Water-soluble adhesive for stable long-term ambulatory EEG recordings.

OBJECTIVE: Conventional methods used to adhere EEG electrodes are often uncomfortable. Here, we present a polymer-based water-soluble EEG adhesive that can be maintained for up to 6 days. The primary outcome measure of this study is the median electrode impedance at day 6. METHODS: Impedance measurements for 841 EEG recordings using a 21 channel 10-20 configuration were remotely logged daily for 6 days after connection. A novel electrode adhesive was used to attach EEG electrodes. Patients were instructed to maintain their electrodes on day 4. RESULTS: Median electrode impedances were significantly below 10kOhms for each day of recording, with a median value on day 6 of 4.18kOhms. Impedance values were significantly lower on day 5 than on day 4, demonstrating that the maintenance process can reduce impedance. Except for day 4-5, the median impedance increased each day. No significant difference was found on the first or final day between clinics or residences from areas of different geographic remoteness. CONCLUSIONS: EEG is able to be recorded in patients homes for 6 days with acceptable impedance and no significant effect of regionality or patients age. SIGNIFICANCE: To the best of our knowledge, this is the first report in the literature of impedance data from long-term ambulatory EEG studies.

neuroBi: A Highly Configurable Neurostimulator for a Retinal Prosthesis and Other Applications.

To evaluate the efficacy of a suprachoroidal retinal prosthesis, a highly configurable external neurostimulator is required. In order to meet functional and safety specifications, it was necessary to develop a custom device. A system is presented which can deliver charge-balanced, constant-current biphasic pulses, with widely adjustable parameters, to arbitrary configurations of output electrodes. This system is shown to be effective in eliciting visual percepts in a patient with approximately 20 years of light perception vision only due to retinitis pigmentosa, using an electrode array implanted in the suprachoroidal space of the eye. The flexibility of the system also makes it suitable for use in a number of other emerging clinical neurostimulation applications, including epileptic seizure suppression and closed-loop deep brain stimulation. Clinical trial registration number NCT01603576 (www.clinicaltrials.gov).