I have no idea how hackernews always reads my mind about this kind of things but I started thinking about this topic due to a personal interest a few days ago.<p>And my question is. Can the ultrasound probe be made of off-the shelf parts. I think I understand why it's not possible with electromagnetic parts alone (kind of a speaker) they just can't vibrate fast enough to reach the Mhz frequency range.<p>But would it be possible to use a regular crystal oscillator they should be cheap, can easily be found for Mhz frequencies and are basically the same technology as the PZTs used in ultrasound probes. Just remove the casing and excite them, would that work?