[JoshTriplett]

It sounds to me like you have a pretty good idea of the technical details and challenges in such a project. You'd need to find someone with medical experience that you could work with to figure out the details, but you could find quite a bit of that expertise just by chatting with your local medical school. And at least in the short-term you won't have to worry about medical device certification, since most of the ideas you've mentioned would not directly get used for medical treatment; any actual diagnosis would still get done by a physician.

If you're serious about being willing to work on this proportionally to how much funding you get, then please by all means start a project. Pick a couple of appropriate ambitious-but-likely-possible goals, set expectations very clearly, and see if you get any takers.

[waterlesscloud]

Would this project need FDA approval? If so, the timeline would be quite long and a million bucks would come nowhere near covering it...

[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.