Cottonseed-Derived Reusable Bio-Carbon Gel Ink for DIW Printing Soft Electronic Textiles

Soft electronics textiles have garnered global attention for their wearability and promising applications in healthcare, energy devices, and artificial intelligence. Recently, direct-ink-writing (DIW) technology has shown a growing trend because of its controllability, ease of fabrication, and efficiency. However, the design novelty of printable ink for soft electronic textiles is severely hampered by the intrinsic challenges of integrating printability, conductivity, stretchability, biocompatibility, and durability. Herein, a reusable DIW bio-carbon gel ink is proposed for printing soft electronic textiles where cottonseed peptone-functionalized multi-wall carbon nanotubes (CPCNTs) exhibit high dispersibility and reactive surface groups, enabling stable cross-linking with phytic acid (PA) and polyvinyl alcohol (PVA) to form a strong ionic polymer composite. Encouragingly, the gel ink can be directly exploited to design complex circuits and versatile electronics via DIW printing on both polymeric and textile substrates. The viscoelasticity, mechanical recovery, electric properties, robustness, and stretchable architectures enable it to function as flexible circuits, smart sensors, and renewable generators. As demonstrations, multifunctional applications are presented by real-time healthcare monitoring, LED lighting, and power generation. Furthermore, this printable gel ink is effectively assembled into an integrated wearable unit for robot manipulation and real-time gesture recognition, suggesting a significant printing strategy for next-generation wearable electronics.