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Nondestructive characterization for PDMS thin films using a miniature fiber optic photoacoustic probe

This paper presents a nondestructive ultrasound test method for characterizing resonant frequencies of polydimethylsiloxane (PDMS) thin films by using a miniature fiber optic photoacoustic (PA) probe. The PA probe was fabricated with an optical fiber and the synthesized gold nanocomposite. During the experiment, a PDMS film with thickness of 25 μm was cured and immersed into water media within a designed holder to clamp the film. An acoustic pulse was generated from the PA probe, propagated in the water media and excited the clamped film. A fiber optic pressure sensor based on Fabry-Perot (FP) principle was applied to collect excited acoustic signals on the other side of the film. The sensed response of the acoustic pulse was used to compute the resonant frequencies of the PDMS thin film based on de-convolution method.