A Programmable Liquid Ultrasound Transduer

Conventional ultrasound energy harvesters are solid with an acoustic impedance up to ~37 MRayl, which is about 20 times higher than that of biological tissues (1.63 MRayl). This impedance mismatch largely undermines the energy conversion efficiency and the spatial-access freedom for in vivo ultrasound energy harvester implantation. Here, to the best of our knowledge, we for the first time report a liquid ultrasound energy harvester with an ultralow acoustic impedance of ~1.66 MRayl, which shows near-zero impedance mismatch with biological tissues. Based on a coupling of magneto-viscoelasticity and magnetic induction, the liquid ultrasound energy harvester can deliver an unprecedentedly high-power density of ~21.63 mW cm-2 at a lower incident spatial peak temporal peak ultrasound intensity of ~1.36 W cm-2. Furthermore, it is programmable, deformable and can be adaptive to the dynamically evolving biological tissue surfaces via arbitrary dimensional architecture design. The liquid ultrasound energy harvester provides a seamless interface with biological tissues and is expected to revolutionize the current ultrasound technology.