FullDive

FullDive is the use of technology to fully immerse one's consciousness in virtual reality. Developed by Kayaba Akihiko, it led to the creation of the device called NerveGear. It is the basis of most of the stories in the entire Sword Art Online series.

A NERve Direct Linkage Environment System or NERDLES (ニードルス) is required for a FullDive.

Known VR Consoles

 * Nerve Gear
 * AmuSphere
 * MediCuboid
 * Soul Translator
 * Neuro Linker (Accel World crossover)

NerveGear
The NerveGear (ナーヴギア) was created by Argus. It only has a single interface that covers the player's whole head and face. It completely controls the player's consciousness by redirecting the signals the brain sends to the body and sending its own waves to stimulate the five senses. It has its own battery source, as well as a high frequency electromagnetic microwaves transmitter. NerveGear, when first produced, only puzzles, education related, or environmental type games were brought out. So, Sword Art Online was a major excitement to the gamers. This design trapped 10,000 players during the official launch of Sword Art Online in September 2022. It is the first VR technology that has been mass-produced.

AmuSphere
AmuSphere (アミュスフィア) is the revised version of the NerveGear which was co-developed by RECTO Progress Inc.. The system has been modified to make it safer than its predecessor by changing the microwaves transmitter to a low frequency one and the incorporation of various sensors that continually monitor blood pressure and brain waves which provoke a safety logout feature in case that the person's statuses become abnormal. In addition, the AmuSphere does not completely block out signals from the body, like its predecessor, the NerveGear did, so some players may pay extra for specialized rooms designed to make the experience all the more real.

MediCuboid
MediCuboid (メディキュボイド) belongs to the same generation as the AmuSphere, but it was developed by the government research with information provided by Koujirou Rinko. It is above the AmuSphere because it is composed by a complete bed, rather than just a helmet; it connects not only to the medulla, but to the spinal cord also, besides possess a greater processing power allowing an interaction with deeper parts of the brain. All these improvements provide the user with enhanced reflexes and reaction time. However, this helmet is used specifically for medical purposes, specifically for patients in Terminal Care. The users of MediCuboid hardly uses their own body to come back to the real world; instead, they use another screen, whether wirelessly or an antenna, to see reality through cameras and microphones (which helps the most with the blind or deaf).

Beyond FullDiving
During Project Alicization, a new technology is hinted at which is called Brain Machine Interface, or BMI for short, where the mind is accelerated to x times the normal, giving the person the ability to perform processing x times faster. The BMI uses a different FullDive technique. It starts with «Soul Translation». Kirito explained that this complexity is of the brain: the synapse is the sole transmitter between neurons, and then goes into a theory: Quantam brain dynamics, which is like the cell frame to support its structure, like a skull. However, it is in a shape of a tube, which has a light particle, or evanescent photon, a quantum. The collection of photons in the computer, is called «Fluctuating Light», shortened to «Fluctlight». The «Soul Translator» translate «Fluctlight», or the words humans understand and write out the information into a form that could be read.

Usage
To use Nerve Gear and AmuSphere, the player places the game console over the head. Then, the player will lay down in a comfortable position. Afterwards, the helmet-like game will activate through the initiation words «Link Start». Tecnología de inmersión total

Trivia

 * Though it is not seen or mentioned in the SAO series, the Neuro Linker is a device like the AmuSphere serving the same purpose as a VR device.