Optimization of Dispersants for Bioresorbable Conductive Inks and Their Applications

Biodegradable electronic devices exhibit great potential to mitigate environmental pollution and biological hazards. A previously developed anhydride-assisted room temperature-sintered zinc nanoparticles(Zn NPs) conductive ink demonstrated sintering at room temperature with low energy consumption. In this sintering strategy,the type and mass fraction of dispersants in the ink considerably influence the diffusion of water molecules and the binding process of water and anhydride. Nevertheless,challenges remain in the unclear selection mechanism of dispersants in ink systems and the limited conductive value of inks. To solve this problem,we assessed the water vapor transmission rates of polyethylene glycol(PEO),poly(butylene adipate-co-terephthalate),poly(lactic-co-glycolic acid),and polylactic acid as well as their conductive inks for using as film polymers and dispersants,respectively,to further optimize the polymer selection in the ink system and underscored the unique advantages of PEO in the system. Subsequently,we performed conductivity,bending,and peeling tests on inks with varying relative molecular weights and PEO mass fractions using a four-probe tester,a tensile testing machine,and 3M-612 tape,respectively. Experimental results showed that PEO,with a mass fraction of 2% and a molecular weight of 70 000,is the optimal dispersant,yielding an improved ink conductivity of 87 650.81 S/m. Additionally,various biodegradable electronic devices were fabricated on polyvinyl alcohol substrates using the optimized ink via screen printing. Among them,interconnected wires illuminated light-emitting diodes under a bent state at a central angle of 225°,a stress sensor recognized finger bending/stretching actions based on resistance changes,a heater realized a temperature increase to 54 ℃ in 200 s at 1.25 W power,and the final device underwent rapid degradation within 60 s in water. These biodegradable devices demonstrated remarkable electrical , mechanical , and electrothermal responses and degradation performances,satisfying the requirements for large-scale manufacturing and practical applications in the electronics industry. Thus,this research holds considerable implications for addressing the pressing issue of electronic waste. © 2024 Tianjin University. All rights reserved.