I am seasoned in writing software and product design. I know healthcare is a very promising field but I don't have good knowledge of the industry. Some similar consumer wearables in healthcare would be the fit bit, a glucose meter or a heart rate monitor.
I spent a few years at Intel's Digital Health Group (we had a phalanx of PhD's and MD's on staff trying to answer your question). As others have mentioned, this is a very crowded and complicated space. Even more so if the device needs FDA approval. Since you lack deep domain knowledge, step 1 is finding a partner (ideally a clinician with many years experience) who has it, and also has a nose for business opportunity. Let them guide you toward a problem that needs solving.