Graphene bubbles with controllable curvature
  Raised above the substrate and elastically deformed areas of graphene in the form of bubbles are found on different substrates. They come in a variety of shapes, including those which allow strong modification of the electronic properties of graphene. We show that the shape of the bubble can be controlled by an external electric field. This effect can be used to make graphene-based adaptive focus lenses. 
T. Georgiou, L. Britnell, P. Blake, R. V. Gorbachev, A. Gholinia, A.   K. Geim, C. Casiraghi, K. S. Novoselov
cond-mat.mes-hall