I do my PhD in in-air ultrasound with phased arrays and talk to the medical guys at conferences/labs that we talk to and it's soooo much harder in solids/liquid

I do my PhD in in-air ultrasound with phased arrays and talk to the medical guys at conferences/labs that we talk to and it's soooo much harder in solids/liquids. The frequency is significantly higher, think 1-10MHz instead of like 40khz, so any normal electronics are out the window.