Topographic characterization of unworn contact lenses assessed by atomic force microscopy and wavelet transform

Ţălu, Ștefan; Stępień, K.; Çağlayan, Mustafa Oğuzhan

doi:10.1002/jemt.22580

Cited by 9 publications

(3 citation statements)

References 20 publications

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“…Recently was reported (Ţălu, Stępień, & Caglayan, ) about wavelet analysis to characterize the 3D surface morphology. Wavelet analysis also provides information about irregularity of topography (Stępień, ).…”

Section: Introductionmentioning

confidence: 99%

Influence of scanning rate on quality of AFM image: Study of surface statistical metrics

Sobola

Ţălu

Solaymani

et al. 2017

Microscopy Res & Technique

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The purpose of this work is to study the dependence of AFM-data reliability on scanning rate. The three-dimensional (3D) surface topography of the samples with different micro-motifs is investigated. The analysis of surface metrics for estimation of artifacts from inappropriate scanning rate is presented. Fractal analysis was done by cube counting method and evaluation of statistical metrics was carrying out on the basis of AFM-data. Combination of quantitate parameters is also presented in graphs for every measurement. The results indicate that the sensitivity to scanning rate growths with fractal dimension of the sample. This approach allows describing the distortion of the images against scanning rate and could be applied for dependences on the other measurement parameters. The article explains the relevance and comparison of fractal and statistical surface parameters for characterization of data distortion caused by inappropriate choice of scanning rate.

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Section: Introductionmentioning

confidence: 99%

Influence of scanning rate on quality of AFM image: Study of surface statistical metrics

Sobola

Ţălu

Solaymani

et al. 2017

Microscopy Res & Technique

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“…As mother wavelets differ in properties, it is important that appropriate wavelets be selected for signal analysis and this can be done statistically [27]. Some mother wavelets used in signal analysis are able to improve image resolution or isolate and identify patterns that cannot be detected otherwise [28].…”

Section: Roughnessmentioning

confidence: 99%

Dimensional and Shape Accuracy of Foundry Patterns Fabricated Through Photo-Curing

2019

Teh. vjesn.

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This paper deals with the potential use of the PolyJet Matrix (PJM) technology and digital materials to fabricate foundry patterns. The primary purpose of the study was to assess the dimensional and shape accuracy of additively manufactured objects by determining the draft angle as well as the roundness, waviness and roughness parameters. The experiments were conducted for cylindrical samples printed using VeroWhite liquid polymer resin. The analysis focused on the relationship between the build direction and the geometry and surface finish of prints. Three different orientations, i.e. 0º, 45º and 90º, were considered. The surface texture analysis involved comparing the statistical, graphical and numerical data, including calculation results obtained with the wavelet transform method. The findings confirm that the build direction has a significant effect on the dimensional and shape accuracy of prints and that the PJM technology can be used to fabricate precise foundry patterns, especially in investment (lost-wax) casting.

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“…The evaluation of 3‐D surface microtexture of CLs at a micro/nano level (Giovanzana, Ţălu, & Nicoară, 2020; Ţălu, 2013; Ţălu, Stępień, & Caglayan, 2015) have been dedicated in last decade based on new modern mathematical tools (Ţălu, 2012b; Ţălu, Bramowicz, Kulesza, Fiorillo, & Giovanzana, 2017; Ţălu & Stach, 2014).…”

Section: Introductionmentioning

confidence: 99%

Advanced morphological analysis of siloxane‐hydrogel contact lenses

Ţălu

2021

Microscopy Res & Technique

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The purpose of this work is to provide a better understanding of three‐dimensional (3‐D) surface texture of siloxane‐hydrogel contact lenses (CLs) using atomic force microscopy (AFM) and stereometric analysis. The 3‐D surface texture characterization of unworn/worn siloxane‐hydrogel CLs made of Filcon V (I FDA group) was performed with stereometric analysis. The atomic force microscopy (AFM) measurements of surface roughness and micromorphology of CLs were made using a Nanoscope V MultiMode (Bruker) in intermittent‐contact mode, in air, on square areas of 5 × 5 μm. Stereometric study of 3‐D surface texture was made according with ISO 25178‐2:2012 for CLrins (taken from the blister and rinsed with deionized water); CLss (preserved for 12 hr in saline solution and rinsed with deionized water); CLworn‐smooth (worn for 8 hr and presenting the smooth type morphology), and CLworn‐sharp (worn for 8 hr and presenting the sharp‐type morphology). The 3‐D surface texture of siloxane‐hydrogel CLs was found to have specific morphological characteristics. Statistical parameters revealed local geometrical and morphological spatial structures at nanometer scale attributed to the specific interactions at the CLs surface. Before wear, the surface micromorphology of Filcon V CLs is regular with uniformly distributed microasperities and relatively small heights (Sq = 0.6 nm). After 12 hr in saline, it is found that the micromorphology changes relatively easily, but retaining the main morphological characteristics (Sq = 1.2 nm). After 8 hr of wear, there are two typical micromorphologies: smooth type, characterized by gutter structures and isolated microasperities (Sq = 2.5 nm), while the sharp type has an appearance with compactly arranged microasperities of hill type flanked by compactly arranged microregions of valley type (Sq = 2.2 nm). Surface statistical parameters allow manufacturers in developing the next generation of CLs with improved surface texture while improving biocompatibility and minimizing the impact of the material on corneal physiology. Furthermore, the micro‐elastohydrodynamic lubrication due to surface texture at a nanometer scale between the back surface of the CL with the corneal surface and the front surface of the CL with the under‐surface of the eyelid can be deeper and more nuanced to understand in light of modern tribological theories.

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Topographic characterization of unworn contact lenses assessed by atomic force microscopy and wavelet transform

Cited by 9 publications

References 20 publications

Influence of scanning rate on quality of AFM image: Study of surface statistical metrics

Influence of scanning rate on quality of AFM image: Study of surface statistical metrics

Dimensional and Shape Accuracy of Foundry Patterns Fabricated Through Photo-Curing

Advanced morphological analysis of siloxane‐hydrogel contact lenses

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