Disposable Endoscope Cap Maintaining Clear Surgical Visualization under Fogging and Fouling.

Lens fogging and biological contamination are persistent unmet needs in endoscopic surgery that degrade visualization, disrupt procedural continuity, and compromise patient safety. To address these limitations, we have developed the superlubricious high-clarity interface for endoscopic lens defense cap (SHIELD-C), a single-use snap-on endoscope cap designed to maintain stable endoscopic visualization by forming a durable liquid-liquid interface on the cap surface. SHIELD-C employs a dual-layer architecture consisting of a covalently grafted polydimethylsiloxane (PDMS) brush base layer and an infused silicone oil top layer, forming a stable and optically transparent liquid-liquid interface. This configuration maintains high optical clarity (optical transmittance of >90% across the visible range) while effectively suppressing adhesion of blood and mucus (sliding angle of <10°). Importantly, the liquid interface enables rapid intraoperative recovery of surface functionality through simple lubricant replenishment, allowing immediate restoration of visual clarity without interrupting the surgical workflow. The antifouling durability as well as the optical stability of SHIELD-C were systematically validated through in vitro tests under chemically and mechanically challenging conditions with additional confirmation in clinically relevant ex vivo surgical models. These results identify SHIELD-C as a stable liquid-liquid interface cap that enhances the reliability and continuity of endoscopic visualization under lens-fouling conditions.