Eco-friendly composite supercritical purification enables simultaneous lightweighting and strengthening of reed membranes for bioelectronics
Reed membrane, a natural cellulosic material traditionally used in musical instruments, holds promise in flexible electronics due to its abundance, low cost, and excellent biocompatibility. However, its native form contains water-soluble ions and lipid-soluble waxes that hinder performance in acoustic and electronics by compromising electrical insulation and mechanical stability. Here, supercritical fluid superposition purification (SCSP-WA) is introduced, which utilizes supercritical CO2 with water and acetone as bipolar co-solvents to selectively remove these impurities. Post-SCSP-WA treatment, the reed membrane exhibits significant enhancements in mechanical strength and electrical insulation, achieving a 4-fold increase in elongation at break, improved tensile strength and Young’s modulus, and a 98.5% reduction in leakage current, all while maintaining low and stable capacitance. These improvements stem from the restructuring of the fibrous network into a porous, interconnected microstructure. Material characterization (X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM)) confirmed the effective removal of magnesium and waxy functional groups, along with enhanced fiber crosslinking. Cytotoxicity tests further validated the biocompatibility of the SCSP-WA-treated membranes. This environmentally sustainable approach expands the potential of reed membranes in flexible bioelectronics and bio-integrated acoustic systems.