The ability to bridge the resolution and functionality of 2D printed electronics with the design complexity of 2.5D and 3D electronics will open opportunities in device performance and integration. In this work, aerosol jet printing is explored for direct write patterning of high aspect ratio graphene structures. The graphene ink properties are tailored for the unique constraints of high aspect ratio manufacturing for both 2D and 3D printing at the microscale, balancing low viscosity required to support ultrasonic atomization in the system with low fluidity when deposited on the substrate. High electrical conductivity (~27.5 kS m-1) of graphene following post-processing is coupled with a high surface area microstructure and high-resolution patterning, achieving hollow structures with a base diameter as low as 75 µm and height as high as 200 µm compatible with flexible substrate. Such structures, combined with the design freedom of aerosol jet printing, provide compelling characteristics for a range of devices in packaging, energy, wearables and sensing among other applications.
