Ultra-stretchable and Conductive Polyacrylamide/Carboxymethyl Chitosan
Composite Hydrogels as Flexible Sensors
There is a great demand for the fabrication of soft electronics using
hydrogels due to their biomimetic structures and good flexibility.
However, conventional hydrogels have poor mechanical properties, which
restricts their applications as stretchable sensors. Herein, a facile
one-step strategy is proposed to fabricate tough hydrogels with a
semi-interpenetrating network structure by free-radical polymerization.
The obtained polyacrylamide/carboxymethyl chitosan composite hydrogels
possess outstanding transmittance and excellent mechanical performances,
with tensile breaking stress of 260 kPa, breaking strain of 3300%, and
toughness of 2400 kJ/m3. These hydrogels have low modulus of
~10 kPa, fast recoverability after unloading, and high
conductivity of ~0.85 S/m without the addition of other
conductive substances. The ionic conductivity of the gels originates
from the counterions of carboxymethyl chitosan, affording the hydrogels
as resistive-type sensors. The resultant hydrogel sensors demonstrate a
broad strain window, excellent linear response, high sensitivity with a
gauge factor, and great durability, capable of monitoring diverse human
motions. This work provides a new strategy to develop stretchable
conductive hydrogels with promising applications in the fields of
artificial intelligence and flexible electronics.