As the frequent oil spill accidents happens and large quantities of oily wastewater from all kinds of industries are being discharged, the environment has been seriously polluted and our living areas have been horribly threatened. To deal with these issues, attentions have been aroused on the treatments of the oily wastewater. Recently, numerous superwettable materials have been fabricated. In this review, we summarize the new development of the materials for the separation of oil/water mixtures, mainly including the immiscible and emulsified mixtures. For the separation of immiscible ones, special materials with fixed wettability are firstly detailed, where three types of materials can be classified based on their wettability, i.e. superhydrophobic and superoleophilic materials, superhydrophilic and underwater superoleophobic materials, and superhydrophilic and su-peroleophobic materials. Then, the smart materials with switchable wettabilities responsive to external stimulus, for instance, light, solvent, pH, temperature, and electrical potential, are presented. Meanwhile, the single, dual, and multiple stimu-lus-responsive materials are also described. As for the separation of emulsified oil/water mixtures, the materials for the sepa-ration of water-in-oil (W/O), oil-in-water (O/W), and both water-in-oil (W/O) and oil-in-water (O/W) emulsions are sequen-tially introduced. Finally, some challenges are discussed and the outlook in this filed is proposed.

The most important feature of Modular Self-reconfigurable Robot (MSRR) is the adaption to complex environments and changeable tasks. A critical difficulty is that the operator should regulate a large number of control parameters of modules. In this paper, a novel locomotion control model based on chaotic Central Pattern Generator (CPG) is proposed. The chaotic CPG could produce various rhythm signals or chaotic signal only by changing one parameter. Utilizing this characteristic, a unified control model capable of switching variable locomotion patterns or generating chaotic motion for modular self-reconfigurable robot is presented. This model makes MSRR exhibit environmental adaptability. The efficiency of the control model is verified through simulation and experiment of UBot MSRR platform.

Bio-inspiration is a starting point from which to design engineering products by learning the secrets of living creatures. We present the design, analysis, and experimental results of a robotic platform inspired by the basilisk lizard, which is well known for its ability to run on water surface. The goal is to develop a robotic platform for amphibious locomotion on ground and water using a single configuration. A tripod gait is achieved with a hexapedal configuration and four-bar-based repeated motion of the legs. The hexapedal configuration is empirically proven to have an advantage in terms of rolling stability on water. On ground, the tripod gait can satisfy the requirements of static stability to make the center of gravity and center of pressure occur at the same position. The footpad design was determined based on an empirical study of the rolling stability and lifting force. The theoretical background and experimental results are presented to validate the ability of the proposed design to run on water and on the ground.

This paper deals with two novel structures for mobile robots. The original inspiration of the robots comes from a sala-mander and a specific kind of spiders. Our robots have some especial moving capabilities causing to increase the robot ma-neuverability. Indeed, the capability of rolling motion is added to ordinary quadruped robots. This capability causes increment in maneuvering of the robots. Manipulators can be embedded into the robots to add the ability of transferring materials into the shell and conducting some tasks such as repairing. In this paper, after analysis of motion principles of the rolling robots, their dynamic equations are derived. Different simulations of two bioinspired mobile robots are presented in order to scrutinize various capabilities of the proposed designs. Walking capabilities of the robots and their advantages are discussed in detail. The comprehensive simulation results of the robots in various motion modes are presented. Finally the first prototype is introduced to verify the motion mechanisms.

To automatically adapt to the shape of different objects with enough grasping force is a challenge in the design of under-actuated anthropomorphic hands, because the grasped object is easily ejected from the hands during underactuated grasping process. The goal of this paper is to develop a design method of underactuated anthropomorphic hands to guarantee reliable adaption to different grasped objects. An analysis method is developed to investigate the evolution of motion and force in the whole underactuated grasping process. Based on the evolution of motion and force, the underactuated grasping process is decomposed into four aspects including initial contact state, grasp terminal state, grasp trajectory and rate of progress. More-over, the influence factors of such four aspects are found as the form of the combinations of underactuated mechanism pa-rameters. According to the four aspects of the underactuated grasping process, this paper presents a stepwise parameter design method through optimization of parameter combinations step-by-step. The reliable adaptive grasp for a wide scale of grasped object size is achieved. Experimental setups are constructed to corroborate the results from the theory analysis and design.

We present a dynamic model of a fish robot with a Non-uniform Flexible Tail (NFT). We investigate the tendencies of the thrust and swimming speed when the input driving moment changes. Based on the proposed dynamic model of the NFT, we derive the thrust estimation, equation of motion, and performance evaluation of a fish robot with a NFT. By defining the optimal stiffness of the NFT in simulation, a fish robot prototype is then designed and fabricated. A series of experiments are performed to verify the proposed model. Experiment results are in good agreement with simulation data. The results show that the thrust and swimming speed of the fish robot are proportional to the amplitude of the driving moment. There are two resonant fre-quencies (f = 1.4 Hz and 2.2 Hz), the maximum thrust and swimming speed (about 0.7 BL•s−1) are found to be around f  = 1.4 Hz. The above results inidicate the proposed model is suitable for predicting the behavior, thrust and swimming speed of a fish robot with a NFT.

Inspired by the general tau theory in animal motion planning, a collision-free four-dimensional (4D) trajectory generation method is presented for multiple Unmanned Aerial Vehicles (UAVs). This method can generate a group of optimal or near-optimal collision-free 4D trajectories, the position and velocity of which are synchronously planned in accordance with the arrival time. To enlarge the shape adjustment capability of trajectories with zero initial acceleration, a new strategy named intrinsic tau harmonic guidance strategy is proposed on the basis of general tau theory and harmonic motion. In the case of multiple UAVs, the 4D trajectories generated by the new strategy are optimized by the bionic Particle Swarm Optimization (PSO) algorithm. In order to ensure flight safety, the protected airspace zone is used for collision detection, and two collision resolution approaches are applied to resolve the remaining conflicts after global trajectory optimization. Numerous simulation results of the simultaneous arrival missions demonstrate that the proposed method can effectively provide more flyable and safer 4D trajectories than that of the existing methods.

A honeybee uses its brush-like tongue (glossa) to dip nectar and the setae densely distributed on it can increase the amount of trapped nectar observably. The glossa is often simplified as a cylinder covered by uniformly distributed and vertically erected setae during the drinking process, herein variations of the dimensions together with the erection angles of glossal setae are assumed to be negligible. In this paper, a dynamic model for the glossa retraction phase under the specific erection pattern of glossal setae is established, and the energy saving mechanism is extensively studied by comparing four types of erection pat-terns. Then the theoretically-optimal configuration, which satisfies the minimum energy consumption, is achieved from the dynamic model. Using the scanning electron microscope and a specially-designed high-speed camera system, we measure the dimensions of the glossal satae and capture dynamics of the hairy glossa in nectar feeding. It is proven that the erection angle of the glossal setae varies along the tongue axis, which shows a high concordance with our theoretically-optimal configuration. Compared with the hypothetical uniform distribution mode of glossal setae proposed by former researchers, we obtain a 16% increase in energy saving from actual erection pattern.

Cavefish, with sensitive lateral lines, can swim freely and locate preys in invisible and complex cave environments, though their eyes are greatly degenerated. Investigations on the morphology and distribution characteristics of their lateral line systems would benefit our understanding of the high-sensitivity mechanism of the fish. In this study, the arrangement and morphology of the lateral lines are described for two species of Sinocyclocheilus: S. macrophthalmus and S. microphthalmus, which live in the karst caves in Guangxi, China. The behavior experiments indicate that the lateral line system of the S. macrophthalmus is more sensitive at a low vibration frequency range from 20 Hz to 70 Hz. The cephalic and trunk lateral line systems both contribute to the efficient object-locating capability. For both of the two species of cavefish, the diameter of the lateral canal nearby the neuromasts is narrower than that nearby the canal pores. This variation can increase the normal pressure to the surface of the cupula, and increase the sensitivity of the canal lateral line system.

The Chinese fire belly newts (Cynops orientalis) have the ability to escape from the glass tank with vertical walls. An experimental device was developed to investigate the sticking and climbing behaviors of the newts. The detaching angles of the newt on the surfaces of glass, PMMA, and SUS 304 stainless steel at dry, little-water, and plenty-water conditions were meas-ured and used as an index to evaluate the sticking and climbing abilities of the newts on tilted surface. The experimental results show that the newts have a strong ability to stick on tilted surface, particularly on the surface with little water. Morphological studies of the toe pads and belly were carried out by SEM and cryo-SEM to clarify the sticking mechanisms. It is found that the toe pad of the newt consists of a dense array of nanopillars with ca 100 nm – 300 nm diameter surrounded by small channels. This structure is supposed to facilitate high adhesion to substrate by providing capillary forces, and promote the squeeze-out of fluid between the toe pad and substrate in flooded case.

Mollusc shells are renowned for their mechanical strength and toughness. To better understand the mineralization process of the shell, structure of the body whorl and base of Conus litteratus (Conus shell) were in detail investigated by using scanning electron microscopy. Three-point bending tests were taken to demonstrate that each layer of crossed-lamellar structures is indispensable to enhance the whole strength of the shells. The results show that the conch shell is composed of hierarchical structure from nano scale to macro scale, and the basic constituent is long rod-shaped aragonite. Different positions of the shell have varied structures, and the base is more complicated than the body whorl. The mechanical properties of Conus are highly anisotropic and the arrangement of middle layer has a great influence on the bending strength. The outer and inner layers are very thin but play a protective role for the middle layer.

In this study, gecko-inspired polydimethylsiloxane (PDMS) microfiber surfaces were fabricated by combining Inductively Coupled Plasma (ICP) and micro-mold casting. The effect of roughness and surface energy of counterface on the adhesion of gecko-inspired microfiber surfaces and its superhydrophobicity and wet self-cleaning were studied. The adhesion of gecko-inspired microfiber surfaces depended on the roughness of the counterfaces due to the influences of contact area and interlocking mechanism. SEM images of interfaces between counterfaces with different roughness and gecko-inspired mi-crofiber surfaces revealed the matched and dis-matched contact directly. The gecko-inspired microfiber surface got the larger adhesive force from the higher surface energy counterface, which is consisted with Johnson-Kendall-Roberts (JKR) theory. The smaller dimension and lower duty ratio of microfibers on PDMS resulted in the increasing of Water Contact Angle (WCA) and the decreasing of Sliding Angle (SA) compared to those of smooth PDMS. Particularly, sample P-8-28-20 had the biggest WCA (155?) and SA (7?), which displayed the superhydrophobicity and the best wet self-cleaning efficiency in all samples. The present studies showed that the roughness and surface energy of counterface both affected the adhesion of gecko-inspired microfiber surfaces. The smaller dimension and lower duty ratio of microfibers on PDMS endowed it with the superhydro-phobicity and the wet self-cleaning abilities.

Porous nanofiber-microsphere mats of collagen (COL)/polyvinyl alcohol (PVA) containing salicylic acid (SA) as model drug were prepared by electrospinning for the assessment of drug delivery system. The electrospun fibrous mats were crosslinked by UV-radiation or glutaraldehyde to weaken the degree of drug burst release and morphology damage when meeting water. The morphology and chemical structures of COL/PVA-SA electrospun fibers were characterized by SEM and FTIR. The crosslinking of UV-radiation did not destroy the morphology of COL/PVA-SA electrospun fibers in the crosslinking process, however, the crosslinking of glutaraldehyde did it. In vitro release studies showed that COL/PVA-SA electrospun fibers efficiently controlled the release of drugs by the crosslinking of UV-radiation for 4 h. The transport mechanism that controlled the release of drugs from electrospun mats was Fickian diffusion.

Titanium and its alloys are widely used as materials for bio-medical applications, such as implants. However, ions of the alloy can release to the body region and spread into the blood circulation. In this study, plasma nitriding and CrN coating techniques are used in order to overcome the problem of ion release. The objective of this study was to investigate the effects of plasma nitrided pure titanium on the structural properties and corrosion behaviors before and after CrN coating in Ringer’s solution at 37 ?C. The structural properties were investigated using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). A diffusion layer and a compound layer composed of δ-TiN and ε-Ti2N phases were observed on the surface of nitrided pure titanium. Corrosion tests were made for the determination of electrochemical properties with the help of Potentio-stat/Galvanostat device. The results show that corrosion behaviors of untreated and treated samples have similar characteristic.

Natural fibers can play a major role in composite industry due to its renewable, biodegradable, and eco-friendly properties. Areca Fruit Husk (AFH) is rich in fiber, but is wasted in large quantity from tobacco industries. Comprehensive characterization of AFH fiber is done to examine its morphological, physical, mechanical, chemical and thermal properties. High cellulose content of the fiber (57.35 wt%) provides better tensile strength (231.66 MPa) whereas the porous surface morphology (40.8 %) ensures better bonding with the matrix. Moreover, the low density of the fiber (0.78 g•cm−3) makes it an attractive alternative for hazardous synthetic fibers. The semi-crystalline nature and large crystalline size of the fiber reduce the water absorption char-acteristics. The thermo gravimetric analysis confirms its stability up to 240 ?C, which is higher than the polymerization tem-perature. The results confirm the potential of AFH fibers as a reinforcement in bio-reinforced polymer composites for automo-tive and structural applications.

The fundamental characteristics and the flow mechanism of a Vibrating Flow Pump (VFP) with a jelly-fish valve, which can be applied to a novel artificial heart, were studied theoretically and experimentally. By using water as the working fluid, the measurement methodology for the typical unsteady flow for VFP was developed here. The effects of the frequency, amplitude and inner diameter of the vibrating pipe, and thickness of the silicone rubber sheet of the jelly-fish valve on the basic per-formance of VFP were systematically investigated. A high-speed observation technique and simple theoretical model analysis were also introduced for further detailed discussion. Quantitative contributions of the individual parameters to the pumping performance were shown through the experiment, which would give us essential knowledge for establishing design criteria of VFP. The theoretical model, which agreed with the experiment and the high-speed observation, elucidated the pumping mechanism with respect to the role of inertia of the inner fluid.