Stimulation of peripheral nerves using conductive hydrogel electrodes.

Nerve block via electrical stimulation of nerves requires a device capable of transferring large amounts of charge across the neural interface on chronic time scales. Current metal electrode designs are limited in their ability to safely and effectively deliver this charge in a stable manner. Conductive hydrogel (CH) coatings are a promising alternative to metal electrodes for neural interfacing devices. This study assessed the performance of CH electrodes compared to platinum-iridium (PtIr) electrodes in commercial nerve cuff devices in both the in vitro and acute in vivo environments. CH electrodes were found to have higher charge storage capacities and lower impedances compared to bare PtIr electrodes. Application of CH coatings also resulted in a three-fold increase in in vivo charge injection limit. These significant improvements in electrochemical properties will allow for the design of smaller and safer stimulating devices for nerve block applications.

Perceived driving safety and estimated blood alcohol concentration (BAC) the morning after drinking amongst young Australians attending a music festival: a cross-sectional survey.

BACKGROUND: Alcohol-related motor vehicle crashes remain a significant and costly public health issue globally. Particularly young people are over-represented in these incidents. This study set out to explore the factors that influence individuals' perceptions of their safety to drive, and the factors related to a change in intention to drive. METHODS: Four hundred nine young people aged 18-40 attending an Australian multi-day music festival completed a survey measuring demographics, alcohol use, amount of sleep obtained the previous night, intention to drive, number of passengers, perceived safety to drive, estimated BAC (measured in g/210 L) and change in intention to drive following a BAC measurement via breathalysers. Statistical analyses involved univariate tests of association and multivariate logistic regression. RESULTS: Only one in five participants felt they were completely safe to drive. Males self-rated as less safe to drive than females. Multivariate analyses showed that licence class, sleep hours, units of alcohol consumed in the past 24 h and estimated BAC had statistically significant associations with driving safety perception. Participants who slept for greater than seven hours the previous night were three times more likely to feel safe to drive than those who had less than five hours of sleep (OR 3.05 (95% CI 1.25, 7.45)). Forty-one percent of participants changed their intended time of driving after having their BAC measured with a breathalyser. There was a statistically significant association between changing the intention to drive to a later time with an increase in each extra passenger in a participant's vehicle (OR 1.53 (95% CI 1.02, 2.30)). CONCLUSIONS: Whilst concerning behaviours relating to high-risk alcohol consumption were found, the study uncovered promising findings about young peoples' perceptions of their safety to drive, and their propensity to change their driving intention. The strong correlation between hours of sleep, estimated BAC, units of alcohol consumed and license class with perception of driving safety suggests an increased awareness among young people and promotion of these factors may potentially improve actual driver safety. The influence of number of passengers on intention to drive later is another important consideration for future road safety research or promotion.

Analysis of the voltage response to identify macromolecule quantities in an electrolyte.

Current techniques of detecting proteins in solution can prove to be time consuming and expensive. Although low cost techniques are available, these are often slow and inaccurate. The authors propose an innovative technique for detecting the presence of proteins and other organic macromolecules in an electrolyte by analyzing the voltage waveform resulting from a biphasic, constant-current, charge-balanced electrical stimulation. Initial experiments have proven the viability of the technique. However due to the limitation of technique accuracy, further refinement of the measurement approach is required.

ARM-based visual processing system for prosthetic vision.

A growing number of prosthetic devices have been shown to provide visual perception to the profoundly blind through electrical neural stimulation. These first-generation devices offer promising outcomes to those affected by degenerative disorders such as retinitis pigmentosa. Although prosthetic approaches vary in their placement of the stimulating array (visual cortex, optic-nerve, epi-retinal surface, sub-retinal surface, supra-choroidal space, etc.), most of the solutions incorporate an externally-worn device to acquire and process video to provide the implant with instructions on how to deliver electrical stimulation to the patient, in order to elicit phosphenized vision. With the significant increase in availability and performance of low power-consumption smart phone and personal device processors, the authors investigated the use of a commercially available ARM (Advanced RISC Machine) device as an externally-worn processing unit for a prosthetic neural stimulator for the retina. A 400 MHz Samsung S3C2440A ARM920T single-board computer was programmed to extract 98 values from a 1.3 Megapixel OV9650 CMOS camera using impulse, regional averaging and Gaussian sampling algorithms. Power consumption and speed of video processing were compared to results obtained to similar reported devices. The results show that by using code optimization, the system is capable of driving a 98 channel implantable device for the restoration of visual percepts to the blind.

Retinal neurostimulator for a multifocal vision prosthesis.

A neurostimulator application-specific integrated circuit (ASIC) with scalable circuitry that can stimulate 14 channels, has been developed for an epi-retinal vision prosthesis. This ASIC was designed to allow seven identical units to be connected to control up to 98 channels, with the ability to stimulate 14 electrodes simultaneously. The neurostimulator forms part of a vision prosthesis, designed to restore vision to patients who have lost their sight due to retinal diseases such as retinitis pigmentosa and macular degeneration. For charge balance, the neurostimulator was designed to stimulate with current sources and sinks operating together, and with the ability to drive a hexagonal mosaic of electrodes to reduce the electrical crosstalk that occurs when multiple bipolar stimulation sites are active simultaneously. A hexagonal mosaic of electrodes surrounds each stimulation site and has been shown to effectively isolate each site, increasing the ability to inject localized independent charge into multiple regions simultaneously.