Wearable electronics with development trends such as
miniaturization,
multifunction, and smart integration have become an important part
of the Internet of Things (IoT) and have penetrated various sectors
of modern society. To meet the increasing demands of wearable electronics
in terms of deformability and conformability, many efforts have been
devoted to overcoming the nonstretchable and poor conformal properties
of traditional functional materials and endowing devices with outstanding
mechanical properties. One of the promising approaches is composite
engineering in which traditional functional materials are incorporated
into the various polymer matrices to develop different kinds of functional
composites and construct different functions of stretchable electronics.
Herein, we focus on the approach of composite engineering and the
polymer matrix of silicone rubber (SR), and we summarize the state-of-the-art
details of silicone rubber-based conductive composites (SRCCs), including
a summary of their conductivity mechanisms and synthesis methods and
SRCC applications for stretchable electronics. For conductivity mechanisms,
two conductivity mechanisms of SRCC are emphasized: percolation theory
and the quantum tunneling mechanism. For synthesis methods of SRCCs,
four typical approaches to synthesize different kinds of SRCCs are
investigated: mixing/blending, infiltration, ion implantation, and
in situ formation. For SRCC applications, different functions of stretchable
electronics based on SRCCs for interconnecting, sensing, powering,
actuating, and transmitting are summarized, including stretchable
interconnects, sensors, nanogenerators, antennas, and transistors.
These functions reveal the feasibility of constructing a stretchable
all-in-one self-powered microsystem based on SRCC-based stretchable
electronics. As a prospect, this microsystem is expected to integrate
the functional sensing modulus, the energy harvesting modulus, and
the process and response modulus together to sense and respond to
environmental stimulations and human physiological signals.