Asus Zenfone 9 fingerprint scanner

Robert Triggs / Android Authority

In just a few short years, under-display fingerprint scanners have gone from exciting cutting edge to commonplace. Push-button security doesn’t sound all that exciting by comparison, but we do indeed live in a golden age of technology. After spending time with the Asus Zenfone 9 and Sony Xperia 1 IV, I’m now convinced that side-mounted fingerprint scanners are the best implementation, at least for now. Let me explain.

They are faster, for one. Miles faster not only in terms of unlocking, but also registration. The Zenfone 9’s scanner is so fast that I physically can’t remove my finger fast enough for it to fail. We also rated the Poco F4’s side scanner as excellent in this regard. Sony’s Xperia 1 IV isn’t quite as fast, but it’s still more precise and accurate than many of the in-screen scanners I’ve used in recent years.

The Zenfone 9’s power button scanner is so fast that I physically can’t lift my finger fast enough for it to fail.

Compared to the icy Google Pixel 6, the experience is night and day. The types available on wet (and dry) finger screens are very difficult as well as screen protectors, which is not the case with physical scanners.

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There are other benefits as well. The scanners hidden in the power button are just as discrete, but you always know where they are. The variation within the display is obviously well hidden, but guessing exactly where the reader is when the screen is off can be problematic. Scan areas are also often very small, you have to be careful to avoid rescanning. In comparison, the power button is easy to find. Likewise, cheap optical scanners (I’m bad at you again, Pixel) emit a blinding light when reading in the dark. No one likes to burn their retinas just to check WhatsApp.

On good authority: How bad is the Pixel 6’s fingerprint scanner?

Sony Xperia 1 III vs Sony Xperia 5 III buttons

Robert Triggs / Android Authority

Button-based fingerprint scanners can also be smarter. Asus’s Zenfone 9, for example, has mappable gestures to quickly launch apps, remove the notification shade, launch Google Assistant, and more. Double-tapping the button, pressing and holding, or quickly swiping up or down expands quick access to the features you use without blocking the lock or home screen. It’s the kind of simple, straightforward feature that incredibly simply adds tons of value, but it seems to have eluded flagship manufacturers who are too busy chasing the latest tech fads.

Of course, fingerprint gestures are nothing new. Back when phones still sported bezel-less chin-based scanners, and when manufacturers thought the back of the phone was the best place to put them, sloppy gestures were popular. For example, the original Pixel lets you drop the notification shade by swiping on the back of the phone. But their integration into the existing power button is very nice, and in theory, it could be available on any smartphone, regardless of its design identity.

The fingerprint gestures that are installed on the buttons are very nice, every phone should have it.

Of course, that doesn’t mean there aren’t some great under-display fingerprint scanners on the market. The Vivo X80 Pro’s 3D ultrasonic sensor (pictured below) stands out as the best current example. With a large scanning area, one-touch fingerprint enrollment and app launch shortcuts, it’s intuitive, smart and clearly a step up from what’s currently on the market, even in the premium flagship space.

See also: This is an in-display fingerprint reader done right

While it offers a glimpse into the future of in-display technology, the X80 Pro remains an outlier in the world of in-display technology. Hopefully we’ll see more phones with this scanner in the near future, but cost, trade-offs in internal space and display support may remain a barrier to entry for a while. Certainly as far as the mainstream is concerned.

The side-mounted fingerprint sensor is a better combination of form and function.

Of course, not every in-button fingerprint scanner is perfect, but the modern era seems to have proven the formula. Whether you’re splurging on the $1,600 Xperia 1 IV or cashing in on the €399 Poco F4, a fast, reliable, and secure experience is within reach. Meanwhile, the Zenfone 9 has convinced me that fingerprint gestures are so useful yet simple enough that every smartphone should have them. If that means backing off from under-display fingerprint scanners for a few years until the technology catches up, then so be it. It’s simply a better marriage of form and function.