Measurement of Mechanical Properties of Soft Materials by a Visual Sensing Based Nanoindentation

Precise measurement of the mechanical properties of soft materials at micro/nanoscale is crucial in numerous fields, such as biomechanics, polymer physics, and micro/nanofabrication. However, discrepancies exist in measurement results from different measurement techniques, especially in the measures requiring long-term characterization. Here, we propose a visual sensing based indentation method for accurate characterization of mechanical properties of soft materials. In this method, two microcantilevers are employed. A microbead is attached to the end of each microcantilever for tracking purposes. By applying a visual sensing technique, measurement resolutions of 0.43 nm and 1.28 nm are achieved in the lateral and axial directions, respectively. This enables precise detection of cantilever deflection and hence the applied forces. The principle of the method is presented. The experiments were designed to validate the proposed method on polydimethylsiloxane thin films by extracting Young’s modulus and characterizing long-term relaxation. This method provides an effective approach for the accurate measurement of mechanical properties, especially for soft materials.