I bought my current MacBook Air two years ago. I trained its TouchID button for a couple of my fingers, and absolutely love that feature. But over time its TouchID button has become increasingly finicky. I cleaned it (with alcohol on a Q-Tip) but no help. So yesterday I retrained the button, and it’s now as reliable as it used to be.

So why the need for retraining? It’s certain that my MacBook’s digital record of my fingerprints didn’t degrade. So it must be that my fingerprints have changed somewhat. And no, I didn’t sand ‘em off.

The TouchID feature is so handy that it’s well worth the short time required for retraining every couple of years.

BTW – I’ve long wondered about the sensor technology in the little plastic TouchID button. How in the world does it capture the intricacies of a fingerprint with such speed? Checking the web I found this:

“…The sensor uses advanced capacitive touch to capture high-resolution images of your fingerprint. Touch ID reads fingerprints in 360-degrees of orientation, analyses the sub epidermal layers of the skin and categorises each fingerprint into arch, loop or whorl categories…”

https://www.google.com/amp/s/w...need-to-know.amphtml

So thousands of microscopic capacitive touch sensors in that little button? Apparently… a chip, no doubt. Other interesting info about the TouchID button in the article too.

Maybe it's the fingerprint reader button that's degrading. I doubt your fingerprints would to an appreciable degree.