Anisotropic elastic properties of chiral sculptured thin films at micro-scale evaluated by resonance frequency spectra

• We evaluate the elastic property of sculptured thin films (STFs) at micro-scale.
• We design a vibration testing system for micro-specimen.
• The micro-structural features are important to the dynamic behavior of STFs.
• The anisotropic elastic property of STF is an interesting feature for dynamic design.

Chiral sculptured thin films (STFs) are nano-engineered to meet the requirements of a variety of applications such as micro filters, sensors, and waveguides due to their unique frequency characteristics which cannot be achieved by conventional solid materials. For the design, it is necessary to understand the elastic properties of STFs. To facilitate this, we developed an advanced micro-scale vibration testing process. In the testing, specially designed micro-specimens with surface areas of tens by tens of microns are excited using a piezoelectric (PZT) actuator and the resonance frequencies are detected by a laser device in the vertical or lateral directions successfully. The anisotropy elastic modulus of STFs composed of helical nano-springs are identified on the basis of vibration testing. The thin film shows strong characteristic anisotropy that the solid one hardly can attain. The micro-scale testing technique can be extended to other materials and microstructures.