used to qualitatively define sensible upper and lower bounds for the DOE, which is then used to quantitatively optimise the electrical conductivity of the ink after printing and curing.

After formulation, the ink (and additional layers for the case of multi-layered devices) is printed on an ultrathin, water-soluble PVA as the SF. The composite structure, comprising the SF and printed layer(s) is then floated in a water bath to allow the SF to dissolve. The floating patterns are then ‘fished’ out from the water-bath using the target substrates, allowing the pattern to adhere directly on to the substrate. This process is highly versatile, capable of printing on to different substrates to fabricate functional devices without the loss of the conductive properties of the printed graphene patterns after the transfer.

We demonstrate this by conformally printing conductive graphene patterns to fabricate single and multi-layered devices on to multiple hard (glass, 3D printed thermoplastics), flexible and porous (bandages) and non-porous (nitrile gloves), and even on soft substrates such as marshmallows and gummy candies. These structures are then used to demonstrate applications of conformal printing, including joule heaters on glassware, resistive sensors on off-the-shelf candies and electrodes on non-conductive objects, making them capable 