Optimizing endoscope lens performance with PTFE hydrophobic surface treatment via dip and spin coating

Abstract

Endoscopes are essential for visualizing the human body’s interior in modern medicine. However, they face issues due to bodily fluid buildup during surgery, which hinders their function. A potential solution is applying a hydrophobic layer, such as polytetrafluoroethylene (PTFE), to the lens. This prevents fluid adhesion, simplifies cleaning, and enhances visibility. This study investigated dip and spin coating techniques to develop hydrophobic surfaces using PTFE on three lens materials: acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), and polycarbonate (PC). Physicochemical attributes of uncoated and PTFE-coated samples were evaluated. Both dip and spin coating techniques achieved successful PTFE coating on ABS-, SAN-, and PC-based endoscope lenses. Dip-coated PTFE SAN samples exhibited higher light transmittance, while spin-coated SAN samples showed greater water contact angles. Scanning electron microscope and atomic force microscope analyses revealed uneven distribution and roughness with dip coating, while spin coating uniformly deposited a hydrophobic PTFE layer on the SAN-based endoscope lens. TGA and DSC findings revealed minimal impact of PTFE coatings on the thermal stability of SAN. Compared with commercially coated SiO₂ and TiO₂ samples, the PTFE-coated samples showed superior hydrophobic properties and comparable light transmittance. This study highlights the capability of PTFE coating to improve the water-repelling properties of endoscope lenses while preserving their ability to transmit light effectively.