A mixer for an exhaust aftertreatment system is disclosed. The mixer includes a body portion that is configured to be disposed in an exhaust conduit of an exhaust aftertreatment system upstream of an exhaust aftertreatment device. The mixer also includes an airfoil portion that is disposed on the body portion and reversibly movable between a deployed position and a retracted position, wherein in the deployed position the airfoil portion provides a deployed resistance to an exhaust gas flow and in the retracted position provides a retracted resistance thereto, and the deployed resistance is greater than the retracted resistance, the body portion and airfoil portion comprising a mixer. The mixer further includes a bimetallic couple that is operatively joined to the mixer and configured to reversibly move the airfoil portion from the retracted position to the deployed position.