The design, development and evaluation of an array-based FES system with automated setup for the correction of drop foot

Functional electrical stimulation has been shown to be a safe and effective means of correcting drop foot of central neurological origin. However, despite recent technological advances, the set-up of surface stimulators remains a challenge for many users with drop foot. The automation of the setup process through the use of electrode arrays has been proposed as a way to address this problem. This paper describes a series of research and clinical studies which have led to the first demonstration of unsupervised automated setup of an electrode-array based drop foot stimulator. Finally, future research plans are discussed

A review of the design and clinical evaluation of the ShefStim array-based functional electrical stimulation system

Functional electrical stimulation has been shown to be a safe and effective means of correcting foot 12 drop of central neurological origin. Current surface-based devices typically consist of a single channel stimulator, 13 a sensor for determining gait phase and a cuff, within which is housed the anode and cathode. The cuff-mounted 14 electrode design reduces the likelihood of large errors in electrode placement, but the user is still fully responsible 15 for selecting the correct stimulation level each time the system is donned. Researchers have investigated different 16 approaches to automating aspects of setup and/or use, including recent promising work based on iterative learning 17 techniques. This paper reports on the design and clinical evaluation of an electrode array-based FES system for 18 the correction of drop foot, ShefStim. The paper reviews the design process from proof of concept lab-based study, 19 through modelling of the array geometry and interface layer to array search algorithm development. Finally, the 20 paper summarises two clinical studies involving patients with drop foot. The results suggest that the ShefStim 21 system with automated setup produces results which are comparable with clinician setup of conventional systems. 22 Further, the final study demonstrated that patients can use the system without clinical supervision. When used 23 unsupervised, setup time was 14 minutes (9 minutes for automated search plus 5 minutes for donning the 24 equipment), although this figure could be reduced significantly with relatively minor changes to the design

Application of angular rate gyroscopes as sensors in electrical orthoses for foot drop correction

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

An Implantable Stimulator for Selective Stimulation of Nerves

Acute experimentation performed at many centres over the last twenty years has shown techniques which allow small neurones to be stimulated without large, the reverse of the normal recruitment order usually encountered during electrical stimulation; one-way excitation of neurones; and excitation of only a region of a nerve. These techniques should improve neural prosthesis by, for example: avoiding pain during stimulation and requiring electrode sites and therefore fewer incisions. To enable chronic clinical experiments of these advanced methods, there is a need for a specialised chronically-implantable stimulator, which can control either dipolar, tripolar or pentapolar nerve cuff electrodes. This thesis is concerned with the design and development of such a stimulator and, in particular, a fully customised analogue integrated circuit that converts incoming digital words into corresponding stimulation currents. A binary word is transmitted to the implant, which defines the current waveform parameters for the electrodes. This word is loaded into a shift register at the input. Part of the word is presented to a digital to analogue converter, to specify stimulation amplitude, and a pulse generator, which generates either a quasi-trapezoidal, or a square shaped stimulation waveforms. Four novel low offset linear transconductors provide the stimulation currents that are switched to the desired outputs. The charge balancing of the stimulation waveform is realised by a very long time-constant switched capacitor integrator. The major difficulties in the design of the analogue full custom IC proved to be the linear transconductor stages and the integrator. Results for the test ICs are presented and the design of a complete stimulator system is described

Future developments in brain-machine interface research

Neuroprosthetic devices based on brain-machine interface technology hold promise for the restoration of body mobility in patients suffering from devastating motor deficits caused by brain injury, neurologic diseases and limb loss. During the last decade, considerable progress has been achieved in this multidisciplinary research, mainly in the brain-machine interface that enacts upper-limb functionality. However, a considerable number of problems need to be resolved before fully functional limb neuroprostheses can be built. To move towards developing neuroprosthetic devices for humans, brain-machine interface research has to address a number of issues related to improving the quality of neuronal recordings, achieving stable, long-term performance, and extending the brain-machine interface approach to a broad range of motor and sensory functions. Here, we review the future steps that are part of the strategic plan of the Duke University Center for Neuroengineering, and its partners, the Brazilian National Institute of Brain-Machine Interfaces and the École Polytechnique Fédérale de Lausanne (EPFL) Center for Neuroprosthetics, to bring this new technology to clinical fruition

Doctor of Philosophy

dissertationParalysis can be ameliorated through functional electrical stimulation (FES) of the intact peripheral nerves. The Utah Slanted Electrode Array (USEA) can improve FES systems by providing selective access to many independent motor unit populations.This dissertation includes three studies that expand the role of USEAs in FES applications. The fi rst study leverages the selectivity of the USEA to independently activate the hamstring muscles. Because the di fferent biarticular hamstring muscles can either ex or extend the limb (at the knee or hip), the ability to selectively activate each one independently is required to evoke functional movements such as stance and gait. USEAs implanted in the muscular branch of the sciatic nerve were able to selectively activate each muscle of the hamstring group. Activation of these muscles was graded with increasing stimulus strength, and provided ample dynamic range to allow for fine control of muscle force. The second study demonstrates the ability of the USEA to selectively block neural activity. Upper motor neuron damage can cause hyperre exia and spasticity as well as paralysis. By delivering high-frequency sinusoids through electrodes of the USEA, ber subsets in a nerve were blocked while allowing the remainder of the nerve to function normally. Sinusoids delivered through different electrodes allowed for deactivation of di fferent muscles. The ability to selectively interrupt activity in fiber subpopulations within a nerve will provide new therapeutic options for the positive symptoms of upper motor neuron damage. The fi nal study addresses the practical difficulty of choosing the appropriate stimulus parameters to evoke functional movements. In a USEA-based FES system, the electrodes and stimulus parameters that evoke the desired responses must be identifi ed empirically. USEAs were implanted into three diff erent hind limb nerves, and the response evoked by each electrode was measured noninvasively using 3-D endpoint force. Each electrode was classifi ed as evoking limb flexion or limb extension, and a range of stimulus intensities was identifi ed that evoked a graded force response. Excitation overlap between selected electrode pairs was quantifi ed using the refractory technique. This method will allow for electrode and stimulus parameter selection for use in an FES system using minimal, noninvasive instrumentation

Biocompatible/Biodegradable Materials for Implantable Mg-Air Batteries

Biodegradable implantable medical bionics can be used to diagnose and/or treat disease and eventually disappear without surgical removal. If an “external” energy source is required for effective operation, then a biocompatible/biodegradable battery would be ideal. This thesis is focused on the development of biocompatible/biodegradable air cathode materials and polymer electrolytes for implantable Mg-air batteries. Bioresorbable Mg alloy serves as the anode because of its benign biological function and high theoretical capacity. Polypyrrole with excellent electroactivity and biocompatibility satisfies the requirements for cathodes. To obviate its inherent non-biodegradability, a biopolymer component affording biodegradability is introduced in forming a composite. Polymer electrolyte is desirable to fabricate miniaturized Mg-air batteries. The biopolymer-ionic liquid polymer electrolyte can achieve both high ionic conductivity and biodegradability

Topics in Neuromodulation Treatment

"Topics in Neuromodulation Treatment" is a book that invites to the reader to make an update in this important and well-defined area involved in the Neuroscience world. The book pays attention in some aspects of the electrical therapy and also in the drug delivery management of several neurological illnesses including the classic ones like epilepsy, Parkinson's disease, pain, and other indications more recently incorporated to this important tool like bladder incontinency, heart ischemia and stroke. The manuscript is dedicated not only to the expert, but also to the scientist that begins in this amazing field. The authors are physicians of different specialties and they guarantee the clinical expertise to provide to the reader the best guide to treat the patient