Research Toward Anti-fogging Laparoscope

With the popularity of laparoscopic surgery, the mirror atomization, caused bywater vapor as well as surgical smoke and dust, made a serious impact on the continuityof the operation and efficiency. Preparation of antifogging and anti-contamination filmto overcome the above-mentioned drawback of laparoscopy is to raise a major issue inlaparoscopic visual effects.In this paper, we chose TiO₂as the fog-free and anti-contamination materialapplied on laparoscopic lens. TiO₂films of different roughness varied with thicknesswere prepared by electron beam evaporation method. In order to obtain a suitablesurface morphology and higher roughness, which may affect the hydrophilic propertiesof TiO₂thin films, we did not use ion source. The base pressure of the vacuum chamberis2×10-3Pa, and material source is Ti2O3particles （diameter1-2mm, purity of99.99%）.During the evaporation process, O₂was charged into the vacuum chamber （purity of99.99%） to ensure that the final film material would not get component changes due toloss of oxygen. The evaporation rate is0.3nm/s. During the depositing process, XTC22type quartz crystal film thickness instrument real-time monitored the deposition rate andfilm thickness, and feedback compensation mechanism was used to ensure the stabilityof the evaporation rate. After depositing the TiO₂onto a glass substrate, the coatedsubstrates were annealed in a muffle furnace at500°C for1hour. Before and after thisprocess, the topography of the TiO₂surfaces was scanned with a NanoScope atomicforce microscope （AFM） in tapping mode. X-ray diffraction （XRD） was used forcrystalline phase detection, and the use of static contact angle of droplets （ContactAngel） indirect response to the hydrophilic properties of the TiO₂films.Static contact angle measurement showed that, before annealing, the CA value ofthe film surface generally is between40°⁶0°, but after annealing, the CA value isreduced to0°¹0°. There was no UV irradiation during the experiment, thus weexcluded the possibility of chemical reaction that may lead to the hydrophilicperformance improvement. The topography of the sample showed morphologicaltransformation before and after annealing films. This is specifically corresponds tocrystallization （anatase formation） after annealing. In addition, hydrophilic properties ofthicker TiO₂film （500nm²000nm） is better than thinner ones （150nm³00nm）. Andafter annealing, thin films and thick films show different surface morphology. Inaddition, the thicker film surface roughness is significantly smaller than the roughness of the thinner ones. This shows that the roughness is not the dominant factor for thehydrophilic properties of TiO₂films, but special film surface morphology determinesthe hydrophilic properties.Soak-drying cycle can detect the durability of the hydrophilic TiO₂films. Threesuccessive wetting and drying cycles weaken the hydrophilic properties of TiO₂thinfilms obtained in this experiment. And after5cycles, they completely lost theirhydrophilic properties. In addition, during the loop detection process, we found that thesmaller surface roughness （²nm） can significantly strengthen the characteristics of thefilm surface resistant to dirt.