PDMS composites with photostable NIR dyes for multi-modal ultrasound imaging

All-optical ultrasound (OpUS) imaging has emerged as an imaging paradigm well-suited for minimally invasive surgical procedures. With this modality, ultrasound is generated when pulsed or modulated light is absorbed within a coating material. By engineering wavelength-selective coatings, complementary imaging and therapeutic modalities can be integrated with OpUS. Here, we present a wavelength-selective composite material comprising a near-infrared absorbing dye and polydimethylsiloxane. The optical absorption for this material peaked in the vicinity of 1064 nm, with up to 91% of incident light being absorbed, whilst maintaining lower optical absorption at other wavelengths. This material was used to generate ultrasound, demonstrating ultrasound pressures $$  MPa, consistent with those used for imaging applications. Crucially, long exposure photostability and device performance were found to be stable over a one hour period (peak pressure variation $$ %), longer than required for standard clinical imaging applications.