Transcranial direct-current stimulation
Transcranial direct current stimulation (tDCS) is a form of neurostimulation which uses constant, low current delivered directly to the brain area of interest via small electrodes. tDCS was originally developed to help patients with brain injuries such as strokes. Tests on healthy adults demonstrated that tDCS can increase cognitive performance on a variety of tasks[citation needed], depending on the area of the brain being stimulated. tDCS has been utilized to enhance language and mathematical ability, attention span, problem solving, memory, and coordination.
https://en.wikipedia.org/wiki/Transcranial_direct-current_stimulation
http://www.nature.com/news/2011/110413/full/472156a.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3238088/
Design
The brain is an electrochemical organ. It can be influenced by tablets and electro-magnetic field. The ZEN mask is an ultralight portable transcranial micro-polarizer.

4 built-in electrodes with weak electric current stimulate the frontal part of the brain
Dynamic voltage

The range of voltages is chosen taking into account the dynamic characteristics of the impedance (the sum of the resistance of the skin and internal resistance). The current range is limited by automatic cut-off.
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Electrode 1
Electrode 2

ZEN mask automatically adapts to any user without additional settings in the safe range.
The potential difference between the electrodes makes it possible to automatically determine the optimum force of action. Alloyed stainless steel electrodes and the development of electrodes specially for ZEN.
Charging
ZEN mask has a built-in micro USB charging

Built-in battery
Charging in one hour
Charging micro-USB
Software protection
ZEN mask automatically turns off all the power-on functions when plugged into the USB network
ZEN mask is connected to the laptop by micro-USB
ZEN mask works without recharging for five days
USB cable included

46
For a good sleep, the ease of falling asleep and using a ZEN mask is important. Weight bandage is only 46 grams. The entire component base was selected by the criterion of minimum weight. This is the lightest and thin accessory of all existing on the market gadgets for sleep.
Benefits
Micropolarization is also useful for preventive purposes.
So describes the benefits of the St. Petersburg Scientific Research Psychoneurological Institute:
Safely
Safe, non-invasive, highly effective way of correction of impaired functions of the central, peripheral and autonomic nervous system, having a wide range of indications and a narrow range of conditional restrictions.
Recovery
Normalizes the electrical properties of the nervous tissue. It restores the production and carrying out of bioelectric impulses, facilitates the restoration of physiological and the formation of compensatory functional connections in the cerebral cortex.
Healing
Has a general biological anti-inflammatory, anti-edema, analgesic, trophic, bactericidal action.