Human-centered Electric Prosthetic (HELP) Hand

In developing countries such as India, there is a higher rate of amputations among the population but a lack of viable, low cost solutions. Through a partnership with Indian non-profit Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS), the team designed a functional, robust, and low cost electrically powered prosthetic hand that communicates with people with unilateral, transradial amputations in urban India through a biointerface. The device uses compliant tendon actuation, small linear servos, and a wearable sleeve outfitted with electromyography (EMG) sensors to produce a device that, once placed inside a prosthetic glove, is anthropomorphic in both look and feel. The hand is capable of forming three grips through the use of a manually adjustable opposable thumb: the key, pinch, and wrap grips. The hand also provides vibrotactile user feedback upon completion of a grip. The design includes a prosthetic gel liner to provide a layer of cushion and comfort for safe use by the user. These results show that it is possible to create a low cost, electrically powered prosthetic hand for users in developing countries without sacrificing functionality. In order for this design to be truly adjustable to each user, the creation of an easily navigable graphical user interface (GUI) will have to be a future goal. The prosthesis prototype was developed such that future groups can design for manufacturing and distribution in India

SKIN-INSPIRED HYDROGEL-ELASTOMER COMPOSITE WITH APPLICATOIN IN A MOISTURE PERMEABLE PROSTHETIC LIMB LINER

Recent advances in fields such as 3D printing, and biomaterials, have enabled the development of a moisture permeable prosthetic liner. This project demonstrates the feasibility of the invention by addressing the three primary areas of risk including the mechanical strength, the permeability, and the ability to manufacture. The key enabling technology which allows the liner to operate is the skin inspired hydrogel elastomer composite. The skin inspiration is reflected in the molecular arrangement of the double network of polymers which mimics collagen-elastin toughening in the natural epidermis. A custom formulation for a novel tough double network nanocomposite reinforced hydrogel was developed to improve manufacturability of the liner. The liner features this double network nanocomposite reinforced hydrogel as a permeable membrane which is reinforced on either side by perforated silicone layers manufactured by 3d printing assisted casting. Uniaxial compression tests were conducted on the individual hydrogels, as well as a representative sample of off the shelf prosthetic liners for comparison. Permeability testing was also done on the same set of materials and compared to literature values for traditional hydrogels. This work led to the manufacture of three generations of liner prototypes, with the second and third liner prototype being tested with human participants

Investigation of upper limb prosthesis functionality using quantitative design tools

Upper limb prostheses offer those with limb loss a solution to restore some of their lost functionality by allowing them to participate in bilateral tasks, especially those required for daily living. Whilst there is a wide range of upper limb prostheses available, there remain high device rejection rates. Low functionality and discomfort are major factors in prosthesis rejection, which had been identified as challenges more than 60 years ago. These issues have not been effectively addressed due the lack of design tools for engineers and clinicians. Upper limb prostheses have seen greater technological advances than the methods to evaluate them effectively, which has resulted in over-engineered designs which do not meet the needs of their user. In this thesis , I aim to improve future upper limb prostheses through the development of three design tools. These design tools seek to quantify the functionality of prosthetic devices using motion capture analysis, virtual environments, and joint optimisation. By developing these tools, there is greater opportunity to optimise prostheses earlier in the design cycle which can result in improved functionality. It is anticipated that improvements in functionality will increase user satisfaction and therefore reduce device rejection rates Motion capture analysis was used to study the compensatory movements that arise from operating an upper limb prosthesis. Using a motion capture suit, the motor strategy of a participant was compared between using their biological hand and using a prosthesis through the use of an able-bodied adaptor. It was found that the shoulder and trunk had to make the most compensatory movements to complete several grasping tasks due to the lack of degrees of freedom at the distal end of the prosthesis. Without forearm supination/pronation and wrist extension/flexion, the participant had to approach the grasping tasks from a different angle, sometimes having to lean backwards and abduct their upper arm. The methodology of utilising a motion capture suit as a design tool to quantitatively assess the compensatory movements caused by a prosthetic device was successfully demonstrated. Virtual environments, in conjunction with quantitative grasp quality metrics, can be used to assess the performance of the upper limb prosthesis extremity alone, uninfluenced by user bias. A dynamic virtual environment is presented to simulate several grasping tasks with five upper limb prosthetic devices. Contact information from these grasping tasks are used to calculate the quality of the grasp and provide an overall grasping functionality score. From the simulation results, it was found that more degrees of freedom do not necessary equate to better grasping performance. The positions of force vectors during grasp formation are vital and they must be well- balanced in order to result in stable grasps. Simulated grasping and quantitative analysis in a virtual environment has been demonstrated, which can be used to better plan grasping paths and therefore improve the grasping functionality of upper limb prosthesis designs. Prosthesis users desire their devices to have a low mass, have a low cost, and have high functionality. However, these are conflicting design objectives and decisions must be made to which design considerations to prioritise. A multi-objective model was used to balance these three objectives and select the most suitable components that make up a prosthesis. A modularity scheme was used to divide an upper limb prosthesis into three categories: socket, forearm, and terminal device. In each category, several components were considered which can either be manufactured by conventional engineering or additive manufacturing. Each component would provide a unique value determined by a several quantitative utility functions. Based on satisfaction studies in the literature, the multi-objective optimisation model found that a Split Hook terminal device with an additively manufactured socket and forearm was the optimal design as it provided a low mass and excellent grasping functionality. This model has been demonstrated to work with different user requirements to intelligently select the most appropriate upper limb components within the modularity scheme. Overall, methods were developed which covered aspects of prosthesis design from clinical testing of prosthetic devices, functionality assessments of Computer Aided Design models, and intelligent selection of prosthesis components for individual requirements. It is hoped that these design tools may enable better communication between engineers and clinicians to ensure that users receive devices that are to their satisfaction

Investigation into the control of an upper-limb myoelectric prosthesis

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN053608 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Design and Evaluation of a Knee-Extension-Assist

Quadriceps muscle weakness is a condition that can result from a wide variety of causes, from diseases like polio and multiple sclerosis to injuries of the head and spine. Individuals with weakened quadriceps often have difficulty supplying the knee-extension moments required during common mobility tasks. Existing powered orthoses that provide an assistive knee-extension moment are large and heavy, with power supplies that generally last less than two hours. A new device that provides a knee-extension-assist moment was designed to aid an individual with quadriceps muscle weakness to stand up from a seated position, sit from a standing position, and walk up and down an inclined surface. The knee-extension-assist (KEA) was designed as a modular component to be incorporated into existing knee-ankle-foot-orthoses (KAFO). The KEA consists of three springs that are compressed, as the knee is flexed under bodyweight, by cables that wrap around a sheave at the knee. The KEA returns the stored energy from knee flexion as an extension moment during knee extension. During swing or other non-weight bearing activities, the device is disengaged from the KAFO by decoupling the sheave from the KAFO knee joint, allowing free knee joint motion. A prototype was built and mechanically tested to determine KEA behaviour during loading and extension and to ensure proper KEA function. For biomechanical evaluation, able-bodied subjects used the prototype KEA while performing sit-to-stand, stand-to-sit, ramp ascent, and ramp descent tasks. The KEA facilitated sitting and standing, providing an average of 53 % of the required extension moment for the two participants, which allowed one participant to reduce quadriceps usage by 38 % and the other to perform sit-to-stand in a slower and more controlled manner that was not possible without the KEA. KEA use during ramp gait caused an overall increase in quadriceps activation by 76 %, on average, with use. Future efforts will be made to modify the design to improve functionality, especially for ramp gait, and to reduce device size and weight

Neurostimulation of the Rat Motor System

Ce document fait la synthèse d'un ensemble de travaux concernant la nature de la plasticité neuronale et la manière dont la neurostimulation peut être utilisée pour améliorer la récupération motrice après une atteinte neurologique. Nous commençons par les principes fondamentaux généraux des neurosciences, la structure du système nerveux moteur chez l'homme et le rat, ainsi qu'une brève discussion sur les lésions neurologiques. Les sujets sont vastes et couverts avec la brièveté nécessaire, mais ils fournissent un contexte essentiel pour les chapitres suivants, présentés sous forme d'articles scientifiques. Dans le premier article, nous passons en revue le domaine de la neurostimulation sous ses aspects fondamental et clinique avec l'Accident Vasculaire Cerebral (AVC) en tant que maladie modèle pour les lésions neurologiques. Nous classifions les interventions de stimulation en trois modèles différents d'induction de la plasticité. Notre thèse centrale est qu'une meilleure compréhension des règles sous-jacentes de la plasticité, accompagnée de progrès dans une plus grande précision spatio-temporelle, est nécessaire pour faire avancer le domaine de la neurostimulation. Dans le deuxième article, nous décrivons, étape par étape, un nouveau protocole pour évaluer l'excitabilité corticospinale chez le rongeur éveillé pendant le comportement libre, ainsi que les plateformes matérielles et logicielles associées que notre équipe a développées à cette fin. L'une de ses principale caractéristique est la possibilité d'évaluer l'excitabilité corticomotrice en boucle fermée, en fonction de l'EMG, une nouvelle façon d'accroître l'uniformité des mesures sur des animaux en comportement. Cette plateforme de développement sera utile aux neuroscientifiques intéressés par l'évaluation de l'excitabilité du système nerveux chez les rongeurs éveillés par le biais d'une interrogation électrique ou optogénétique, un intermédiaire important avant les essais chez les primates non humains et éventuellement chez les humains. Dans le troisième article, nous avons utilisé cette plateforme prototype pour étudier la stimulation électrique associative appariée et le rôle de la plasticité dépendant de la synchronisation des potentiels d'action chez des rats implantés de façon chronique, sans l'influence de l'anesthésie. Nous nous sommes concentrés sur la variation systématique de l'intervalle entre la stimulation corticale et musculaire dans notre cohorte d'animaux afin de révéler l'effet de la synchronisation relative de l'activité aux niveaux cortical et spinal. Nous n'avons pas observé de potentialisation significative dans tous les intervalles de stimulation testés, mais plutôt des tendances vers des effets de type LTD dans la plupart des conditions de synchronisation. Nous discutons des raisons possibles pour lesquelles nous avons observé ces résultats. Dans le dernier article et dans le projet en cours, nous décrivons les premiers travaux prometteurs impliquant la neurostimulation optogénétique et électrique, ainsi que la réadaptation post-AVC comme tremplin pour des recherches futures. Nous concluons par une discussion générale et nous nous projetons dans l'avenir, tant à moyen qu'à long terme. La poursuite scientifique, tant sur le plan personnel que sur celui du domaine, se poursuivra, comme il se doit. Bien que ce travail soit conçu pour être lu dans un ordre séquentiel, chaque chapitre est indépendant. Collectivement, les travaux de cette thèse posent les bases et plaident en faveur d'une meilleure compréhension de la plasticité neuronale, du développement d'outils pour l'évaluer et de l'étude de ses applications pratiques pour parvenir à une meilleure récupération motrice après une lésion neurologique.This document synthesizes a body of work concerning the nature of neural plasticity and how neurostimulation may be used to improve motor recovery after neurological insult. We begin with general foundational principles in neuroscience, the structure of the nervous and motor systems in humans and rats, and a brief discussion of neurological injury. The topics are broad and covered with the necessary brevity, but provides critical context for the following chapters. In the first paper, we review the fields of neurostimulation across the clinical and basic science domains in the service of stroke as a model disease for neurological injury, framing the field in terms of three different models of plasticity induction. Our central thesis here is that enhanced understanding of the underlying rules of plasticity, accompanied with advances in greater spatiotemporal precision is necessary to move the field of neurostimulation forward. In the second paper we describe a stable, novel step-by-step protocol to assess corticospinal excitability in the awake, freely behaving rodent, and the associated hardware and software platforms that our team has developed for this purpose. A core feature enables corticomotor excitability assessment in a closed-loop, Electromyogram (EMG)-dependent manner, a novel way of increasing consistency during free behavior in untrained animals. This development platform will be of use to neuroscientists interested in assessing the excitability of the nervous system in awake, unrestrained rodents via electrical or optogenetic interrogation, an important intermediary before trials in non-human primates and eventually humans. In the third paper, we used this prototype platform to investigate electrical paired associative stimulation and the role of spike-timing-dependent plasticity in chronically implanted rats, without the influence of anaesthesia. Our focus was on systematically varying the Inter-Stimulus Interval (ISI) between cortical and muscle stimulation in our animal cohort in order to reveal the effect of relative activity timing at both the cortical and spinal levels. We did not observe significant potentiation across all of the stimulus intervals we tested, but instead observed trends towards Long-Term Depression (LTD)-like effects in the short term across most timing conditions. We discuss possible reasons why we observed these results. In the final paper and project currently in progress, we describe early promising work involving optogenetic and electrical neurostimulation, and stroke recovery as a launchpad for future investigations. We conclude with a general discussion and peer into the future, both in the medium term and the long term. The scientific pursuit, both personally and as a field will continue, as it should. Although this work is designed to be read in sequential order, each chapter stands alone. Collectively, the work in this thesis lays the groundwork and argues for a greater understanding of neural plasticity, development of tools to assess it, and study of its practical applications to achieve enhanced motor recovery after neurological injury

Development of soft modular robotics

This thesis covers the development and validation of soft robots in providing upper limb assistive motion. The main purpose of this research is to develop highly compliant and resilient actuators that generate motion for elbow and shoulder movements. To accomplish the purpose of the study, the fabrication, geometric construction along with experimental data of pressure, torque and range of motion of all developed actuators are described. The main contribution of this thesis is the development of soft actuators that transfer force via elastic deformation in order to generate assistive motion; features such as flexibility and soft contact with the skin ensure excellent safety potential of the actuators. To reduce the instability phenomenon attributed to the elastic response of rubber under large deformations that leads to bulging, the implementation of a pleated network design and embedded braided mesh network is presented. Bulging was reduced and torque output was increased with the integration of braided mesh into the silicone rubber actuator. The soft actuators developed for elbow and shoulder motion was tested on ten healthy participants thereby demonstrating its comfort, ease of use, fitting and removal as well as its practicality as an assistive apparatus for stroke patients. The use of soft robotics to provide shoulder motion was also assessed by the integration of soft robotics with a gravity compensated exoskeleton. The developed soft actuators were powered with electro-pneumatic hardware components presented in a compact, embedded form. Positive and negative air pressure control was implemented by a piecewise linear control algorithm with the performance of the controller shown. The design of a novel muscle made entirely of silicone rubber that contract upon actuation was described together with the manufacturing procedure, design parameters and measurement results of performance of these muscles such as the velocity of shortening, isometric contraction and maximal obtainable muscle force (without shortening). The muscles are manufactured to mimic the skeletal muscles present in the human body. These muscles are composed of a number of wedge-like units in series, the number of these wedge units increase the contraction. The soft muscles were characterized in order to find optimum design parameters that results in more contraction and speed; the muscles were tested on a model hinge joint to execute flexion/extension of the forearm at the elbow. Aside from contracting, the muscle has an interesting capability of producing bidirectional bending by the regulation of internal positive and negative air pressure in each wedge unit. In order to measure performance data relating to range of motion from bending, rotary and muscle actuators, computer vision processing was made use of. Soft robots are made with materials that experience large deformations, the sensors used to obtain measurement data can either be through the use of embedded sensors or visual processing. The use of embedded sensors can be cumbersome, resulting in limitation of its performance. The visual processing algorithms implemented to measure performance data such as angle of motion, bending angle and contraction ratio in real-time using a Webcam is described. Visual processing concepts such as colour tracking, template matching, camera calibration were applied. The developed vision system was applied to execute vision based motion control which is able to move the soft robot to a desired position using high level vision control and lower level pressure control. The material described in the preceding paragraphs are presented in an interrelated format. A concise introduction to the thesis is presented in the first chapter. An extensive survey of the field of soft robotics including materials, manufacturing procedure, actuation principles, primary accomplishments, control and challenges are presented in the literature review chapter, together with a review of rehabilitation devices. Since this work focused on the use of silicone rubber as actuator material, a brief introduction to working with silicone rubber as an engineering material is presented in the third chapter. The conclusions of the work and suggestions for future research are provided at the last chapter of this thesis

Evaluation of the clinical outcome of curvilinear transport distraction osteogenesis and revascularised fibula free flaps in the reconstruction of large post-maxillectomy defects

Background: Maxillary defects caused by trauma or tumour resection in the head and neck region can be devastating to the patient from a cosmetic and functional perspective. Patients who undergo maxillectomy procedures experience a substantial deterioration in their primary oral functions such as breathing, mastication, salivation, deglutition and phonation, which has a collective adverse influence on their quality of life (QOL). The revascularised free fibula flap (RFFF) has been demonstrated to be most reliable for the reconstruction of maxillary defects, and has been regarded as the 'gold standard.' A novel method of regenerating bone and soft tissue through the process of curvilinear transport distraction oseteogenesis (CTDO) has been developed and compared with the RFFF technique. Method: A prospective cohort study of 6 post-maxillectomy patients was compared regarding the clinical outcome of function and aesthetics with a group of 6 patients who had undergone RFFF reconstruction. The new bone (regenerate) was compared with the parent bone from which it had been generated. Objective measuring tools were employed to assess pre and post quality of life (QOL) aspects. The RFFF patients were not subjected to any invasive procedures save to undergo a clinical evaluation and undergo a CT scan of their maxillae. A cohort of 6 participants was treated prospectively using CTDO and the results were analysed within that cohort. These results were compared with a retrospective group of 6 participants of similar age and gender distribution who had undergone RFFF reconstruction as an external control. The patented Hendricks-Vicatos (H-V) maxillary transport distractor was applied to all selected participants by the primary investigator under general anaesthesia at Groote Schuur Hospital or a private clinic. The H-V maxillary transport distractor (5 prototypes) was pre-shaped and pre-fitted onto a 3-D model of the participant's maxilla, in a laboratory. This method reduced clinical installation time. If teeth were present in the area to be distracted, then at least 2 teeth were removed from the maxilla, preferably three months before the date of distraction. In the first few cases, this was the protocol for developing bone stock. This protocol was revised in the last 2 patients of the study, where no teeth were extracted at all. A linear fracture (bi-cortical) was created in the maxilla in a vertical direction (segmentally) to develop a mobile, well-vascularised transport disc. This carrier disc was attached to the metal plate of the 'crawler' via small titanium screws. The crawler was then moved on the reconstruction plate (BiometTM Zimmer Biomet

Improving the validity of shod human footstrike modelling with dynamic loading conditions determined from biomechanical motion capture trials

This thesis presents and evaluates a number of finite element footstrike models developed to allow the performance of prospective athletic footwear designs to be evaluated in a virtual environment. Successful implementation of such models would reduce the industry’s traditional reliance on physical prototyping and therefore reduce the time and associated costs required to develop a product. All boundary conditions defined in each of the footstrike models reported were directly determined from biomechanical motion capture trials to ensure that the loading applied was representative of shod human running. Similarly, the results obtained with each model were compared to digitised high speed video footage of experimental trials and validated against biomechanical measures such as foot segment kinematics, ground reaction force and centre of pressure location. A simple model loaded with triaxial force profiles determined from the analysis of plantar pressure data was found to be capable of applying highly representative load magnitudes but the distribution of applied loading was found to be less accurate. Greater success at emulating the deformation that occurs in the footwear during an entire running footstrike was achieved with models employing kinematic foot segment boundary conditions although this approach was found to be highly sensitive to the initial orientation of the foot and footwear components, thus limiting the predictive capacity of such a methodology. A subsequent model was therefore developed to utilise exclusively kinetic load conditions determined from an inverse dynamic analysis of an experimental trial and demonstrated the greatest predictive capacity of all reported models. This was because the kinematics of the foot were allowed to adapt to the footwear conditions defined in the analysis with this approach. Finally, the reported finite element footstrike models were integrated with automated product optimisation techniques. A topology optimisation approach was first utilised to generate lightweight midsole components optimised for subject‐specific loading conditions whilst a similar shape optimisation methodology was subsequently used to refine the geometry of a novel footwear design in order to minimise the peak material strains predicted

Technology 2000, volume 1

The purpose of the conference was to increase awareness of existing NASA developed technologies that are available for immediate use in the development of new products and processes, and to lay the groundwork for the effective utilization of emerging technologies. There were sessions on the following: Computer technology and software engineering; Human factors engineering and life sciences; Information and data management; Material sciences; Manufacturing and fabrication technology; Power, energy, and control systems; Robotics; Sensors and measurement technology; Artificial intelligence; Environmental technology; Optics and communications; and Superconductivity