This smartphone HR and RR rate measurement will be useful for personal health monitoring in general. I am working around tourist spots and have seen tourists seeking medical devices during travelling such as bp measuring machine. Smartphone vital sign measurement would suit travelers so that they don’t have to buy one for the short term use.
Apart from human, I am thinking of using this kind of technology in animal and pet health. Because the pet couldn’t talk, some of the owner would probably love to know and take care of their pet health status. Moreover, without intrusive methods, it could be used to measure the observation of animals in national parks as well.