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Measuring the Modulus of Hydrated Contact Lenses via Surface Wrinkling



Jun Y. Chung, Young J. Lee, Peyton Hopson, Michael J. Fasolka, Christopher M. Stafford


One of the most important considerations in the evaluation of hydrogels for biomedical and contact lens applications is the elastic modulus. The elastic modulus relates to several important factors including flexibility, comfort, adhesion, swelling behavior, and the potential for cell proliferation and growth. While current methods for assessing the modulus of hydrogel materials sufficient for quality control, they are not readily adaptable to the latest innovations in contact lens design, such as bifocal or multifocal contact lenses. Thus, there is a critical need for new measurement strategies that provide spatial mapping of the mechanical properties across a contact lens specimen. Furthermore, the ability to measure depth-dependent properties would also be very attractive. We have developed a metrology based on surface wrinkling that provides an accurate measure of the modulus of soft materials such as hydrogels and elastomers. In this talk, we will discuss some of the measurement challenges and solutions we have developed for working with soft, hydrated contact lens materials. The accuracy of the measurement platform will be highlighted with respect to in-sample and sample-to-sample variability, humidity, and contact lens formulation. We will also discuss the application of coherent anti-Stokes Raman spectroscopy to profile the water distribution as a function of depth within the hydrogel specimen.
Proceedings Title
American Chemical Society Division of Polymeric Materials: Science and Engineering| |Proceedings of the ACS Division of Polymeric Materials: Science & Engineering |ACS
Conference Dates
April 6-10, 2008
Conference Location
New Orleans, LA
Conference Title
American Chemical Society (Acs)


contact lens, hydrogel, light scattering, polymer, thin film, wrinkling
Created April 6, 2008, Updated February 19, 2017