Biomimetic Mustard Seed-Inspired Brush-Free Alternative for Effective Endoscope Channel Cleaning and Decontamination

Inadequate cleaning of flexible endoscope channels remains a major cause of healthcare-associated infections despite established reprocessing protocols. We developed biomimetic carbon balls inspired by mustard seed surface features as a brush-free adjunct for endoscope channel cleaning, combining mild mechanical action with adsorption-based removal of organic debris. Activated carbon (AC) balls and carbon fiber (CF) balls with diameters of 1.8-3.0 mm were fabricated to fit 2.5-3.5 mm working channels and characterized by TGA, BET, SEM, and EDS. Cleaning performance was evaluated using tomato powder residue and microbiological validation, and computational fluid dynamics was used to assess flow behavior in a 2.7 mm channel containing a 2.6 mm ball under suction. CF balls showed more uniform thermal degradation (8.9% residual mass at 1000 °C) and a ribbed fibrous morphology. In contrast, AC balls exhibited porous, irregular structures with strong adsorption capacity, characterized by high thermal stability (86.4-89.3% residual mass) and pore volumes of 0.087-0.108 cm³/g and BET surface areas of 63.00 m²/g and 21.65 m²/g. After residue exposure, AC surfaces retained more particulate matter, while CF surfaces remained cleaner and promoted more pronounced wall interaction. Microbiological testing showed effective decontamination, with bacterial counts reduced below the detection limit. CFD analysis demonstrated pressure-driven gap flow, elevated local velocity, and vortex-induced wall shear stress sufficient to enhance debris removal without apparent channel damage. These results suggest that mustard seed-inspired carbon balls provide a promising brush-free strategy for endoscope reprocessing by integrating adsorption, hydrodynamic agitation, and gentle scouring to improve cleaning safety and efficacy.