Fig 1

Schematic of preparation processes of the flexible and transparent tunable capacitor. a Graphene growth on Cu foil by CVD. b BMN film grown on graphene/Cu substrate by LMBE. c Another graphene layer transferred on BMN/graphene/Cu substrate. d Removal of Cu foil. e Removal of etchant residue in distilled water. f Transfer of the capacitor onto the quartz substrate. g Capacitor patterned with Au electrode. h Release of capacitor in water. i Capture of the other side of capacitor by quartz substrate. j Reversal of quartz substrate/capacitor. k Patterned with Au electrode on the other side capacitor. l Release of the patterned capacitor in water. m Optical micrographs of patterned Au on the top (left) and (bottom) graphene electrode. n Film capacitor floating on water. o The transparent capacitor around a fused silica rod