Mechanical characterization of contact lenses by microindentation: Constant velocity and relaxation testing

详细信息    查看全文

• 作者：Sung Jin Lee ; Gerald R. Bourne ; Xiaoming Chen ; W. Gregory Sawyer ; Malisa Sarntinoranont
• 关键词：Hydraulic conductivity ; pHEMA-MAA ; Poroelastic ; Polymer ; Hysitron
• 刊名：Acta Biomaterialia
• 出版年：2008
• 出版时间：September 2008
• 年：2008
• 卷：4
• 期：5
• 页码：1560-1568
• 全文大小：990 K

文摘

Non-destructive methods for testing material properties allow for multiple tests to be performed on the same sample, which will speed up the design and testing process for hydrogel contact lenses. The mechanical properties of contact lenses were investigated by microindentation testing. Indenter force responses were recorded for two modes of testing: constant velocity and relaxation indentation. From these tests, we characterized the biphasic properties of a hydrogel contact lens: Young’s modulus of the solid matrix and hydraulic permeability. Measured indenter force response was fit to finite element (FE) simulation results over a range of Young’s modulus (E) and hydraulic permeability (k) over a short testing time scale (2 s). Estimated hydraulic permeability, 1–5 × 10⁻¹⁵ m⁴ (N s)⁻¹, was similar to previously measured values for Etafilcon A. However, values determined for Young’s modulus, 50–60 kPa, were lower than previously measured.