Conformal Printing of Graphene for Single- and Multilayered Devices onto Arbitrarily Shaped 3D Surfaces

Printing has drawn a lot of attention as a means of low per-unit cost and high throughput patterning of graphene inks for scaled-up thin-form factor device manufacturing. However, traditional printing processes require a flat surface and are incapable of achieving patterning onto 3D objects. Here, a conformal printing method is presented to achieve functional graphene-based patterns onto arbitrarily shaped surfaces. Using experimental design, a water-insoluble graphene ink with optimum conductivity is formulated. Then single- and multilayered electrically functional structures are printed onto a sacrificial layer using conventional screen printing. The print is then floated on water, allowing the dissolution of the sacrificial layer, while retaining the functional patterns. The single- and multilayer patterns can then be directly transferred onto arbitrarily shaped 3D objects without requiring any postdeposition processing. Using this technique, conformal printing of single- and multilayer functional devices that include joule heaters, resistive deformation sensors, and proximity sensors on hard, flexible, and soft substrates, such as glass, latex, thermoplastics, textiles, and even candies and marshmallows, is demonstrated. This simple strategy promises to add new device and sensing functionalities to previously inert 3D surfaces.