Please propose a design for better hardware then. You'll make a fortune and do a lot of good in the process.

Seriously, what would motivate you to make a comment like that? Do you think medical device engineers and clinicians are unaware of the false alarm issue and haven't already tried a variety of improvements? There is an inherent trade-off between false alarms and missing a real problem. And devices need to be not only accurate but also affordable, durable, and cost effective. It's not easy to get this right.