Engineers from KAIST and Seoul National University have developed electronic inks that enable the printing of flexible circuits with adjustable stiffness. This innovation paves the way for creating devices capable of altering their mechanical properties—from as rigid as plastic to as elastic as rubber—depending on usage conditions.

The key to this development lies in the use of gallium, a metal that melts at a temperature close to that of the human body. The scientists created the inks by mixing microparticles of gallium with polyurethane. When heated, these inks form electrically conductive networks that can change their rigidity.

This technology allows for the creation of electronics that can be rigid for protection and then soften for user comfort or integration with the body. Examples include multifunctional devices that transform from portable gadgets into wearable medical devices, and neural probes that remain firm during insertion and then soften within brain tissue. This development holds immense potential for future functional electronics, medicine, and robotics.