Heat-free printing method yields metal interconnects

Abstract

Researchers have exploited the unusual phase-change behavior of a liquid metal to devise heat-free procedures for printing metal patterns on numerous temperature-sensitive materials, including Jell-O (Adv. Funct. Mater. 2019, DOI: 10.1002/adfm.201903687). The team used the methods to make metallic connections for circuits on nonrigid materials, a fabrication step needed for developing wearable electronics and flexible, foldable displays. Electronic devices that bend and stretch like athletic wear could lead to new applications in sports, medicine, and robotics. But traditional circuitry fails when it’s flexed, and nontraditional materials that would be used in flexible electronics, such as thin fabrics, paper, and skin, are incompatible with the high-temperature steps typically used for fabricating circuits. Aiming to bypass those shortcomings, Andrew Martin, Martin Thuo, and coworkers at Iowa State University turned to liquid-metal droplets encapsulated in a nanometer-thin oxide skin. Made of Field’s metal, a bismuth-indium-tin alloy that melts at 62 °C, the droplets