http://news.mit.edu/2019/engineers-demonstrate-lighter-flexible-airplane-wing-0401

Instead of requiring separate movable surfaces such as ailerons to
control the roll and pitch of the plane, as conventional wings do, the new
assembly system makes it possible to deform the whole wing, or parts of it, by
incorporating a mix of stiff and flexible components in its structure. The tiny
subassemblies, which are bolted together to form an open, lightweight lattice
framework, are then covered with a thin layer of similar polymer material as the
framework.

While it would be possible to include motors and cables to produce the forces
needed to deform the wings, the team has taken this a step further and designed
a system that automatically responds to changes in its aerodynamic loading
conditions by shifting its shape — a sort of self-adjusting, passive
wing-reconfiguration process.

“We’re able to gain efficiency by matching the shape to the loads at different
angles of attack,” says Cramer, the paper’s lead author. “We’re able to produce
the exact same behavior you would do actively, but we did it passively.”