Friction studies of hydrogel contact lenses using AFM: non-crosslinked polymers of low friction at the surface

Kim, Seong Han; Marmo, Chris; Somorjai, Gábor A.

doi:10.1016/s0142-9612(01)00175-2

Cited by 63 publications

(56 citation statements)

References 33 publications

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“…Observations were made using both Scanning Electron Microscopy (SEM) and AFM, indicating that cast-molded lenses show lower root-meansquare (RMS) roughness values, in agreement with the results of Rabke et al [1] and Grobe et al [2]. Kim et al [4,5] investigated the surface of hydrogel pHEMA-based CLs by using AFM and measuring the friction and adhesive forces. They found that in saline solution these magnitudes were significantly reduced, compared to those measured for the surface-dehydrated state.…”

Section: Introductionsupporting

confidence: 76%

“…In the case of soft CLs, made of hydrogel or siloxane-hydrogel, the hydration equilibrium of the surface can affect the adhesion values, which are higher in a surfacedehydrated lens [4]. The same could be expected for the Young modulus.…”

Section: Nanomechanical Analysismentioning

confidence: 87%

“…These studies clearly show that the fabrication technique has a notable influence on the lens roughness, being the cast-molded lenses those showing lower Rq values. Kim et al [4,5] also reported values of Rq in pHEMA-based hydrogel lenses ranging from 8 to 23 nm.…”

Section: Topographic Analysismentioning

confidence: 98%

“…The Atomic Force Microscopy (AFM) is a technique that becomes useful to determine these properties, as was pointed out in an earlier work by Rabke et al [1]. Consequently, several authors [2][3][4][5][6][7][8][9][10][11][12][13][14][15] performed studies on CLs and using the AFM technique, but none of them used the Peak Force Quantitative Nanomechanics mode to determine the nanomechanical properties, such as the adhesion or the Young modulus, also named elastic modulus.…”

Section: Introductionmentioning

confidence: 99%

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AFM in mode Peak Force applied to the study of un-worn contact lenses

Torrent‐Burgués

Sanz

2014

Colloids and Surfaces B: Biointerfaces

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Contact lenses (CLs) are of common use and the biocompatibility, topography and mechanical properties of the used materials are of major importance. The objective of this contribution is to apply the AFM in mode Peak Force to obtain surface topography and mechanical characteristics of un-worn CLs of different materials. One material of hydrogel, two of siloxane-hydrogel and one of rigid gas permeable, were used in the There is no significant influence of the environment, water or saline solution, on the measured properties.

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Section: Introductionsupporting

confidence: 76%

Section: Nanomechanical Analysismentioning

confidence: 87%

Section: Topographic Analysismentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

AFM in mode Peak Force applied to the study of un-worn contact lenses

Torrent‐Burgués

Sanz

2014

Colloids and Surfaces B: Biointerfaces

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“…Kim et al [25] reported that the friction of a soft contact lens surface was significantly reduced under the lubrication of saline solution, whereas Liu and Bhushan found that using perfluoropolyether (PFPE) as a lubricant could significantly improve the frictional behavior of a silicon surface [26]. Microscopic AFM measurements have also been reported to be very effective for exploring the boundary lubrication of various lubricants for the engineering and biological materials because frictional coefficients between two rubbing surfaces can be measured without being affected by the surface roughness of rubbing materials [27].…”

Section: Introductionmentioning

confidence: 99%

Effect of protein concentrations of bovine serum albumin and γ-globulin on the frictional response of a cobalt-chromium femoral head

Duong

Lee

Cho

et al. 2012

J Mater Sci: Mater Med

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The study aims to identify the concentration-dependent role of bovine serum albumin (BSA) and γ-globulin in the lubricating ability of a cobalt-chromium femoral head. The frictional coefficients of the cobalt-chromium femoral head decreased with increasing BSA concentrations from 10 to 40 mg/ml and showed statistical differences between any of the BSA concentration groups, except between the 30 and 40 mg/ml concentration groups. In γ-globulin, the frictional coefficients significantly decreased at concentrations of 2.5 and 5.0 mg/ml as compared with the PBS control group, but significant increases were observed at 7.5 and 12.5 mg/ml. These results suggest that the friction of the cobalt-chromium femoral head is dependent on the concentration of both BSA and γ-globulin. However, there is a maximum concentration for BSA to act as an effective boundary lubricant, while the lubricating ability of γ-globulin is most effective in the physiological concentration range within human synovial fluid.

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Surface mechanical properties of pHEMA contact lenses: Viscoelastic and adhesive property changes on exposure to controlled humidity

Opdahl

Kim

Koffas

et al. 2003

J Biomedical Materials Res

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The surface mechanical properties of poly(hydroxyethyl)methacrylate (pHEMA)-based contact lenses were monitored as a function of humidity by atomic force microscopy (AFM). Surface viscoelastic and adhesion values were extracted from AFM force versus distance interaction curves and were found to be strongly dependent on the bulk water content of the lens and on the relative humidity. At low relative humidity, 40-50%, the dehydration rate from the surface is faster than the hydration rate from the bulk, leading to a rigid surface region that has mechanical properties similar to those measured on totally dehydrated lenses. At relative humidity values > 60%, the dehydration rate from the lens surface rapidly decreases, leading to higher surface water content and a softer surface region. The results indicate that, in an ocular environment, although the bulk of the pHEMA contact lens is hydrated, the surface region may be in a transition between a dehydrated glassy state and a hydrated rubbery state.

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Friction studies of hydrogel contact lenses using AFM: non-crosslinked polymers of low friction at the surface

Cited by 63 publications

References 33 publications

AFM in mode Peak Force applied to the study of un-worn contact lenses

AFM in mode Peak Force applied to the study of un-worn contact lenses

Effect of protein concentrations of bovine serum albumin and γ-globulin on the frictional response of a cobalt-chromium femoral head

Surface mechanical properties of pHEMA contact lenses: Viscoelastic and adhesive property changes on exposure to controlled humidity

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