CAREER: Graded and Reliable Aerosol Deposition for Electronics (GRADE): Understanding Multi-Material Aerosol Jet Printing with In-Line Mixing

Computer-controlled printing technologies allow manufacturing of precise and complex parts. When these methods are used to print electronic materials, they can produce devices such as sensors and circuits. There is a strong motivation to print parts that contain gradients in material composition and properties, which can mimic biological materials, improve mechanical interfaces, and enable advanced electronic functionality. This Faculty Early Career Development Program (CAREER) award supports fundamental research to understand and control multi-material aerosol jet printing, a technology well suited for manufacturing such material gradients for electronic devices. This printing method can mix micro-scale droplets of different inks during the deposition process to change the material composition, and coordinate this material change with patterning in three dimensions. This technology is relevant to aerospace, biomedical, automotive, energy, and defense applications, thus promoting national prosperity and security. Moreover, the research pursues fundamental advances in manufacturing, aerosol and fluid dynamics, and materials science, thus advancing the progress of science. Alongside the core research objectives of this research, an outreach program will be established to engage 4th-5th grade students with science and engineering concepts via interactive digital printing activities, and game- and project-based learning will be incorporated in undergraduate manufacturing engineering coursework to improve workforce development. The goal of this project is to establish mechanistic knowledge and control of multi-material aerosol jet printing for patterning material gradients. Different materials will be mixed in the aerosol phase within the printhead, allowing digital control of the mixing ratio. Mixing mechanisms for the aerosol, liquid, and colloid phases will be evaluated to understand the effects of materials chemistry, ink formulation, aerosol physics, and print parameters on the mixing efficacy, uniformity, and control using a combination of experiments, simulation, and theory. The ability to fabricate custom gradients in material composition and properties will stimulate broad research of material-processing-structure-property relationships for functionally graded materials in the context of hybrid electronics, including electromagnetic devices, electrochemistry, interfacial mechanics, and biomimetic structures. To guide development of this capability, this project will pursue vertically graded interfaces to reduce failure from thermal expansion mismatch, along with laterally graded conductors to support biocompatible circuits. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.