Effects of nanoscale film thickness on apparent stiffness of and cell-mediated strains in polymers

The mechanical properties of compliant materials such as polymeric films and biological membranes that are of nanoscale in thickness are increasingly extracted from scanning probe microscope-enabled nanoindentation. These films are applied in various fields that require multiaxial loading conditions. The Hertzian contact models developed for linear elastic materials of semi-infinite thickness fail to accurately predict the elastic modulus E for these compliant materials. This makes it necessary to understand the evolution of stress and strain fields of these nanoscale structures. In this thesis we employ computational simulations that are based on experimental parameters for contact based analysis of compliant polymer thin films, to decouple the effect of thickness and angle of indentation on calculated mechanical properties. Traction applied by living cells to these compliant films are studied in detail. We thus identify the range of strains and material thickness for which contact models could be used to accurately predict the elastic stiffness of these polymeric films of nanoscale (<100 nm) thickness using scanning probe microscope-enabled experiments, and the volumes over which adhered cells deform these films. The key results of this thesis enable accurate experimental analysis of polymeric thin film elastic properties, and design of synthetic polymeric substrata that will dominate the mechanical environment of adhered cells.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Oommen, Binu K

Advisor dc:contributor.advisor

• Krystyn J. van Vliet.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/37689

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/37689