Owing to their fluid nature and excellent conductivity, gallium-based liquid metals (LMs) are promising materials for flexible electronics.
However, LMs don’t stick well to fabrics, and their significant surface tension causes them to ball up during 3D printing rather than form continuous circuits.
A team of researchers mixed LM and alginate for their ink. They stirred the solution and removing the excess liquid resulted in LM microdroplets coated with an alginate microgel shell.
The team 3D printed the new ink onto various surfaces, including paper, polyester fabrics, nonwoven fabrics, and acrylic-based tape. Although the printed patterns were not initially conductive, the researchers activated them by stretching, pressing, or freezing, which ruptured the dried alginate networks to connect the LM microdroplets.
After activation, the printed circuits had excellent electrical conductivity and strain-sensing properties.
The team 3D printed a series of electronics onto commercial clothing to demonstrate the ink’s capabilities. They published a near-field communication tag on a T-shirt that directed a smartphone placed nearby to open a website.
The LM-alginate ink can be recycled by soaking the fabric in a weak sodium hydroxide solution, recovering fresh liquid metal for new applications.
The research has been published here.