Influence of gold nanoparticle concentration on photoacoustic response of Au-PDMS nanocomposite films

Polydimethylsiloxane composite films containing light-absorbing materials are widely used in photoacoustic ultrasonic transducers. Their photoacoustic performances are crucial to the application of ultrasound transducers. This work investigated the effect of gold nanoparticle volume fraction on the photoacoustic pressure of gold-polydimethylsiloxane nanocomposite films based on a multiscale model. The variation in density, heat capacity, thermal conductivity, thermal expansion coefficient, longitudinal wave sound velocity, and absorption coefficient of the nanocomposites are discussed as a function of gold nanospheres doping volume fraction. As the gold nanoparticle volume fraction increases, comprehensively considering the contribution of each physical parameter to the photoacoustic pressure amplitude results in an underestimation of the photoacoustic pressure amplitude. Such deviation generates an optimum concentration that maximizes the photoacoustic pressure amplitude when the thickness of the composite film remains constant. On this basis, the film thickness and gold nanosphere volume fraction are optimized. The optimized results are of great theoretical significance in improving the performance of laser-induced photoacoustic transducers.