Water striders have remarkable water-repellent legs that enable them to stand effortlessly and move quickly on water. Fluid physics indicates this feature is due to a surface-tension effect caused by the special hierarchical structure of the legs, which are covered with a large number of inclined setae with fine nanogrooves inducing water resistance. This inspires us to fabricate special water-repellent structure on functional surfaces through the cooperation between the surface treatment and the surface micro- and nanostructures, which may bring great advantages in a wide variety of applications. In this paper we present a procedure for fabricating biomimetic water strider legs covered with setae using Polycarbonate Track-Etched (PCTE) mem-branes as templates. By choosing appropriate membrane lengths, diameters, pitches and densities of the setae, the biomimetic legs can be fabricated conveniently and at a low cost. Furthermore we investigated the relationship between stiffness of the molding materials, high aspect ratio and density, which affect the fidelity of fabrication and self adhesion, to optimize the stability of setae. The knowledge we gained from this study will offer important insights into the biomimetic design and fab-rication of water strider setae.

Ultra High Molecular Weight Polyethylene (UHMWPE) has been widely used as a bearing material for artificial joint re-placement over forty years. It is usually crosslinked by gamma rays irradiation before its implantation into human body. In this study, UHMWPE and UHMWPE/nano-hydroxyapatite (n-HA) composite were prepared by vacuum hot-pressing method. The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation. The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine (model MM-200) under deionized water lubrication. Micro-morphology of worn surface was observed by metallographic microscope. Contact angle and hardness of the materials were also measured. The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation. Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA. While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation. The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear, and that of n-HA filled material is mainly characterized as abrasive wear. After gamma irradiation, the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced. Unfilled and filled materials after irra-diation are mainly shown as slight fatigue wear. The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

Whereas conservative therapies aim to stall the advance of disease, regenerative medicine strives to reverse it. The capacity of most tissues to regenerate derives from stem cells, but there are a number of barriers which have to be circumvented before it will be possible to use stem-cell-based therapies. Such therapies, however, are expected to improve human health enormously, and knowledge gained from studying stem cells in culture and in model organisms is now laying the groundwork for a new era of regenerative medicine. One of the most prominent methods to study stem cell differentiation is to let them to form embryoid bodies. Under favourable conditions any stem cell line will form embryoid bodies. However, the mechanism of the formation of embryoid bodies is not very well understood, and to produce them in the laboratory is in no way trivial – an important technical barrier in stem cell research. Recently, the embryoid body cultivation step has been successfully circumvented for the derivation of osteogenic cultures of embryonic stem cells. Here we report on a simple and reusable system to cultivate embryoid bodies in extremely short times. The method is inspired by the principles that lead to the establishment of the biomimetic triangle.

We report the fabrication process of piezoelectric cellulose paper and the enhancement method of its piezoelectric property. Stretching method with different wet-drawing ratios was introduced to increase the piezoelectric property of cellulose paper during regeneration process. It is observed that the Young’s modulus and the piezoelectric charge constants are very dependent on the drawing ratio and the direction of nanofibrils of piezoelectric paper. Using the enhanced piezoelectric property, we prove that the flexible regenerated piezoelectric cellulose can be applied to the potential acoustic applications such as thin piezoelec-tric paper speaker.

Poly (vinyl alcohol)/hydroxylapatite (PVA/HA) composite hydrogel was prepared by repeated freezing and thawing. The water loss properties of the resultant hydrogel were investigated by using optical microscope. Long time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA content. The micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D profiler. The results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water loss. Long time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase, decrease, slow decrease and stable balance, and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA content. It is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

This paper presents the development of a mesoscale self-contained quadruped mobile robot that employs two pieces of piezocomposite actuators for the bounding locomotion. The design of the robot leg is inspired by legged insects and animals, and the biomimetic concept is implemented in the robot in a simplified form, such that each leg of the robot has only one degree of freedom. The lack of degree of freedom is compensated by a slope of the robot frame relative to the horizontal plane. For the implementation of the self-contained mobile robot, a small power supply circuit is designed and installed on the robot. Ex-perimental results show that the robot can locomote at about 50 mm•s–1 with the circuit on board, which can be considered as a significant step toward the goal of building an autonomous legged robot actuated by piezoelectric actuators.

In present, there are increasing interests in the research on mechanical and control system of underwater vehicles. These ongoing research efforts are motivated by more pervasive applications of such vehicles including seabed oil and gas explora-tions, scientific deep ocean surveys, military purposes, ecological and water environmental studies, and also entertainments. However, the performance of underwater vehicles with screw type propellers is not prospective in terms of its efficiency and maneuverability. The main weaknesses of this kind of propellers are the production of vortices and sudden generation of thrust forces which make the control of the position and motion difficult.
On the other hand, fishes and other aquatic animals are efficient swimmers, posses high maneuverability, are able to follow trajectories, can efficiently stabilize themselves in currents and surges, create less wakes than currently used underwater vehicle, and also have a noiseless propulsion. The fish’s locomotion mechanism is mainly controlled by its caudal fin and paired pectoral fins. They are classified into Body and/or Caudal Fin (BCF) and Median and/or paired Pectoral Fins (MPF). The study of highly efficient swimming mechanisms of fish can inspire a better underwater vehicles thruster design and its mechanism.
There are few studies on underwater vehicles or fish robots using paired pectoral fins as thruster. The work presented in this paper represents a contribution in this area covering study, design and implementation of locomotion mechanisms of paired pectoral fins in a fish robot. The performance and viability of the biomimetic method for underwater vehicles are highlighted through in-water experiment of a robotic fish.

Based on photogrammetry technology, a novel localization method of micro-polishing robot, which is restricted within certain working space, is presented in this paper. On the basis of pinhole camera model, a new mathematical model of vision localization of automated polishing robot is established. The vision localization is based on the distance-constraints of feature points. The method to solve the mathematical model is discussed. According to the characteristics of gray image, an adaptive method of automatic threshold selection based on connected components is presented. The center coordinate of the feature image point is resolved by bilinear interpolation gray square weighted algorithm. Finally, the mathematical model of testing system is verified by global localization test. The experimental results show that the vision localization system in working space has high precision.

With an ultimate range up to 1000 km, a maximum operating depth of 6000 m, and a generous payload capacity, Auto-sub6000 is well placed to become one of the world’s most capable deep diving Autonomous Underwater Vehicles (AUVs). Recently, Autosub6000 successfully completed its first deep water engineering trials, and in September 2008, fitted with a multibeam sonar, will carry out its first science missions. This paper will describe how we are tackling the design issues that specifically affect a deep diving AUV which must be capable of operating with true autonomy, independently of the mother ship, namely: carrying adequate energy for long endurance and range, coping with varying buoyancy, and maintaining accurate navigation throughout missions lasting up to several days. Results from the recent engineering trails are presented, and future missions and development plans are discussed.

Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves, which have an effect on the coloration of Morpho butterflies and enhance the hydrophobicity of natural surfaces. We investigated the micro-scale and nano-scale structures on the wing surfaces of insects and found that the hierarchical multiple roughness structures help in en-hancing the hydrophobicity. After examining 10 orders and 24 species of flying Pterygotan insects, we found that micro-scale and nano-scale structures typically exist on both the upper and lower wing surfaces of flying insects. The tiny structures such as denticle or setae on the insect wings enhance the hydrophobicity, thereby enabling the wings to be cleaned more easily. And the hydrophobic insect wings undergo a transition from Cassie to Wenzel states at pitch/size ratio of about 20. In order to examine the wetting characteristics on a rough surface, a biomimetic surface with micro-scale pillars is fabricated on a silicon wafer, which exhibits the same behavior as the insect wing, with the Cassie-Wenzel transition occurring consistently around a pitch/width value of 20.

Twenty-nine species of butterflies were collected for observation and determination of the wing surfaces using a Scanning Electron Microscope (SEM). Butterfly wing surface displays structural anisotropism in micro-, submicro- and nano-scales. The scales on butterfly wing surface arrange like overlapping roof tiles. There are submicrometric vertical gibbosities, horizontal links, and nano-protuberances on the scales. First-incline-then-drip method and first-drip-then-incline method were used to measure the Sliding Angle (SA) of droplet on butterfly wing surface by an optical Contact Angle (CA) measuring system. Relatively smaller sliding angles indicate that the butterfly wing surface has fine self-cleaning property. Significantly different SAs in various directions indicate the anisotropic self-cleaning property of butterfly wing surface. The SAs on the butterfly wing surface without scales are remarkably larger than those with scales, which proves the crucial role of scales in determining the self-cleaning property. Butterfly wing surface is a template for design and fabrication of biomimetic materials and self-cleaning substrates. This work may offer insights into how to design directional self-cleaning coatings and anisotropic wetting surface.

The biological immune system is a complex adaptive system. There are lots of benefits for building the model of the immune system. For biological researchers, they can test some hypotheses about the infection process or simulate the responses of some drugs. For computer researchers, they can build distributed, robust and fault tolerant networks inspired by the functions of the immune system. This paper provides a comprehensive survey of the literatures on modelling the immune system. From the methodology perspective, the paper compares and analyzes the existing approaches and models, and also demonstrates the focusing research effort on the future immune models in the next few years.

In the post-genomic biology era, the reconstruction of gene regulatory networks from microarray gene expression data is very important to understand the underlying biological system, and it has been a challenging task in bioinformatics. The Bayesian network model has been used in reconstructing the gene regulatory network for its advantages, but how to determine the network structure and parameters is still important to be explored. This paper proposes a two-stage structure learning algo-rithm which integrates immune evolution algorithm to build a Bayesian network .The new algorithm is evaluated with the use of both simulated and yeast cell cycle data. The experimental results indicate that the proposed algorithm can find many of the known real regulatory relationships from literature and predict the others unknown with high validity and accuracy.