Active chainmail fabrics for soft robotic applications

This paper introduces a novel type of smart textile with electronically responsive flexibility. The chainmail inspired fabric is modelled parametrically and simulated via a rigid body physics framework with an embedded model of temperature controlled actuation. Our model assumes that individual fabric linkages are rigid and deform only through their own actuation, thereby decoupling flexibility from stiffness. A physical prototype of the active fabric is constructed and it is shown that flexibility can be significantly controlled through actuator strains of ≤10%. Applications of these materials to soft-robotics such as dynamically reconfigurable orthoses and splints are discussed

Chinese Whispers: A brief history of eponymous orthopaedic examinations

Eponymous orthopaedic examinations frequently appear in modern clinical examinations, yet their original description and cause for change are often omitted from medical education today. This is important to appreciate in order to understand their diagnostic relevance in modern medicine and subsequent interpretation of results by fellow clinicians. This article reviews the original description of these tests by their namesakes, how they have evolved over time and their relevance in orthopaedics today. An online literature review (PubMed) was conducted of the original descriptions and other published literature detailing their history, evolution, sensitivity and specificity. While elements of these tests have been lost naturally over time to the ‘Chinese Whispers’ effect, most have evolved positively secondary to a deepening anatomical and pathological understanding of their target conditions. They retain some usefulness in clinical medicine, however it is recognized that their diagnostic value is invariably supplanted by improvements in diagnostic imaging

Instrumented elbow orthosis

Although work on exoskeleton technology started as early as in the 1960’s, it is mostly recognized and used as devices to aid in the rehabilitation process and for military purposes. The use of wearable and portative exoskeleton technology for functional compensation is less well understood for the upper limbs in comparison with the lower limbs. A review of current upper limb exoskeleton technology suggests that there is limited attention to the interaction between the exoskeleton and the human. In order to control or compensate movement, exoskeletons transfer forces through a physical coupling between the device and the human limb (exoskeleton-human interface). This exoskeleton-human interface is a physical coupling that requires the consideration of optimal and safe force transfer (magnitude, direction and locations) as well as user comfort; considerations that have been overlooked by current exoskeleton technology. Before implementing a highly specialized electronic control system between the user and exoskeleton, it is necessary to design a truly wearable, safe and comfortable mechanical structure. The aims of this study are to modify a commercial elbow orthesis by instrumenting it with a control system and force sensors in order to measure the following parameters: dynamic stiffness and pressure between the orthosis and the human skin. This instrumented orthosis is further controlled by the user through a mouth switch. The instrumented orthosis is employed to monitor forces and stiffness during activities of daily life which involve self-care and domestic life for a fully abled person. Upper limb exoskeleton designers could use this data to fabricate technology that exerts forces that are safe and within what the end user considers comfortable. This modified orthosis will be used in a future study in individuals with spinal cord injury from C5 to C8 levels

Identifying key experience-related differences in over-ground manual wheelchair propulsion biomechanics

OBJECTIVE: The purpose of this study was to investigate technique differences between expert and novice manual wheelchair users during over-ground wheelchair propulsion. METHOD: Seven experts (spinal cord injury level between T5 and L1) and six novices (non-wheelchair users) pushed a manual wheelchair over level ground, a 2.5% cross slope and up a 6.5% incline (7.2 m length) and 12% incline (1.5 m length). Push rim kinetics, trunk and shoulder kinematics and muscle activity level were measured. RESULTS: During the level and cross slope tasks, the experts completed the tasks with fewer pushes by applying a similar push rim moment over a greater push arc, demonstrating lower muscle activity. During the incline tasks, the experts required fewer pushes and maintained a greater average velocity, generating greater power by applying a similar push rim moment over a greater push arc with greater angular velocity, demonstrating greater trunk flexion and higher shoulder muscle activity. CONCLUSIONS: This study identifies experience-related differences during over-ground manual wheelchair propulsion. These differences are particularly evident during incline propulsion, with the experts generating significantly greater power to maintain a higher velocity

Sclerostin does not play a major role in the pathogenesis of skeletal complications in type 2 diabetes mellitus

In contrast to previously reported elevations in serum sclerostin levels in diabetic patients, the present study shows that the impaired bone microarchitecture and cellular turnover associated with type 2 diabetes mellitus (T2DM)-like conditions in ZDF rats are not correlated with changes in serum and bone sclerostin expression. INTRODUCTION: T2DM is associated with impaired skeletal structure and a higher prevalence of bone fractures. Sclerostin, a negative regulator of bone formation, is elevated in serum of diabetic patients. We aimed to relate changes in bone architecture and cellular activities to sclerostin production in the Zucker diabetic fatty (ZDF) rat. METHODS: Bone density and architecture were measured by micro-CT and bone remodelling by histomorphometry in tibiae and femurs of 14-week-old male ZDF rats and lean Zucker controls (n = 6/group). RESULTS: ZDF rats showed lower trabecular bone mineral density and bone mass compared to controls, due to decreases in bone volume and thickness, along with impaired bone connectivity and cortical bone geometry. Bone remodelling was impaired in diabetic rats, demonstrated by decreased bone formation rate and increased percentage of tartrate-resistant acid phosphatase-positive osteoclastic surfaces. Serum sclerostin levels (ELISA) were higher in ZDF compared to lean rats at 9 weeks (+40 %, p < 0.01), but this difference disappeared as their glucose control deteriorated and by week 14, ZDF rats had lower sclerostin levels than control rats (-44 %, p < 0.0001). Bone sclerostin mRNA (qPCR) and protein (immunohistochemistry) were similar in ZDF, and lean rats at 14 weeks and genotype did not affect the number of empty osteocytic lacunae in cortical and trabecular bone. CONCLUSION: T2DM results in impaired skeletal architecture through altered remodelling pathways, but despite altered serum levels, it does not appear that sclerostin contributes to the deleterious effect of T2DM in rat bone

Characterization of bespoke force sensors for tailored applications

Bespoke force sensors made with active polymer composites are inexpensive, thin and flexible, hence popular in wearable electronics, however their wider application is limited due to the lack of literature studying their voltage response related errors. We present the voltage response characterization of bespoke force sensors made with an active polymer composite, silver coated fabric, stainless steel thread and silver epoxy. Characterization of the effects of static and dynamic loading was completed with a mechanical testing machine. Static tests consisted of loading and unloading at 0.01, 0.1, 0.5 and 1 N/s, and drift tests for 120 minutes up to 10 N every 1 N. Dynamic tests consisted of a sinusoidal load of 5 N ± 1 N applied at 0.05, 0.1 and 0.5 Hz for 60 minutes. The force-voltage relationships were modelled using an exponential function. Maximum mean drift error was observed when applying different static loads for 120 minutes each. Drift error is minimal at 5 s (<1%)and at 60 (< 5%) minutes with loads under 1 N. Maximum hysteresis of 18% was observed at a 1 N/s loading rate. The maximum drift error after one hour of dynamic loading was observed at 0.5 Hz and is minimal (-0.00004%). The cost of fabricating these sensors is very low compared with commercially available options. These sensors can be fabricated in any shape and size with the added advantage of being able to set the location of the electronic connections as desired

Plaster of Paris-Short History of Casting and Injured Limb Immobilzation

Various materials have been used since ancient times to help immobilise fractures. In this review, we discuss the history and developments of these materials as well as plaster of Paris. There has been a recent trend away from non-operative management of fractures, and skills in the use of plaster of Paris are declining. For the successful treatment of patients, it is important to appreciate how plaster works, how it should be used, and what can go wrong. In this review, we also discuss principles of applications and complications of plaster of Paris

A deep learning approach to non-linearity in wearable stretch sensors

There is a growing need for flexible stretch sensors to monitor real time stress and strain in wearable technology. However, developing stretch sensors with linear responses is difficult due to viscoelastic and strain rate dependent effects. Instead of trying to engineer the perfect linear sensor we take a deep learning approach which can cope with non-linearity and yet still deliver reliable results. We present a general method for calibrating highly hysteretic resistive stretch sensors. We show results for textile and elastomeric stretch sensors however we believe the method is directly applicable to any physical choice of sensor material and fabrication, and easily adaptable to other sensing methods, such as those based on capacitance. Our algorithm does not require any a priori knowledge of the physical attributes or geometry of the sensor to be calibrated, which is a key advantage as stretchable sensors are generally applicable to highly complex geometries with integrated electronics requiring bespoke manufacture. The method involves three-stages. The first stage requires a calibration step in which the strain of the sensor material is measured using a webcam while the electrical response is measured via a set of arduino-based electronics. During this data collection stage, the strain is applied manually by pulling the sensor over a range of strains and strain rates corresponding to the realistic in-use strain and strain rates. The correlated data between electrical resistance and measured strain and strain rate are stored. In the second stage the data is passed to a Long Short Term Memory Neural Network (LSTM) which is trained using part of the data set. The ability of the LSTM to predict the strain state given a stream of unseen electrical resistance data is then assessed and the maximum errors established. In the third stage the sensor is removed from the webcam calibration set-up and embedded in the wearable application where the live stream of electrical resistance is the only measure of strain - this corresponds to the proposed use case. Highly accurate stretch topology mapping is achieved for the three commercially available flexible sensor materials tested