Some recent phones use ultrasound to sense the dermal layer of your finger which also has the fingerprint ridges. These don’t have problems with dirt and even a scar on your finger won’t stop ...

Supposedly this offers better security, as well as a more accurate fingerprint scans — aided by the fact sound waves aren’t as affected by dirt, moisture and whatever else might be in the way.

If I work in the garden and get dirt on my fingers? Even worse. Rubbing my hands on my pants means I now have to toss my pants in the wash, and the scanner might still fail. Fingerprint scanners ...