Vivo's using ultrasound sensors that can apparently read your prints across a bigger area beneath the screen. (In comparison, the last model did the same scanning trick with a tiny camera sensor, but that's something apparently only possible with OLED screens).

When Engadget Senior Editor, Chris Velazco, tested it out in person, the tech wasn't exactly flawless, taking multiple attempts to unlock with a fingerprint. It's also folded into a concept phone -- one with a pop-out selfie cam, no less. The chances of an identical phone appearing in the west are pretty slim.

Not all phones are born flagships, but that's no longer a good enough excuse not to upgrade from a PIN you made back when Brangelina was a thing. The Alcatel 5 might be a middleweight in spec sheet terms, but it still folds in both a fingerprint sensor and face unlock features. It doesn't sound particularly foolproof: the "Face Key" will attempt to detect 100 points on the user's face to verify, so it's possible photos might be enough to trip it up. Still, the unlock feature was swift enough during our brief time with it earlier this week. Somehow, you can even go cheaper: the Alcatel 3 slides in just under 200 Euros.

Other options

Also announced this week, LG's V30S ThinQ isn't a huge leap beyond last year's V30, and it doesn't pack any new methods to unlock. It does, however, offer voice unlock, something that snuck into the debut V30 last year but hasn't been adopted on any other devices, as far as we can tell. It's not hard to see why: Asking Google Assistant / Siri questions in public is hard enough, let alone with the frequency we all unlock our phones. Still, it's yet another method to add to the pile.

We'll throw in a quick hat-tip to Apple and Face ID. Its True Depth camera system -- that's why there's a notch -- is made up of a bunch of sensors (ambient light, infrared and proximity) that detect your face, even in the dark. It offers a more secure version of simple camera-based face recognition and is surprisingly smooth and hassle-free -- so much that Huawei is looking to fold in similar tech into its next phone but better, of course.

For now, it's still a mess of techniques out there, and you get what you pay for when it comes to reliability and security. It might, however, be a sign to upgrade your smartphone security.

Catch up on the latest news from MWC 2018 right here.