Design and preparation of organic materials having the ability to automatically restore their mechanical and physical properties are of great importance because of the extensive application ranging from aerospace components to microcircuitry, where the accessibility is highly limited and the reparability of materials is lower. The self-healing behavior is actually a dy-namic property of material, resembling what is possessed by nature living systems. Therefore, fabrication of most self-healing materials is actually inspired by nature. This tutorial review focuses on the basic chemical mechanisms that have been suc-cessfully adopted in designing self-healing organic materials. It specially covers recent development in the design of materials with durable, easy repairable or self-healing superhydrophobic surfaces and coatings.

This paper presents a wheeled wall-climbing robot with the ability to climb concrete, brick walls using circular arrays of miniature spines located around the wheel. The robot consists of two driving wheels and a flexible tail, just like letter “T”, so it is called Tbot. The simple and effective structure of Tbot enables it to be steerable and to transition from horizontal to vertical surfaces rapidly and stably. Inspired by the structure and mechanics of the tarsal chain in the Serica orientalis Motschulsky, a compliant spine mechanism was developed. With the bio-inspired compliant spine mechanism, the climbing performance of Tbot was improved. It could climb on 100? (10? past vertical) brick walls at a speed of 10 cm•s−1. A mechanical model is also presented to analyze the forces acting on spine during a climbing cycle as well as load share between multi-spines. The simu-lation and experiment results show that the mechanical model is suitable and useful in the optimum design of Tbot.

In this paper, we propose a miniaturized tadpole-like robot using an electromagnetic oscillatory actuator. The electro-magnetic actuator has a simple structure with a moving-magnet type and the body size is 13 mm (length) × 11 mm (height) × 10 mm (width). A tail has the thickness of 100 μm and the length of 20 mm which is twice of the body-length (BL). The tail attached to the oscillatory actuator generates undulatory propulsion for the forward swimming. Moreover, the tadpole robot enables the change of the direction by controlling input signal patterns applied to the oscillatory actuator. Prototypes of the tadpole robot have been manufactured and the thrust force and swimming speed are measured to evaluate the performance of the biomimetic robot in water at various tail-beat frequencies. The maximum thrust force is 42 mN at the tail-beat frequency of
30 Hz with voltage of 3 V, enabling the tadpole robot to swim at the speed of 210 mm•s−1 (6 BL•s−1). The tadpole robot can also change its moving direction with the angular velocity of 21 deg•s−1 at the half pulse pattern of 30 Hz.

This paper presents a multi-agent robotic ?sh system used for mariculture monitoring. Autonomous robotic ?sh is designed to swim underwater to collect marine information such as water temperature and pollution level. Each robotic ?sh has 5 degrees of freedom for controlling its depth and speed by mimicking a sea carp. Its bionic body design enables it to have high swimming efficiency and less disturbance to the surrounding sea lives. Several onboard sensors are equipped for autonomous 3D naviga-tion tasks such as path planning, obstacle avoidance and depth maintenance. A robotic buoy ?oating on the water surface is deployed as a control hub to communicate with individual robots, which in turn form a multi-agent system to monitor and cover a large scale sea coast cooperatively.  Both laboratory experiments and ?eld testing have been conducted to verify the feasibility and performance of the proposed multi-agent system.

A bioinspired autopilot is presented, in which body saccadic and intersaccadic systems are combined. This autopilot en-ables a simulated hovercraft to travel along corridors comprising L-junctions, U-shaped and S-shaped turns, relying on mini-malistic motion vision cues alone without measuring its speed or distance from walls, in much the same way as flies and bees manage their flight in similar situations. The saccadic system responsible for avoiding frontal collisions triggers yawing body saccades with appropriately quantified angles based simply on a few local optic flow measurements, giving the angle of inci-dence with respect to a frontal wall. The simulated robot negotiates stiff bends by triggering body saccades to realign its tra-jectory, thus traveling parallel with the wall along a corridor comprising sharp turns. Direct comparison shows that the per-formance of this new body saccade-based autopilot closely resembles the behavior of a fly using similar body saccade strategy when flying along a corridor with an S-shaped turn, despite the huge differences in terms of the inertia.

A new modeling approach is presented for mathematically describing the drag due to wing flapping. It is shown that there is an aerodynamic cost of flapping in terms of an increase in the drag when compared with non-flapping. The drag increase con-cerns the induced drag which results from lift generation. There are two effects that yield the induced drag increase caused by flapping. The first effect is due to changes in the direction of the lift vectors at the left and right wings during the flapping cycle by tilting them according to the flapping angle of the wings. Because of tilting the lift vectors, more lift has to be generated than is required for the vertical force balance in flapping flight. This lift enlargement causes an increase of the induced drag. The second effect that increases the induced drag is due to changes in the magnitude of the lift vector in the course of the flapping cycle. Changes in the magnitude of the lift vector are necessary for generating thrust which is required for the longitudinal force balance. As a result, both effects of lift vector changes cause a drag increase when compared with non-flapping. Solutions on an analytical basis and as well as results using a computational fluid dynamics method are presented.

Some nectarivorous animals have evolved highly specialized tongues to gather nectar from flowers. Here we show that the Italian honeybee, Apis mellifera ligustica, uses the uniformly-distributed ridges on the internal wall of the mouthpart to reduce drag while drinking nectar. We discovered that the tip of the tongue is covered with bushy setae and resembles a brush, and the ridges are parallel distributed on the inner wall of the galeae. Using high-speed camera, we recorded the morphology of the mouthpart when dipping the sucrose water. Considering the ridges and the movement rule of the glossa, we proposed a model for analyzing the mechanism of drag reduction. Theoretical estimation of the friction coefficient with respect to the dipping frequency indicates that the erectable bushy hairs and the ridges can significantly reduce friction when a honeybee drinks nectar. Results show that dimensions of the ridges play a key role in reducing friction. It can be concluded that the ridges on the galeae of honeybee’s mouthpart can reduce the friction coefficient by 86% compared with the case of the transverse distribution co-efficient S = 40. Finally, the capability of drag reduction in the mouthpart of honeybee may inspire a creative concept for de-signing efficient viscous micropumps.

Plant of carnivorous genus Nepenthes alata has evolved specific pitchers to prey insects for survival in the barren habitat, especially its slippery zone. The excellent slippery function has received considerable interest because of its potential applica-tion in antifriction surface design. The surface morphologies of intact and de-waxed slippery zones were characterized using  scanning electron microscope and scanning white-light interferometer. Hierarchical structures with anisotropic micro- lunate structure and nano- wax crystals were found on the slippery zone. Due to the hierarchical structures, the slippery zone is hy-drophobic. It shows a significant anisotropic wettability with static contact angles 153.3? and 140.1? in the directions perpen-dicular and parallel to the upward direction (toward the peristome), respectively. The sliding angles are ~3? and ~10? in the downward and upward directions, respectively. Crawling experiments indicate that the microscopic surface roughness and the brittleness of the wax crystals may reduce insect attachment in different modes according to the insect mass differences. Moreover, artificial slippery surfaces inspired by the slippery zone of Nepenthes alata were fabricated. Traction experiments quantitatively verified that the friction force of replicated lunate structures with Ra-2.54 ?m surface roughness was reduced by about 25% as compared to flat surface with Ra-0.56 ?m surface roughness for cricket claws.

The aim of this paper is to characterize the microrelief and wettability of lotus leaf, waterlily leaf and biomimic ZnO surface with potential engineering applications. The characterizations of morphologies reveal that the top surface of lotus leaf is textured with 4 μm – 10 μm size protrusions and 70 nm – 100 nm nanorods, while the top surface of waterlily leaf is textured with wrinkle and decorated with concave coin-shaped geometric structure. The wettabilities of water and oil on lotus leaf and waterlily leaf under different surroundings were systematically researched. It is indeed interesting that the leaves of the two typical plants both living in the aquatic habitats possess opposite wettabilities: superhydrophobicity for top surface of lotus leaf (156?) while quasi-superhydrophilicity for top surface of waterlily leaf (15?). We have succeeded in fabricating the superhy-drophobic ZnO nanorods semiconductor material (151?) employing a simple method inspired by the detailed structures and chemical composition of lotus leaf.

Diatoms possess intricately complicated nanopatterned silica outer shells, the so called frustules. Due to their excellent three-dimensional (3D) nanostructures, diatom frustules have attracted attentions from many fields to look for potential appli-cations, such as structural material design, light harvesting, photonics, molecular separation and bio-sensing. However, the mechanical property of frustule, especially the role of each single portion that structures a frustule, need to be clearly examined in order to provide a scientific support to frustule utilization. The reported work uses the Finite-Element (FE)-based simulation to investigate the relative mechanical properties of the frustule of the diatom Coscinodiscus sp. as compared with reference non-frustule structures. A three-dimensional model for the three featured layers of this frustule and a simplified model for its girdle band are built with the assistance of ABAQUS. A basic-cell concept is suggested; and the comparative results of several simulation groups are reported. The numerical results indicate that the seven-unit-cell model is able to catch the essential me-chanics of the Coscinodiscus sp. frustule under pressure and that the layered and porous structure of this frustule can effectively resist pressure.

A novel thin film organic bionic leaf was prepared by a solution-casting method to simulate the thermal effect of transpi-ration and solar spectrum reflection characteristics of plant leaves. The main components of the bionic leaf are polyvinyl alcohol (PVA), lithium chloride (LiCl) and chromium sesquioxide (Cr2O3). The thin film was modified by chemical cross-linking, and its surface was modified by alkylsilane to prevent excessive swelling. The thin film can simulate the thermal effect of natural leaf transpiration because that the hygroscopic PVA and LiCl can absorb and desorb water due to the high and low humidity of the ambient air at night and day, respectively. The thin film has the similar solar spectrum reflection characteristics to those of plant leaves due to the Cr2O3 and the water content of the hygroscopic materials. The measured diurnal maximum radiation temperature difference between the organic bionic leaf and the Osmanthus fragrans leaf was only 0.55 ?C. In addition, the solar spectrum reflection measurements revealed that the organic bionic leaf could precisely simulate the key solar spectrum reflec-tion characteristics of plant leaves.

In order to architecturally and functionally mimic native Extracellular Matrix (ECM), a novel micro/nano-fibrous scaffold of hydroxyapetite/poly(lactide-co-glycolide) (HA/PLGA) composite was successfully prepared by melt-spinning method. A porous three-dimensional scaffold fabricated by melt-molding particulate-leaching method was used as control. This kind of scaffold comprising both nanofiber and microfiber had an original structure including a nano-network favorable for cell adhe-sion, and a micro-fiber providing a strong skeleton for support. The microfibers and nanofibers were blended homogeneously in scaffold and the compression strength reached to 6.27 MPa, which was close to human trabecular bone. The typical mi-cro/nano-fibrous structure was more beneficial for the proliferation and differentiation of Bone Mesenchymal Stem Cells (BMSCs). The calcium deposition and Alkaline Phosphatase (ALP) activity were evaluated by the differentiation of BMSCs, and the results indicated that the temporary ECM was very beneficial for the differentiation of BMSCs into maturing osteoblasts. For repairing rabbit radius defects in vivo, micro/nano-fibrous scaffold was used for the purpose of rapid bone remodeling in the defect area. The results showed that a distinct bony callus of bridging was observed at 12 weeks post-surgery and the expression of osteogenesis-related genes (bone-morphogenetic protein-2, Osteonectin, collagen-I) increased because of the ECM-like structure. Based on the results, the novel micro/nano-fibrous scaffold might be a promising candidate for bone tissue engi-neering.

High Density Polyethylene (HDPE) composites reinforced with treated bio-filler from Argan-Nut Shell (ANS) at various filler contents are prepared by extrusion and injection molding processes. The microstructures of the composites are charac-terized by Fourier Transform Infrared Spectroscopy (FTIS) and Scanning Electron Microscopy (SEM); the thermal stability is analyzed by Thermogravimetric Analysis (TGA), and their mechanical properties are investigated by dynamical mechanical analysis and rheological testing. The morphological and structural results indicate an improvement in adhesion between the ANS fillers and HDPE matrix upon alkali treatment. The mechanical properties of the composites show a significant increase in young’s modulus with the addition of filler, a gain of 58% is marked compared to neat polymer. Thermal analysis reveals that the incorporation of bio-filler in polymer results in a decrease in decomposition temperatures. This research offers an ecological alternative to upgrade the valorization of abundant and unexploited Moroccan resources. In addition, the possibility of finding uses for ANS in composite manufacturing will help open new markets for what is normally considered waste or for use in low value products.

The motion of an Ionic Polymer Metal Composite (IPMC) cantilever under a periodic voltage control is modeled. In our finite element 3D model, we follow both the free tip displacements and the blocking forces for various thicknesses and elastic constants of the ionomer membrane. It turns out that the maximum displacement of the free tip strongly depends on the value of the Young’s modulus of the electrodes. Furthermore, the maximum blocking force, Fmax, increases with the thickness of the ionomer membrane. At constant values of Young’s moduli of the electrodes and ionomer membrane thickness, if the Young’s modulus of the ionomer membrane varies within the range from 0.2 MPa to 1 GPa, the change of Fmax is less than 10 %.  The simulated maximal displacements, blocking forces and electrical currents are compared with the corresponding sets of ex-perimental data, respectively. Qualitative agreement between the simulated and the respective measured data profiles is ob-tained. Furthermore, it is found that the assumption of electrostatic interactions in the cation depleted region of the ionomer membrane has a negligible effect. The advantage of the model consists in its simplicity.

The compaction characteristics of biomimetic press roller with ridge structures, inspired from the geometrical features of the ventral surface of dung beetle (Copris ochus Motschulsky), were investigated in this work. Field tests were carried out at three weights (300 N, 500 N and 700 N) and two forward velocities (0.64 m•s−1 and 1.04 m•s−1) for biomimetic press roller and conventional press roller. To determine compaction performance, rolling resistance, soil bulk density, soil moisture content, emergence rate and percent change of plant spacing were measured. Roller weight was proved to be the major contributory factor on soil compaction. Biomimetic press roller decreased rolling resistance by 2.98% –17.69% at the velocity of 0.64 m•s−1, and by 6.59% –18.57% at the velocity of 1.04 m•s−1 compared with the conventional press roller. Both biomimetic roller and conventional roller can achieve proper bulk density for corn seeds under the experimental conditions. However, compared with the conventional roller, biomimetic roller helped soil conserve more moisture. The highest emergence rate was found when the biomimetic roller worked with a weight of 700 N and velocity of 0.64 m•s−1. Percent change of plant spacing was lower using the biomimetic press roller compared with that using the conventional roller, because that adjacent ridge structures of the biomi-metic roller can well constrain the flow of soil during compacting process.

The patterns of ultrasonic backscattered echoes represent valuable information pertaining to the geometric shape, size, and orientation of the reflectors as well as the microstructure of the propagation path. Accurate estimation of the ultrasonic echo pattern is essential in determining the object or propagation path properties. This paper proposes a parameter estimation method for ultrasonic echoes based on Artificial Bee Colony (ABC) algorithm which is one of the most recent swarm intelligence based algorithms. A modified ABC (MABC) algorithm is given by adding an adjusting factor to the neighborhood search formula of traditional ABC algorithm in order to enhance its performance. The algorithm could overcome the impact of different search range on estimation accuracy to solve the multi-dimensional parameter optimization problems. The performance of the MABC algorithm is demonstrated by numerical simulation and ultrasonic detection experiments. Results show that MABC not only can accurately estimate various parameters of the ultrasonic echoes, but also can achieve the optimal solution in the global scope. The proposed algorithm also has the advantages of fast convergence speed, short running time and real-time parameters esti-mation.