Gecko has the ability to climb fl exibly on various natural surfaces because of its fi ne layered adhesion system of foot, which 
has motivated researchers to carry out a lot of researches on it. Signifi cant progresses have been made in the gecko-like dry 
adhesive surfaces in the past 2 decades, such as the mechanical measurement of adhesive characteristics, the theoretical 
modeling of adhesive mechanism and the production of synthetic dry adhesive surfaces. Relevant application researches 
have been carried out as well. This paper focuses on the investigations made in recent years on the gecko-like dry adhesive 
surfaces, so as to lay the foundation for further research breakthroughs. First, the adhesion system of gecko’s foot and its 
excellent adhesive characteristics are reviewed, and the adhesive models describing the gecko adhesion are summarily 
reviewed according to the diff erent contact modes. Then, some gecko-like dry adhesive surfaces with outstanding adhesive 
characteristics are presented. Next, some application researches based on the gecko-like dry adhesive surfaces are introduced. 
Finally, the full text is summarized and the problems to be solved on the gecko-like dry adhesive surfaces are prospected.

Individuals with cerebral palsy and muscular dystrophy often lack fi ne motor control of their fi ngers which makes it diffi cult 
to control traditional powered wheelchairs using a joystick. Studies have shown the use of surface electromyography to steer 
powered wheelchairs or automobiles either through simulations or gaming controllers. However, these studies signifi cantly 
lack issues with real world scenarios such as user’s safety, real-time control, and effi ciency of the controller mechanism. 
The purpose of this study was to design, evaluate, and implement a hybrid human–machine interface system for a powered 
wheelchair that can detect human intent based on artifi cial neural network trained hand gesture recognition and navigate 
a powered wheelchair without colliding with objects around the path. Scaled Conjugate Gradient (SCG), Bayesian Regularization (BR), and Levenberg Marquart (LM) supervised artifi cial neural networks were trained in offl ine testing on eight 
participants without disability followed by online testing using the classifi er with highest accuracy. Bayesian Regularization 
architecture showed highest accuracy at 98.4% across all participants and hidden layers. All participants successfully completed the path in an average of 5 min and 50 s, touching an average of 22.1% of the obstacles. The proposed hybrid system 
can be implemented to assist people with neuromuscular disabilities in near future.

This paper describes a novel gait pattern recognition method based on Long Short-Term Memory (LSTM) and Convolutional 
Neural Network (CNN) for lower limb exoskeleton. The Inertial Measurement Unit (IMU) installed on the exoskeleton to 
collect motion information, which is used for LSTM-CNN input. This article considers fi ve common gait patterns, including walking, going up stairs, going down stairs, sitting down, and standing up. In the LSTM-CNN model, the LSTM layer 
is used to process temporal sequences and the CNN layer is used to extract features. To optimize the deep neural network 
structure proposed in this paper, some hyperparameter selection experiments were carried out. In addition, to verify the 
superiority of the proposed recognition method, the method is compared with several common methods such as LSTM, CNN 
and SVM. The results show that the average recognition accuracy can reach 97.78%, which has a good recognition eff ect. 
Finally, according to the experimental results of gait pattern switching, the proposed method can identify the switching gait 
pattern in time, which shows that it has good real-time performance.

The buoyancy of traditional Underwater Glider (UG) with a rigid hull is aff ected by the changing marine parameters, making 
it diffi cult for the vehicle to dive deeper with good motion characteristics. In the present work, the development of a novel 
UG for neutral buoyancy, which is equipped with a Flexible-Liquid-Rigid (FLR) composite hull, is presented. The innovative hull that imitates the buoyancy regulation mechanism of marine organisms is easily adaptable to the changing marine 
environment. The rigid part of the composite hull withstands hydrostatic pressure for inner function modules of the vehicle. 
The liquid of the composite hull mainly serves as a buoyancy compensation to mitigate the eff ect of buoyancy variation 
caused by the changing marine parameters. The fl exible covering provides a good hydrodynamic shape for the vehicle under 
the internal liquid pressure. The buoyancy variation due to the composite hull compression as well as changes of seawater 
density and temperature was comprehensively considered in the design process and integrated to the dynamic model. In 
addition, sea trials were performed to verify the motion characteristics of the proposed vehicle. The results reveal that the 
Flexible-bodied Underwater Glider (FUG) has a better gliding performance in practice.

The bio-inspired aerial–aquatic vehicle off ers attractive perspectives for future intelligent robotic systems. Cormorant’s 
webbed-feet support water-surface takeoff is a typical locomotion pattern of amphibious water birds, but its highly maneuverable and agile kinetic behaviors are inconvenient to measure directly and challenging to calculate convergently. This paper 
presents a numerical Computational Fluid Dynamic (CFD) technique to simulate and reproduce the cormorant's surface 
takeoff process by modeling the three-dimensional biomimetic cormorant. Quantitative numerical analysis of the fl uid fl ows 
and hydrodynamic forces around a cormorant’s webbed feet, body, and wings are conducted, which are consistent with 
experimental results and theoretical verifi cation. The results show that the webbed feet indeed produced a large majority of 
the takeoff power during the initial takeoff stage. Prior lift and greater angle of attack are generated to bring the body off the 
water as soon as possible. With the discussion of the mechanism of the cormorant’s water-surface takeoff and the relevant 
characteristics of biology, the impetus and attitude adjustment strategies of the aerial–aquatic vehicle in the takeoff process 
are illustrated.

Soft robots have unique advantages over traditional rigid robots and have broad application prospects in many fi elds. To 
expand their bioinspired applications, we propose a novel Soft Pneumatic Actuator (SPA) associated with spiral confi guration inspired by the structure and unwinding motion of the seahorse tail. Diff erent from bending motion of common soft 
actuators, the spiral SPA can generate unwinding motion as input air pressure increases. First, to explore the eff ect of diff erent initial spiral types on unwinding performance, three typical spiral SPAs are designed and simulated while keeping the 
outside arc of actuator body constant. Second, a static model of the spiral SPA is established by combining the hyperelastic 
material model, geometric relationships, and virtual work principle. To improve model accuracy, two geometric correction 
parameters are employed and their physical signifi cance is analyzed by fi nite element simulations. Third, a prototype of the 
logarithmic spiral SPA (Log_spiral SPA) is fabricated and a Fiber Bragg Grating (FBG) sensor array is designed to detect and 
reconstruct unwinding shapes of the prototype. Finally, the unwinding performance, static model and output force capability 
of the prototype are tested and verifi ed. Furthermore, we discuss prospects for this novel spiral SPA and test its practical 
applications in inchworm-like motion, assisting fi nger rehabilitation and object capture.

A novel bionic piezoelectric actuator based on the walrus motion to achieve high performance on large working stroke 
for micro/nano positioning systems is fi rst proposed in this study. The structure of the proposed walrus type piezoelectric 
actuator is described, and its motion principle is presented in details. An experimental system is set up to verify its feasibility and explore its working performances. Experimental results indicate that the proposed walrus type piezoelectric actuator could realize large working stroke with only one driving unit and one coupled clamping unit; the maximum stepping 
displacement is Δ L max = 19.5 μm in the case that the frequency f = 1 Hz and the voltage U = 120 V; the maximum speed 
V max = 2275.2 μm · s ?1 when the frequency f = 900 Hz and the voltage U = 120 V; the maximum vertical load m max = 350 g 
while the voltage U = 120 V and the frequency f = 1 Hz. This study shows the feasibility of mimicking the bionic motion 
of the real walrus animal to the design of piezoelectric actuators, which is hopeful for the real application of micro/nano 
positioning systems to achieve large working stroke and high performance.

Venus fl ytrap can sense the very small insects that touch its tactile receptors, known as trigger hairs, and thus capture prey 
to maintain its nutrient demand. However, there are few studies on the trigger hair and its morphological structure and 
material properties are not fully understood. In this study, the trigger hair is systematically characterized with the help of 
diff erent instruments. Results show that trigger hair is a special cantilever beam structure and it has a large longitudinal 
diameter ratio. Besides, it is composed of a hair lever and a basal podium, and there is a notch near the hair base. The crosssection of the trigger hair is approximately a honeycomb structure, which is composed of many holes. Methods to measure 
mechanical properties of trigger hair are introduced in this paper. Based on the mechanical tests, trigger hair proved to be 
a variable stiff ness structure and shows a high sensitivity to the external force. These features can provide supports for the 
understanding of the high-sensitivity sensing mechanism of trigger hairs from the perspective of structure and material, and 
off er inspirations for the development of high-performance tactile sensors.

To adapt to a complex and variable environment, self-adaptive camoufl age technology is becoming more and more important in all kinds of military applications by overcoming the weakness of the static camoufl age. In nature, the chameleon can 
achieve self-adaptive camoufl age by changing its skin color in real time with the change of the background color. To imitate 
the chameleon skin, a camoufl aged fi lm controlled by a color-changing microfl uidic system is proposed in this paper. The 
fi lm with microfl uidic channels fabricated by soft materials can achieve dynamic cloaking and camoufl age by circulating 
color liquids through channels inside the fi lm. By sensing and collecting environmental color change information, the control signal of the microfl uidic system can be adjusted in real time to imitate chameleon skin. The microstructure of the fi lm 
and the working principle of the microfl uidic color-changing system are introduced. The mechanism to generate the control 
signal by information processing of background colors is illustrated. “Canny” double-threshold edge detection algorithm 
and color similarity are used to analyze and evaluate the camoufl age. The tested results show that camoufl aged images have 
a relatively high compatibility with environmental backgrounds and the dynamic cloaking eff ect can be achieved.

Unexpected ice accumulation tends to cause many problems or even disasters in our daily life. Based on the superior electrothermal and photothermal function of the carbon nanotubes, we introduced a superhydrophobic/electrothermal/photothermal synergistically anti-icing strategy. When a voltage of 15 V was applied to the superhydrophobic sample, the surface 
could rapidly melt the ice layer (~ 3 mm thickness) within 530 s at the environmental temperature of ? 25 °C. When the 
near-infrared light (808 nm) irradiates on the superhydrophobic sample, the ice could be rapidly removed after 460 s. It was 
found that the superhydrophobicity helps the melted water to roll off immediately, and then solves the re-freeze problem the 
traditional surfaces facing. Moreover, the ice can be completely melted with 120 s when the superhydrophobic/electrothermal/
photothermal synergistically anti-icing strategy was utilized. To improve the mechanical robustness for practical application, 
both nanoscale carbon nanotubes and microscale carbon powders were utilized to construct hierarchical structure. Then 
these dual-scale fi llers were sprinkled onto the semi-cured elastomer substrate to prepare partially embedded structure. Both 
hierarchical structure and partially embedded structure were obtained after completely curing the substrate, which imparts 
excellent abrasion resistance (12.50 kPa, 16.00 m) to the prepared sample. Moreover, self-healable poly(urea–urethane) 
elastomer was introduced as the substrate. Thus, the cutted superhydrophobic sample can be mended by simply contacting 
at room temperature.

Brass is widely used in machinery, electronic appliances and emerging industries. The corrosion resistance of laser-induced 
superhydrophobic surface of brass needs to be improved. In recent years, bionic surface with slippery coating has attracted 
much attention because of its excellent corrosion inhibition performance. Here, we fi rst prepared the superhydrophobic 
surface of brass by nanosecond laser ablation combined with fl uoroalkyl silane modifi cation, and then injected silicone oil 
into the prepared superhydrophobic matrix to obtain a slippery coating surface. PDP and EIS tests in 3.5 wt.% NaCl solution showed that the corrosion resistance of the slippery surface was better than that of the superhydrophobic surface. This 
study can play a certain role in promoting the development of metal anticorrosive coating and is of great signifi cance in the 
preparation of slippery surface by laser induction, and provides a convenient and eff ective means for metal anticorrosion in 
the industrial fi eld.

Inspired by nature, a superhydrophobic and magnetic melamine sponge (BFSM-MF) was fabricated by a one-step dip-coating 
method. Aiming at replacing nano-Fe 3 O 4 particles with a complex preparation process and high cost, the commercial and 
cheap Fe 3 O 4 originated from magnetite was employed as a magnetic substance. To acquire superhydrophobicity, the hierarchical mirco/nano-sized structure with low surface energy was mainly contributed by bonding hydrophobic Fe 3 O 4 and 
graphene with silicone resin onto the surface of the melamine sponge. The results demonstrated that the water and oil static 
contact angle values of BFSM-MF were 160° and 0°, revealing that BFSM-MF was superhydrophobic and super-oleophilic. 
Moreover, the self-cleaning ability, magnetic-driven oil absorption ability and continuous oil–water separation performance 
of BFSM-MF have also been evaluated. As expected, BFSM-MF possessed magnetic-driven oil absorption ability and the 
oil–water separation effi ciency for light oil reaches 98% ± 1%. In addition, the adsorption capacity and recycling performance 
of diff erent organic solvents were systematically investigated. Therefore, the development of biomimetic, fl uorine-free and 
superhydrophobic foam with magnetic-driven eff ect has potential application value in marine oil spill treatment and separation of domestic oil pollution.

The structural characteristics of the surfaces of sharkskin have great infl uence on their aerodynamic performance. It has been 
proved that the sharkskin’s ribbed structure can improve the aerodynamic performance of the parts up to 10%. At present, the 
main processing methods for this structure are laser, rolling, etc., which have low effi ciency and poor surface integrity. Belt 
grinding is widely used in the surface grinding and polishing. It plays an important role in improving the surface integrity 
and can realize the micro-structure machining at the same time. To achieve drag reduction, based on the characteristics of 
drag reduction of Bionic-Ribbed Structures (BRS), diff erent BRS (V, trapezoid and wave) on a blade were processed and 
studied. First, this paper introduces the theory of drag reduction induced by BRS and processing methods of diff erent BRS 
on a blade by belt grinding, and carried out the verifi cation of the belt-grinding methods. Then, diff erent BRS models were 
established on the blade with diff erent tip angles, and the aerodynamic performance was analyzed through simulation. It 
was found that the low-velocity layer near the BRS decreased when tip angle increased. Its wall shear stress also increased 
and tip angle of 45o had the best performance regardless of which BRS was. Some suggestions were given for belt grinding. 
The velocity along height from valley of BRS and velocity streamline was demonstrated. Secondary vortex was observed. 
Velocity gradient and vortex were the main reasons for the diff erence of wall shear stress.

Hydrogel has been widely used in the research of bionic articular cartilage due to their similarity in structure and functional 
properties to natural articular cartilage. In this research, polyvinyl alcohol and betaine monomer were used as raw materials to prepare a high-strength double-network hydrogel by a combination of ultraviolet (UV) irradiation and freeze–thaw 
methods. The structure of samples was characterized by Fourier transform infrared spectroscopy and X-ray diff raction, 
and the morphology of the samples was characterized by scanning electron microscope and three-dimensional white light 
interferometer. In addition, we also studied the swelling ratio, water content, mechanical properties and tribological properties of the samples. We found that the addition of betaine monomer and the UV irradiation time had a positive eff ect on the 
mechanical properties and tribological properties of the samples.

Polyvinyl alcohol (PVA) hydrogels with excellent characteristics are considered as promising cartilage replacement materials. 
However, there are still some main issues to be solved for PVA hydrogel, such as poor mechanical strength and disordered 
structure. Inspired by the highly ordered structure of biological soft tissues such as articular cartilage, here, we prepared a
high-strength but anisotropic polyvinyl alcohol-nanohydroxyapatite-polyacrylic acid (PVA-HA-PAA) composite hydrogel 
by directional stretching, freezing–thawing, and annealing method. Stretching of an as-prepared isotropic PVA-HA-PAA 
composite hydrogel leads to the orientation of PVA crystallites and PVA chains, which enables the formation of ordered 
structure and more hydrogen bonds via freezing under stretching. The microstructure, water content, swelling and creep 
performance, tensile and bio-tribology properties of the composite hydrogel are studied, the results indicated that the properties of the hydrogel are aff ected by stretching due to the formation of ordered structure in the anisotropic hydrogel. For 
instance, the elastic modulus and tensile strength of the anisotropic hydrogel reach 5.703 MPa and 18.958 MPa, respectively, 
which is signifi cantly enhanced by comparing with isotropic hydrogel. Moreover, the friction property is anisotropic, and the 
Coeffi cient Of Friction (COF) reduced in the parallel direction. Thus, this work provides a simple and practicable strategy 
to design strong and anisotropic hydrogels for potential applications in biomedical materials such as cartilage substitute.

Multifunctional phase change composites are in great demand for all kinds of industrial technologies and applications, which 
have both superior latent heat capacity and excellent solar-thermal conversion capability. In this research, biomimetic phase 
change composites are made by inspired by natural systems, successfully getting the high thermal conductivity of carbon 
foam and magnetism of composites together, to establish a novel solar-thermal energy storage method. The morphology 
and the thermal characteristics of biomimetic phase change composites have been characterized. The results showed that 
the maximum storage effi ciency of the biomimetic phase change materials increased by 56.3% compared to that of the based 
materials, and it can further be improved by the application of magnetic fi eld. Meanwhile the heat transfer process of solarthermal conversion and energy storage in biomimetic porous structure under the external physical fi elds has been explained 
by simulation. Thus, the magnetic fi eld-induced method applied in this research has better solar-thermal energy storage 
characteristics within a porous structure by dynamically controlling the magnetism, which has potential uses for various 
sustainable applications, including waste-heat recovery, energy conservation in building, and solar-thermal energy storage.

In nature, bees with damaged tongues are adapted to have a feat in collecting nectariferous sources in a large spectrum of 
concentrations (19%–69%) or viscosities (10 –3 Pa·s to 10 –1  Pa·s); however, eff ects of nectar property on compensated dipping behavior remain elusive. Combining the bee tongue anatomy, high-speed videography, and mathematical models, we 
investigate responses of honey bees with damaged tongues to fl uidic sources in various properties. We fi nd that, bees with 
80% damaged tongues are deprived of feeding capability and remarkably, the dipping frequency increases from 4.24 Hz to 
5.08 Hz while ingesting 25% sugar water when the tongue loses 0–30% in length, while declines from 5.08 to 3.86 Hz in case 
of 30% damaged tongue when sucrose concentration increases from 25% to 45%. We employ the energetic compensation 
rate and energetic utilization rate to evaluate eff ectiveness of the compensation from the perspective of energetic regulation. 
The mathematical model indicates that the energetic compensation rate turns higher in bees with less damaged tongues 
for ingesting dilute sugar water, demonstrating its capability of functional compensation for combined factors. Also, the 
tongue-damaged bees achieve the highest energetic utilization rate when ingesting ~ 30% sugar water. Beyond biology, the 
fi ndings may shed lights on biomimetic materials and technologies that aim to compensate for geometrical degradations 
without regeneration.