Investigation of the Photothermal Excited Microcantilevers Based on Modified Couple Stress Theory

In microscale and sub-micron scale, scale effect highlights and the classical continuum mechanics cannot describe microstructure-dependent size effects. So many non-classical theories were put forward. The modified couple stress theory was established by introducing a material parameter to characterize the scale effect. In this paper, the dynamic responses of microcantilever under photothermal excitation are studied using the modified couple stress theory. The microcantilever deflection governing equation was given, and deflections were obtained numerically using relaxation method. Comparison was made between numerical results with that obtained with experimental measurement and showed a good agreement. According to the numerical results, the scale effect becomes remarkable as the ratio of thickness to the material parameter changes from zero to one. Also, the results showed that this ratio has prominent effect on the resonant frequency of microcantilever.