  Soft electronics are a promising and revolutionary alternative for
traditional electronics when safe physical interaction between machines and the
human body is required. Among various materials architectures developed for
producing soft and stretchable electronics, Liquid-Metal Embedded Elastomers
(LMEEs), which contain Ga-based inclusions as a conductive phase, has drawn
considerable attention in various emerging fields such as wearable computing
and bio-inspired robotics. This is because LMEEs exhibit a unique combination
of desirable mechanical, electrical, and thermal properties. For instance,
these so-called multifunctional materials can undergo large deformations as
high as 600% strain without losing their electrical conductivity. Moreover, the
desperation of conductive liquid-metal inclusions within the entire medium of
an elastomer makes it possible to fabricate autonomously self-healing circuits
that maintain their electrical functionality after extreme mechanical damage
induction. The electrically self-healing property is of great importance for
further progress in autonomous soft robotics, where materials are subjected to
various modes of mechanical damage such as tearing. In this short review, we
review the fundamental characteristics of LMEEs, their advantages over other
conductive composites, materials used in LMMEs, their preparation and
activation process, and the fabrication process of self-healing circuits.
Additionally, we will review the soft-lithography-enabled techniques for
liquid-metal pattering.
