application to fabric authentication

Geometric patterns have been used since ancient times as a means of decoration in art and architecture, with distinctive styles demonstrated in Islamic and Japanese cultures. They are now also being used as communication media, allowing information embedded in the pattern to be imparted in applications such as barcodes. By combining simple graphical tiles into geometric patterns, Professor Hiroshi Ito, from Nihon University in Japan, believes that the interesting structure of such patterns may make them less obstructive when printed onto materials, therefore making them easier to use in broader applications. Ito's focus lies in information binding to geometric patterns that encompass results for patterns known as dragon curves as well as Penrose tiling. This builds on his previous work using serpentine patterns, which involves manipulating two cells to create repetitive patterns reminiscent of the undulation of a snake. In this latest study, Ito and his colleagues consider the use of these patterns combined with a filter for use in applications such as document authentication.

Soft Materials, Stretchable Mechanics, and Optimized Designs for Body-Wearable Compliant Antennas.

Among the various methods to develop flexible wearable antennas, a serpentine, mesh structure has been a great interest because of its mechanical reliability upon applied strain. However, there is still a significant lack of design guidelines for the open-mesh concept that account for both material and electromagnetic (EM) properties of antennas. In this work, we introduce a comprehensive study of materials, mechanics, fabrication, and system integration for the development of stretchable dipole and patch antennas that have networks of two-dimensional serpentine patterns. A set of computational modeling and experimental validation of open-mesh structures provides the key design guidelines to offer the maximum mechanical stretchability and minimum effective moduli of wearable antennas. Integration of the thin-film antenna traces with various substrates captures the versatility of the deterministic fabrication and material transfer printing methods. The influence of antenna stretching on the EM properties, including return loss, electric and magnetic fields, and far-field radiation patterns, is investigated. EM characterization with mechanical stretching results in different properties of fabricated antennas. The simulation study of specific absorption rates shows a potential for safe applications of dipole and patch stretchable antennas on the human skin.

Serpentine-pattern effects on the biaxial stretching of percolative graphene nanoflake films

Stretchable strain sensors based on percolative arrangements of conducting nanoparticles are essential tools in stretchable electronics and have achieved outstanding performance. Introducing serpentine patterns for strain-sensing materials is a very effective method for enhancing stretchability with a quantified structural resistance through a simple, reliable, and facile approach. Here, we investigate serpentine-pattern effects in the electrical responses to biaxial stretching for percolative graphene-nanoparticle films. Graphene nanoplatelet films are applied to a stretchable substrate using a facile spray-coating technique, for a variety of serpentine pattern shapes, aspect ratios, pattern frequencies, and number of coatings. The electrical responses after applying biaxial stretching (x-axis and y-axis) are measured and analyzed for comparison. The serpentine patterns that would be suitable for stretchable electrodes, sensitive sensors, and highly stretchable sensors are then identified. This work demonstrates the advantage of using serpentine patterns for stretchable strain sensors and offers guidelines for selecting suitable pattern types for strain sensors in stretchable-electronics applications.

Integrated manufacture of polymer and conductive tracks for real-world applications

The present study demonstrates for the first time a unique UK-designed and built Additive Manufacturing (AM) hybrid system that combines polymer based structural deposition with digital deposition of electrically conductive elements. This innovative manufacturing system is based on a multi-planar build approach to improve on many of the limitations associated with AM, such as poor surface finish, low geometric tolerance and poor robustness. Specifically, the approach involves a multi-planar Material Extrusion (ME) process in which separated build stations with up to 5 axes of motion replace traditional horizontally-sliced layer modelling. The construction of multi-material architectures also involved using multiple print systems in order to combine both ME and digital deposition of conductive material. To demonstrate multi-material 3D Printing (3DP) we used three thermoplastics to print specimens, on top of which a unique Ag nano-particulate ink was printed using a non-contact jetting process, during which drop characteristics such as shape, velocity, and volume were assessed using a bespoke drop watching system. Electrical analysis of printed conductive tracks on polymer surfaces was performed during mechanical testing (static tensile and flexural testing and dynamic fatigue testing) to assess robustness of the printed circuits. Both serpentine and straight line patterns were used in the testing of Ag particle loaded ink and they showed very similar resistance changes during mechanical exposure. Monitored resistance and stress changed as a function of strain exhibiting hysteresis with more prominent residual strain during stretching and compression cycles and 3-point bending flexural tests of PA and CoPA substrates. Bare and encapsulated tracks exhibited low electrical resistivity (1–3*10−6 Ω*m), and its change was more rapid on ABS and minor on PA and CoPA when increasing tensile and flexural strain up to 1.2% and 0.8%, respectively. Resistance of Ag tracks on ABS also increased rapidly during fatigue testing and the tracks easily fractured during repeated stretching-compression cycles at 1% and 1.2% strain. No resistance changes of Ag tracks printed on PA and CoPA were observed at lower strain amplitudes whereas at higher strain amplitudes these changes were the lowest for conductive tracks on CoPA. Thermal analyses were conducted to determine the printed material’s glass transition temperature (Tg), stability and degradation behavior to find the optimum annealing conditions post printing. The novel AM printer has the ability to fabricate fully functional objects in one build, including integrated printed circuitry and embedded electronics. It enables product designers and manufactures to produce functional saleable electronic products. This new technology also gives the opportunity for designers to improve existing products, as well as create new products with the added advantages of geometrically unconstrained 3DP.

PEM Electrolyzer Characterization and Limitations When Using Carbon-Based Hardware and Material Sets

In contradiction to the more established research field of proton exchange membrane fuel cells (PEMFCs), the research and development field for proton exchange membrane water electrolysis (PEMWE) is an upcoming and growing area. Over the past decades, a specific fuel cell research hardware configuration has been widely accepted for material development work that requires typical performance and durability tests on subscale cells. This hardware consists of thick endplates often made of aluminum, gold plated copper current collectors that are insulated with a sheet material from the endplate and graphite flow-fields that contain the flow channel structure. The latter may be machined in many designs ranging from single to multiple serpentine or parallel flow patterns. In contrast to the fuel cell field, the electrolysis research field does not yet have established material sets. Operating conditions are harsher than in a fuel cell system, since the potentials required for the oxygen evolution reaction are significantly higher. In commercial water electrolysis systems this is compensated by typically using titanium material sets that are often protected against oxidation through coating processes. Such material choices make small scale research hardware and porous transport layers expensive and very difficult to source. In this work, we show that the stability of traditional carbon-based fuel cell materials is sufficient for electrolyzer initial performance characterization procedures such as cell conditioning, a limited number of polarization curve measurements, and electrochemical impedance spectroscopy. We identify and quantify the onset of carbon degradation and define a strategy that allows the utilization of standard fuel cell hardware for specific PEMWE experiments. With knowledge that existing fuel cell materials can be applied in electrolyzer research by acknowledging the associated limitations, fuel cell research hardware and experience can be more readily transferred to the younger and rapidly growing electrolyzer research field.

Folding Approaches for Tensioned Precision Planar Shell Structures

An origami-based engineering approach is applied to the folding design of tensioned precision space structures. Tension is a viable means of stiffening a flat antenna aperture, especially when stowed volume is paramount. Three folding patterns are described, and the design guidelines are developed. Deployment kinematics follow the simplicity of a single-degree-of-freedom mechanism for two of the three patterns. The panels are rigid, and articulations occur along the prescribed lines. These deployment architectures are compatible with storable tubular extendible member booms, articulated trusses, or continuous longeron coilable trusses, all commonly used to deploy spacecraft structures. High areal packaging densities were demonstrated: for a diamond pattern with a high deployed aspect ratio and for spiral and serpentine patterns compatible with high and low deployed aspect ratios. A double-layer material hinge method is also presented and used to enable the structures to fold, deploy, and be tensioned to a planar state.

Performance of electrochemical cell with various flow channels for Bunsen reaction in the sulfur–iodine hydrogen production process

Renewable hydrogen production through sulfur–iodine (SI) cycle is energy efficient and environmentally friendly. Electrochemical cell (EC) has recently been proposed to carry out the Bunsen reaction in the cycle. Existing studies on the EC are limited only to time-consuming experiments whereas cell performance with respect to flow channel is very few. In this study, numerical study is conducted for determining the impact of flow channel on the EC performance of electrochemical Bunsen reaction. Five different configurations of flow channel are physically modelled. A three dimensional, steady state and laminar flow through EC is simulated by solving the governing equations, and show good agreement with experimental data at low current density. It is found that the flow field, local current and potential of serpentine, straight parallel and spiral tubular flow channels distribute almost uniformly, except the significant vortex regions and high resistance at the square bends of straight parallel channel due to the sudden geometric changes. The flow maldistribution in Z-type and U-type parallel flow channels makes them unsuitable for EC. The straight parallel flow channel is found to be optimal due to its low pressure drop as well as low electric power input, followed by serpentine and spiral tubular patterns. The simulation concerning flow channels design favors improving EC performance and the thermal efficiency of SI cycle.