A shielding technique developed by Magnus and Erin Hansen aboard the USS Raven that let a small vessel pass undetected by Borg sensors, later copied by Voyager for the Delta Flyer.
Multi-adaptive shielding was created by the exobiologists Magnus and Erin Hansen, the parents of Seven of Nine, during their long study of the Borg in the 2350s. It allowed their ship, the USS Raven, to shadow a Borg cube for months without being noticed.
The Hansens' work is shown in the Voyager two-parter Dark Frontier, in which Captain Janeway has their field notes studied for anything useful to a raid on a Borg sphere. A brief failure of the shielding had been enough to expose the Raven and lead to the family's assimilation.
Voyager's crew adapt the design for the Delta Flyer, which uses it to follow the Borg Queen's vessel to the Unicomplex and recover Seven of Nine.