Measurement of surface stress: Description of an interferometric method

In a recent publication, we proposed a new experimental method for measuring the absolute surface stress of a thin crystalline sheet based on the deformation of very thin sheets (thickness e < 10 mu m) submitted to disymmetrical surface stresses (S-1 on one side of the sheet, S-2 on the other). This paper demonstrates that Michelson interferometry can be used to measure a surface stress change of 2-3 10(-3) J.m(-2) if the thickness and the Young modulus of the sheet are accurately known. Using a silicon substrate sample we found that one fourth of a monolayer of silver reduces the surface stress by 0.45 J.m(-2).