Soft Electronics Based on Liquid Conductors

Soft electronics is an emerging field that is lending great convenience to daily life. Soft electronics have shown great potentials in health monitoring, soft robotics, the Internet of Things, and so forth. Though soft electronics based on solid conductors have been intensively investigated and some considerable progress has been achieved, the intrinsic shortcomings of solid conductors are becoming the Achilles' heel of soft electronics. Fortunately, many of the disadvantages of solid conductors can be offset by liquid conductors. Following the attractive advantages of liquid materials, in particular high flexibility, infinite deformability, self-healing, and ease of doping/being doped, this review article summarizes a history of soft electronics based on liquid conductors and introduces the most up-to-date liquid conducting materials together with their representative featured functions. Particular applications in sensors, batteries, supercapacitors, thermoelectric conversion, and even memory devices are discussed in detail to intuitively emphasize how liquid conductors benefit soft electronics. In addition, limitations of liquid conductors are also discussed, as well as the key challenges and some innovative strategies to overcome them. Finally, future perspectives are put forward to develop soft electronics that are fully composed of liquid circuits.