EPSCoR Research Fellows: NSF: Air-Free Materials and Processing Science for Extreme Environment Additive Electronics

Liquid-phase printing technologies can create complex parts using computer-controlled deposition of materials in the form of inks or pastes. By creating such inks or pastes with electronic materials, these technologies can fabricate functional devices, such as sensors, antennas, and circuits. Silver is a common material for conductive inks, because it is resistant to oxidation.

The ability to print other materials, including air-sensitive metals, is desired to broaden the range of functionality for printed circuits. This award supports fundamental research to understand ink development and processing for air-sensitive materials, with a specific focus on materials for electronics in harsh environments, such as high and low temperatures.

This collaboration with NASA researchers will study fundamental challenges in the development of inks based on air-sensitive materials, how particles can be fused together following printing to create cohesive wires, and the reliability of the resulting circuits under adverse conditions. Electronic systems that can function in extreme environments are highly relevant for energy, infrastructure, aerospace, and space applications, and this research thus contributes to advancing national prosperity and security.

Related activities to mentor undergraduate researchers and support outreach to K-12 students will also support workforce development and diversification within engineering.

The objective of this project is to develop material-process-structure-property relationships for additively manufactured electronics in extreme environments, emphasizing fabrication and reliability physics of low redox-potential conductors. The low-volume, high-mix nature of printed electronics aligns with diverse needs for electronics compatible with harsh environments, as exemplified by space electronics.

Iowa State and NASA Marshall Space Flight Center have complementary capabilities for printing of air-sensitive metals and alloys for electronic devices and circuits, and this project will leverage NASA expertise in space electronics and reliability testing. The research activities comprising this project are structured into three objectives focused on printing process fundamentals, material sintering, and characterization for reliability, respectively.

These efforts will use nickel alloy nanoparticles as a case study, particularly constantan (CuNi) and invar (FeNi) for their unique thermal properties – reduced sensitivity of electrical properties to temperature changes and low temperature thermocouple utility for constantan, and a small coefficient of thermal expansion for invar. Printing capabilities under inert atmosphere will support processing of these materials in nanoparticle form via aerosol jet and extrusion printing.

Sintering will be a critical element of the research, with efforts to compare thermal and photonic sintering to better understand effects of sintering strategies and parameters on material microstructure, and ultimately on the resulting functional properties. Direct research efforts will be guided by adverse environments of interest to NASA, particularly low-temperature operation and stability to thermal cycling, but the broader knowledge and strategies will also inform high temperature printed electronics.

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.