Surface acoustic waves inside polystyrene microparticles through photoacoustic microscopy

Abstract

We demonstrate surface acoustic waves inside polystyrene microspheres of different sizes experimentally through photoacoustic microscopy and validate the experimental result with simulation. A novel method for sample preparation of a lifted sample is also presented where the microparticles are suspended in agarose above the surface of the petridish. Another objective of this study was to investigate the results with different laser focus hitting on the microparticles and their impact on photoacoustic images and photoacoustic signals. An absorbing microsphere is excited with a pulsed laser of wavelength 532 nm and the photoacoustic signal is detected using a 40 MHz transducer. On analyzing the photoacoustic signals from microspheres, we find the signature of surface acoustic waves.