In this research we propose a novel inchworm robot, which is composed of an Electromagnetic Oscillatory Actuator (EOA) and claws. The EOA consists of a yoke, a magnet, and a coil. The overall robot size is 12.2 mm × 11 mm × 9 mm (length × height × width). The locomotion of the robot is achieved by different amounts of slips when the robot stretches and contracts its front leg. To realize locomotion, the working conditions were calculated theoretically and the calculated input signal was applied to the robot. The performance of the inchworm robot was evaluated experimentally with varying input voltages and frequencies. A simple op-amps based driving circuit was used to provide a square-wave input. Travel speed, average distance per step of the robot, and moving distance of the leg and body at each step were measured. The maximum travel speed was 36 mm•s−1 at 30 Hz, which validates our simple locomotion strategy experimentally.

Regarding walking robots, biomimetic design has attracted a great deal of attention. Currently, studies have focused mainly on performance analysis and the design of some specific biomimetic walking robots. However, the systematic type synthesis of bionic quadruped robots has seldom been studied. In this paper, a new approach to type synthesis for quadruped walking robots is proposed based on the generalized function (GF) set theory. The current types of typical walking robots are analyzed using the GF set theory. The research status and existing problems are investigated. The skeletal systems of quadruped mammals are analyzed. The motion characteristics of all joints of quadruped mammals are denoted by GF sets. A process of conversion from biological types to serial, parallel and hybrid types is proposed. Limb types in serial, parallel and hybrid topology are synthe-sized. Finally the quadruped robots with serial, parallel and hybrid topology are produced. Two of these types have been suc-cessfully used for the design of walking rescue robots that is suitable for responding to nuclear accidents.

We investigated the effect of wing kinematics modulation, which was achieved by adjusting the location of trailing-edge constraint at the wing-root, i.e., by adjusting the wing-root offset, on the generation of aerodynamic forces in a hovering in-sect-mimicking Flapping-Wing Micro Air Vehicle (FW-MAV) by numerical and experimental studies. Three-dimensional wing kinematics measured using three synchronized high-speed cameras revealed a clear difference in the wing rotation angle of a wing section for different wing-root offsets. The extrapolated wing kinematics were in good agreement with the measured ones for various wing-root offsets. The Unsteady Blade Element Theory (UBET) was used to estimate the forces generated by the flapping wings and validated by comparison with results of measurements performed using a load cell. Although the thrust produced by a flapping wing with a wing-root offset of 0.20  was about 4% less, its force-to-input-power ratio was about 30% and 10% higher than those with the offsets of 0.10 and 0.15 , respectively. This result could be explained by analyzing the effective Angle of Attack (AoA) and the force components computed by the UBET. Thus, a flapping wing with a wing-root offset of 0.20  can be regarded as an optimal twist configuration for the development of the FW-MAV.

Pigeons (Columba livia) have excellent flying and orienting abilities and are ideal study subjects for biologists who re-search the underlying neurological mechanisms that modulate flying and allow birds to find their way home. These mechanisms also attract the engineers who want to apply pigeon locomotion to the design of flying robots. Here, we identified the mo-tor-related brain nuclei and revealed their relationship in spatial distribution in pigeons under light anesthesia and freely moving conditions respectively. Flapping and lateral body movements were successfully elicited when electrical microstimulation was applied to the diencephalon, medial part of the midbrain, and medulla oblongata of lightly anesthetized pigeons (N = 28) whose heads were fixed. The current thresholds for stimulating different nuclei and behavior ranged from
10 μA to 20 μA. During freely moving tests (N = 24), taking off and turning were induced by a wireless stimulator through microelectrodes implanted in specific nuclei or brain regions. The results showed that electrical stimulation of these nuclei elicited the desired motor behavior. In addition, regulatory mechanisms were identified in the motor-related regions and nuclei of pigeons. Overlapping in the behavior elicited by stimulation of different regions indicates that complicated neural networks regulate motor behavior. Therefore, more studies need to be conducted involving simultaneous stimulation at multiple points within the nuclei involved in the networks.

In this study, to fabricate dual-pore scaffolds with interconnected pores, Non-solvent Induced Phase Separation (NIPS) and Wire-Network Molding (WNM) techniques were combined. First, a mold with uniform slits was prepared, and needles were inserted into the mold. Subsequently, polycaprolactone (PCL) pellets were dissolved in tetrahydrofuran (THF) at a specified ratio. The slurry was mixed using hot plate stirrer at 1200 rpm for 24 hours at 40 ?C. The PCL slurry was subsequently injected into the mold. Thereafter, to exchange the THF (solvent) with the ethanol (non-solvent), the mold was soaked in an ethanol bath. After removing the mold from the ethanol bath, the needles were removed from the mold. Consequently, dual-pore scaffold with interconnected pores was obtained. The surface morphology of the fabricated scaffolds were observed using Scanning Electron Microscope (SEM). Moreover, cell culture experiments were performed using the CCK-8 assay, and the characteristics of cells grown on the dual-pore scaffolds were assessed and were compared with the NIPS-based 3D plotting scaffold.

Replacement of damaged long bones is still a significant challenge in surgery. In the present study, a NiTi Shape Memory Alloy (SMA) constructed with graded porosity imitating human long bone structure was fabricated via a dedicated moulding procedure. The outer layer (porosity 14 %) and inner layer (porosity 52 %) of the bone-like graded NiTi alloy were found to be co-axial very well with the interface with a good metallurgical bonding. Moreover, the compression strength and elastic modulus of the graded-porosity NiTi SMAs were found to be 360.6 MPa and 6.7 GPa, respectively, which have been improved by its coaxiality compared with the one with poor coaxiality. The graded-porosity NiTi SMAs exhibit resembling mechanical performance as human long-bones, and are considered to be better implant candidates for long bone replacement.

In this research we propose a novel inchworm robot, which is composed of an Electromagnetic Oscillatory Actuator (EOA) and claws. The EOA consists of a yoke, a magnet, and a coil. The overall robot size is 12.2 mm × 11 mm × 9 mm (length × height × width). The locomotion of the robot is achieved by different amounts of slips when the robot stretches and contracts its front leg. To realize locomotion, the working conditions were calculated theoretically and the calculated input signal was applied to the robot. The performance of the inchworm robot was evaluated experimentally with varying input voltages and frequencies. A simple op-amps based driving circuit was used to provide a square-wave input. Travel speed, average distance per step of the robot, and moving distance of the leg and body at each step were measured. The maximum travel speed was 36 mm•s−1 at 30 Hz, which validates our simple locomotion strategy experimentally.

The NiCrBSi/WC biomimetic coatings were prepared on the low carbon steel substrate by plasma spray welding with mixed powders (WC-Co12+NiCrBSi) based on the bionic principles, and the coating characteristics were investigated. The results indicate that the coatings have a full metallurgical bond in coating/substrate interface, and consist mainly of γ-Ni, WC, Cr23C6, Cr7C3, Ni3Si, Cr5B3, and FeNi3 phases. The powder composition influences the microstructures and properties of the coatings. The WC content and the hardness of coatings increase with the mass fraction of WC-Co12 powder. The biomimetic coatings have much higher wear resistance compared with the low carbon steel, which is attributed to the combination of hard WC and chromium carbide particles (bionic units) and soft γ-Ni matrix in the coatings. It is favorable to prepare the biomimetic coating by plasma spray welding with the mixed powders (20wt%WC-Co12+80wt%NiCrBSi) for improving the wear resis-tance of the coating.

Hydroxyapatite (HAp) is an extensively studied material with known biocompatible and osteoconductive properties in bone tissue reconstruction. The improvement of the osteogenetic potential of HAp has been tested through modification of its structure, by replacing Ca2+ ions with Co2+ ions. In our study, we comparatively analyze the osteogenetic potential of the syn-thesized HAp and Co2+-substituted HAp (HAp/Co) designed on the nano-scale with the aim of specifically stimulating osteo-genesis in vivo. We present a quantitative study of the microscopic organization and structure of the newly formed tissue in a bone defect after 12 weeks and 24 weeks. A quantitative analysis of the calcium, magnesium and phosphorus content in the defect and its close environment was used to determine the deposition of minerals after bone reconstruction. The defect recon-structed with HAp/Co nanoparticles (Co2+ content 12 wt%) was filled with a new tissue matrix composed of dense collagen fibers containing centers of mineralization after 24 weeks. The mineral deposition rate was also higher when the defect was reconstructed with HAp/Co than when it was filled with pure HAp. A histological analysis confirmed that the alveolar bone, in which osteoporosis-induced defects were repaired using HAp/Co nanoparticles, was recuperated.

We report on a biomimetic approach for the construction of a deformation element in vehicles which absorbs energy in the case of lateral collisions. We aim at simultaneously maximising the energy absorption capacity of the component and mini-mising its weight. The examined deformation element, a crash-pad is inspired by the structure of a diatom which is known for its structural stability. As the natural counterpart, our crash pad is characterized by an undulated shape. The three undulations of the crash pad are of different height and provide for a sequential absorption of the impact energy. Compression tests were performed on the prototypes of the crash pad that were produced from different materials, namely a conventional talc reinforced poly-propylene and a natural fibre reinforced plastic. Compression tests revealed that the bioinspired crash pads performed better or equal than their technical counterpart. As required, the bioinspired components deformed continuously with the increase in deformation force. Since the differences in the properties of the used materials were small, the increased energy absorption properties were predominantly due to the structure of the biomimetic deformation element.

The morphology and wettability of Water Bamboo Leaves (WBL) and their biomimetic replicas were investigated. The particular morphology structures of samples were characterized by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). The static wettability of samples was assessed by contact angle measurements, while the dy-namic wettability was analyzed by high speed camera system. The wettability mechanism of WBL was also explained by Cassie model. Artificial surfaces were fabricated by duplicating WBL surface microstructures using PDMS in large area (5 cm ? 3 cm). The results show the main structure characteristics of this leaf surface are sub-millimeter groove arrays, micron-scale papillae and a superimposed layer with 3D epicuticular wax sculptures hierarchical structure, and the static Water Contact Angle (WCA) of 151?±2? and Water Sliding Angle (WSA) of 4?–6? indicate that WBL surface is superhydrophobic. The combination of wax film and microstructure of WBL surface gives its surface excellent superhydrophobic property. Complex hierarchical patterns with features from sub-millimeter to micron-scale range are well reproduced. The reason for the absence of nanostructures is melting of plant epidermal wax during the curing process. The WCA values on artificial WBL and negative PDMS replica are 146? ± 3? and 137? ± 2?, respectively, demonstrating preferable hydrophobicity. Differences in wetting behavior between natural leaves and artificial leaves originate from an inaccurate replication of the chemistry and structures of the three-dimensional wax projections on the leaf surface. Nevertheless, the morphological features of the leaf transferred to the replica improve signifi-cantly the hydrophobic properties of the replica when compared with the smooth PDMS reference. This study may provide an inspiration for the biomimetic design and construction of large area roughness-induced hydrophobic and anti-sticking material surface.

Cattail, a type of herbaceous emergent aquatic macrophyte, has upright-standing leaves with a large slenderness ratio and a chiral morphology. With the aim of understanding the effect of chiral morphology on their mechanical behavior, we investi-gated, both experimentally and theoretically, the twisting chiral morphologies and wind-adaptive reconfigurations of cattail leaves. Their multiscale structures were observed by using optical microscope and scanning electron microscopy. Their me-chanical properties were measured by uniaxial tension and three-point bending tests. By modeling a chiral leaf as a pre-twisted cantilever-free beam, fluid dynamics simulations were performed to elucidate the synergistic effects of the leaf’s chiral mor-phology and reconfiguration in wind. It was observed that the leaves have evolved multiscale structures and superior mechanical properties, both of which feature functionally gradient variations in the height direction, to improve their ability to resist lodging failure by reducing the maximal stress. The synergistic effect of chiral morphology and reconfiguration can greatly improve the survivability of cattail plants in wind.

A biofluid dynamics mathematical model is developed to study peristaltic flow of non-Newtonian physiological liquid in a two-dimensional asymmetric channel containing porous media as a simulation of obstructed digestive (intestinal) transport. The fractional Oldroyd-B viscoelastic rheological model is utilized. The biophysical flow regime is constructed as a wave-like motion and porous medium is simulated with a modified Darcy-Brinkman model. This model is aimed at describing the diges-tive transport in intestinal tract containing deposits which induce impedance. A low Reynolds number approximation is em-ployed to eliminate inertial effects and the wavelength to diameter ratio is assumed to be large. The differential transform method (DTM), a semi-computational technique is employed to obtain approximate analytical solutions to the boundary value problem. The influences of fractional (rheological material) parameters, relaxation time, retardation time, amplitude of the wave, and permeability parameter on peristaltic flow characteristics such as volumetric flow rate, pressure difference and wall friction force are computed. The present model is relevant to flow in diseased intestines.

In the present article, peristaltic transport of copper nano fluid in a curved channel with complaint walls is studied. Shape effects of nanosize particles are discussed. The mathematical formulation encompasses momentum and heat conservation equations with appropriate boundary conditions for compliant walls. Sophisticated correlations are employed for thermal conductivity of the nanoparticles. The nonlinear boundary value problem is normalized with appropriate variables and closed-form solutions are derived for stream function, pressure gradient and temperature profile. A detailed study is performed for the influence of various nanoparticle geometries (bricks, cylinders and platelets). With greater curvature value, pressure gradient is enhanced for various nanoparticle geometries. Temperature is dramatically modified with nanoparticle geometry and greater thermal conductivity is achieved with brick shaped nanoparticles in the fluid.