Encoder-Controlled Functional Electrical Stimulator for Bilateral Wrist Activities-Design and Evaluation.

Upper limb impairment following stroke is often characterized by limited voluntary control in the affected arm. In addition, significant motor coordination problems occur on the unaffected arm due to avoidance of performing bilateral symmetrical activities. Rehabilitation strategies should, therefore, not only aim at improving voluntary control on the affected arm, but also contribute to synchronizing activity from both upper limbs.

Transcranial direct current stimulation: A review of electrode characteristics and materials.

Electrode characteristics are crucial in transcranial direct current stimulation (tDCS) since electrode design and placement determine the cortical area being modulated, current density and spatial resolution of stimulation. Early research on tDCS sought to determine optimal parameters for stimulation by specifying maximum current, duration and sizes of electrodes. Further research focused on determining efficient ways to deliver stimulation to targeted regions on the cortex with minimal discomfort to the user by altering electrode size, placement, shape and material.

A review of transcranial electrical stimulation methods in stroke rehabilitation.

Transcranial electrical stimulation (TES) uses direct or alternating current to non-invasively stimulate the brain. Neuronal activity in the brain is modulated by the electrical field according to the polarity of the current being applied. TES includes transcranial direct current stimulation (tDCS), transcranial random noise stimulation, and transcranial alternating current stimulation (tACS).

Reducing the sensation of electrical stimulation with dry electrodes by using an array of constant current sources.

Hydrogel electrodes are commonly used for functional and other electrical stimulation applications since the hydrogel layer has been shown to considerably reduce the perception of stimulation compared to dry electrodes. However, these hydrogel electrodes must be changed regularly as they dry out or become contaminated with skin cells and sweat products, thus losing their adhesiveness and resistive properties. Dry electrodes are longer lasting but are more uncomfortable due to unequal current distribution (current hogging).