That joke might seem like a bad one, but it kinda fits when we talk of fingerprint scanners on smartphones. They started from the bottom after all, and now seem to have reached their home (or so we think). But to understand this better, let’s start from the beginning. Or actually from the bottom. Of smartphones.

Starting from the base-ics…

Once upon a time, smartphones had to depend on passwords, pin and pattern locks to keep peepy-eyes from breaking and entering. But those were a little tedious to use, and well, depended on human memory (people forgot them!). To solve this problem, a new security messiah was born, a biometric measurement based on the unique print of each individual, (drum roll, please) – the fingerprint scanner. Fingerprint scanners changed the way people used and secured their phones. And one of the very first residences of the scanners was the chin bezel of the smartphone, below the display (hence, started from the bottom, if you were still wondering what the joke in the opening line was about). It stayed there for quite a while, but as the hatred for bezels grew stronger, and the demand for an edge-to-edge screen increased, the chin eventually had to shrink. The poor fingerprint scanner had to no choice but to migrate. To the back of the phone.

…Going from front to back…

A long journey from the face to the back of the smartphone was covered and suddenly, the fingerprint scanner seemed like it had found a permanent address. This new home was not as accessible as the first one, where you could just put your thumb on the chin and Voila! The phone would unlock. Here, your finger had to travel a little extra to reach the part on the back where the tiny, little, recessed circle (mostly) resided and had to unlock your phone from there. It was not inconvenient but, it was another design element and another button to keep in mind. This was because unlike on the front, the fingerprint scanner on the back did not serve any other purpose other than to unlock the phone, whereas those on phone chins usually also took on the role of a home button.

But shifting the fingerprint scanner to the back was a very small price to pay for those beautiful, tall, edge-to-edge, nearly bezel-less displays. Happy at the back, the biometric scanner stayed there for a while. But after seeing the scanner settling so well on the back, the front suffered from FOMO (we guess, or maybe the back just got fed up of it) and offered a fancier, more glamorous place for the scanner to stay– under the display, that way it would not only return to the front and but would also be a USP that any smartphone would be really lucky to have.

…Stepping from below to within the display…

These in-display fingerprint scanners were not like your regular, old school scanners. Looking at a sleeping phone with an in-display scanner, you might not even be able to tell if it has one or not (some glow in the dark, though). What looks like a regular display at first glance, actually has a fingerprint scanner buried under. No button, no tiny recessed circles, just a display, with a scanner underneath. The best possible place for the migrating scanner, right? Well, that may be a popular opinion but we tend to disagree. For, though this was a fancy residence for the scanner, basics like speed and accuracy struggled. You see, the house under the display worked a little differently than mainstream sensors, as most of these optical in-display scanners capture the image of your fingerprint and then match it with your fingerprint every time you try to unlock your smartphone. They work. But there are times when they do not. And they often take time. Yes, even on some super expensive smartphones.

…But happiest on the sidelines!

Even while the fingerprint scanner was migrating from the front to the back, and then back to the front, it had taken a slight, not very noticed, detour in the middle to find rented accommodation on the side of the smartphone (most notably in the short-lived Nextbit Robin). Of course, it did not stay there for which now seems to be making a comeback. And that is the place we like the best. Yes, THE BEST! Smartphones like the Honor 20 Pro, Samsung Galaxy S10E, and the more recently launched and far more mainstream Redmi Note 9 series and the Realme 6 series came with a fingerprint scanner mounted on the side. Basically, a flattened power/lock button with a slightly coarse texture, similar to the one on the circular fingerprint scanner on the back, these scanners on the side are not just scanners. They have two roles – they are both Iron Man and Tony Stark. In most cases, a side-mounted fingerprint scanner doubles up as a power/lock button, too. And we called it Iron Man because Iron Man is pretty chill about his identity as both Iron Man and Tony Stark, like our scanner on the side, unlike Superman who is kind of shy about being known as Clark Kent. Sorry, rambling, back to business. Having a fingerprint scanner on the side also means one less button or touchpoint to put on the phone as compared to physical scanners. It might lose some glamour points against the in-display scanner, but it is definitely more cost-efficient and generally faster and more accurate. And hey, it also declutters the back (you now only have cameras on the back). Finally, reaching for a scanner on the side feels much more natural and easier than going on the back to find a point or finding one on the display. For, we are actually used to reaching out for the power/lock button anyway, which reside almost always on the side anyway. This is the same button but with more functionality added to it. With fingerprint scanners on the side, we can unlock our phones by just merely picking them up – you do not have to specifically reach out to a point on the screen or a button on the back, but simply head to the good old power button. You do not even have to move the phone – just put your finger on the side. We love! It is too early to say that the side of the phone will be a permanent home to the fingerprint scanner. Hey, as we pointed out, the poor thing has traveled all over the phone in recent years. And people are still working on faster, in-display scanners. But if there is one place, that is perfect for the fingerprint scanner in our opinion, it is on the side-lines as of now. Literally.