Utilization of fullerenes nanoparticles for ultrasound applications in developing a high-efficiency acoustic emission source

Fullerenes have exhibited excellent performance in solar cells, electric transducer and catalysts. The rather high absorption coefficient, combined with its low specific heat capacity, as well as hydrophobicity and antioxidant, are key features for applications in acoustic emission (AE), which has never been reported. Here, we fabricate and characterize a flexible an AE source based on the fullerenes-polydimethylsiloxane (PDMS) composite. By controlling the composite concentration or thickness, the center frequency can be changed in laser ultrasound excitation. The assembled transducer simultaneously achieves relatively wide frequency range (10-dB bandwidth$>$10 MHz) and efficient laser ultrasound conversion $(1.13\times 10^{-2})$. The mechanical robustness of the AE source is also quantitatively characterized in water. Notably, compared to graphene nano-flakes, the fullerenes exhibit a more than threefold increase in excitation amplitude. Owing to high-intensity ultrasound excitation of the fullerenes-PDMS composite, the structure characteristics of centimeter-scaled physical models are clearly resolved by irradiating the material as a laser-ultrasound source. To construct a compact fiber-optic exciter, the fullerenes-PDMS film is additionally applied to a fiber end via dip coating. The findings suggest that fullerenes possess significant competitive advantages as a high-efficiency AE source in the field of ultrasound applications.