Increasing Hydrophilicity and Transparency of Diamond-Like Carbon Thin Films with Dopants for an Anti-Fogging Laparoscope Coating

Laparoscopes are prone to fogging which can lead to a limited field of view during surgical procedures. Current methods of mitigating fogging issues are not efficient or can require costly modification to the laparoscope. Previous studies of diamond-like carbon (DLC) coatings found doping the films improved hydrophilic qualities, suggesting their possible use as antifogging coatings for laparoscopes. For this work, two series of DLC films, doped with either SiO and Al₂O₃ were investigated.

The biocompatibility, transparency, and stability of these films were assessed through cellular assays, spectrophotometry, and simulated body fluid soaking experiments. Contact angle and surface energy measurements were performed to assess the hydrophilic qualities of the films. Plasma cleaning was utilized as a surface treatment to improve hydrophilicity; time-studies were performed to assess the stability of this treatment. Raman spectroscopy, atomic force microscopy, and adhesion tests were performed to assess the physical characteristics of the films.

The silicon monoxide doped films demonstrated improved transparency and hydrophilic qualities. Samples subjected to plasma cleaning had contact angles under 5° when measured within 60 minutes of treatment. From the time-studies performed, the hydrophilicity of the SiO doped films was improved for over 24 hours after treatment. The aluminum oxide doped films demonstrated transparency results of up to 97% over the visible spectrum indicating this dopant helped improve transparency. After plasma cleaning samples demonstrated a contact angle of 8° within 60 minutes of treatment. Both series demonstrated similar biocompatibility results with cellular assay viability values being statistically similar to the control media. No delamination of the films from either series was observed when soaked in simulated body fluid over the course of 40 weeks. The results of this research show promise for DLC as an antifogging coating for laparoscopes.