Material removal mechanism in and experiments of electrorheological polishing of foldable intraocular lenses at low temperatures

The traditional method of manufacturing foldable acrylate intraocular lenses (IOLs) involves injection molding and ultraprecision diamond turning. Due to the lack of in-depth research on the material removal mechanism for soft and flexible biomaterials, traditional processing methods cannot produce high-quality surfaces of foldable IOLs. This paper presents a new manufacturing method of low-temperature-assisted electrorheological polishing to improve the surface quality of foldable IOLs. The effects of temperature on the mechanical properties, including the mean azimuth shift at the end of the molecular chain, diffusion coefficient, stress-strain response, etc., and the evolution of the material removal mechanism of abrasive particles under the electrorheological effect with temperature were systematically studied by molecular dynamics. With decreasing temperature, the mechanism of material removal from the IOL surface by abrasive particles changed from compaction removal to furrow removal, and the surface roughness decreased, which revealed that the machinability of the acrylate material could be greatly improved at low temperatures (approximately-20 degrees C). In addition, a new low temperature-assisted electrorheological polishing system for IOLs was designed. An orthogonal test showed that the temperature had the most significant influence on the surface roughness, consistent with the molecular dynamics analysis results. The surface roughness of the material polished at-20 degrees C decreased from 491 nm to 9 nm, which indicates that low-temperature-assisted electrorheological polishing is an effective method for fabricating foldable acrylate IOLs with high efficiency and quality.