This is really interesting! And perhaps surprisingly doesn't trigger any immediate major technical red flags (as someone who has worked with MRI and phased array beamforming), as many HN HW articles do.

My only criticism from the tech video would be that they spend some time lauding the nanometer deflection sensitivity, which might lead some to believe that's indicative of the image resolution. It's not, and it's somewhat of a distraction -- that's just giving us amplitude information, which is comparatively less important than correlated time/phase across the 100k sensors. They do later on state ~mm resolution, which is still great!

Doppler and motion blur may be an issue (e.g. heart beating), as one slice requires a full ring of sequential exposures. But still way faster than MRI, so probably fine.

On a lighter note, it could seriously change the meaning of get FUCT (Full body Ultrasound Computational Tomography)!

MRI physicist here as well. I have a basic understanding of ultrasound, and this looks like an array of transducers organized to perform tomography, just as CT did for Xray.

However Ultrasound quality depends highly on transducer-skin contact.

Any physicists here to comment on the effects of sonar through liquid and the effects on image resolution and field of view?

Ultrasound researcher working on fast microvascular imaging here. Depends on the datarates, you can generally get pretty good blood flow data pretty fast, with <.5 seconds per slice if you do it with appropriate algorithms. A lot of this depends on motion though as you said, as the issue is generally getting a high-enough SNR (blood flow is generally 30-40 dB below tissue in energy, except for the biggest of vessels). Generally, higher frequencies have less of a separation between blood and tissue, but they have issue with attenuation. But I think with enough SNR (and with their element count that may indeed be possible), they could get pretty good blood flow data across the whole body.