It is no secret that we like slide rules around the Hackaday bunker, and among our favorites are the cylindrical slide rules. [Chris Staecker] likes them, too, and recently even 3D printed a version.

A few weeks back, we reported on a research group that figured out how to measure heartrate using perturbations in WiFi signals. [Nick Bild] was interested in this so-called “Pulse-Fi” technique, but ...