The paper revealed the fine structure of the scorpion (Mesobuthus martensii) pectines and showed how the fine structure of the pecten influences odor flow. The first step of our investigation was to prove that scorpion pectines work as olfactory and this was done via experiments utilizing paraffin coverage. Subsequently, the location, morphology, section structure, and arrange-ment of the pectines were studied via stereomicroscopy and Scanning Electron Microscopy (SEM). The fine structure of pecten comprises a comb-like structure with 24-30 knife-like teeth and thousands of micron bowl-like pecten sensilla in staggered arrangement on the surface of the tooth. Computational Fluid Dynamics (CFD) was applied to predict odor flow around the pecten via the relevant Reynolds numbers. The comb-like structure amplified the odor flow velocity similar to an amplifier, transporting the odor flow of increased velocity to the micron pecten sensilla, improving transport efficiency of the odor flow. The staggered arrangement of the pecten sensilla generated a vortex, improving contact duration between pecten sensilla and odorant molecules. Thus, the pecten fine structure was likely acting as an effective comb with non-smooth teeth for the transport and capture of odorant molecules.

In this study, we investigated the dynamic functions of the tip region of the butterfly proboscis through which liquid is sucked during liquid feeding. The microstructures and flow patterns in the tip region of the proboscis were in vivo analyzed. The tip region can be divided into two functional sections: namely adhesion and suction sections. The liquid adheres to the adhesion section during liquid suction. Although the tip region has numerous slits connected to food canal of the proboscis, liquid is mainly sucked through the suction section, which section is submerged in the fluid pulled by the adhesion section and then successfully imbibes liquid. To check the dynamic functions of the tip region, we fabricated a suction tip model having adhesion and suction parts. The in vitro model experiments show that the hydrophilicity of the adhesion part and the existence of the suction inlet improve the liquid uptake driven by a suction pump. This study may provide insights for the biomimetic design of nectar-feeding butterflies.

Many biological structures can perform highly-dexterous actions by using dynamic surfaces. To deal with the contradictive demands of high feeding efficiency and low energy expenditure during nectar feeding, the glossal surface of a honeybee un-dergoes shape changes, in which glossal hairs erect together with segment elongation in a drinking cycle. In this paper, we extracted a transmission link embedded in the glossa from postmortem examination and found that the compliance of the in-tersegmental membranes provides more possibilities for this highly kinematic synchronicity. According to the morphing phe-nomena of honeybee’s glossa, we proposed a compliant mechanism model to predict the deformation behavior of honeybee considering elastic properties of the glossal intersegmental membranes. The increase of membrane stiffness may improve the capacity of elastic potential energy transfer, but will still result in the increase of mass. An index is introduced to evaluate the contradiction for optimizing structural parameters. This work may arouse new prospects for conceptual design of mi-cro-mechanical systems equipped with bio-inspired compliant mechanisms.

The unique photo-thermal energy conversion property of polar bear hairs has long been regarded as an essential element to enable this creature to survive in extremely cold conditions. However, the relevant research was ineffectual to provide sufficient evidence of its solar energy harvesting property. In this paper, the properties of polar bear hairs were analyzed and compared systematically with those of domestic sheep wool through the measurements in the aspects of photo-thermal conversion effi-ciency, scanning electron microscope, fluorescence spectral and transmission of UV-visible spectra. Moreover, this study was much more focused on exploring ultraviolet utilization property of polar bear hair than previous research. The research results demonstrated that the photo-thermal property of polar bear hair was superior to those of wool fiber, especially in harvesting ultraviolet part. The potential benefits of this research lie in the development of bionic solar energy collective devices, especially in artificial solar energy collection fibers and textile products.

Plant can take water from soil up to several metres high. However, the mechanism of how water rises against gravity is still controversially discussed despite a few mechanisms have been proposed. Also, there still lacks of a critical transportation model because of the diversity and complex xylem structure of plants.
This paper mainly focuses on the water transport process within xylem and a mathematical model is presented. With a simplified micro channel from xylem structure and the calculation using the model of water migration in xylem, this paper identified the relationship between various forces and water migration velocity. The velocity of water migration within the plant stem is considered as detail as possible using all major forces involved, and a full mathmetical model is proposed to calculate and predict the velocity of water migration in plants.
Using details of a specific plant, the velocity of water migration in the plant can be calculated, and then compared to the experimental result from Magnetic Resonance Imaging (MRI). The two results match perfectly to each other, indicating the accuracy of the mathematical model, thus the mathematical model should have brighter future in further applications.

Helical conductive particles have attracted much attention in preparing stretchable conductive materials because of their structural flexibility and uniform strain distribution under deformation. In this paper, Spirulina-templated silver micro springs were fabricated using electroless deposition of silver onto Spirulina surface. To investigate their potential application as con-ductive fillers for stretchable materials, they were mixed into polydimethylsiloxane (PDMS) uniformly, and then the mixture was spin coated on a polyfluortetraethylene (PTFE) plate to form a thin film, during which, micro springs tended to align its major axis along the radial direction of the plate. The tensile tests of micro springs were carried out using the film along the alignment direction of micro springs on the custom-made setup. Under the optimal condition of coating thickness of 0.67 μm, helical pitch of 29 μm and annealing temperature of 300 ?C, the average elongation of micro springs can reach up to ~106.9%, which indicates that the as-prepared Spirulina-templated silver micro springs are promising flexible conductive fillers for fabricating stretchable conductive materials.

Carbon Fiber (CF) reinforced polyetheretherketone (PEEK) composite is one of the most promising implant biomaterials used in orthopedics. In this article, unfilled PEEK and CF/PEEK specimens were prepared by vacuum hot pressing method, and their tribological properties were evaluated by sliding against a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy block. The influences of mass fraction of carbon fibers in CF/PEEK and the surface oxidation treatment of carbon fibers were explored. The results showed that the water contact angles on the surfaces of CF/PEEK specimens decreased, indicating that their surface wettability was improved. The hardness value of CF/PEEK was significantly improved, the friction coefficients of CF/PEEK were effectively reduced and its wear resistance was enhanced compared with unfilled PEEK. The leading effect on CF/PEEK tribological properties was the mass fraction of CF, followed by surface oxidation of CF, and the calf serum solution had better lubricity than that of saline and deionized water.

In the present work, Polyhydroxybutyrate (PHB)/Hydroxyapatite (HA) porous composites (10%, 20%, 30 %, 40%, 50% weight HA) were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical properties with a high content of the bioactive component (HA). Porous PHB/20% HA scaffolds have shown high mechanical properties (compressive strength of 106 MPa and Young’s modulus of 901 MPa). A high volume fraction of interconnected pores (> 50 vol.%) was achieved with pore size of 50 μm – 500 μm. Biocompatibility of porous pure PHB and PHB/20%HA, as its osseointegration were assessed in vitro and after implantation in laboratory animals. PHB/20% HA (–5% ± 0.9%) and pure PHB (–3% ± 1.4%) samples after 24 hours of incubation with human leucocytes showed no significant level of cytotoxicity when p = 0.648 (p-value). In vitro massive adhesion of mouse Multipotent Mesenchymal Stromal Cells (MMSC) to the surface of both porous samples was shown. PHB/20% HA induced more intensive MMSC proliferation compared to pure PHB, which are 31% ± 6.1% and 20% ± 5.7 % respectively when p = 0.039. We observed the resorption (implant surface area was reduced by 49 %) and integration of the porous PHB/20% HA samples into surrounding tissues after 30 days of implantation. The signs of osteoclasts accumulation, neo-angigenesis and new bone formation were observed, which make PHB/20% HA promising for bone tissue engineering.

Piezoelectric materials exhibit a response to mechanical-electrical coupling, which represents an important contribution to the electrical-mechanical interaction in bone remodeling process. Therefore, the study of the piezoelectric effect on bone re-modeling has high interest in applied biomechanics. The effects of mechano-regulation and electrical stimulation on bone healing are explained. The Boundary Element Method (BEM) is used to simulate piezoelectric effects on bones when shearing forces are applied to collagen fibers to make them slip past each other. The piezoelectric fundamental solutions are obtained by using the Radon transform. The Dual Reciprocity Method (DRM) is used to simulate the particular solutions in time-dependent problems. BEM analysis showed the strong influence of electrical stimulation on bone remodeling. The examples discussed in this work showed that, as expected, the electrically loaded bone surfaces improved the bone deposition. BEM results confirmed previous findings obtained by using the Finite Element Method (FEM). This work opens very promising doors in biomechanics research, showing that mechanical loads can be replaced, in part, by electrical charges that stimulate strengthening bone density. The obtained results herein are in good agreement with those found in literature from experimental testing and/or other simu-lation approaches.

Multifunctional materials combining fluorescence for drug delivery have been successfully developed by post grafted Aggregation-Induced Emission luminogens (AIEgens) onto Mesoporous Bioactive Glass (MBG). The synthesized hybrid materials combine porous structure of MBG and strong luminescence of AIEgens, showing ordered two-dimensional hexagonal mesostructure and strong blue emission. It is worth noting that the emission color of the hybrid materials can reversible cycled between blue and yellow by changing the pH value of water solution. More importantly, the hybrid materials exhibit a drasti-cally improved apatite forming ability by soaked in Simulated Body Fluid (SBF). Furthermore, the hybrid materials can be used for site-specific delivery of doxorubicin hydrochloride (DOX) triggered by the mildly acidic pH environment, suggesting that the AIEgens functionalized mesoporous bioactive glass have great potential applications as drug-loading biomaterial for im-aging guided therapy.

In this paper, the finger muscular forces were estimated and analyzed through the application of inverse dynamics-based static optimization, and a hand exoskeleton system was designed to pull the fingers and measure the dynamics of the hand. To solve the static optimization, a muscular model of the hand flexors was derived. The experimental protocol was devised to analyze finger flexors in order to evaluate spasticity of the clenched fingers; muscular forces were estimated while the flexed fingers were extended by the exoskeleton with external loads applied. To measure the finger joint angles, the hand exoskeleton system was designed using four-bar linkage structure and potentiometers. In addition, the external loads to the fingertips were generated by cable driven actuators and simultaneously measured by loadcells which were located at each phalanx. The ex-periments were performed with a normal person and the muscular forces estimation results were discussed with reference to the physical phenomena.

Force Myography (FMG), which monitors pressure or radial deformation of a limb, has recently been proposed as a po-tential alternative for naturally controlling bionic robotic prostheses. This paper presents an exploratory case study aimed at evaluating how FMG behaves when a person with amputation uses a hand prosthetic prototype. One volunteer (transradial amputation) participated in this study, which investigated two experimental cases: static and dynamic. The static case considered forearm muscle contractions in a fixed elbow and shoulder positions whereas the dynamic case included movements of the elbow and shoulder. When considering eleven different hand grips, static data showed an accuracy over 99%, and dynamic data over 86% (within-trial analysis). The across-trial analysis, that takes into account multiple trials in the same data collection set, showed a meaningful accuracy respectively of 81% and 75% only for the reduced six grips setup. While further research is needed to increase these accuracies, the obtained results provided initial evidence that this technology could represent an in-teresting alternative that is worth exploring for controlling prosthesis.

The aim of our work is to improve the existing user-exoskeleton models by introducing a simulation architecture that can simulate its dynamic interaction, thereby altering the initial motion of the user. A simulation architecture is developed that uses the musculoskeletal models from OpenSim, and that implements an exoskeleton control algorithm and human response model in Matlab. The musculoskeletal models need to be extended with the response of a user to external forces to simulate the dy-namic interaction. A set of experiments was performed to fit this response model. A validation test showed that more than 80% of the variance of the motion could be explained. With the human response model in the combined simulation architecture, a simulation in which an object connects with the exoskeleton or with the human is performed. The effect of the exoskeleton on, among others, muscle excitation and altered motion can be assessed with this architecture. Our work can be used to better predict the effect an exoskeleton has on the user.

Energy efficiency is important in the performance of quadruped robots and mammals. Flexible spine motion generally exists in quadruped mammals. This paper mainly explores the effect of flexible spinal motion on energy efficiency. Firstly, a planar simplified model of the quadruped robot with flexible spine motion is introduced and two simulation experiments are carried out. The results of simulation experiments demonstrate that both spine motion and spinal flexibility can indeed increase energy efficiency, and the curve of energy efficiency change along with spinal stiffness is acquired. So, in order to obtain higher energy efficiency, quadruped robots should have flexible spine motion. In a certain speed, there is an optimal spinal stiffness which can make energy efficiency to be the best. Secondly, a planar quadruped robot with flexible spine motion is designed and the conclusions drawn in the two simulation experiments are verified. Lastly, the third simulation experiment is carried out to explore the relationship between the optimal spinal stiffness, speed and total mass. The optimal spinal stiffness increases with both speed and total mass, which has important guiding significance for adjusting the spinal stiffness of quadruped robots to make them reach the best energy efficiency.

A physical model for a micro air vehicle with Flapping Rotary Wings (FRW) is investigated by measuring the wing kine-matics in trim conditions and computing the corresponding aerodynamic force using computational fluid dynamics. In order to capture the motion image and reconstruct the positions and orientations of the wing, the photogrammetric method is adopted and a method for automated recognition of the marked points is developed. The characteristics of the realistic wing kinematics are presented. The results show that the non-dimensional rotating speed is a linear function of non-dimensional flapping frequency regardless of the initial angles of attack. Moreover, the effects of wing kinematics on aerodynamic force production and the underlying mechanism are analyzed. The results show that the wing passive pitching caused by elastic deformation can sig-nificantly enhance lift production. The Strouhal number of the FRW is much higher than that of general flapping wings, indi-cating the stronger unsteadiness of flows in FRW.

Dragonflies are excellent flyers among insects and their flight ability is closely related to the architecture and material properties of their wings. The veins are main structure components of a dragonfly wing, which are found to be connected by resilin with high elasticity at some joints. A three-dimensional (3D) finite element model of dragonfly wing considering the soft vein joints is developed, with some simplifications. Passive deformation under aerodynamic loads and active flapping motion of the wing are both studied. The functions of soft vein joints in dragonfly flight are concluded. In passive deformation, the chordwise flexibility is improved by soft vein joints and the wing is cambered under loads, increasing the action area with air. In active flapping, the wing rigidity in spanwise direction is maintained to achieve the required amplitude. As a result, both the passive deformation and the active control of flapping work well in dragonfly flight. The present study may also inspire the design of biomimetic Flapping Micro Air Vehicles (FMAVs).

In previous work, we modified blade element theory by implementing three-dimensional wing kinematics and modeled the unsteady aerodynamic effects by adding the added mass and rotational forces. This method is referred to as Unsteady Blade Element Theory (UBET). A comparison between UBET and Computational Fluid Dynamics (CFD) for flapping wings with high flapping frequencies (>30 Hz) could not be found in literature survey. In this paper, UBET that considers the movement of pressure center in pitching-moment estimation was validated using the CFD method. We investigated three three-dimensional (3D) wing kinematics that produce negative, zero, and positive aerodynamic pitching moments. For all cases, the instantaneous aerodynamic forces and pitching moments estimated via UBET and CFD showed similar trends. The differences in average vertical forces and pitching moments about the center of gravity were about 10% and 12%, respectively. Therefore, UBET is proven to reasonably estimate the aerodynamic forces and pitching moment for flight dynamic study of FW-MAV. However, the differences in average wing drags and pitching moments about the feather axis were more than 20%. Since study of aerodynamic power requires reasonable estimation of wing drag and pitching moment about the feather axis, UBET needs further im-provement for higher accuracy.

Weakly electric fish has an ability to generate a low-frequency electric field actively to locate the surrounding object in complete darkness by sensing the change of the electric field. This ability is called active electrolocation. In this paper, we designed a two-dimensional (2D) experimental platform of underwater active electrolocation system by simulating weakly electric fish. On the platform, location characteristics based on frequency domain were investigated. Results indicated that surface shape of 3D location characteristic curves for the 2D underwater active electrolocation positioning system was convex upwards or concave down which was influenced by the material of probed objects and the frequency of the electric field exci-tation signal. Experiments also confirmed that the amplitude of the electric field excitation signal and the size of the probed object will only influence the amplitude corresponding to 3D location characteristic curves. Based on above location charac-teristics, we present three location algorithms including Cross Location Algorithm (CLA), Stochastic Location Algorithm (SLA) and Particle Swarm Optimization (PSO) location algorithm in frequency domain and achieved the task of the underwater positioning system. Our work may have reference value for underwater detection study.

The use of biomimetic tandem flapping foils for ships and underwater vehicles is considered as a unique and interesting concept in the area of marine propulsion. The flapping wings can be used as a thrust producing, stabilizer and control devices which has both propulsion and maneuvering applications for marine vehicles. In the present study, the hydrodynamic per-formance of a pair of flexible flapping foils resembling penguin flippers is studied. A ship model of 3 m in length is fitted with a pair of counter flapping foils at its bottom mid-ship region. Model tests are carried out in a towing tank to estimate the propulsive performance of flapping foils in bollard and self propulsion modes. The same tests are performed in a numerical environment using a Computational Fluid Dynamics (CFD) software. The numerical and experimental results show reasonably good agreement in both bollard pull and self propulsion trials. The numerical studies are carried out on flexible flapping hydrofoil in unsteady conditions using moving unstructured grids. The efficiency and force coefficients of the flexible flapping foils are determined and presented as a function of Strouhal number.

Wood plastic biocomposites of biodegradable poly(butylene succinate) (PBS) and Padauk sawdust was successfully pre-pared by using a twin screw extruder and an injection molding machine. The effects of water absorption and sunlight exposure on some properties of the composites were investigated. Water absorption of PBS composites was found to follow the Fick’s law of diffusion, while the diffusion coefficient increased with increasing wood content. Maximum water absorption of around 4.5% was observed at 30 wt.% sawdust. Optical micrograph indicated the swelling of wood particles by around 1% – 3% after 30 days of water immersion. The tensile and flexural strengths reduced slightly both under the water immersion and sunlight exposure. After 90 days of exposure, the composites clearly looked paler than the non-weathered ones. Thermal scan indicated the re-duction of crystalline region due to the plasticization effect derived from water molecules.

The present study evaluates the potential of a bio-inspired pulsation damper in a vane pump used in mobile hydraulic ap-plications. Pressure pulsations caused by such positive displacement pumps can lead to malfunctions and noise in a hydraulic system. A common measure to reduce pressure pulsations is the integration of pressure pulsation dampers downstream of the pump. This type of damping measure can also be found in biology as e.g. in the human blood circulatory system. Such working principles found in living organisms offer a high potential for a biomimetic transfer into technical applications. The newly developed bio-inspired damper consists of cellular rubbers with non-linear viscoelastic material properties. In order to evaluate the new damping method, pressure pulsations were measured at two different back pressures and at a wide engine speed range of the vane pump. For further assessment, different setups, varying the stiffness of the cellular rubber materials and the damper volume, were tested. Within the tested back pressures, the pressure pulsations could be reduced by up to 40%. The developed integrated pulsation damper offers a high potential to dampen pressure pulsations of positive displacement pumps used in mobile hydraulic applications operating below 10 bar.