What kind of surface was used for the Mona Lisa painting and what kind of paint?

The Mona Lisa was painted on poplar panel using oil paints. Da Vinci carried this piece of work around with him for many years, never truly finishing it. He would continue working on other pieces but always came back to this portrait. Da Vinci used a style of painting called sfmato, a technique employed to produce a smokey, shaded effect.