Apps want to be your new doctor’s office. Is that a good idea?

The same devices used to take selfies are being repurposed and commercialized for quick access to information needed for monitoring patient health. A fingertip pressed against a phone’s camera lens can measure a heart rate. The microphone, kept by the bedside, can screen for sleep apnea.

In the best of this new world, the data is conveyed remotely to a medical professional for the convenience and comfort of the patient — all without the need for costly hardware.