The
design and synthesis of conductive hydrogels with
antifreezing,
long-term stable, highly sensitive, self-healing, and reusable is
a critical procedure to enable applications in flexible electronics,
medical monitoring, soft robotics, etc. Herein, a novel zwitterionic
composite hydrogel possessing antifreezing, fast self-healing performance,
water retention, and adhesion was synthesized via a simple one-pot
method. LiCl, as an electrolyte and antifreeze, was promoted to dissociate
under the electrostatic interaction with zwitterions, resulting in
the composite hydrogels with high electrical conductivity (7.95 S/m)
and excellent antifreeze ability (â45.3 °C). Meanwhile,
the composite hydrogels could maintain 97% of the initial water content
after exposed to air (25 °C, 55% RH) for 1 week due to the presence
of salt ions. Moreover, the active groups of zwitterions could form
conformal adhesion between the composite hydrogels and skin, which
was particularly crucial for the stable signal output of the sensor.
The dynamic borate ester bonds, active group of zwitterions, and the
hydrogen bond between different components could achieve rapid self-healing
(2 h, self-healing efficiency to 97%) without any external intervention.
Notably, the developed PBAS-Li (polyÂ(vinyl alcohol) Borax/acrylamide/zwitterionic-LiCl) hydrogel not only succeeded
in sensitively detecting human motions but also could precisely captured
handwritings signals and subtle pulse waves on the neck and wrist.
The above findings demonstrated the great potential of PBAS-Li hydrogels in the field of flexible electronic devices.