Direct Laser Writing of Porous-Carbon/Silver Nanocomposite for Flexible Electronics

In this Research Article, we demonstrate
a facile method for the fabrication of porous-carbon/silver nanocomposites
using direct laser writing on polymeric substrates. Our technique
uses a combination of CO2 laser-induced carbonization and
selective silver deposition on a polyimide sheet to create flexible
highly conductive traces. The localized laser irradiation selectively
converts the polyimide to a highly porous and conductive carbonized
film with superhydrophilic wettability. The resulting pattern allows
for selective trapping of aqueous silver ionic ink solutions into
the carbonized regions, which are converted to silver nanoparticle
fillers upon an annealing step. Elemental and surface morphology analysis
via XRD and SEM reveals a uniform coating of Ag nanoparticles on the
porous carbon. The Ag/C composite lowers the sheet resistance of the
original laser carbonized polyimide from 50 to 0.02 Ω/□.
The resulting patterns are flexible and electromechanically robust
with less than 0.6 Ω variation in resistance after >15000
bending flexion cycles at a radius of curvature of 5 mm. Furthermore,
using this technique, we demonstrate the fabrication of a wireless
resonant pressure sensor capable of detecting pressures ranging from
0 to 97 kPa with an average sensitivity of −26 kHz/kPa.