title: Direct Laser Writing of Porous-Carbon/Silver Nanocomposite for Flexible Electronics.
abstract: 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.
authors.affiliation: Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.|School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Rahim
authors.initials: R
authors.lastname: Rahimi
authors.affiliation: Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.|School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Manuel
authors.initials: M
authors.lastname: Ochoa
authors.affiliation: Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States.|School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Babak
authors.initials: B
authors.lastname: Ziaie
keywords: flexible electronics; laser carbonization; nanocomposite; pyrolysis; silver nanoparticle