Biosurface and Biotribology最新文献

The hydro lipid film is an emulsion of sweat and sebum that covers the surface of the human skin and affects the tribological properties of the human skin. This study investigates the effects of the composition of the sebum on the average coefficient of friction. A range of simplified sebums was developed and the friction behaviour was investigated. Five realistic sebums showed a strong variation in friction results, indicating that interpersonal differences in frictional behaviour might have their origin in differences in sebum composition. A more detailed investigation employing controlled variations of individual ingredients showed that friction is highly sensitive to the amount of squalene in the sebum. The amount of fatty acids in the sebum also showed some effects, whilst the amount of cholesterol does not appear to be relevant for the friction behaviour. The main new outcome from this study is that the composition of sebum has a significant effect on the friction response of skin in ways that are currently not yet fully understood.

The traditional bionic upper limb structure design is limited by the motion pair and cannot guarantee the flexibility of the mechanical structure. The tensegrity structure has the characteristics of high deformability, strong self-adaptability, and resistance to multi-directional impact. According to the biological characteristics of the upper limbs of the human body, an anatomical study is performed on the upper limb wrist joints that achieve adduction/abduction, flexion/extension, to obtain the relationship between the movements of the related bones and muscles, and to simplify the shape and structure of the wrist. Equivalent mapping of a mechanical model based on two-bar tensile properties. Through the contraction and stretching of the spring, the movement characteristics of the human muscles are realised, and the optimised bionic upper limb wrist tensioning robot without motion pair is further obtained. Adams simulation is used to verify that the bionic tensile wrist can simulate the change movement of the human wrist. The experimental platform was built and a physical prototype was made and the prototype was tested. The results show that the bionic tensile wrist can realise the adaptive motion characteristics of the human wrist well and stably, which proves the validity and feasibility of this design method.

Wear occurring at the bearing surface and the consequent generation of wear debris has been identified as the primary cause of aseptic loosening in metal-on-polyethylene (MoP) hip joint replacements. The accurate estimation of volume change in polyethylene cups due to creep and wear is, therefore, an important step for identifying the cause of failure and improving the longevity of MoP prosthesis. The purposes of this study were to present and apply a co-ordinate measuring machine (CMM)-based method for assessing the volume change of retrieved components due to wear and creep by using a combination of CMM data and a bespoke computer programme. The method was firstly validated against the standard gravimetric technique, and then applied to four retrieved polyethylene cups for wear assessment and analysis. The results show that the volume changes calculated using the present method match well with those assessed through the gravimetric technique. The CMM-based method presented in the study is capable of effectively and reliably determining the volume change and characterising the wear patch of retrieved components from MoP hip joint replacements.

In vitro and in vivo testing can provide insight into knee joint mechanics and implant performance. However, these methods are costly and time-consuming, which always limits their widespread use during the design stage of the implant. This review presents a critical analysis of computational modelling (in-silicon) techniques including (i) development of a generic model of total knee replacement (TKR) and application of material properties, loading, and boundary conditions; (ii) design and execution of computational experiments; and (iii) practical applications and significant findings. The results show that the generic model and techniques provide significant insight into the general performance of TKR but have limited explicit validation. The introduction of design-of-experiments, probabilistic, and neural network methodologies in computational modelling has enabled simulation at the population level. Further advances in subjective modelling appear to be limited, mainly because of the lack of subjective materials and boundary conditions. Computational modelling will increasingly be used in the preclinical testing and design of TKR. This modelling should include subjective, multi-scale, and closely corroborated analyses to account for the variability of TKR.

Biological flow receptors show astonishing performance and are used as models for the design of novel flow sensors. However, the functional importance of interfacial microstructures is seldom discussed in previous review papers. Herein, this review summarises the underlying biomechanical principles in the biological flow receptors and describes the recent progress in bio-inspired flow sensors, in which the underlying sensing-enhancement mechanisms are emphasised.

The biocompatibility of implantable nickel–titanium biomaterials relies on the quality of their surfaces. In this study, nickel–titanium surfaces are coated with phenolic thin films of tannic acid and pyrogallol with the purpose of studying their corrosion resistance in physiological environments. Three tests are performed: the open-circuit potential test, potentiodynamic polarisation and potentiostatic electrochemical impedance spectroscopy. Polarisation measurements are scrutinised in order to gain knowledge concerning the kinetics of the cathodic and anodic reactions, while the open-circuit potentials and impedance spectroscopy help to study the electrolyte–surficial interactions. It is found that coating nitinol with polyphenols results in the depletion of the native oxide layer and thus a decrease of corrosion resistance. Pyrogallic treated nitinol surfaces (with a corrosion rate of 0.119 mm/year) are half as electrochemically corrosion resistive as tannic acid-coated substrate. Therefore, it is proposed that tannic treated nitinol would be a better option if implanted on biomaterial surfaces.

Nano rotor is of great value in military and civilian applications. Due to its nano size, it works at an ultra-low Reynolds number and aerodynamic performance deteriorates dramatically. The bio-inspired nano rotor is carried out to improve the rotor propulsive performance. Unsteady vortex lattice method (UVLM) model is established fully considering the influence of induced drag and wake vortex distortion on aerodynamic forces. The aim is to quickly and accurately simulate the flow field around the bio-inspired nano rotor and to efficiently perform the aerodynamic calculation to optimise the design of the bio-inspired rotor. The rotor parameters and motion parameters such as aspect ratio, taper ratio and camber are studied using UVLM. It is found that the aerodynamic performance of the rotor increased with the aspect ratio. The quality factor changes parabolically with the taper ratio and camber, and there is an optimal value for the ratio and camber, respectively. The influences of pitching angle and frequency are investigated as well. Results show that the bio-inspired motion improves the propulsion performance of nano rotor.