20.500.12556/RUL-162806 Picosecond photoacoustic generation of ultrasounds with composites of graphene-decorated gold nanoparticles Photoacoustic or light-to-pressure transducer materials exhibit tremendous potential across various disciplines and applications, embracing theragnostic ultrasounds and permeabilization of biological barriers for drug delivery or for gene transfection. Here, we report the photoacoustic response in the picosecond excitation regime of graphene and gold nanoparticles decorated graphene dispersed in a polydimethylsiloxane polymer matrix. A novel decoration method was developed to nucleate Au nanoparticles of 25 nm on the graphene surface without reducing agent. We observed that the picosecond excitation enforced by the stress confinement generates high-frequency waves, with bandwidths of −6 dB and −20 dB of around 70 MHz and 130 MHz respectively, and peak pressure > 5 MPa. Further, the presence of gold surface decoration leads to a better dispersibility of the flake into the polymer matrix and to an increasing bandwidth at −6 dB up to 85 MHz. The decrease in source thickness leads to an increase in ultrasound frequency, which retains its value even when the laser fluence is increased up to 150 mJ cm$^{–2}$. This enables the generation of high pressures while keeping the same bandwidth. We experimentally show that the photoacoustic waveform can be tailored by changing the temporal duration of the laser light, the geometry of the acoustic source, and the nature of the graphene absorber. Flexible decoration and fabrication methods of thin films, along with the generation of high-frequency and high-pressure ultrasound waves, offer new perspectives for the use of physical methods to permeabilize biological barriers and develop high-resolution photoacoustic imaging systems. graphene composites gold nanoparticles decoration photoacoustics high-frequency ultrasound photoacoustic waves grafenski kompoziti dekoracija z zlatimi nanodelci fotoakustika ultrazvok fotoakustično valovanje true false true Angleški jezik Slovenski jezik Članek v reviji 2024-09-27 10:32:50 2024-09-27 10:32:56 2024-10-02 03:29:35 0000-00-00 00:00:00 2024 0 0 12 str. pt. A, art. 110236 Vol. 131 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 535 2211-3282 10.1016/j.nanoen.2024.110236 208436739 1-s2.0-S2211285524009881-main.pdf 1-s2.0-S2211285524009881-main.pdf 1 B246BFB43A3545C773B836368581497E dd0dd810ff4fd223683d6a8e95798a36dcdc6da2b178c5d91483d6e51f8bde17 4644390a-7cab-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=192238 https://www.sciencedirect.com/science/article/pii/S2211285524009881 1 f88b286e-7caa-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=192237 Fakulteta za strojništvo 0 0 0