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Microbubble resonators for photoacoustic and photothermal characterisation of nanoparticles suspensions

Year: 2024
Type: article
Abstract: \nWe discuss the implementation of Whispering Gallery Modes Microbubble resonators (MBRs) as unique platforms for photoacoustic (PA) detection and photothermal (PT) spectroscopy. In a first experiment, the MBR transducer allowed to detect the PA signal generated by a suspension of gold nanorods (GNRs) within its core, leveraging on the MBR sharp optical spectrum and high sensitivity towards mechanical perturbations. Both static and flow-cytometry configuration were tested, finding that the MBR mechanical modes help detection by decoupling the environmental noise from the PA oscillation. In a second experiment, the MBR transducer allowed to reconstruct the GNRs absorption spectrum through the photothermal (PT) conversion, leveraging on high sensitivity towards temperature variations. We verified the scattering-free nature of the detection by using milk-stained GNRs suspension. We also found that the active locking of the MBR resonance increases the system sensitivity by an order-of-magnitude. These results make MBRs interesting candidates for combined PA and PT characterisation of extremely small samples for medical diagnosis, quality controls in food safety and chemical production processes.\n
Language: English
Open Access status: green
OpenAlex ID: W6940981219
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