CryFibril (also referred to as "Nano-Weave" or "Nano-Fiber") is the single most important component of CryNet's Nanosuit (as well as the CryNet Nanosuit 2), and is the most advanced artificial muscle in existence.
CryFibril is one of the most complex and advanced components of the Nanosuit, giving the wearer unsurpassed physical performance and protection on the battlefield when compared to other artificial muscle systems. It also functions as a medium for the nanosuit modal functions such as the cloak ability.
CryFibril was first used to great effect in the Nanosuit 1.0 and set the standard for all other Nanosuits (the four-modes radial system being the greatest). With it, the operator could run faster, jump higher, and hit harder than any human alive, thus performing at super-human levels. It was soon after copied by other companies and governments (most notably being the North Koreans and their Nanosuit) but all of their iterations were "inferior" compared to Crynet's. It has since then undergone significant upgrades, most notably those within the CryNet Nanosuit 2 where the upgraded CryFibril became twice as light, 32% stronger, gained 20% more energy storage capacity, the ability to extract energy via solar, radiation, kinetic, and through carbon released by carrion (biologically dead corpses). The newest version of CryFibril supports a dark blue color compared to the pure black found on the older version. The CryFibril also powers the SECOND system utilized by the Nanosuit 2.
It is apparent that CryFibril is able to fuse and bond with the human body, as shown and mentioned in Crysis 2 and Crysis: Legion, when Alcatraz suffers fatal wounds at the beginning of the game, shortly before being rescued by Prophet and given the Nanosuit. Later on, when the Nanosuit is being scanned, it is shown to have bonded with Alcatraz's body through the wounds. The CryFibrill is mentioned at the beginning as a semi-organic component to the armor, suggesting it could be alive, or simply replicates biological properties.