Graded Mxene-Doped Liquid Metal as Adhesion Interface Aiming for Conductivity Enhancement of Hybrid Rigid-Soft Interconnection

Hybrid rigid-soft electronic system combines the biocompatibility
of stretchable electronics and the computing capacity of silicon-based
chips, which has a chance to realize a comprehensive stretchable electronic
system with perception, control, and algorithm in near future. However,
a reliable rigid-soft interconnection interface is urgently required
to ensure both the conductivity and stretchability under a large strain.
To settle this demand, this paper proposes a graded Mxene-doped liquid
metal (LM) method to achieve a stable solid–liquid composite
interconnect (SLCI) between the rigid chip and stretchable interconnect
lines. To overcome the surface tension of LM, a high-conductive Mxene
is doped for the balance between adhesion and liquidity of LM. And
the high-concentration doping could prevent the contact failure with
chip pins, while the low-concentration doping tends to maintain the
stretchability. Based on this dosage-graded interface structure, the
solid light-emitting diode (LED) and other devices integrated into
the stretchable hybrid electronic system could achieve an excellent
conductivity insensitive to the exerted tensile strain. In addition,
the hybrid electronic system is demonstrated for skin-mounted and
tire-mounted temperature-test applications under the tensile strain
up to 100%. This Mxene-doped LM method aims to obtain a robust interface
between rigid components and flexible interconnects by attenuating
the inherent Young’s modulus mismatch between rigid and flexible
systems and makes it a promising candidate for effective interconnection
between solid electronics and soft electronics.