Control-based approach to broadband viscoelastic spectroscopy: PDMS example

In this article, a novel nanoscale broadband viscoelastic spectroscopy approach is proposed. The proposed approach utilizes the recently developed model-less inversion-based iterative control (MIIC) technique for accurate measurement of the material response to the applied excitation force over a broad frequency band. Current nanomechanical measurement is slow and narrow-banded and thus not capable of measuring rate-dependent phenomena of materials. In the proposed approach, an input force signal with dynamic characteristics of band-limited white-noise is utilized to rapidly excite the nanomechanical response of the material over a broad frequency range. Then, the MIIC technique is used to compensate for the hardware adverse effects, thereby allowing the precise applications of such an excitation force and measurement of the material response (to the applied force). The proposed approach is illustrated by implementing it to measure the creep compliance of poly(dimethylsiloxane) (PDMS) over a broad frequency range over 3 orders of magnitude.