Fully Depleted Silicon On Insulator (FD-SOI) is an innovative technology used in semiconductor manufacturing.
The NXP SoCs used in the Apalis iMX8 and the Colibri iMX8X are built with this technology.
Compared to the bulk-silicon transistors, FD-SOI has several advantages:
These advantages make the Apalis IMX8 and the Colibri IMX8X a very good choice in applications where high reliability and/or low power are a requirement.
For more information about FD-SOI see this article by semwiki.