Abstract
AbstractPrinting 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.
Highlights
A number of methods have been explored for the deposition of 2D materials for functional devices, printing holds specific promise for high-volume, low-cost and large-area manufacturing.[1,2,3,4] These include inkjet,[3,4,5,6] screen[7,8] and roll-to-roll (R2R) gravure and flexographic printing which are already widely used in the large-scale, ultra-low-cost production of packaging materials, everyday documents, magazines and newspapers.[9]
Screen printing has emerged as an effective method in depositing high-viscosity graphene inks directly on to the substrates, typically via a stencil made of a fine synthetic fibre mesh that is capable of depositing ∼10-16 μm thick layers of ink.[9,10]
We note that the general concept we present here has been previously demonstrated for the deposition or transfer printing of nanomaterials and functional structures on to flat and 3D objects
Summary
A number of methods have been explored for the deposition of 2D materials for functional devices, printing holds specific promise for high-volume, low-cost and large-area manufacturing.[1,2,3,4] These include inkjet,[3,4,5,6] screen[7,8] and roll-to-roll (R2R) gravure and flexographic printing which are already widely used in the large-scale, ultra-low-cost production of packaging materials, everyday documents, magazines and newspapers.[9]. Several techniques have been explored to achieve conformal functional printing of 2D material, carbon nanotube and metal nanoparticle-based inks These include aerosol jetting[17] or specially adapted inkjet or screen printing that manipulate arbitrarily-shaped substrates via rotary systems around ink nozzle heads or printing mesh.[18] these usually require highly complex and expensive printer designs that are capable of only depositing functional patterns on to one object at a time. Among the various strategies discussed above, we propose that water or solvent-assisted printing is potentially the most promising method for large-area deposition of functional 2D material inks directly on to arbitrarily shaped objects This is due to the ability of this technique to conform to the complex topographies of 3D objects. We further demonstrate the capability of this method in the fabrication of multi-layered devices by printing graphene/polyurethane(PU)/graphene parallel-plate capacitors on arbitrarily shaped objects
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