Setup Of Electrodes Research Articles

Electro-osmotic instability of concentration enrichment in curved geometries for an aqueous electrolyte

We report that an electro-osmotic instability of concentration enrichment in curved geometries for an aqueous electrolyte, as opposed to the well-known one, is initiated exclusively at the enriched interface (anode), rather than at the depleted one (cathode). For this instability, the limitation of unrealistically high material Peclet number in planar geometry is eliminated by the strong electric field arising from the line charge singularity. In a model setup of concentric circular electrodes, we show by stability analysis, numerical simulation, and experimental visualization that instability occurs at the inner anode, below a critical radius of curvature. The stability criterion is also formulated in terms of a critical electric field and extended to arbitrary (2d) geometries by conformal mapping. This discovery suggests that transport may be enhanced in processes limited by salt enrichment, such as reverse osmosis, by triggering this instability with needle-like electrodes.

Novel flexible cap for application of transcranial electrical stimulation: a usability study

BackgroundAdvances in transcranial electrical stimulation (tES) are hampered by the conventional rubber electrodes manually attached to the head with rubber bands. This procedure limits montages to a few electrodes, is error prone with respect to electrode configurations and is burdensome for participants and operators. A newly developed flexible cap with integrated textile stimulation electrodes was compared to the conventional setup of rubber electrodes inserted into sponges fixated by rubber bands, with respect to usability and reliability. Two operators applied both setups to 20 healthy volunteers participating in the study. Electrode position and impedance measures as well as subjective evaluations from participants and operators were obtained throughout the stimulation sessions.ResultsOur results demonstrated the superiority of the flexible cap by means of significantly higher electrode configuration reproducibility and a more efficient application. Both, operators and volunteers evaluated the flexible cap as easier to use and more comfortable to wear when compared to the conventional setup.ConclusionIn conclusion, the new cap improves existing and opens new application scenarios for tES.

Electro-flotation harvesting of microalgae using a combination of electrode types

This study aims to search for a proper system for electro-flotation harvesting of microalgae Dunaliella salina with a minimization of metal contamination. The electro-flotation was realized by an application of constant electrical current via planar electrodes. An applied electrical current caused a cell aggregation and produced small bubbles which levitated cell clusters to form a foam layer containing concentrated microalgae on the top surface of the culture fluid. Since erosion induced by electrolysis did not occur for cathodes (negative electrodes), we tested the harvesting by using planar cathodes, lying in the bottom of the reactor, made from different materials and forms. For a given electrical current, all cathodes resulted in a similar harvesting efficiency as well as the energy consumption. Unlike the cathode, the anode (positive electrodes) usually erodes in the electrolytic process. To avoid contamination of released metal, we used only graphite plates as the anode. Different settings of graphite anode plates (located above the cathode) were studied. For a given electrical current, all cases of anode settings had a similar harvesting efficiency but the energy consumption increased with the distance between the anode and the cathode. For a given setup of electrodes, we showed that both the harvesting efficiency and the energy consumption increased with the applied electrical current. By considering the above results as well as the fact that the stainless steel plate is cheaper and easier to handle in comparison to the graphite plate, we suggest that a combination of graphite anode and stainless steel cathode is an appropriate set for microalgae harvesting with an avoidance of metal contamination. Furthermore, for a convenience of the collection of the levitated microalgae cells, the top surface should be leaved widely opened by setting the graphite anode plates near the wall of the reactor. Finally, we demonstrate a usage of the electrode combination for a large scale harvesting of the microalgae Dunaliella salina cultured with outdoor conditions in a salt production company located in Nakhon Ratchasima, Thailand.

A feasibility pilot using telehealth videoconference monitoring of home-based NMES resistance training in persons with spinal cord injury.

The objective of the study was to investigate the feasibility and initial efficacy of telehealth communication in conjunction with surface neuromuscular electrical stimulation (NMES) resistance training (RT) to induce muscle hypertrophy. This was a home-based setting of within-subject control design of trained vs controlled limbs. Five men with chronic (>1 year postinjury) motor-complete spinal cord injury (SCI) participated in a twice-weekly telehealth videoconference program using home-based NMES-RT for 8 weeks. Stimulation was applied to the knee extensor muscle group of the trained leg, while the untrained leg served as a control. Participants received real-time feedback to ensure a proper setup of electrodes and stimulator to monitor subject safety throughout the entire training session. Magnetic resonance imaging was used to measure cross-sectional areas (CSAs) and intramuscular fat (IMF) of the whole thigh and individual muscle groups. Average two-way travel time, distance traveled in miles and total cost of gas per mile were calculated. Participants had 100% compliance. Trained whole and absolute knee extensor muscle CSA increased by 13% (P=0.002) and 18% (P=0.0002), with no changes in the controlled limb. Absolute knee flexor and adductor CSAs increased by 3% (P=0.02) and 13% (P=0.0001), respectively. Absolute whole thigh and knee extensor IMF CSAs decreased significantly in the trained limb by 14% (P=0.01) and 36% (P=0.0005), respectively, with no changes in controlled limb. The pilot work documented that using telehealth communication is a safe, feasible and potentially cost-reducing approach for monitoring home-based NMES-RT in persons with chronic SCI. All trained muscles showed detectable muscle hypertrophy with concomitant decrease in ectopic adipose tissue.

Effects of Transcranial Alternating Current Stimulation on Cognitive Functions in Healthy Young and Older Adults.

Recently, transcranial alternating current stimulation (tACS) has emerged as a tool to enhance human cognitive processes. Here, we provide a brief summary of the rationale behind tACS-induced effects on task-relevant brain oscillations and associated cognitive functions and review previous studies in young subjects that have applied tACS in cognitive paradigms. Additionally, we present pilot data where we administered theta-tACS (6 Hz) over the temporoparietal cortex and a supraorbital reference for 20 min during implicit language learning in healthy young (mean/SD age: 22/2) and older (mean/SD age: 66/4) adults, in a sham-controlled crossover design. Linear mixed models revealed significantly increased retrieval accuracy following tACS-accompanied associative learning, after controlling for session order and learning success. These data provide the first implementation of tACS during cognitive performance in older adults and support recent studies suggesting that tACS in the theta frequency range may serve as a tool to enhance cognition, possibly through direct modulation of task-relevant brain oscillations. So far, studies have been heterogeneous in their designs, leaving a number of issues to be addressed in future research, including the setup of electrodes and optimal stimulation frequencies to be employed, as well as the interaction with age and underlying brain pathologies in specific patient populations.

Electrode Set-Up for EDM-Drilling of Large Aspect-Ratio Microholes

Holes of 0.3-0.4mm diameter and large depths are typical features in aerospace components of Ni-based and Ti-based alloys. The EDM process is a popular manufacturing method for this type of precision holes in difficult-to-machine materials. Optimization of this technology requires taking into account different aspects such as process parameters, electrode material and electrode set-up. These variables affect process performance in terms of processing time, dimensional tolerances and electrode wear. In this paper it is shown that the set-up of low-diameter electrodes can be carried out in conventional EDM machines, avoiding thus much more expensive processes such as the WEDG technology. Cu-W electrodes of diameter 0.2mm and aspect ratio over 100:1 can be prepared on the same machine where EDM-drilling will take place with a radial error below 5 m and surface finish Ra=0.5 m. Electrode diameter as low as 50 m has been achieved using this method. Application to EDM-drilling of Ti6Al4V using this type of electrodes is presented in this work.

Neurophysiological Requirements for Implanted Cochlear Prostheses

Regarding the neurophysiological requirements for implanted cochlear prostheses, we have discussed (i) the complexity of speech sounds, (ii) problems of intensity, then (iii) the frequency problem, and (iv) finally the possibility of a frequency transposition to the genuine frequency range of a single fibre of any mechanoreceptor and its connecting nerve fibre (less than 1 kHz) for the construction of an intracochlear prosthesis. In general it would seem necessary to seek compromises based on the fact that speech, at least the vowels, contains redundancy and that the use of additional sensory channels might be helpful for cochlear implants. Certainly besides other preprocessing techniques for speech information, the multichannel stimulation set-up of special electrodes has to be used to convey a sufficient amount of speech information to restore the faculty of speech perception in completely deaf patients. Decompression of intensity range and compression of frequency range might be especially useful.