High-frequency (> 65 MHz) broadband transparent transducer with ultrathin gold electrode for dual-mode photoacoustic and laser-induced ultrasound microscopy.

For high-performance combined photoacoustic (PA) and Ultrasound (US) microscopy, precise coaxial alignment of the US and laser beams is essential. This can be realized using broadband transparent ultrasound transducers (TUTs). However, the current dual-mode imaging systems encounter significant challenges in simultaneous PA and US data acquisition due to sequential transmission of light and ultrasound and mechanical movement of dual-mode probes, leading to longer acquisition times and potential registration inaccuracies. To overcome these limitations, we propose a recently developed high-frequency broadband TUT with an ultrathin (< 10 nm) gold electrode, achieving a center frequency of 65.6 MHz and a -6 dB bandwidth of 71.6 %. The ultrathin gold electrode facilitates laser-induced ultrasound (LUS), enabling simultaneous acquisition of PA and US images. In vivo experiments demonstrate that LUS imaging can effectively replace conventional US imaging, offering highly efficient dual-mode PA/US imaging with minimized registration errors.