Inkjet printing of silver film on polydimethylsiloxane for soft electronics

Abstract

This study reports an optimized inkjet printing strategy for creating conductive patterns on polydimethylsiloxane (PDMS) substrates, addressing limitations in previous methods such as poor film uniformity, low conductivity, and limited mechanical resilience. Surface modification using dielectric barrier discharge plasma at 30 W for 1 s achieved a uniform water contact angle of 50°, enhancing surface uniformity without damaging the substrate. Optimized printing parameters—including droplet spacing (23 μm), jetting voltage (27 V), substrate temperature (60 °C), and multilayer deposition—resulted in silver films with a thickness of 3.1 μm and conductivity of 2.89 × 10⁶ S/m. High-frequency performance was validated using a printed transmission line with a 200 μm line width, showing an insertion loss of −0.98 ± 0.03 dB at 9.5 GHz. Mechanical durability was confirmed through 5000 bending cycles, with only a 1.13-fold increase in sheet resistance. Compared to previous PDMS-based inkjet systems, this method offers improved electrical, RF, and mechanical stability. While the process uses commercially available materials and low-energy steps for cost-effectiveness, challenges remain in scalability and environmental sensitivity. These results demonstrate a significant advancement in printed electronics on flexible substrates, supporting future integration into wearable, biomedical, and high-frequency applications.