Fabrication of Robust Paper-Based Electronics by Adapting Conventional Paper Making and Coupling with Wet Laser Writing

Abstract

Paper offers the potential as a sustainable substrate for electronics, yet a key remaining challenge is patterning. While most demonstration studies pattern by printing conducting inks onto cellulose, we adapt conventional paper making to create a stable non-conducting composite of graphene oxide (GO; 30%) and cellulose (70%) and then pattern this composite using wet laser writing. Specifically, the GO/cellulose composite is as follows: soaked in a HAuCl 4 solution; laser patterned to simultaneously reduce GO (rGO) and generate metallic gold seeds (typical writing speed 20 s•cm −2 ); and then incubated (30 min) in HAuCl 4 solution to "grow" gold nanoparticles (Au NPs) in the pre-seeded patterned region. Various methods demonstrate that laser patterning induces spatially selective chemical changes in the composite. Functionally, the patterned region (Au NPs/rGO/cellulose) shows a 200-fold increase in conductivity (1362 S m −1 ) compared to the unpatterned region (GO/cellulose). As a simple demonstration, we fabricated patterned composite paper electrodes and demonstrate excellent electrochemical sensing performance in terms of sensitivity, selectivity, stability, and repeatability. We envision that laser patterning of composite paper offers unprecedented opportunities for scalable manufacturing because conventional papermaking can generate the stable substrate and laser patterning can be extended from serial writing to parallel photolithographic methods common in electronics fabrication.

Emergence of integrated biosensing-enabled digital healthcare devices

“…One study reported paper made from CF/GO/cellulose, whereby to enable the assembly of GO sheets onto the surface of the cellulose fibers, cationic polyacrylamide (CPAM) was used to control the interfacial interactions. 70 In same study, high-performance, long-lasting paper-based sensors for portable electrochemical detection were demonstrated. 70 In another study, a lens-free optofluidic plasmonic sensor was used for the real-time and label-free monitoring of molecular binding events over a wide field-of-view.…”

“…70 In same study, high-performance, long-lasting paper-based sensors for portable electrochemical detection were demonstrated. 70 In another study, a lens-free optofluidic plasmonic sensor was used for the real-time and label-free monitoring of molecular binding events over a wide field-of-view. 71 Also, Roy et al developed screen-printed microfluidic technology to monitor diabetic foot ulcers using a portable potentiostat (DFU).…”

Direct Laser Writing: From Materials Synthesis and Conversion to Electronic Device Processing

“…Wang et al. [ 173 ] integrated writing strategies to fabricate electrochemical sensors made of gold, by laser‐induced reduction of HAuCl 4 over GO‐modified paper substrates and subsequent electroless Au growth, envisioning R2R fabrication strategies based on this DLW setup. The authors demonstrated the capability of fabricated sensors for hydrogen peroxide detection in milk samples.…”

“…[124] However, other formulations using gelatine matrices have also been employed. [162,163] Several metallic salts have been used for this purpose, including metal nitrates, chlorides and acetates, such as AgNO 3 , [42,147,[163][164][165][166][167] AgClO 4 , [158,162] Cu(NO 3 ) 2 , [82,103,115,160,164,[168][169][170][171] Cu(CH 3 COO) 2 , [172] HAu-Cl 4 , [40,147,173,174] PtCl 4 , [42] and NiCl 2 . [147] Regarding reducing agents, polyvinylpyrrolidone (PVP) is a common choice, whose decomposition produces formic acid, able to reduce metal ion species.…”

“…[158,166] Another reported mechanism for the formation of metallic films involves the use of semiconductor NPs as reducing agents. [147,173,174] Upon laser exposure, the electrons in the valence band are promoted to the semiconductor's conduction band, promoting the reduction of metal ions at their surface. Simultaneously, the laser beam is also proposed as an optical trap, that drives the semiconductor NPs toward the irradiation path, leading to robust writing of metal/semiconductor composite patterns (Figure 8d).…”