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The article focuses on wearable neuroprosthesis (NP) that uses transcutaneous electrical stimulation (TES) for partial restoration of motor and sensory functions after damage to the nervous system. TES uses pairs of electrodes on the skin to send short electrical charge pulses that results in hyperpolarization and depolarization of excitable cellular membranes. The first and second generation of NP systems and problems are described which include somewhat limited muscle selectivity, increased rate of muscle fatigue and complexity in application.

The overall goal of the research is to improve control for electrical stimulation-based assistance of walking in hemiplegic individuals. We present the simulation for generating offline input (sensors)-output (intensity of muscle stimulation) representation of walking that serves in synthesizing a rule-base for control of electrical stimulation for restoration of walking. The simulation uses new algorithm termed moving-window dynamic optimization (MWDO). The optimization criterion was to minimize the sum of the squares of tracking errors from desired trajectories with the penalty function on the total muscle efforts. The MWDO was developed in the MATLAB environment and tested using target trajectories characteristic for slow-to-normal walking recorded in healthy individual and a model with the parameters characterizing the potential hemiplegic user. The outputs of the simulation are piecewise constant intensities of electrical stimulation and trajectories generated when the calculated stimulation is applied to the model. We demonstrated the importance of this simulation by showing the outputs for healthy and hemiplegic individuals, using the same target trajectories. Results of the simulation show that the MWDO is an efficient tool for analyzing achievable trajectories and for determining the stimulation profiles that need to be delivered for good tracking. [ABSTRACT FROM AUTHOR]

We designed a new surface multi-pad electrode for the electrical stimulation of the forearm that is effective in controlling functional grasp in hemiplegic patients. The electrode shape and size were designed on the basis of the surface stimulation map of the forearm, determined from measurements in seven hemiplegic patients who had limited or absent voluntary movements of the fingers, thumb and wrist. The stimulation map for each patient was assessed with a conventional set of single pad Pals Platinum electrodes. Since the sites for the stimulation varied greatly between patients, the end result was a rather large multi-pad electrode. Modulating multi-pad electrode size, shape, position and individual pad stimulation parameters allows us to accommodate the diversity of the neural tissues in patients that need to be activated for functional grasp. This also allows asynchronous activation of different portions of the muscle and dynamic adaptation of the stimulation sites to appropriate underlying tissues during functional use. The validity of the determined stimulation map was tested in the same group of hemiplegic patients. The selected set of active pads resulted in fully functional and reproducible palmar and lateral grasps similar to healthy-like grasps.

We describe here the Walkaround, a new rehabilitation device that allows walking without hand support of individuals with limited ability to control posture. The design of this device was motivated by the recent development of functional electrical therapy of walking in individuals with hemiplegia, who in many cases need postural and body weight assistance while walking. The Walkaround assists humans with a compromised posture, inability to fully support the body weight on one leg, and prevents their falls. These three features are accomplished by an ergonomic lumbar belt being attached to a rigid wheeled frame by a suspensor system. The height of the frame which interfaces the ground by three telescopic bars, the size of the belt, and the pretension of the suspension system, can all be adjusted to complement the size and the needs of the potential user. The amount of body weight support can be adjusted by setting the lengths of telescopic bars and the pretension of the springs in the suspensors. The prototype device was tested on five individuals with hemiplegia. The walking assisted by the Walkaround was significantly faster (Deltav = 0.13 m/s p 0.05) in comparison to walking assisted by a therapist. The symmetry index between paretic and non affected leg was decreased (Delta R(stance) = -7.4% p 0.05, Delta R (swing) =-9.2%, p 0.05, symmetry improved) when walking assisted by the Walkaround. The users and therapists were positive about the performance of the Walkaround. The users felt safer and the therapists were relieved from the physical effort allowing them to concentrate more on assisting - a nearly normal walking pattern.