source of graphene and type of binder used, the above discussion provides a systematic and universal approach to achieve optimised ink formulation.

Water-assisted conformal printing method
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![Water assisted conformal printing. **a** Schematic of screen printing of graphene ink on to the SF. **b** Screen printed conductive pattern array on water-soluble SF. **c** Schematic of the water assisted conformal printing process starting with the floating of the printed SF on water followed by the dissolution of the surrounding SF, leaving behind residual wet SF underneath to act as an adhesive to the substrate. Immersion of the substrate into the water bath to ‘fish’ the conductive pattern out which eventually adheres to the substrate by drying of the SF. **d** Interaction of the printed graphene ink with water soluble SF over 120 s. The SF is coloured using a food dye. **e** Photograph of the graphene pattern on a glass rod with representative SEM views of the top and cross section. Scale bar 5 $\mu$m **f** Comparison of R$_s$ before and after water assisted conformal printing across a variety of printed graphene ink thicknesses on PET.[]{data-label="panel2"}](panel2){width="\textwidth"}

Figure \[panel2\]a-g schematically illustrates the key steps in the water-assisted conformal printing process. This involves 