Tushar Parlikar, product manager for Alphabet Verily's wearables program
Who needs it? If such a sensor existed, it would be a user-friendly and continuous way to monitor people with high blood pressure, who are at a higher risk of heart disease, diabetes and strokes, as well as to monitor overall heart health. The promise of such technologies is to catch potential problems long before they're life-threatening.
Who's working on it? Many academic and industry groups, according to Parlikar, including Harry Asada's robotics team at MIT, and cardiovascular researcher Ramakrishna Mukkamala at Michigan State University. A variety of venture-backed start-ups are also working on it too, with mixed success.
Why is it so challenging? Parlikar said there have been several attempts to estimate blood pressure non-invasively using optical sensors, with a slew of different methods. But most have resulted in inaccurate or inconsistent results.
Where would a wearable fit on the body? The wrist, ear canal, face and chest are all options, says Parlikar. And that makes it an attractive possibility for smartwatch makers.
What's the timeline? Parlikar isn't particularly optimistic about what he calls "pulse transit time" methods, which have been tried for decades. But for all other methods, including measuring the the velocity of the pulse wave, he thinks it's probably several years away.