Aerosol Jet Printing of Multilayered Graphene for Capacitive Touch Sensing and Joule Heating Applications

Adoption of additively manufactured electronics for low and high-volume manufacturing is hindered by available inks and printing variations. Achieving repeatable and consistent features on flexible substrates remains challenging due to ink formulation and process limitations. Herein, we report a ternary-solvent formulation of 2D graphene-based ink, optimized to control volatility, surface tension, and viscosity for stable ultrasonic atomization. By optimizing process parameters such as nozzle size, focusing ratio, and platen temperature, we demonstrate high-resolution printing using an aerosol jet printer (AJP), achieving feature sizes down to 5 µm in the as-printed state, where linewidths are defined directly by the printing process without post-print geometric refinement. Thermal annealing is subsequently employed to enhance conductivity. To demonstrate AJP's process flexibility for fabricating functional devices, interdigitated electrodes (IDEs) for capacitive touch sensing and serpentine structures for Joule heating were printed. The printed IDEs operate without dielectric coatings and exhibited consistent capacitive response (∼2 pF) to direct touch stimuli, while the heater demonstrated uniform and tunable thermal output (up to ∼56°C) under low-power operation (150 mW). These results demonstrate an ink formulation that enables high-resolution patterning and highlights AJP's potential as a scalable, lithography-free platform utilizing solution-processed 2D materials for electronics and sensors.