The equilibrium gap method with modeling parameters: identifiability conditions and sensitivity

The use of a Nomarski shear-interferometer with a sinusoidal phase modulation and four integrating buckets allows one to obtain the displacement field of the surface of a micro-cantilever observed in reflection microscopy. One can apply an electrostatic loading to this micro-object, which is first represented as an unknown pressure field. When retrieving both the flexural stiffness field and the load field using the equilibrium gap method, one may model the applied loading as a pure pressure field. This paper intends first to assess the effect of a modeling error, and then to test the identifiability conditions if one uses a parameterized description of the loading to fit measured kinematic data. The influence of the measurement noise on the identified parameters is then semi-analytically derived, and the global identification algorithm is applied to experimental data.