Performance improvement of poly(lactic acid) films for bioelectronics with eco-friendly supercritical fluids combined with activated-carbon technique

The rise of bioelectronics has sparked significant interest in exploring biocompatible and environmentally friendly materials including Poly(lactic acid) (PLA), which is the only biologically derived material capable of large-scale production. However, its suitability as an electronic material is limited due to inadequate electrical, optical, and mechanical properties arising from inherent impurities. In this study, lower molecular weight PLA was dissolved in chloroform and spin-coated into ultra-thin (1.689 μm) films as dielectric layer in capacitor devices. We explored the low-temperature supercritical fluid-activated carbon adsorption technique (LTSCF-AC) to remove residual solvent molecules from PLA film and thus improve its comprehensive properties. The leakage current decreased by about 70 times, and the capacitance values decreased and become more stable at different frequencies. The extremely thin PLA film exhibits excellent optical and mechanical properties. In particular, following LTSCF-AC treatment, optical transmittance and refractive index of PLA films improved significantly. Additionally, the Young's modulus increased by 61.5% while tensile strength and elongation at break doubled compared to their initial values. These simultaneous enhancements of insulation, transparency, deformation resistance, and tensile strength highlight the huge potential of low-temperature and eco-friendly LTSCF-AC in improving the performance of PLA. These advancements not only broaden the application of PLA in bioelectronics but also providing new avenues for improving bioelectronic devices.