[JoshTriplett]

Long-term, some of these devices would need FDA approval, but many of them wouldn't.

Speaking as a non-expert (only familiar with FDA approval processes through the experiences of friends and colleagues): none of these devices would constitute a class II or III medical device, since they'd only act as an early-warning system rather than as a primary diagnostic tool or direct treatment system. Some of these devices might fall under class I (which also includes things like tongue depressors), but meeting class I wouldn't necessarily prove insanely onerous, and some care would likely allow avoiding class I as well in some cases.