Bionic Structure Research Articles

Dragonfly-Inspired 3D Bionic Folding Grid Structure Design

Abstract: The method proposed in this paper provides a new research idea for biomimetic three-dimensional grid structure material design. The wings of a dragonfly exhibit a complex grid structure, comprising approximately 1–2% of its total weight, yet demonstrating exceptional mechanical efficiency. In order to investigate the feasibility of applying the design optimization method simulating this structure to the material structure design, we adopted a multi-step method to realize the formation of multi-scale grid structures and folds. Initially, the main vein of the front wing was simulated using a branching structure generation technique. Subsequently, a Voronoi grid was overlaid to generate the complete bionic grid structure. Finally, the fold structure of the wing was simulated using origami principles to create a three-dimensional grid structure. This method can obtain the rigid–flexible coupling 3D grid structure by simulating the 3D fold structure design of the dragonfly wing. The results show that the proposed method can obtain structural materials with excellent structural properties by simulating the structural characteristics of dragonfly wings.

Legged Robot with Tensegrity Feature Bionic Knee Joint.

Legged robots, designed to emulate human functions, have greatly influenced numerous sectors. However, the focus on continuously improving the joint motors and control systems of existing legged robots not only increases costs and complicates maintenance but also results in failure to accurately mimic the functionality of the human skeletal‒muscular system. This study introduces a bionic legged robot structure that leverages the tensegrity principle, drawing inspiration from the human leg's structural morphology and kinematic mechanisms. By designing a system that distinguishes between rolling and sliding movements, the human knee's variable instantaneous center of rotation (ICR), is successfully replicated showcasing its capabilities in achieving gait resemblance and vibration absorption. The tensegrity unit's features, including remarkable deformability, self-recovery, and the four-bar mechanism's singular position characteristic, alongside a rope unlocking mechanism reminiscent of human muscles, facilitate in situ compliance-rigid-compliance transitions of the knee joint without the need for knee joint motors, relying solely on ground contact through the foot. This innovation overcomes the conventional dependency of legged robots on joint motors, as the system requires only a single DC motor positioned at the hip joint and a straightforward control program to seamlessly execute a complete cycle of a single leg's movement.

Design and mechanical analysis of a novel modular bionic earthworm robot with upright functionality

With the escalating demand for exploration within confined spaces, bionic design methodologies have attracted considerable attention from researchers, primarily due to the intrinsic limitations of human access to hazardous environments. However, contemporary bionic robots primarily attain linear motion through the axial radial deformation of their body segments, thereby lacking the upright functionality that is characteristic of these organisms. In response to the limitations associated with current bionic earthworm robots concerning upright capability and stiffness modulation, we propose an innovative bionic robot that incorporates upright functionality and programmable stiffness. Initially, we present a bionic robot unit module that is capable of attaining an upright posture. A mechanical model is established in accordance with the principle of minimum potential energy to facilitate various compression and deflection functionalities. Through comprehensive simulation and experimental studies, we validate the model’s high precision in predicting compression and deformation behaviors. Furthermore, the effects of varying spring stiffness values (k) on device performance are systematically investigated, thereby enabling tailored stiffness adjustments for each module. This programmability empowers the robot to adapt to a broader spectrum of environmental demands. Ultimately, we construct a multi-module robot and successfully evaluate its upright functionality under diverse compression and deformation conditions. The proposed bionic structure, characterized by its enhanced ease of control and programmable stiffness, exhibits considerable potential for applications in complex and unstructured environments.

In-situ Polymerization Induced Seed-Root Anchoring Structure for Enhancing Stability and Efficiency in Perovskite Solar Modules.

The escape of organic cations over time from defective perovskite interface leads to non-stoichiometric terminals, significantly affecting the stability of perovskite solar cells (PSCs). How to stabilize the interface composition under environmental stress remains a grand challenge. To address this issue, we utilize thiol-functionalized particles as a "seed" and conduct in situ polymerization of 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA) as a "root" at the bottom of the perovskite layer. In this process, the thiol group acts as the initiation site for the polymerization of HFMA, while the fluorine groups in HFMA firmly anchor the organic cations of the perovskite through multiple hydrogen bonds. This strategy resembles how seeds take root in soil to prevent soil erosion. This bionic seed-rooting structure effectively stabilizes the stoichiometry of the perovskite, thus suppressing the escape of organic cations. As a result, the perovskite films with seed-rooting structures exhibit enhanced stability under harsh vacuum thermal conditions (150 °C, < 10 Pa). The resulting PCS achieves an efficiency of 25.64% and a 22.4 cm2 module efficiency of 22.61%. After 1300 hours of 1-sun illumination at 85% relative humidity and 65 °C (ISOS-L-3 protocol), the perovskite solar module maintains 90% of its initial efficiency.

The Tribological Reduction Mechanism of the Rubber Hexagonal Surface Texture of the Screw Pump Stator

This paper develops a composite weaving structure, combining hexagonal micro-bumps and hexagonal grooves, in the design of the rubber surface of the screw pump. This allows us to solve the problem of high torque and fast wear of the rubber stator during the operation of screw pump lifting oil recovery, based on the bionic hexagonal surface structure, traditional surface damping principle, and fluid dynamic pressure lubrication theory. Finite element analysis is first conducted to quantitatively analyze the impacts of the parallel side distance, groove width, and groove depth on the surface flow field and wall pressure field of the composite hexagonal structure. Based on the simulation law, the rubber surface laser structure is then designed and prepared by nanosecond laser processing. Afterward, tribological experiments are conducted under the condition of long-term immersion in the actual extraction fluid of shale oil wells. This aims at simulating the actual downhole oil production conditions and quantitatively studying the impact of the size of the composite hexagonal structure on the lubrication characteristics of the friction part of the stationary rotor, as well as the effect of abrasion reduction. The results show that, within the simulation range, the smaller the parallel side distance, the higher the load-carrying capacity. In addition, the hexagonal weave with a parallel side distance of 3 mm has a higher wall load carrying capacity than that with distances of 4 mm and 5 mm. When the groove width is equal to 0.4 mm, the oil film load carrying capacity is higher than that in the case of 0.2 mm. When the groove depth increases, the oil film pressure first increases and then stabilizes or decreases after reaching 0.3 mm. In the hexagonal weave, the friction ratio of the rotor is equal to 0.4 mm. In the tribological experiment of hexagonal weave, the smaller the parallel side distance, the smaller the friction coefficient, and the 0.5 mm weave has the highest performance.

Designing Bouligand‐inspired reinforcement for creating wood fiber‐reinforced composites with excellent bending properties

AbstractFiber‐reinforced composites with a bionic Bouligand structure are known for their excellent mechanical properties. Currently, most of the research in this field focuses on man‐made fibers, and research on natural unidirectional fiber materials is still limited. This paper designing Bouligand‐inspired reinforcement for creating wood fiber‐reinforced composites. We investigate the effects of the helix angle on the bending properties, impact resistance and extreme environments of the material through a combination of experimental methods, finite element analysis, and theoretical modeling. Morphological analysis using scanning electron microscopy (SEM) to further explore fracture mechanisms. The findings reveal that the load–displacement curves predicted by the finite element method closely align with the experimental results. The bionic composites demonstrate not only strong bending properties but also significant impact resistance. Notably, the highest bending strength, bending modulus, and impact strength were achieved at a small helix angle of 12.8°, reaching values of 184.66 MPa, 10.21 GPa and 28.03 kJ/m2. The bouligand structure is designed to withstand extreme environments. This research significantly expands the potential applications of the bionic Bouligand structure within the realm of wood fiber‐reinforced composites.Highlights Preparation of Bouloigand‐like composites utilizing wood. Helix stacking angle affects the performance of WFRCs. Finite element analysis was employed to predict the mechanical properties. “Green” composites exhibit exceptional mechanical properties. Expanding the application areas of wood fiber‐reinforced composites.

Oxalis-Inspired, Two-Stage Interlocking of Bionic Micro-Jigsaw Structure in Laser-Induced Graphene-Based Pressure Sensor

Oxalis-Inspired, Two-Stage Interlocking of Bionic Micro-Jigsaw Structure in Laser-Induced Graphene-Based Pressure Sensor

Unidirectional Polyvinylidene/Copper-Impregnated Nanohydroxyapatite Composite Membrane Prepared by Electrospinning with Piezoelectricity and Biocompatibility for Potential Ligament Repair.

Ligament tears can strongly influence an individual's daily life and ability to engage in physical activities. It is essential to develop artificial scaffolds for ligament repairs in order to effectively restore damaged ligaments. In this experiment, the objective was to evaluate fibrous membranes as scaffolds for ligament repair. These membranes were created through electrospinning using piezoelectric polyvinylidene fluoride (PVDF) composites, which contained 1 wt.% and 3 wt.% of copper-impregnated nanohydroxyapatite (Cu-nHA). The proposed electrospun membrane would feature an aligned fiber structure achieved through high-speed roller stretching, which mimics the properties of biomimetic ligaments. Nanoparticles of Cu-nHA had been composited into PVDF to enhance the pirzoelectric β-phase of the PVDF crystallines. The study assessed the physicochemical properties, antibacterial activity, and biocompatibility of the membranes in vitro. A microstructure analysis revealed that the composite membrane exhibited a bionic structure with aligned fibers resembling human ligaments. The piezoelectric performance of the experimental group containing 3 wt.% Cu-nHA was significantly improved to 25.02 ± 0.68 V/g·m-2 compared with that of the pure PVDF group at 18.98 ± 1.18 V/g·m-2. Further enhancement in piezoelectric performance by 31.8% was achieved by manipulating the semicrystalline structures. Antibacterial and cytotoxicity tests showed that the composite membrane inherited the antibacterial properties of Cu-nHA nanoparticles without causing cytotoxic reactions. Tensile tests revealed that the membrane's flexibility of strain was adequate for use as artificial scaffolds for ligaments. In particular, the mechanical properties of the two experimental groups containing Cu-nHA were significantly enhanced compared with those of the pure PVDF group. The favorable piezoelectric and flexible properties are highly beneficial for ligament tissue regeneration. This study successfully developed PVDF/Cu-nHA piezoelectric fibers for a biocompatible, unidirectional piezoelectric membrane with potential applications as ligament repair scaffolds.

Research on the influence of conical micro array chip parameters on fog water collection

Abstract Conducting research on water collection based on the bionic cactus conical spine structure holds significant importance for arid regions, the key parameters of conical micro array chip affecting the contact area between the micro cones and the fog determine the fog water collection. However, the influence of the conical arrays parameters including cone angle and arrangement on water collection is rarely studied. We present research on the influence of conical micro array chip parameters on fog water collection. The conical micro array chips with different parameters including the cone apex angle and arrangement pattern were designed, and the experiments of the fog water collection were conducted. The experiments explored the impact of arrangement patterns, cone apex angle, the distance and orientation of the conical micro array chip (CMAC) relative to the fog flow, and the surface properties (hydrophilic and hydrophobic) of the CMAC on fog water collection efficiency. Through these experiments, the law of influence of key parameters of the conical arrays on fog water collection efficiency was obtained. The experiments indicate the CMAC with large cone apex angle, hexagonal arrangement and hydrophilic surface has a better water collection efficiency . Further, this research can be beneficial to the advancement and application of water collection devices in arid environments.

Study on the Influence of Bionic Structure on the Sealing Performance of Centrifugal Pump Sealing Ring

In order to improve the sealing performance of a sealing ring in order to improve the efficiency of the centrifugal pump, based on the bionics principle, a calculation model for the bionic groove surface sealing ring structure of the centrifugal pump is established, based on the Realizable k-ε turbulence model. The external characteristics, internal flow field distribution and leakage characteristics of centrifugal pumps with different bionic groove surface structures and groove diameters are analyzed, and the influence of bionic surface structure on the sealing performance of the centrifugal pump sealing ring is studied. The results show that the bionic groove structure has a certain promoting effect on the external characteristics of the pump; a sealing ring with a circular groove structure can improve the efficiency, greatly reduce the leakage, and has better sealing performance, which are important influences on the performance and stability of the centrifugal pump. Among the three different diameters of the circular groove, the optimal groove diameter of the surface structure is 0.2 mm, where leakage is the least, volume efficiency is the largest, and sealing performance is the best.

Directed Inward Migration of S-Vacancy in Bi2S3 QDs for Selective Photocatalytic CO2 to CH3OH.

The directional migration of S-vacancy is beneficial to the separation of photogenerated carriers and the transition of electrons in semiconductors. In this study, Bix/Bi2-xSy@carboxylic-cellulose (CC) photocatalyst with bionic chloroplast structure is obtained by electron beam irradiation to induce S-vacancy in Bi2S3@CC. The results of CO2 photoreduction experiments demonstrate that the reduction rate of CO2 to CH3OH by Bix/Bi2‒xS2.89@CC-450 samples is 10.74 µmol·g-1·h-1, and the selectivity is 92.82%. The results show that the inward migration behavior of the borderline S-vacancy (b-Sv) induces the redistribution of electrons in Bix/Bi2-xSy@CC. The Bi° clusters in Bix/Bi2-xSy@CC is conducive to adsorb CO2, and the internal S-vacancy (i-Sv) is conducive to adsorb CH3OH, which accelerate the transfer of gas-phase products to realize the controllable conversion of CO2 and photoreduction products at the gas-liquid-solid three-phase interface. This study provides a new idea for the development and utilization of green photocatalysts in clean energy.

Transport of lithium droplets between two nonparallel iron plates: A molecular dynamics study

The use of bionic structures for the efficient and passive directional transportation of liquid droplets is crucial in numerous industrial applications. Compared with conventional fluids, liquid metals are stable under a wide range of environmental conditions owing to their excellent physicochemical properties. However, the directional transportation of liquid metals remains challenging. Herein, inspired by the pecking feeding mode of shorebirds, we performed a series of systematic molecular dynamics simulations to study the directional transport of liquid lithium (Li) between non-parallel iron (Fe) plates. The simulations demonstrate that cyclically closing and opening the Fe plates induces the movement of Li droplets toward the tip of the beak-shaped plate. Increasing the opening angle and applying a positive strain of the Fe plates can increase the transport velocity of the Li droplets. Nevertheless, the dissolution of Fe atoms in the liquid Li due to corrosion hinders the transportation of Li droplet across the Fe plate. We simulated the impact of two surface nanostructures on Li transport behavior and found that saw-tooth nanostructures decrease transport efficiency and lead to droplet breakup, whereas nanogrooves improve transport capacity by promoting the capillary effect. This work indicates that understanding the mechanism and influencing factors of liquid Li transport between non-parallel plates is essential for the design of bionic structures for the efficient transport of liquid metals.

Modeling and Control Experiments of a Fishtail-Like Pneumatic Soft Actuator

As the exploration of deep-sea resources continues, underwater actuators with conventional motors as the main building blocks can no longer meet the increasingly demanding needs. Inspired by bionics, researchers have started to work on underwater actuators with bionic structures. In this study, we designed and implemented a novel Fishtail-like Pneumatic Soft Actuator (FPSA). This innovative actuator configuration is inspired by the tail structure of Body and/or Caudal Fin (BCF) mode fish. The actuator's motion is achieved by controlling the expansion and contraction of the pneumatic soft muscles on both sides. And by constructing an experimental platform, we conducted an in-depth performance characterization, revealing the existence of a frequency-dependent nonlinear hysteresis characteristic of the FPSA. In order to accurately characterize this property, we built a dynamic model of the FPSA and successfully identified the uncertain parameters in the model by applying the nonlinear least squares method. The validation results show that the constructed model can accurately describe the nonlinear hysteresis characteristics of the FPSA. Finally, we successfully realized the high-precision trajectory tracking control of the endpoint of the FPSA using a PID controller. This result provides relevant ideas for the research of novel underwater bionic actuators.

Quasi-Static Mechanical Biomimetics Evaluation of Car Crash Dummy Skin.

Accurate replication of soft tissue properties is essential for the development of car crash test dummy skin to ensure the precision of biomechanical injury data. However, the intricacy of multi-layer soft tissue poses challenges in standardizing the development and testing of dummy skin materials to emulate soft tissue properties. This study presents a comprehensive testing and analysis of the compressive mechanical properties of both single and multi-layered soft tissues and car crash dummy skin materials, aiming to enhance the biofidelity of dummy skin. We presented one-term Ogden hyperelastic models and generalized Maxwell viscoelastic models for single-layer and multi-layer soft tissues, as well as dummy skin materials. The comparative analysis results indicate that the existing dummy skin material fails to fully consider the strain-rate-dependent characteristic of soft tissue. Furthermore, dummy skin materials exhibited ~3 times shorter relaxation times and ~2-3 times lower stress decay rates compared to soft tissues, suggesting a less viscous nature. This study provides an accurate representation of the mechanics of soft tissue and dummy skin under quasi-static compressive loading. The findings are instrumental for the development of novel bionic skin materials or structures to more precisely replicate the biomechanical properties of soft tissues, thereby enhancing the accuracy and reliability of car crash test dummies.

Design and Testing of a Bionic Seed Planter Furrow Opener for Gryllulus Jaws Based on the Discrete Element Method (DEM)

In addition to improving the efficacy of the furrow opener by ensuring consistent seeding depth, the gryllulus jaw geometry curve was integrated into the furrow opener. Soil particles were modeled using the DEM combined with the Hertz–Mindlin with JKR model, and simulation tests were conducted using the DEM corn stover model. Three geometric curves of gryllulus jaws were extracted. The effect of each curve and magnification on the manipulation results was clarified by the simulation test. Subsequently, field trials were conducted to evaluate the stability of the seeding depth of the bionic structure. The experiment showed that the No. 1 structure with a magnification of 1000 was the best, and the stability was 42.10% higher than that of the original structure. The results of this research can provide key structural and simulation parameters for the development of planter furrow openers with both efficient straw crushing and stable sowing depth functions, which is of great significance for the improvement of agricultural machinery.

Continuous Multi-Target Approaching Control of Hyper-Redundant Manipulators Based on Reinforcement Learning

Hyper-redundant manipulators based on bionic structures offer superior dexterity due to their large number of degrees of freedom (DOFs) and slim bodies. However, controlling these manipulators is challenging because of infinite inverse kinematic solutions. In this paper, we present a novel reinforcement learning-based control method for hyper-redundant manipulators, integrating path and configuration planning. First, we introduced a deep reinforcement learning-based control method for a multi-target approach, eliminating the need for complicated reward engineering. Then, we optimized the network structure and joint space target points sampling to implement precise control. Furthermore, we designed a variable-reset cycle technique for a continuous multi-target approach without resetting the manipulator, enabling it to complete end-effector trajectory tracking tasks. Finally, we verified the proposed control method in a dynamic simulation environment. The results demonstrate the effectiveness of our approach, achieving a success rate of 98.32% with a 134% improvement using the variable-reset cycle technique.

Design, Preparation, and Analysis of the Acoustic Performance of Waste Hemp/PLA Fiber Sound-Absorbing Composites with Different Bionic Structures

Noise pollution is becoming more and more serious, and the environmental friendliness of building materials could be better. To solve these problems, waste hemp fibers were used as reinforcement and polylactic acid (PLA) fibers as matrix. Sustainable biodegradable sound-absorbing composites with different bionic structures were prepared by carding and hot press molding process. The sound absorption properties of bionic structural composites with smooth surface,triangular wedge surface, trapezoidal prismatic surface, sinusoidal wave surface,cylindrical pit surface, and rectangular raised surface were tested. Composites were 30mm in thickness and 100mm in diameters.The bionic sound structure models was constructed according to the extracted bionic structure. The sound performance of the sound-absorbing composites was analyzed by finite element method simulation. The effects of bionic structure and sound characteristic parameters on the sound absorption performance of the composites were investigated and the sound absorption mechanism of the sound composites with bionic structures was revealed. Then the model of the cylindrical pit surface was used as a research object further to optimize the sound absorption performance. The results revealed that the optimized bionic structural composite materials had a sound absorption performance grade of II, with a sound absorption average (SAA) coefficient in the mid-frequency range of 27.16% higher than that of the smooth surface composites. The noise reduction coefficient was 0.603, and the SAA coefficient was 0.583.The results not only find a new way to recycle the waste hemp fibers, but also provide an experimental basis and theoretical basis for the optimization of sound absorption composites in building applications.

Research on a novel flexible bionic artificial anal sphincter.

Artificial anal sphincter is a novel method for the treatment of fecal incontinence. Aiming at the problems of complex mechanical structure, high mechanical failure rate, large volume and poor biocompatibility of existing artificial anal sphincters, this article proposes a novel flexible artificial anal sphincter with bionic structure. A novel flexible artificial anal sphincter was proposed with bionic structure by analogy with the puborectalis, flexible transmission by flexible tendons, good biocompatibility by using thermoplastic urethane and medical silicone, small size and lightweight. The interaction between the rectum and the artificial anal sphincter is simulated by the finite element analysis, and the changes of the anorectal angle and the stress during the traction process of the rectum are analyzed. The results suggest that the formed anorectal angle of <90° may effectively control defecation, so the effectiveness of the artificial anal sphincter is preliminarily verified. When the traction angle was 71° and the intestinal tube was basically closed, the maximum equivalent stress was 148.45 kPa, the maximum and minimum principal stress were 88.37 and 82.74 kPa, which were all below the safety pressure that initially verified the safety of the artificial anal sphincter. The novel flexible artificial anal sphincter may effectively reduce the stress between the device and the rectum and improve the biomechanical compatibility.

Numerical Analysis of Bionic Inlet Nozzle Effects on Squirrel-Cage Fan Flow Characteristics

In order to improve the inlet distortion of the squirrel-cage fan, this study proposes a parametric design method for the bionic structure of the inlet nozzle generatrix, which is spliced by multiple sinusoidal curves, based on the bionic structure of the humpback whale flipper leading-edge nodule. The geometric shape of the bionic generatrix is controlled by three parameters: the number of segments n, the amplitude ratio Tm, and the amplitude of the last curve An. These parameters are optimized through orthogonal tests and numerical simulations, with the aim of improving the fan’s aerodynamic efficiency. Based on the selected solution, a comparative analysis is conducted to examine the impact of cylindrical, conical, and bionic inlet nozzles on inlet distortion and flow evolution within the centrifugal fan. Numerical calculations demonstrate that the fan’s maximum total efficiency, with a bionic inlet nozzle designed in a rational manner, is 5.46% higher than that of the original fan and is 2.01% higher than that of the fan with a conical inlet nozzle. The proposed bionic structure can create a buffer zone at the fan’s inlet, thereby reducing the region of high vorticity caused by the separated flow. Consequently, this improvement leads to enhanced uniformity at the impeller’s inlet. Furthermore, the design method proposed in this study for the inlet nozzle’s bionic structure effectively regulates the airflow angle near the impeller shroud, thereby enhancing the fan’s inlet distortion and improving its overall aerodynamic performance.

Modular arborized fog harvesting device with coordinated mechanism of capture and transport

With global water scarcity a growing problem, fog harvesting technology has emerged as an effective solution. Industrial development and population growth have exacerbated the need for efficient, dismantlable, and assembled fog harvesting devices, as well as the requirement to optimize the droplet capture-transport relationship. In this study, a novel modular bionic 3D tree-like structure for fog harvesting system (3D-TSFHS) was developed to achieve rapid droplet transport by means of Nepenthes-inspired superslip leaves (SSLs). In addition, aluminum (Al) cones with superhydrophilic and superhydrophobic (SHL-SHB) patterns were prepared to enhance the droplet capture efficiency by drawing on the special wettability and structural features of various plants and animals such as cactus, spider silk, desert beetles, lizards and camphor leaves. This artificial design significantly enhances the overall capture and transport relationship. The resulting embedded superslip leaves Al cone fog harvesting (E-SLAC-FH) dramatically improves the fog harvesting efficiency and exhibits excellent durability. Assembling this fog harvesting into a 3D-TSFHS achieves a high fog harvesting efficiency of 0.462 g∙cm−2∙min−1. The system's modular design and its exceptional durability ensure its potential for a wide range of applications in a variety of real-world scenarios.