Miniaturized ultrasound systems are central to emerging biomedical applications such as targeted therapy, drug delivery, and wearable diagnostics. However, intensifying acoustic emission at small scales remains a key challenge, constrained by limits in conventional transducer designs and MEMS technologies. In this work, we demonstrate a novel approach to enhancing ultrasound emission by leveraging the acoustic Purcell effect, enabled by perfluorocarbon nanodroplets (PFCnDs). These nanoscale droplets are engineered to structure the surrounding acoustic environment and modulate the local acoustic density of states, thereby amplifying emission efficiency. We present a theoretical model of nanodroplet-enhanced Purcell emission and validate it through ultrasound measurements in soft-tissue-mimicking media. Our results show an acoustic Purcell factor normalized by droplet diameter (APF/D) of 1.6×105 ± 2.6×102 m−1, exceeding existing acoustic Purcell platforms by over two orders of magnitude. The emission intensity is tuneable via droplet size and concentration, providing precise acoustic output control within biologically safe exposure limits. When applied to B-mode ultrasound imaging, the enhanced emission leads to a 42 ± 1.4 dB contrast increase compared to conventional imaging. This study establishes a new framework for nanoscale acoustic emission enhancement, with implications for low-power, high-contrast ultrasound systems and the integration of nanostructured materials into next-generation acoustic devices.
Zhang et al. (Wed,) studied this question.