Damage to the central nervous system (CNS) leads to the generation of an immune response which culminates with the encapsulation of the damaged area. The encapsulation, known as a glial scar, essentially breaks neural signal pathways and blocks signal transmissions to and from the CNS. The effect is the loss of motor and sensory control for the damaged individual. One method that has been used successfully to treat this problem is the use of a brain-machine interface (BMI) which can intercept signals from the brain and use these signals to control a machine. Although there are many types of BMI devices, implantable devices show the greatest promise with the ability to target specific areas of the CNS, with reduced noise levels and faster signal interception, and the fact that they can also be used to send signals to neurons. The largest problem that has plagued this type of BMI device is that the materials that have been used for their construction are not chemically resilient, elicit a negative biological response, or have difficulty functioning for extended periods of time in the harsh body environment. Many of these implantable devices experience catastrophic failure within weeks to months because of these negative factors. New materials must be examined to advance the future utilization of BMI devices to assist people with CNS damage or disease. We have proposed that two semiconductor materials, cubic silicon carbide (3C-SiC) and nanocrystalline diamond (NCD), which should provide solutions to the material biocompatibility problems experienced by implantable BMI devices. We have shown in this study that these two materials show chemical resilience to neuronal cellular processes, and we show evidence which indicates that these materials possess good biocompatibility with neural cell lines that, in the worst case, is comparable to celltreated polystyrene and, in most cases, even surpasses polystyrene. We have utilized 3C-SiC within an electrode device and activated the action potential of differentiated PC12 cells. This work details our initial efforts to modify the surfaces of these materials in order to improve cellular interaction and biocompatibility, and we examine our current and future work on improving our implantable BMI devices.

Modern research in prosthetic devices and other assistive technologies are constantly pushing boundaries. While the technology is impressive, it is still inaccessible for the greater part of the people in need of it. Advanced devices are often extremely expensive and require regularly maintenance from professionals. Enabling the Future is a global network of volunteers and was founded to face these problems. They design and 3D-print mechanical prosthetics for people in need all over the world. Most of the designs used by Enabling the Future are purely mechanical and do not implement motors. The purpose of this thesis was to take a new approach to the design and construction of low-cost motorized prosthetic hands. By distancing all the electronic components from the hand, including the motor, the project aimed to create a device compatible with all current designs of the Enabling the Future community. To conceptualize this approach a demonstrator was constructed and tested. It utilized a muscle sensor which allowed users to control the hand by tightening their muscles. The distance between the electronic components and the prosthetic hand measured approximately one and a half meters and still transfered enough force, from the motor to the hand, to deliver an adequate grip strength. / Modern forskning inom protestillverkning och andra handikapphjälpmedel gör kontinuerligt stora framsteg. Trots att tekniken är imponerade är den fortfarande otillgänglig för den största del människor som behöver den. Avancerade hjälpmedel är ofta extremt dyra och kräver kontinuerligt underhåll från yrkesverksamma. Enabling the Future, ett globalt nätverk av volontärer, grundades för att utmana dessa problem. De konstruerar och tillverkar 3D-skrivna mekaniska proteser för människor med behov över hela världen. De flesta konstruktioner som används av Enabling the Future är helt mekaniska och använder inga motorer. Syftet med detta kandidatexamensarbete var att med nya tillvägagångssätt konstruera en billig motoriserad handprotes. Genom att placera all elektronik på en distans från handen, inklusive motorn själv, var tanken att skapa ett system som är kompatibelt med de konstruktioner som Enabling the Future använder. För att förverkliga detta konstruerades en prototyp som testats. Prototypen använde sig av en muskelsensor som lät användaren kontrollera proteshanden genom att spänna sin arm. Distansen mellan de elektriska komponenterna och protesen var ungefär en och en halv meter, samtidigt som tillräckligt stor kraft kunde transporteras för att stänga handen med ett tillräckligt grepp.

Yes / Introduction: Clinicians typically use findings from cohort studies to objectively inform judgements regarding the potential (dis)advantages of prescribing a new prosthetic device. However, before finalising prescription a clinician will typically ask a patient to ‘try out’ a change of prosthetic device while the patient is at the clinic. Observed differences in gait when using the new device should be the result of the device’s mechanical function, but could also conceivably be due to patient related factors which can change from day-to-day and can thus make device comparisons unreliable. To determine whether a device’s mechanical function consistently has a more meaningful impact on gait than patient-related factors, the present study undertook quantitative gait analyses of a trans-tibial amputee walking using two different foot-ankle devices on two occasions over a year apart. If the observed differences present between devices, established using quantitative gait analysis, were in the same direction and of similar magnitude on each of the two occasions, this would indicate that device-related factors were more important than patient-related factors. Methods: One adult male with a unilateral trans-tibial amputation completed repeated walking trials using two different prosthetic foot devices on two separate occasions, 14 months apart. Walking speed and sagittal plane joint kinematics and kinetics for both limbs were assessed on each occasion. Clinically meaningful differences in these biomechanical outcome variables were defined as those with an effect size difference (d) between prosthetic conditions of at least 0.4 (i.e. ‘medium’ effect size). Results: Eight variables namely, walking speed, prosthetic ‘ankle’ peak plantar- and dorsi- flexion and peak positive power, and residual knee loading response flexion, peak stance-phase extension and flexion moments and peak negative power, displayed clinically meaningful differences (d > 0.4) between foot devices during the first session. All eight of these showed similar effect size differences during the second session despite the participant being heavier and older. Conclusions: Findings suggest that a prosthetic device’s mechanical function consistently has a more meaningful impact on gait than patient-related factors. These findings support the current clinical practice of making decisions regarding prosthetic prescription for an individual, based on a single session evaluation of their gait using two different devices. However, to confirm this conclusion, a case series using the same approach as the present study could be undertaken.

Various silicone elastomers have been evaluated for use in the prosthetic reconstruction of facial defects. Their strength, texture, flexibility, hardness, ease of preparation, pigment receptivity and retention, and their resistance to cleaning were compared and the data consulted when an elastomer was chosen to restore defects, improve aesthetics and reestablish the confidence of a selection of patients. Detailed case reports are provided, together with information on the adhesives or mechanical methods available for retaining the facial prosetheses. Cyanoacrylate adhesives for use on skin surfaces and as tissue adhesives have been studied in detail. A novel n-butyl 413 cyanoacrylate has been developed with a viscosity, haemostatic property and stability to make it particularly suitable for use in skin grafting and tissue repair. It has already been used with good results on patients with severe burns. An improved formulation, containing a fluorescent dye, can be precisely applied through a specially constructed foot-controlled dispenser illuminated by a fibre-optic supplying UV-light. Cyanoacrylates are already being used as tissue adhesives in place of the conventional but potentially disfiguring suture. The availability of improved, imperceptible adhesives and a precision applicator, which can be used in a modern operating theatre, will extend their effectiveness and satisfy some of the needs of Plastic, and Oral and Maxillo-Facial Surgeons. Portable applicators have potential use in battlefield and in veterinary surgery and overcome the imprecision characteristic of earlier methods. / Loctite UK

The use of non-invasive signal acquisition methods is today the standard for testing pattern recognition algorithms in prosthetic control. Such research had shown consecutively high performance on both prerecorded and real time data, yet when tested in real life they deteriorate. To investigate why, the author who is a congenital amputee, wore a prosthetic system utilizing pattern recognition control on a daily basis for a five-day period. The system generated one new classification every 50 ms and movement execution was made continuously; for classifying open/close; and by winning a majority vote; for classifying side grip, fine grip and pointer. System data was continuously collected and errors were registered through both a manual and an automatic log system. Calculations on extracted data show that grip classifications had an individual accuracy of 47%- 70% while open/close got 95%/98%, but if classified according to a majority vote, grips increased their accuracy to above 90% while open/close dropped to 80%. The conclusion was that majority vote might help complex classifications, like fine grips, while simpler proportional movements is exacerbated by majority voting. Major error sources were identified as signal similarities, electrode displacements and socket design. After the daily monitoring ended the systems functionality was tested using the "Assessment of Capacity for Myoelectric Control". The ACMC results showed that the system has similar functionality to commercial threshold control and thus is a possible viable option for both acquired and congenital amputees. / Användningen av icke-invasiva signalavläsningsmetoder är för nuvarande standarden inom utvärderingar av mönsterigenkännings-algoritmer för proteskontroll. Forskning inom området har konsekvent visat på hög prestanda för både ansamlat och realtids data, men när algoritmerna testas i verkliga livet fungerar de ej väl. För att undersöka varför har författaren, som har en kongenital amputation, burit en protes vilken använder mönsterigenkänningskontroll i sitt vardagliga liv under en femdagars period. Systemet genererade en ny klassificering var 50 ms och rörelse-utförande skedde antingen kontinuerligt; för öppna/stäng; eller genom att vinna en majoritetsröstning, för att klassificera greppen sidogrepp, fingrepp samt peka. Data insamlades kontinuerligt och felklassificeringar registrerades genom både ett manuellt och ett automatiskt markeringssystem. Beräkningar på insamlade data visade att för grepp låg den individuella träffsäkerheten på 47%- 70% medan öppna/stäng var 95%/98%, men om data grupperades ökade träffsäkerheten för greppen till 90% medan för öppna/stäng minskade den till 80%. Slutsatsen blev då att majoritetsröstning hjälper mer komplexa rörelser som grepp, men är hindrande för mer väldefinierade proportionella öppna/stäng rörelser. De största felkällorna identifierades som likheter i signaler, elektrodavbrytningar och design av proteshylsan. Efter slutförd daglig övervakning undersöktes funktionaliteten hos systemet med hjälp av funktionalitetstestet "Assessment of Capacity for Myoelectric Control". ACMC testen visade att systemet hade liknande funktionalitet som kommersiell tröskelkontrol och därmed kan ses som ett möjligt alternativ för kontroll, både hos dem med förvärvade och kongenitala amputationer.

Over one million amputees are living in the United States with major lower limb loss (Ziegler-Graham et al. 2008). Lower limb amputation leads to the functional loss of the ankle plantar flexor muscles, which are important contributors to body support, forward propulsion, and leg swing initiation during walking (Neptune et al. 2001; Liu et al. 2006). Effective prosthetic component design is essential for successful rehabilitation of amputees to return to an active lifestyle by partially replacing the functional role of the ankle muscles. The series of experimental and computer simulation studies presented in this research showed that design characteristics of energy storage and return prosthetic ankles, specifically the elastic stiffness, significantly influence residual and intact leg ground reaction forces, knee joint moments, and muscle activity, thus affecting muscle output. These findings highlight the importance of proper prosthetic foot stiffness prescription for amputees to assure effective rehabilitation outcomes. The research also showed that the ankle muscles serve to stabilize the body during turning the center of mass. When amputees turn while supported by their prosthetic components, they rely more on gravity to redirect the center of mass than active muscle generation. This mechanism increases the risks of falling and identifies a need for prosthetic components and rehabilitation focused on increasing amputee stability during turning. A proper understanding of the effects of prosthetic components on amputee walking mechanics is critical to decreasing complications and risks that are prevalent among lower-limb amputees. The presented research is an important step towards reaching this goal. / text

Introdução: Considerando-se a crescente tendência da utilização de próteses sobre implantes tanto em nossa população quanto em âmbito mundial, ganha importância o estudo das diversas condições envolvidas na longevidade e funcionalidade dessas peças para os indivíduos em geral. Objetivo: Determinar a ocorrência de alterações patológicas associadas a próteses totais implantadas e correlacioná-las a variáveis individuais, das peças protéticas e à participação de leveduras do gênero Candida nesses indivíduos. Metodologia: Pacientes portadores de próteses sobre implantes foram avaliados no momento da remoção das peças para controle e manutenção, após anuência com os termos do consentimento livre e esclarecido. Os participantes tiveram seus fluxos salivares totais avaliados inicialmente. Após a remoção das próteses, as peças foram avaliadas tecnicamente (próteses, implantes, parafusos e abutments), a boca examinada clinicamente, as condições da mucosa subjacente às próteses foram anotadas, e eventuais lesões associadas às próteses foram avaliadas e tratadas. Paralelamente foi realizada coleta de material para exame micológico de dois sítios - mucosa sob a prótese e base da prótese. O material foi coletado com auxílio de swabs e transferido a placas com meio de cultura diferencial (Chromagar®) para observação de crescimento e identificação de leveduras. Resultados: Foram coletados dados referentes a 91 participantes e 102 próteses sobre implantes. Trinta e quadro homens e 57 mulheres com idade média de 66,6 anos. Quatro overdentures, 72 protocolos inferiores e 26 superiores. Nenhum participante apresentou hipossalivação. Candida spp foram identificadas em 70,3% das arcadas inferiores e 85,7% das arcadas superiores. O tempo de uso das próteses interferiu na porcentagem de identificação das leveduras. Candida albicans foi a principal espécie identificada (93% dos casos positivos). Outras espécies identificadas foram: Candida glabrata, C. kruzei e C. tropicalis. Técnicas de higienização adicionais à escovação convencional reduziram a contaminação pelos fungos, enquanto hábitos de fumar ou consumir bebidas alcoólicas a aumentaram. Inflamação em mucosa relacionou-se positivamente à presença de Candida em mucosa e próteses. Oito participantes foram submetidos a intervenções cirúrgicas para remoção de processos proliferativos inflamatórios (8,8%). Foram avaliados 532 implantes, registrando-se perda de 1,13% deles e necessidade de reaperto em 271 parafusos (50,1%). Os dados foram analisados de forma descritiva e submetidos a testes estatísticos adequados ao tipo de dados obtidos. Conclusões: Os resultados obtidos nesta investigação sugerem que os cirurgiões dentistas que trabalham na área da Implantodontia devem rever seus protocolos de orientação aos pacientes e regimes de manutenção das próteses totais sobre implantes, a fim de manter a saúde dos indivíduos, prevenir lesões inflamatórias nos tecidos orais e proporcionar longevidade à reabilitação. / Introduction: Considering the increasing tendency of the use of prostheses on implants in both our population and worldwide, it is important to study the several conditions involved in the longevity and functionality of these parts for individuals in general. Aim: To determine the occurrence of pathological changes associated with full-arch implant-supported fixed prostheses and to correlate them with individual variables, prosthetic specimens and the participation of Candida yeasts in these individuals. Methodology: Patients with full-arch implant-supported fixed prostheses and overdentures were evaluated at the time of removal of the parts for control and maintenance, after consent with the terms of free and informed consent. The participants had their total salivary flows initially evaluated. After the removal of the prosthesis, the pieces were evaluated technically (prostheses, implants, screws and abutments), the mouth examined clinically, the conditions of the mucosa underlying the prostheses were noted, and any lesions associated with the prostheses were evaluated and treated. In parallel, material was collected for mycological examination of two sites - mucosa under the prosthesis and base of the prosthesis. The material was collected with the help of swabs and transferred to plates with differential culture medium (Chromagar®) for observation of growth and identification of yeasts. Results: Data were collected on 91 participants and 102 implants. Thirty-one men and 57 women with mean age of 66.6 years. Four overdentures, 72 in the lower arch and 26 in the upper arch. No participant presented hyposalivation. Candida spp. were identified in 70.3% of the lower arches and 85.7% of the upper arches. The time of use of the prostheses interfered in the percentage of identification of the yeasts. Candida albicans was the main species identified (93% of the positive cases). Other species identified were: Candida glabrata, C. kruzei and C. tropicalis. Hygiene techniques in addition to conventional brushing reduced fungal contamination, while smoking or drinking increased. Inflammation in mucosa was positively related to the presence of Candida in mucosa and prostheses. Eight participants underwent surgical interventions to remove proliferative inflammatory processes (8.8%). A total of 532 implants were evaluated, with a loss of 1,13% of them and the need to re-tighten 271 screws (50.1%). Data were analyzed descriptively and submitted to statistical tests appropriate to the type of data obtained. Conclusions: The results obtained in this research suggest that dental surgeons working in the implantology area should review their patient orientation protocols and maintenance of full-arch implant-supported fixed prostheses in order to maintain the health of individuals, prevent inflammatory lesions in tissues oral and provide longevity to rehabilitation.

Numerous applications in neuroscience research and neural prosthetics, such as retinal prostheses, spinal-cord surface stimulation for prosthetics, electrocorticogram (ECoG) recording for epilepsy detection, etc., involve electrical interaction with soft excitable tissues using a surface stimulation and/or recording approach. These applications require an interface that is able to set up electrical communications with a high throughput between electronics and the excitable tissue and that can dynamically conform to the shape of the soft tissue. Being a compliant and biocompatible material with mechanical impedance close to that of soft tissues, polydimethylsiloxane (PDMS) offers excellent potential as the substrate material for such neural interfaces. However, fabrication of electrical functionalities on PDMS has long been very challenging. This thesis work has successfully overcome many challenges associated with PDMS-based microfabrication and achieved an integrated technology platform for PDMS-based stretchable microelectrode arrays (sMEAs). This platform features a set of technological advances: (1) we have fabricated uniform current density profile microelectrodes as small as 10 microns in diameter; (2) we have patterned high-resolution (feature as small as 10 microns), high-density (pitch as small as 20 microns) thin-film gold interconnects on PDMS substrate; (3) we have developed a multilayer wiring interconnect technology within the PDMS substrate to further boost the achievable integration density of such sMEA; and (4) we have invented a bonding technology---via-bonding---to facilitate high-resolution, high-density integration of the sMEA with integrated circuits (ICs) to form a compact implant. Taken together, this platform provides a high-resolution, high-density integrated system solution for neural and muscular surface interfacing. sMEAs of example designs are evaluated through in vitro and in vivo experimentations on their biocompatibility, surface conformability, and surface recording/stimulation capabilities, with a focus on epimysial (i.e. on the surface of muscle) applications. Finally, as an example medical application, we investigate a prosthesis for unilateral vocal cord paralysis (UVCP) based on simultaneous multichannel epimysial recording and stimulation.

Biotribology, the study of lubrication, wear and friction within the body, has become a topic of high importance in recent times as we continue to encounter debilitating diseases and trauma that destroy function of the joints. A highly successful surgical procedure to replace the joint with an artificial equivalent alleviates dysfunction and pain. However, the wear of the bearing surfaces in prosthetic joints is a significant clinical problem and more patients are surviving longer than the life expectancy of the joint replacement. Revision surgery is associated with increased morbidity and mortality and has a far less successful outcome than primary joint replacement. As such, it is essential to ensure that everything possible is done to limit the rate of revision surgery. Past experience indicates that the survival rate of the implant will be influenced by many parameters, of primary importance, the material properties of the implant, the composition of the synovial fluid and the method of lubrication. In prosthetic joints, effective boundary lubrication is known to take place. The interaction of the boundary lubricant and the bearing material is of utmost importance. The identity of the vital active ingredient within synovial fluid (SF) to which we owe the near frictionless performance of our articulating joints has been the quest of researchers for many years. Once identified, tribo tests can determine what materials and more importantly what surfaces this fraction of SF can function most optimally with. Surface-Active Phospholipids (SAPL) have been implicated as the body’s natural load bearing lubricant. Studies in this thesis are the first to fully characterise the adsorbed SAPL detected on the surface of retrieved prostheses and the first to verify the presence of SAPL on knee prostheses. Rinsings from the bearing surfaces of both hip and knee prostheses removed from revision operations were analysed using High Performance Liquid Chromatography (HPLC) to determine the presence and profile of SAPL. Several common prosthetic materials along with a novel biomaterial were investigated to determine their tribological interaction with various SAPLs. A pin-on-flat tribometer was used to make comparative friction measurements between the various tribo-pairs. A novel material, Pyrolytic Carbon (PyC) was screened as a potential candidate as a load bearing prosthetic material. Friction measurements were also performed on explanted prostheses. SAPL was detected on all retrieved implant bearing surfaces. As a result of the study eight different species of phosphatidylcholines were identified. The relative concentrations of each species were also determined indicating that the unsaturated species are dominant. Initial tribo tests employed a saturated phosphatidylcholine (SPC) and the subsequent tests adopted the addition of the newly identified major constituents of SAPL, unsaturated phosphatidylcholine (USPC), as the test lubricant. All tribo tests showed a dramatic reduction in friction when synthetic SAPL was used as the lubricant under boundary lubrication conditions. Some tribopairs showed more of an affinity to SAPL than others. PyC performed superior to the other prosthetic materials. Friction measurements with explanted prostheses verified the presence and performance of SAPL. SAPL, in particular phosphatidylcholine, plays an essential role in the lubrication of prosthetic joints. Of particular interest was the ability of SAPLs to reduce friction and ultimately wear of the bearing materials. The identification and knowledge of the lubricating constituents of SF is invaluable for not only the future development of artificial joints but also in developing effective cures for several disease processes where lubrication may play a role. The tribological interaction of the various tribo-pairs and SAPL is extremely favourable in the context of reducing friction at the bearing interface. PyC is highly recommended as a future candidate material for use in load bearing prosthetic joints considering its impressive tribological performance.

Les progrès de la mécatronique ont permis d’améliorer les prothèses du membre supérieur en augmentant le catalogue des mouvements prothétiques. Cependant, un fossé se creuse entre les capacités technologiques de la prothèse et leur méthode de contrôle. La commande myoélectrique, qui est la méthode la plus répandue, reste complexe, notamment pour les personnes amputées au niveau trans-huméral qui peuvent avoir un coude actif en plus de la main et du poignet motorisés. Une approche intéressante consiste à utiliser la mobilité du membre résiduel, présente chez la plupart des amputés trans-huméraux, pour contrôler des articulations prothétiques distales comme le coude. Les mouvements du coude sont couplés aux mouvements du membre résiduel selon un modèle de coordination épaule/coude saine. Cette thèse étudie une stratégie de commande d’un coude prothétique utilisant les mouvements du membre résiduel, mesuré par des centrales inertielles, et nos connaissances du contrôle moteur humain. Pour cela, un modèle de la coordination épaule/coude a été construit à partir d’enregistrements de gestes sains de préhension. Ce modèle, implémenté sur un prototype de prothèse, a été testé par 10 individus sains équipés du prototype afin de valider le concept, puis par 6 personnes amputées. Ces dernières ont aussi réalisé la tâche avec une commande myoélectrique conventionnelle afin de comparer les résultats. La commande couplant automatiquement les mouvements de l’épaule et du coude s’est montrée satisfaisante en termes de facilité d’utilisation et de réduction des stratégies de compensation. / Progress in mechatronics has enabled the improvement of upper limb prosthetics increasing the grasps catalog. However, a gap has been growing between the prosthesis technological possibilities and the methods to control it. Indeed, common myoelectric control strategy remains complex, especially for transhumeral amputees who can have an active elbow in addition to a prosthetic wrist and hand. Since most transhumeral amputees have a mobile residual limb, an interesting approach aims at utilizing this mobility to control intermediate prosthetic joints, like the elbow, based on the shoulder/elbow coordination observed in healthy movements. This thesis investigates the possibility of controlling an active prosthetic elbow using the residual limb motion, measured with inertial measurement units, and knowledge of the human motor control. A primary focus has been targeting the reaching movement for which a model has been built using regression tools and kinematic data from several healthy individuals. The model, implemented on a prosthesis prototype, has been tested with 10 healthy participants wearing the prototype to validate the concept, and with 6 amputated individuals. These participants also performed the task with a conventional myoelectric control strategy for comparison purpose. The results show that the inter-joint coordination-based control strategy is satisfying in terms of intuitiveness and reduction of the compensatory strategies.