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Limb loss affects many people from a variety of backgrounds around the world. The most advanced commercially available prostheses for transfemoral amputees are fully active (powered) designs but remain very expensive and unavailable in the developing world. Consequently, improvements of low-cost, passive prostheses have been made to provide high quality rehabilitation to amputees of any background. This study explores the design and evaluation of a smooth-locking-based bionic knee joint to replicate the swing phase of the human gait cycle. The two-part design was based on the condyle geometry of the interface between the femur and tibia obtained from MR images of the human subject, while springs were used to replace the anterior and posterior cruciate ligaments. A flexible four-bar linkage mechanism was successfully achieved to provide not only rotation along a variable instantaneous axis but also slight translation in the sagittal plane, similar to the anatomical knee. We systematically evaluated the effects of different spring configurations in terms of stiffness, position and relaxion length on knee flexion angles during walking. A good replication of the swing phase was achieved by relatively high stiffness and increased relaxation length of springs. The stance phase of the gait cycle was improved compared to some models but remained relatively flat, where further verification should be conducted. In addition, 3D printing technique provides a convenient design and manufacturing process, making the prosthesis customizable for different individuals based on subject-specific modelling of the amputee's knee.

Human finger joints are conventionally simplified as rigid joints in robotic hand design and biomechanical hand modelling, due to their anatomic and morphologic complexity. However, our understanding of the effect of the finger joint configuration on the resulting hand performance is still primitive. In this study, we systematically investigate the grasping performance of the hands with the conventional rigid joints and the biomechanical flexible joints based on a computational human hand model. The measured muscle electromyography (EMG) and hand kinematic data during grasping are used as inputs for the grasping simulations. The results show that the rigid joint configuration currently used in most robotic hands leads to large reductions in hand contact force, contact pressure and contact area, compared to the flexible joint configuration. The grasping quality could be reduced up to 40% and 36% by the rigid joint configuration in terms of algebraic properties of grasping matrix and finger force limit respectively. Further investigation reveals that these reductions are caused by the weak rotational stiffness of the rigid joint configuration. This study implies that robotic/prosthetic hand performance could be improved by exploiting flexible finger joint design. Hand contact parameters and grasping performance may be underestimated by the rigid joint simplification in human hand modelling.

Understanding the distinct functions of human muscles could not only help professionals obtain insights into the underlying mechanisms that we accommodate compromised neuromuscular system, but also assist engineers in developing rehabilitation devices. This study aims to determine the contribution of major muscle and the energy flow in the human musculoskeletal system at four sub-phases (collision, rebound, preload, push-off) during the stance of walking at different speeds. Gait experiments were performed with three self-selected speeds: slow, normal, and fast. Muscle forces and mechanical work were calculated by using a subject-specified musculoskeletal model. The functions of individual muscles were characterized as four functional behaviors (strut, spring, motor, damper), which were determined based on the mechanical energy. The results showed that during collision, hip flexors (iliacus and psoas major) and ankle dorsiflexors (anterior tibialis) were the most dominant muscles in buffering the stride with energy absorption; during rebound, the posterior muscles (gluteus maximus, gastrocnemius, posterior tibialis, soleus) contributed the most to energy generation; during preload, energy for preparing push-off was mainly absorbed by the muscles surrounding knee (vastus, semimembranosus, semitendinosus); during push-off, ankle plantar flexors (gastrocnemius, soleus, posterior tibialis, peroneus muscles, flexor digitorum, flexor hallucis) mainly behaved to generate energy for forward propulsion. With increased walking speed, additional energy (almost 400%) from harder stride was mainly absorbed by the flexor muscles. Hip extensors and adductors transferred more energy (around 150%) to the distal segments during rebound. Soleus and gastrocnemius muscles generated more energy (about 75%) to the proximal segments for propulsion. Along with our previous study of joint-level energy analysis, these findings could assist better understanding of human musculoskeletal behaviors during locomotion and provide principles for the bio-design of related assistive devices from motors performance enhancement to rehabilitation such as exoskeleton and prosthesis.

A variety of prosthetic ankles have been successfully developed to reproduce the locomotor ability for lower limb amputees in daily lives. However, they have not been shown to sufficiently improve the natural gait mechanics commonly observed in comparison to the able-bodied, perhaps due to over-simplified designs of functional musculoskeletal structures in prostheses. In this study, a flexible bionic ankle prosthesis with joints covered by soft material inclusions is developed on the basis of the human musculoskeletal system. First, the healthy side ankle–foot bones of a below-knee amputee were reconstructed by CT imaging. Three types of polyurethane rubber material configurations were then designed to mimic the soft tissues around the human ankle, providing stability and flexibility. Finite element simulations were conducted to determine the proper design of the rubber materials, evaluate the ankle stiffness under different external conditions, and calculate the rotation axes of the ankle during walking. The results showed that the bionic ankle had variable stiffness properties and could adapt to various road surfaces. It also had rotation axes similar to that of the human ankle, thus restoring the function of the talocrural and subtalar joints. The inclination and deviation angles of the talocrural axis, 86.2° and 75.1°, respectively, as well as the angles of the subtalar axis, 40.1° and 29.9°, were consistent with the literature. Finally, dynamic characteristics were investigated by gait measurements on the same subject, and the flexible bionic ankle prosthesis demonstrated natural gait mechanics during walking in terms of ankle angles and moments.

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain, designated as HK4-1T, was isolated from mangrove sediments in Hong Kong, PR China. Based on 16S rRNA gene sequence data, strain HK4-1T was found to belong to the genus Novosphingobium , family Erythrobacteraceae , and showed high similarity to Novosphingobium chloroacetimidivorans BUT-14T (96.88 %) and Novosphingobium indicum H25T (96.88 %). The G+C content of the whole genome of strain HK4-1T was 64.05 mol%. The major fatty acids were C16 : 0, C18 : 1 ω7c and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, sphingoglycolipid and two unknown lipids. The predominant respiratory quinone was Q-10. Based on genomic, phylogenetic, phenotypic, physiological and chemotaxonomic data, strain HK4-1T should be classified as representing a novel species of the genus Novosphingobium , for which the name Novosphingobium mangrovi sp. nov. is proposed. The type strain of Novosphingobium mangrovi sp. nov. is HK4-1T (=MCCC 1K08252T=JCM 35764T).

Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex (AJC) is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders, as well as an essential guide to the design of ankle–foot assistant devices. However, detailed analysis of the continuous 3D motion of the tibiotalar and subtalar joints during normal walking throughout the stance phase is still considered to be lacking. In this study, dynamic radiographs of the hindfoot were acquired from eight subjects during normal walking. Natural motions with six Degrees of Freedom (DOF) and the coupled patterns of the two joints were analyzed. It was found that the movements of the two joints were mostly in opposite directions (including rotation and translation), mainly in the early and late stages. There were significant differences in the Range of Motion (ROM) in Dorsiflexion/Plantarflexion (D/P), Inversion/Eversion (In/Ev), and Anterior–Posterior (AP) and Medial–Lateral (ML) translation of the tibiotalar and subtalar joints (p R2 = 0.87 and 0.86, respectively), and plantarflexion of the tibiotalar joint was coupled with inversion and anterior translation of the subtalar joint during the push-off phase (R2 = 0.93 and 0.75, respectively). This coordinated coupled motion of the two joints may be a manifestation of the AJC to move flexibly while bearing weight and still have stability.

Tactile sensors are instrumental for developing the next generation of biologically inspired robotic prostheses with tactile feedback capability. However, current sensing technology is still less than ideal either in terms of sensitivity under high pressure or compliance with uneven working surfaces. Also, the fabrication of tactile sensors often requires the use of highly sophisticated and costly manufacturing processes further limiting the widespread application of the technology. Here, we challenge the current perspective and propose the use of an in-house 3D printing system to develop a new conformal tactile sensor with enhanced sensing performance. The ability of the sensor to detect multi-directional stimuli is achieved through the integration of the auxetic structure and interlocking features. The unique design of our sensor allows for an extended sensing range (from 0.1 to 0.26 MPa) whilst providing sensitivity on both normal and shear directions at 0.63 KPa− 1 and 0.92 N− 1, respectively. This is further complemented by capacity of the sensor to detect small temperature variations between 40 and 90°C. To demonstrate the feasibility of our approach, the tactile sensor is printed in situ on the fingertip of an anthropomorphic robotic hand, the proximal femur head and lumbar vertebra. The results suggest that it is possible to gain sensorimotor control and temperature sensing ability in artificial upper limbs whilst monitoring the bone-on-bone load, thus opening the door to a new generation of tactile sensors with novel auxetic structure design and enhanced performance for application in human prosthetics.

Prosthetic knees are state-of-the-art medical devices that use mechanical mechanisms and components to simulate the normal biological knee function for individuals with transfemoral amputation. A large variety of complicated mechanical mechanisms and components have been employed; however, they lack clear relevance to the walking biomechanics of users in the design process. This article aims to bridge this knowledge gap by providing a review of prosthetic knees from a biomechanical perspective and includes stance stability, early-stance flexion and swing resistance, which directly relate the mechanical mechanisms to the perceived walking performance, i.e., fall avoidance, shock absorption, and gait symmetry. The prescription criteria and selection of prosthetic knees depend on the interaction between the user and prosthesis, which includes five functional levels from K0 to K4. Misunderstood functions and the improper adjustment of knee prostheses may lead to reduced stability, restricted stance flexion, and unnatural gait for users. Our review identifies current commercial and recent studied prosthetic knees to provide a new paradigm for prosthetic knee analysis and facilitates the standardization and optimization of prosthetic knee design. This may also enable the design of functional mechanisms and components tailored to regaining lost functions of a specific person, hence providing individualized product design.

Flatfoot is a common foot deformity that seriously affects the quality of life. The aim of this study is to develop an accurate and noninvasive method for the diagnosis of flatfoot based on B-mode ultrasound. In this study, 51 patients (the flatfoot group) and 43 healthy subjects (the control group) were included. The plantar fascia angle, a new measurement for use in the diagnosis of flatfoot is proposed, as determined using B-mode ultrasound. For comparison, the calcaneal pitch angle and medial cuneiform height were also measured using lateral X-radiography, based on traditional diagnostic methods. The intraclass correlation values of the plantar fascia angle, the calcaneal pitch angle, and the medial cuneiform height were all more than 0.95, and there is a moderate correlation (r = 0.51) between the medial cuneiform height and the calcaneal pitch angle, and an excellent correlation (r = 0.85) between the plantar fascia angle and the calcaneal pitch angle. The optimal cutoff value, sensitivity, and specificity for medial cuneiform height in flatfoot diagnosis were 12.8 mm, 93.0%, and 54.9%, respectively. The optimal cutoff value, sensitivity, and specificity for plantar fascia angle in flatfoot diagnosis were 9.8°, 97.7%, and 94.1%, respectively. The proposed plantar fascia angle has good sensitivity and specificity in diagnosing flatfoot, therefore supplying a new approach for the noninvasive diagnosis of flatfoot.

The level of joint laxity, which is an indicator of accurate diagnosis for musculoskeletal conditions is manually determined by a physician. Studying joint laxity via artificial joints is an efficient and economical way to improve patient experience and joint proficiency. However, most of study focus on the joint geometry but are inadequate with regard to the tailored mechanical properties of soft tissues. On the basis of collagen fibril deformation, this study proposes bioinspired 3D fibers braided from polyethene multifilament for the reproduction of the controlled nonlinear behavior of ligaments and tendons. Four braided bands are designed, all showing biological behaviors. Two knot-based bands exhibit large toe strains of 10.98% and 5.33% but low linear modulus of 239.84 MPa and 826.05 MPa. The other two bands without knots exhibit lower toe strains of 1.61% and 1.52% but high linear modulus of 2605.27 MPa and 2050.74 MPa. Empirical formulas for braiding parameters (wales and courses) and mechanical properties are expressed to provide a theoretical basis for the mimicry of different tissues in the human body by artificial joints. All parameters have significant effects on the linear region of the load-displacement curve of a fiber due to braided structure, while changing the number of wales facilitates a major contribution to the toe region. A biofidelic human knee has been successfully reconstructed by using bioinspired 3D braided fibers. This study demonstrates that the nonlinear mechanical properties of soft tissues can be replicated by bioinspired 3D braided fibers, further yielding the design of more biomechanically realistic artificial joints.

Benzo [a]pyrene (BaP) is a type of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) with potent carcinogenicity; however, there are limited studies on its degradation mechanism. Here, a strain of Pontibacillus sp. HN14 with BaP degradation ability was isolated from mangrove sediments in Dongzhai Port, Hainan Province. Our study showed that biodegradation efficiencies reached 42.15% after Pontibacillus sp. HN14 was cultured with 20 mg L

The knee joint plays a key role in kinematic and kinetic performances of pedestrain locomotion. The key role of meniscus with matched ligaments in joint stability and movability has not been fully explored in current robotic knee designs. We fabricate a bioinspired robotic knee based on a kinematic model of an anatomical knee in order to reveal the relationship between the meniscus, ligaments and their stability and movability, respectively. The kinematic model was built from magnetic resonance imaging of the human knee with generated contact profiles and customized ligament fibers. Then, the bioinspired knee was designed, and its dynamic stability was maintained by ligaments and specific contact profiles, which were acquired based on the kinematic model. Finally, a monopod robot with the bioinspired knee assembled was developed for dynamic testing. The results show that (1) a smooth rolling–sliding motion can be achieved with the addition of menisci and compatible ligaments; and (2) joint stiffness can be adjusted by changing the springs and activation lengths of ligament fibers. This study gives biomimetic insights into a new design of knee joint for a robotic/prosthetic leg.

Human shoulder joints exhibit stable but highly active characteristics due to a large amount of soft tissues. Finite Element (FE) modelling plays an important role in enhancing our understanding of the mechanism of shoulder disorders. However, the previous FE shoulder models largely neglected the Three-Dimensional (3D) volume of soft tissues and their sophisticated interactions with the skeletons. This study develops a 3D model of the rotator cuff and deltoid muscles and tendons. It also includes cartilage and, for the first time, main ligaments around the joint to provide a better computational representation of the delicate interaction of the soft tissues. This model has potential value for studying the force transfer mechanism and overall joint stability variation caused by 3D pathological changes of rotator cuff tendons. Motion analysis systems and Magnetic Resonance (MR) scans were used to collect shoulder movement and geometric data from a young healthy subject, respectively. Based on MR images, a FE model with detailed representations of the musculoskeletal components was constructed. A multi-body model and the measured motion data were utilised to estimate the loading and boundary conditions. Quasi-static FE analyses simulated four instants of the measured scapular abduction. Simultaneously determined glenohumeral motion, stress/strain distribution in soft tissues, contact area, and mean/peak contact pressure were found to increase monotonically from 0° to 30° of abduction. The results of muscle forces, bone-on-bone contact force, and superior-inferior movement of the humeral centre during motion were consistent with previous experimental and numerical results. It is concluded that the constructed FE shoulder model can accurately estimate the biomechanics in the investigated range of motion and may be further used for the comprehensive study of shoulder musculoskeletal disorders.

It is generally known that forelimbs and hindlimbs play different roles during locomotion, but the possible differences in the biomechanical functions of the metacarpal pad and metatarsal pad remain unknown. This study combined kinematic and pressure data from dogs to investigate the key roles of the metacarpal and metatarsal pads. The peak vertical ground reaction force of the metacarpal pad was found to be larger than that of the metatarsal pad, whereas the peak vertical ground reaction force of the fore toes was equal to that of hind toes, and the vertical deformations of the metacarpal and metatarsal pads were almost equal; moreover, the obtained stiffness of the metacarpal pad was several times greater than that of metatarsal pad based on in vivo measurement data. The results showed that the metacarpal pad demonstrated the biomechanical characteristics of cushion and support; however, the support characteristics of the metatarsal pad were weak. Furthermore, magnetic resonance imaging was performed to gather evidence to interpret the various roles played by the metacarpal pad and the metatarsal pad. It was found that the morphology and volumes of internal adipose tissues were closely related to the functions played by the metapodial pad during movement.

Quantifying the effect of routing and topology of the inter-connected finger extensor mechanism on hand grasping performances is a long-standing research problem for the better clinical diagnosis, surgical planning and biomimetic hand development. However, it is technically demanding to measure the hand performance parameters such as the contact forces and contact area during hand manipulation. It is also difficult to replicate human hand performance through the physical hand model due to its sophisticated musculotendinous structure. In this study, an experimental validated subject-specific finite element (FE) human hand model was used for the first time to quantify the influence of different tendon topologies and material properties on hand grasping quality. It is found that the grasping quality is reduced by 15.94% and 8.54% if there are no extensor hood and lateral band respectively, and the former plays a more important role in transmitting forces and maintaining grasping qualities than the latter. Excluding extensor hood in the topology causes more reductions in hand contact pressure and contact area than omitting lateral band. 7.5% of the grasping quality is lost due to a softened tendon with half of its original Young’s Modulus. Hardened extensor tendon does increase the grasping quality, but the enhancing effect tends to level off once the tendon Young’s Modulus is increased by more than 50%. These results prove that the lateral band and extensor hood are critical components for maintaining grasping quality. The dexterity and grasping quality of robotic and prosthetic hands could be improved by integrating these two components. There is also no need to use very stiff tendon material as it won’t help to effectively enhance the grasping quality.

Plantar fascia plays an important role in human foot biomechanics; however, the morphology and mechanical properties of plantar fascia in patients with flexible flatfoot are unknown. In this study, 15 flexible flatfeet were studied, each plantar fascia was divided into 12 positions, and the morphologies and mechanical properties in the 12 positions were measured in vivo with B-mode ultrasound and shear wave elastography (SWE). Peak pressures under the first to fifth metatarsal heads (MH) were measured with FreeStep. Statistical analysis included 95% confidence interval, intragroup correlation coefficient (ICC1,1), one-way analysis of variance (one-way ANOVA), and least significant difference. The results showed that thickness and Young’s modulus of plantar fascia were the largest at the proximal fascia (PF) and decreased gradually from the proximal end to the distal end. Among the five distal branches (DB) of the fascia, the thickness and Young’s modulus of the second and third DB were larger. The peak pressures were also higher under the second and third MH. This study found a gradient distribution in that the thickness and Young’s modulus gradient decreased from the proximal end to the distal end of plantar fascia in the longitudinal arch of flexible flatfeet. In the transverse arch, the thickness and Young’s modulus under the second and third DB were larger than those under the other three DB in flexible flatfoot, and the peak pressures under the second and third MH were also larger than those under the other three MH in patients with flexible flatfoot. These findings deepen our understanding of the changes of biomechanical properties and may be meaningful for the study of pathological mechanisms and therapy for flexible flatfoot.

Chemical plating has recently been employed for the preparation of flexible piezoresistive sensors; however, plating solutions and processes that affect the sensitivity still need further exploration. In the study, a sponge-based flexible sensor with copper as its conductive material is prepared using electroless plating. The variation in sponge resistance and sensitivity changes with different plating times are studied. It is found that, with the increasing plating time, the conductivity increases and the resistance of sample will decrease. Moreover, the range of resistance difference will decrease under compression, thus the sensitivity decreases. Furthermore, the sensor’s applications were assessed, verifying the practicability of the developed preparation method. This study may bring ideas for the new development of flexible pressure sensors.

The goose’s neck is an excellent stabilizing organ with its graceful neck curves and flexible movements. However, the stabilizing mechanism of the goose’s neck remains unclear. This study adopts a dynamic in vivo experimental method to obtain continuous and accurate stable motion characteristics of the goose’s cervical vertebra. Firstly, the results showed that when the body of a goose was separately moved back and forth along the Y direction (front and back) and Z direction (up and down), the goose’s neck can significantly stabilize the head. Then, because of the limitation of the X-ray imaging area, the three-dimensional intervertebral rotational displacements for vertebrae C4–C8 were obtained, and the role that these five segments play in the stabilization of the bird’s neck was analyzed. This study reveals that the largest range of the adjacent vertebral rotational movement is around the X-axis, the second is around the Y-axis, and the smallest is around the Z-axis. This kinematic feature is accord with the kinematic feature of the saddle joint, which allows the flexion/around X-axis and lateral bending/around Y-axis, and prevents axial rotation/around Z-axis.

BACKGROUND The fifth and sixth cervical vertebrae (C5-C6) represent the high-risk segment requiring surgical correction in cervical spondylosis. Anterior cervical discectomy and fusion (ACDF) of C5-C6 includes an intervertebral fusion cage to maintain foraminal height and is combined with anterior plate fixation. The shape of the intervertebral cage can affect the postoperative outcome, including the rates of fusion, subsidence, and neck pain. This study aimed to use finite element (FE) parametric analysis to compare biomechanical properties of changes in intervertebral cage shape for C5-C6 cervical fusion using the anterior cervical plate and cage (ACPC) fixation system. MATERIAL AND METHODS Five shapes were designed for cervical intervertebral cages, square, oval, kidney-shaped, clover-shaped, and 12-leaf-shaped. The performance was evaluated following implantation into the validated normal C5-C6 FE model using simulation with five physiological conditions. The indicators included the maximum von Mises stress of the endplates, the fusion cages, and the cervical vertebrae. The postoperative subsidence-resistance properties were determined, including the interior stress responses of the intervertebral cages and the surrounding tissues. The fusion-promoting properties were evaluated by the interior stress responses of the bone grafts. RESULTS The optimal shape of the cervical intervertebral cage was the 12-leaf-shape for postoperative subsidence resistance. The kidney shape for the cervical intervertebral cage was optimal for postoperative fusion. CONCLUSIONS FE analysis identified the optimal cervical intervertebral cage design for ACPC fixation of C5-C6. This method may be useful for future developments in the design of spinal implants.

The ankle–foot complex in the human body is one of the major determinants in normal human walking. Most of the research study ankle and foot motion by observing people as they move, measuring desired kinematic and kinetic data indoor or outdoor, and numerical simulations in computer. However, very few studies are able to explore the fundamental mechanical principles underlying human musculoskeletal system. In this paper, we developed a three-dimension (3D) passive dynamic walker with flat feet, toes and ankle springs to investigate the impact of the ankle and toe stiffness in the walking motion. The results suggest that the ankle springs have a main impact on the walking motion, where the anterior spring, over any other position, plays a main role in providing sagittal stability. The springs from the sagittal plane control the pitch angle of the robot which impacts on its velocity and step length. The stability got worse along with the step length and velocity increasing especially when the step length overcame 8 cm. The fact that the best configuration of the ankle joint has stiffer stiffness in the sagittal plane than the coronal plane complies in nature with humans where Tibialis Anterior, Soleus and Gastrocnemius muscles are much stronger than other muscles around the ankle. Furthermore, it can be stated that the medial toe plays a more important role than the lateral one, as blocking the medial toe with the stiffest joint (rigid joint) has a negative effect on walking motion. In conclusion, we show that the ankle stiffness of the robot in anterior–posterior position should be higher than that in medial–lateral position and the stiffness in any position should exceed a minimum level to maintain walking stability. Also, adding toes (medial one should be softer than the lateral) in the foot of the robot may benefit biped locomotion especially when taking longer step length.

The overall distributions of the plantar fascia thickness and Young’s modulus in the ten subjects were systematically investigated in this paper using two-dimensional ultrasound and shear wave elastography (SWE). The statistical analyses showed that ICC1,1 of the plantar fascia thickness and Young’s modulus ranged from 0.950 to 0.991, with the 95% CI in the range of 0.953–0.996. This result indicated that the thickness and Young’s modulus exhibited excellent retest reliability. The conclusion that both the thickness, $d$ , and Young’s modulus, $E$ , of the plantar fascia showed a simple and specific spatial dependence on the characteristics of the gradient distribution can be drawn. As the plantar fascia extends from the calcaneus to the five toes, both the thickness, $d$ , and Young’s modulus, $E$ , of the five bundles of plantar fascia showed a downward trend of a negative exponential function, and the thickness, $d$ , and Young’s modulus, $E$ , were the largest at the tubercle of the calcaneus and closest to the lowest value at the tubercles of the five metatarsal bones. The coefficient of determination (R2) of the fitting curve of thickness, $d$ , and Young’s modulus, $E$ , was higher than 0.959 in all ten subjects. The distribution characteristics of the plantar fascia thickness, $d$ , and Young’s modulus, $E$ , showed good consistency in the healthy subjects in this paper. The conclusions of this paper may provide more accurate references and a basis for material mechanics data for plantar fascia diseases (such as fasciitis) and foot mechanical models (such as finite element models).

This paper presents the design, analysis, and development of an anthropomorphic robotic hand coined MCR-hand II. This hand takes the advantages of both the tendon-driven and linkage-driven systems, leading to a compact mechanical structure that aims to imitate the mobility of a human hand. Based on the investigation of the human hand anatomical structure and the related existing robotic hands, mechanical design of the MCR-hand II is presented. Then, using D-H convention, kinematics of this hand is formulated and illustrated with numerical simulations. Furthermore, fingertip force is deduced and analyzed, and mechatronic system integration and control strategy are addressed. Subsequently, a prototype of the proposed robotic hand is developed, integrated with low-level control system, and following which empirical study is carried out, which demonstrates that the proposed hand is capable of implementing the grasp and manipulation of most of the objects used in daily life. In addition, the three widely used tools, i.e., the Kapandji score test, Cutkosky taxonomy, and Kamakura taxonomy, are used to evaluate the performance of the hand, which evidences that the MCR-hand II possesses high dexterity and excellent grasping capability; object manipulation performance is also demonstrated. This paper hence presents the design and development of a type of novel tendon–linkage-integrated anthropomorphic robotic hand, laying broader background for the development of low-cost robotic hands for both industrial and prosthetic use.

During human walking, mechanical energy transfers between segments via joints. Joint mechanics of the human body are coordinated with each other to adapt to speed change. The aim of this study is to analyze the functional behaviors of major joints during walking, and how joints and segments alter walking speed during different periods (collision, rebound, preload, and push-off) of stance phase. In this study, gait experiment was performed with three different self-selected speeds. Mechanical works of joints and segments were determined with collected data. Joint function indices were calculated based on net joint work. The results show that the primary functional behaviors of joints would not change with altering walking speed, but the function indices might be changed slightly (e.g., strut functions decrease with increasing walking speed). Waist acts as strut during stance phase and contributes to keep stability during collision when walking faster. Knee of stance leg does not contribute to altering walking speed. Hip and ankle absorb more mechanical energy to buffer the strike during collision with increasing walking speed. What is more, hip and ankle generate more energy during push-off with greater motion to push distal segments forward with increasing walking speed. Ankle also produces more mechanical energy during push-off to compensate the increased heel-strike collision of contralateral leg during faster walking. Thus, human may utilize the cooperation of hip and ankle during collision and push-off to alter walking speed. These findings indicate that speed change in walking leads to fundamental changes to joint mechanics.

AIMS The purpose of this study was to detect and compare the surface temperature of plantar vessels in mild diabetic peripheral neuropathy (DPN) patients and healthy controls, to explore a simple, convenient and reliable method for early diagnosis of DPN, and to explore the influence of sex and age on vascular surface temperature. MATERIALS AND METHODS In this study, 60 mild DPN patients (30 males and 30 females) and 60 healthy volunteers were randomly recruited according to their age and sex. Intra-class correlation coefficient was used to evaluate the repeatability of skin temperature measurement in the vascular area. A general linear model was used to analyse the difference of skin temperature between mild DPN patients and healthy controls. RESULTS The infrared detection results of skin temperature corresponding to blood vessels showed excellent test-retest reliability. There was no significant difference in skin temperature between sex and age. But there were significant differences in skin temperature between mild DPN patients and healthy controls, except for the posterior tibial artery. CONCLUSIONS For mild DNP patients, in case of no obvious abnormality in the infrared detection of lower extremity arterial surface temperature, the small vessels have shown early abnormal body surface temperature, that is, the surface temperature of related vessels increased. The research conclusions of this article not only enable us to better understand the correlation between body surface temperature and hemodynamic parameters, but also provide an in vivo, non-invasive, and convenient way of thinking and methods for early diagnosis of DPN.

This study aimed to elucidate the overall spatial distribution of palmar aponeurosis (PA) thickness, d, and Young's modulus, E, through two-dimensional ultrasound and shear wave elastography. Statistical analysis of the collected data of 14 subjects shows that the ICC

BACKGROUND The fifth and sixth cervical vertebra (C5-C6) is the most easily injured segment encountered in clinical practice. The anterior cervical plate and cage (ACPC) fixation system is always used to reconstruct the intervertebral height and maintain the segmental stability. The postoperative effect, such as subsidence, neck pain, and non-fusion, is greatly affected by the cervical cage structure design. This study determined reasonable structure size parameters that present optimized biomechanical properties related to the postoperative subsidence often accompanied with ACPC. MATERIAL AND METHODS Twenty bionic cages with different structural sizes (distance between the center of the cage and groove, groove depth, and groove width) were designed and analyzed based on the regression optimization design and analysis method combined with FE analysis. Because a previous study showed that greater stresses on the endplate are associated with higher risk of subsidence, the optimization object was selected as the stresses on endplate to lower it. RESULTS The postoperative stresses on the endplate of all cages with bionic structure design were proved to be lower than with the original one. The optimal structure size was the distance between the center of the cage and groove=0 mm, groove depth=3 mm, and groove width=4 mm. Regression analysis found the cage with optimized bionic structural parameters resulted in a 22.58% reduction of endplate stress response compared with the original one. CONCLUSIONS The bionic cage with optimized structural sizes can reduce the subsidence risk, suggesting that the optimization method has great potential applications in the biomechanical engineering field.

The snapping shrimp preys by rapidly closing its snapping claw to generate a fast water jet, creating a shockwave that bombards the nearby prey and other shrimp. This behaviour has led to considerable interest and research. However, the structure, surface morphology and mechanical properties of the snapping claw are unreported. We used a combination of techniques including scanning electron microscopy and nanoindentation to characterise the claw. These measurements were coupled with computational fluid dynamics (CFD) to understand how the microstructure contributes to drag reduction. We found that cone-shaped micropapillae, rhombic dents and short straight stripes were hierarchically distributed on the surface of the claw. CFD simulation showed that the micropapillae units changed the interaction between the turbulent and the wall from sliding friction to rolling friction, resulting in tire-shaped vortices. This also reduced the turbulent kinetic energy in the near-wall region, thereby contributing to drag reduction. The cross section of the claw revealed four layers comprising an epicuticle, exocuticle, endocuticle and a membranous layer. The exocuticle is composed of chitin fibres arranged vertically in a lamellar fashion and the endocuticle has a Bouligand-type structure. This special structure provides the snapping shrimp with good mechanical resistance during rapid closure. Both modulus and hardness decreased from the outermost epicuticle to the innermost membranous layer. The gradient modulus and hardness may help to suppress microcracks at the interfaces between different layers. The findings improve our understanding of the unique mechanism of the snapping claw and may lead to the development of novel biomimetic materials with enhanced drag reduction, impact and crack resistance properties.

Summary Humans and animals can achieve agile and efficient movements because the muscle can operate in different modes depending on its intrinsic mechanical properties. For bioinspired robotics and prosthetics, it is highly desirable to have artificial actuators with muscle-like properties. However, it still remains a challenge to realize both intrinsic muscle-like force-velocity and force-length properties in one single actuator simultaneously. This study presents a bioinspired soft actuator, named HimiSK (highly imitating skeletal muscle), designed by spatially arranging a set of synergistically contractile units in a flexible matrix similar to skeletal musculature. We have demonstrated that the actuator presents both intrinsic force-velocity and force-length characteristics that are very close to biological muscle with inherent self-stability and robustness in response to external perturbations. These outstanding properties result from the bioinspired architecture and the adaptive morphing of the flexible matrix material, which adapts automatically to mechanically diverse tasks without reliance on sensors and controllers., Graphical abstract, Highlights • The actuators present intrinsic force-length and force-velocity properties • The actuators provide a variable gearing mechanism to regulate load and velocity • The actuators enable a robotic system in response to external perturbations stably, Biotechnology; Biomechanical engineering; Mechanical systems; Materials mechanics

The simulated calculation is carried out on the ultrasonic detection process for stainless steel resistance spot welding by the finite element technology. It reveals the ultrasonic propagation characteristics and regularity in the inner of the spot welds, and provides a theoretical basis for selecting the Am as a characteristic parameter to represent the fusion state of the spot weld in the actual ultrasonic detection. Then the ultrasonic detection of spot welds with the presence of the porosity defect which easily appears is simulated, and the effect of the porosity on the ultrasonic propagation characteristics is studied. It is found that the ultrasonic reflection and transmission occur at the porosity defect, and finally the correctness and validity of the simulation and the model are verified by the experimental method.

Patellar tendinopathy is among the most widespread patellar tendon diseases in athletes that participate in activities involving running and jumping. Although their symptoms can be detected, especially at the inferior pole of the patella, their biomechanical cause remains unknown. In this study, a three-dimensional finite element model of knee complex was developed to investigate principal stress and strain distributions in the patellar tendon during 0° to 90° knee flexion and slow and fast level-ground walking. Results indicate that the patellar tendon is subjected to tensile stress and strains during all three activities. During flexion, its central proximal posterior region exhibited highest peak stress and strain, followed by central distal posterior, central distal anterior and central proximal anterior region. Similar trends and magnitudes were reported during slow and fast walking. The region with highest principal stresses and strains, central proximal anterior region, also corresponds to the most commonly reported patellar tendinopathy lesion site, suggesting that principal stress and strain are good indicators of lesion site location. Additional factors such as regional variations in material properties and frequency and duration of cyclic loading also need to be considered when determining the biomechanical aetiology of patellar tendinopathy.

Ankle push-off occurs when muscle–tendon units about the ankle joint generate a burst of positive power at the end of stance phase in human walking. Ankle push-off mainly contributes to both leg swing and center of mass (CoM) acceleration. Humans use the amount of ankle push-off to induce speed changes. Thus, this study focuses on determining the faster walking speed and the lowest energy efficiency of biped robots by using ankle push-off. The real-time-space trajectory method is used to provide reference positions for the hip and knee joints. The torque curve during ankle push-off, composed of three quintic polynomial curves, is applied to the ankle joint. With the walking distance and the mechanical cost of transport (MCOT) as the optimization goals, the genetic algorithm (GA) is used to obtain the optimal torque curve during ankle push-off. The results show that the biped robot achieved a maximum speed of 1.3 m/s, and the ankle push-off occurs at 41.27−48.34% of the gait cycle. The MCOT of the bipedal robot corresponding to the high economy gait is 0.70, and the walking speed is 0.54 m/s. This study may further prompt the design of the ankle joint and identify the important implications of ankle push-off for biped robots.

Ankle push-off is defined as the phase in which muscle-tendon units about the ankle joint generate a burst of positive power during the step-to-step transition in human walking. The dynamic walking of a biped robot can be effectively realized through ankle push-off. However, how to use ankle push-off to balance the walking speed and energy efficiency of biped robots has not been studied deeply. In this study, the effects of the step length (the inter-leg angle is 40°, 50°, and 60°), torque and timing of ankle push-off on the walking speed and energy efficiency of biped robots were studied. The results show that when the step length is 50°, the push-off torque is 30 N· m and the corresponding push-off timing occurs at 43% of the gait cycle, the simulated robot obtains a highly economical walking gait. The corresponding maximum normalized walking speed is 0.40, and the minimum mechanical cost of transport is 2.25. To acquire a more economical walking gait of biped robots, the amount of ankle push-off and the push-off timing need to be coordinated. The purpose of this study is to provide a reference for the influence of ankle push-off on the motion performance of biped robots.

In this paper, ultrasonic echo signals of four kinds of stainless steel resistance spot welds, namely failed weld, stick weld, good weld, and defective weld with gas pore, are analyzed in the time domain, frequency domain, and time-frequency domain based on wavelet packet transform. Fourteen ultrasonic characteristic signals which can reflect the different kinds of spot welds are extracted and can be automatically identified and classified by back-propagation (BP) neural network. The method of this paper can realize the intelligent identification of resistance spot welding defects, and the feasibility of this method has been verified in the experiment.

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 dynamic 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 significantly 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.

Previous studies on knee biomechanics have mainly focused on the joint structure itself, largely neglecting the material properties of the muscles and connective tissues around the knee joint. Therefore, this study was purposed to conduct a systematic in vivo examination of the material properties of muscles, tendons, and ligaments, and investigated the respective influences of gender and age on the material properties. The participants were 50 healthy males and females within the following four age groups: 21-30 years, 31-40 years, 41-50 years, and above 51 years. The Young's moduli of the muscles, tendons, and ligaments around the knee joint were measured by shear wave elastography (SWE). Analysis of the Young's modulus results showed that excellent repeatability could be achieved by using SWE. For muscles, the intraclass correlation coefficient (ICC) and 95% confidence interval (CI) ranged between 0.952 and 0.987, and 0.923 and 0.992, respectively. The ICC ranged from 0.920 to 0.941, and the 95% CI was between 0.872 and 0.969 for tendons and ligaments. Additionally, the Young's moduli of the muscles, tendons, and ligaments of males were greater than those of females. With the exception for medial patellar retinaculum (MPR), the Young's moduli of other observed tissues decreased with age for both males and females, indicating that age has a significant impact on the Young's moduli of muscles, tendons, and ligaments. Hence, SWE is a reliable and repeatable technique that can be used to assess the Young's moduli of the muscles, tendons, and ligaments around the knee joint. Furthermore, gender and age affects the material properties. The results of this study provide an in vivo database of the material properties of muscles and connective tissues, and thus may prove useful for the prevention and treatment of knee joint injuries and diseases.

Important aspects of spider locomotion rely on a hydraulic mechanism. So far, this has not been theoretically analysed. In this work, the flow mechanism of a main hydraulic joint in a spider leg was studied. The purpose is to gain insight into a biohydraulic mechanism using an engineering approach to improve our understanding of the hemolymph flow path in the spider’s legs and to contribute to the theoretical analysis of the spider’s hydraulic transmission mechanism, thereby providing an inspiration for advanced biomimetic hydraulic systems. During the study, Micro-CT results were used to reconstruct the detailed flow channel. The high-pressure areas (inlet, joint, and closed leg end) and low pressures in between are also identified. Then, the internal flow field was investigated using computational fluid dynamics. At the same time, the method of dynamic mesh regeneration, elastic smoothing, is used to simulate muscle contraction and joint extension. The different functions of the channels are substantiated by the velocity profiles. Finally, a bionic hydraulic system was designed according to the trajectory of haemolymph in the flow channel.

The objective of this study was to investigate the feasibility of using shear wave elastography (SWE) to indirectly measure passive muscle force and to examine the effects of muscle mass and scan angle. We measured the Young's moduli of 24 specimens from six muscles of four swine at different passive muscle loads under different scan angles (0°, 30°, 60° and 90°) using SWE. Highly linear relationships between Young's modulus E and passive muscle force F were found for all 24 muscle specimens at 0o scan angle with coefficients of determination R2 ranging from 0.984 to 0.999. The results indicate that the muscle mass has no significant effect on the muscle E–F relationship, whereas E–F linearity decreases disproportionately with increased scan angle. These findings suggest that SWE, when carefully applied, can provide a highly reliable tool to measure muscle Young's modulus, and could be used to assess the muscle force quantitatively.

Macroscopic mechanical properties of digitigrade paw pads, such as non-linear elastic and variable stiffness, have been investigated in previous studies. However, little is known about the micro-scale structural characteristics of digitigrade paw pads or the relationship between these characteristics and the exceptional cushioning of the pads. The digitigrade paw pad consists of a multi-layered structure, which is mainly comprised of a stratified epithelium layer, a dermis layer and a subcutaneous layer. The stratified epithelium layer and dermal papillae constitute the epidermis layer. Finite element analyses were carried out and showed that the epidermis layer effectively attenuated the ground impact across impact velocities of 0.05–0.4 m/s, and that the von Mises stresses were uniformly distributed in this layer. The dermis layer encompassing the subcutaneous layer can be viewed as a hydrostatic system, which can store, release and dissipate impact energy. All three layers in the paw pad work as a whole to meet the biomechanical requirements of animal locomotion. These findings provide insights into the biomechanical functioning of digitigrade paw pads and could be used to facilitate bio-inspired, ground-contacting component development for robots and machines, as well as contribute to footwear design.

Most previous cervical spine finite element (FE) models were validated using in vitro cadaver measurement data from literatures. Although in vitro measurement can provide valuable data for model verification, the in vivo mechanical and physiological conditions of the cervical spine during its natural motions cannot be reproduced in vitro. In this study, a human FE model of skull (C0) and spinal vertebrae (C1–T1) was developed. The in vivo kinematic characteristics of head and neck were obtained from optoelectronic system, and used for the validation of the FE model. The simulation results showed good agreement with the measured data in left/right lateral bending and left/right axial rotation, while discrepancy existed during flexion. The predicted segmental cervical vertebral angles were compared against data from previous in vivo experiment, too. Furthermore, the skin shift data from previous study was used to compensate the experimental measurement during flexion and left/right lateral bending. The results showed the model was successfully validated with the in vivo experimental data.

Biological musculoskeletal system (MSK), composed of numerous bones, cartilages, skeletal muscles, tendons, ligaments etc., provides form, support, movement and stability for human or animal body. As the result of million years of selection and evolution, the biological MSK evolves to be a nearly perfect mechanical mechanism to support and transport the human or animal body, and would provide enormously rich resources to inspire engineers to innovate new technology and methodology to develop robots and mechanisms as effective and economical as the biological systems. This paper provides a general review of the current status of musculoskeletal biomechanics studies using both experimental and computational methods. This includes the use of the latest three-dimensional motion analysis systems, various medical imaging modalities, and also the advanced rigid-body and continuum mechanics musculoskeletal modelling techniques. Afterwards, several representative biomimetic studies based on ideas and concepts inspired from the structures and biomechanical functions of the biological MSK are discussed. Finally, the major challenges and also the future research directions in musculoskeletal biomechanics and its biomimetic studies are proposed.

In the panorama of available musculoskeletal modeling software, AnyBody software is a commercial tool that provides a full body musculoskeletal model which is increasingly exploited by numerous researchers worldwide. In this regard, model validation becomes essential to guarantee the suitability of the model in representing the simulated system. When focusing on lumbar spine, the previous works aimed at validating the AnyBody model in computing the intervertebral loads held several limitations, and a comprehensive validation is to be considered as lacking. The present study was aimed at extensively validating the suitability of the AnyBody model in computing lumbar spine loads at L4L5 level. The intersegmental loads were calculated during twelve specific exercise tasks designed to accurately replicate the conditions during which Wilke et al. (2001) measured in vivo the L4L5 intradiscal pressure. Motion capture data of one volunteer subject were acquired during the execution of the tasks and then imported into AnyBody to set model kinematics. Two different approaches in computing intradiscal pressure from the intersegmental load were evaluated. Lumbopelvic rhythm was compared with reference in vivo measurements to assess the accuracy of the lumbopelvic kinematics. Positive agreement was confirmed between the calculated pressures and the in vivo measurements, thus demonstrating the suitability of the AnyBody model. Specific caution needs to be taken only when considering postures characterized by large lateral displacements. Minor discrepancy was found assessing lumbopelvic rhythm. The present findings promote the AnyBody model as an appropriate tool to non-invasively evaluate the lumbar loads at L4L5 in physiological activities.

The study of three-dimensional human kinematics has significant impacts on medical and healthcare technology innovations. As a non-invasive technology, optoelectronic stereophotogrammetry is widely used for in-vivo locomotor evaluations. However, relatively high testing difficulties, poor testing accuracies, and high analysis complexities prohibit its further employment. The objective of this study is to explore an improved modeling technique for quantitative measurement and analysis of human locomotion. Firstly, a 3D whole body model of 17 rigid segments was developed to describe human locomotion. Subsequently, a novel infrared reflective marker cluster for 17 body segments was constructed to calibrate and record the 3D segmental position and orientation of each functional body region simultaneously with high spatial accuracy. In addition, the novel calibration procedure and the conception of kinematic coupling of human locomotion were proposed to investigate the segmental functional characteristics of human motion. Eight healthy male subjects were evaluated with walking and running experiments using the Qualisys motion capture system. The experimental results demonstrated the followings: (i) The kinematic coupling of the upper limbs and the lower limbs both showed the significant characteristics of joint motion, while the torso motion of human possessed remarkable features of segmental motion; (ii) flexion/extension was the main motion feature in sagittal plane, while the lateral bending in coronal plane and the axial rotation in transverse plane were subsidiary motions during an entire walking cycle regarding to all the segments of the human body; (iii) compared with conventional methods, the improved techniques have a competitive advantage in the convenient measurement and accurate analysis of the segmental dynamic functional characteristics during human locomotion. The modeling technique proposed in this paper has great potentials in rehabilitation engineering as well as ergonomics and biomimetic engineering.

Extenics is a newly developed interdisciplinary subject combining mathematics, philosophy and engineering. It provides useful formalized qualitative tools and quantitative tools for solving contradictory problems. In this paper, extension theory is introduced briefly and the primary applications of this theory and methods in bionic engineering research are discussed. The extension model of biological coupling functional system is established. In order to identify the primary and secondary sequencing of coupling elements, the Extension Analytic Hierarchy Process (EAHP) was adopted to analyze the contribution of each coupling element to the coupling functional system. Thus, the influence weight factor of each coupling element can be determined, so as to provide a new approach for solving primary and secondary sequencing problem of coupling elements in a quantitative way, and facilitate the subsequent bionic coupling study.

Nd 1+ x Fe 10 Mo 2 N y nitrides with permanent magnetic properties were prepared by heating fine Nd Fe Mo particles in an N 2 atmosphere followed by milling. The best composition and nitriding and milling conditions to obtain a high coercivity and energy product for the nitrides were investigated. H c and B r of magnetically aligned samples increased and decreased monotonically respectively with increasing milling time after nitriding irrespective of composition and nitriding conditions. The room temperature properties μ o H c = 0.7 T, B r = 0.4 T and ( BH ) max = 42 kJ m −3 were obtained.

Background.Soft tissue artifact (STA) is increasingly becoming a focus of research as the skin marker method is widely employed in motion capture technique. At present, medical imaging methods provide reliable ways to investigate the cervical STA. Among these approaches, magnetic resonance imaging (MRI) is a highly preferred tool because of its low radiation.Methods.In the study, the 3D spatial location of vertebral landmarks and corresponding skin markers of the spinous processes of the second (C2), fifth (C5), and sixth (C6) cervical levels during flexion and lateral bending were investigated. A series of static postures were scanned using MRI. Skin deformation was obtained by the Mimics software.Results.Results shows that during flexion, the maximum skin deformation occurs at C6, in the superior–inferior (Z) direction. Upon lateral bending, the maximum skin displacement occurs at C2 level, in the left–right (Y) direction. The result presents variability of soft tissue in the terms of direction and magnitude, which is consistent with the prevailing opinion.Discussion.The results testified variability of cervical STA. Future studies involving large ranges of subject classification, such as age, sex, height, gravity, and etc. should be performed to completely verify the existing hypothesis on human cervical skin deformation.