PDMS Composites with Photostable NIR Dyes for B-Mode Ultrasound Imaging

All-optical ultrasound has rapidly progressed as an imaging paradigm well-suited to application in minimally invasive surgical scenarios, moving from benchtop to in vivo studies. In this work, we build on previous studies, demonstrating B-mode all-optical ultrasound imaging using a composite comprising a photostable near-infrared absorbing dye and polydimethylsiloxane. This composite is cost-effective and simple to manufacture, and capable of generating broadband (ca. 35 MHz) and high-pressure (ca. 1.5 MPa) ultrasound. The composite was compared with an established ultrasound-generating composite: reduced graphene oxide with polydimethlysiloxane. Both materials were coated on multimode optical fibres and were optically and ultrasonically characterized. Further, the transmitters were coupled with a piano-concave microresonator for ultrasound reception and synthetic aperture B-mode pulse-echo US imaging of a tungsten wire phantom and ex vivo swine aorta tissue was performed. The images acquired using each transmitter were compared in terms of the image resolution and signal-to-noise ratio.