Cellulose Oleogel-Based OleoPlast for Sustainable Electronic Substrates and Conductive Composites

The rapid growth of electronics is increasingly contributing to the problem of electronic waste (e-waste), necessitating the development of new biodegradable and biobased substrates and conductive materials from renewable resources¹. This work introduces OleoPlast, a novel bioplastic developed by our group, derived from cellulose-based oleogel and designed to function as both a substrate and conductive material for electronics². OleoPlast not only offers biodegradability but also allows for customizable mechanical properties without compromising its dielectric stability (εr ~3), making it suitable for a range of applications from flexible, wearable electronics to rigid, biofiber-reinforced composites.
As a proof-of-concept, a wide-band monopole antenna with circular polarization was redesigned using OleoPlast as the substrate. The antenna, fabricated with edible gold leaf electrodes, demonstrated resonance within a frequency range from 1.5 GHz to 3 GHz, covering technologies such as WiFi, Bluetooth, and GPS. Simulation results showed a good match with experimental impedance data, with the reflection scattering parameter (S₁₁) below −10 dB, indicating efficient electromagnetic coupling and optimal power transfer at a 50 Ω reference port².
Additionally, OleoPlast was used to develop a low-cost conductive composite incorporating expanded graphite. The composite achieved a resistivity of approximately 0.01 ohm-meter. Targeting biomedical applications, such as rehabilitation monitoring and EEG dry electrodes, the conductivity of the material and antibacterial properties were further enhanced by incorporating copper nanoparticles. This versatile platform can be processed through various techniques such as extrusion, hot pressing, and Fused Filament Fabrication (FFF). Strain gauge sensors were also developed using the same material, calibrated for sensing different force ranges, from a few kPa to several MPa.

References

1 Honarbari, A. et al. A Green Conformable Thermoformed Printed Circuit Board Sourced from Renewable Materials. ACS Applied Electronic Materials (2023).
2 Lamanna, L. et al. Beyond Plastic: Oleogel as gel-state biodegradable thermoplastics. Chemical Engineering Journal 498, 154988 (2024).