In-Glass Fingerprint Sensor: Testing the limits!

Earlier in the year you might remember we did an article on that in-glass fingerprint reader you know all these bezel-less phones are coming out now there's no room on the front for a fingerprint reader unless you put it underneath the glass, so we've got to see a demo of it in action in an unreleased vivo phone, well today of course now we have that phone it's here it's in the studio it's the Vivo x21 and it's out now it exists, snapdragon 660, 6 GB of ram, 3200 Mah battery and a 6.3 inch 1080p OLED display with of course the optical fingerprint sensor underneath, so now that we have it in the flesh it kind of feels like we have no choice, but to test the limits of it or push it to the limits.
In-Glass Fingerprint Sensor: Vivo X21

This is a small optical sensor underneath the glass of an OLED display and the sensor itself is really small it's maybe the size of a fingernail and when we say optical sensor we literally mean it's the OLED shining up light to reflect off of your finger and the sensor reading the reflection of your finger to see the fingerprint, so naturally there are a couple possible limitations to this just because of how the technology works that we can think of but you know there's limitations with touch ID too but if we're going to see this in the future of smart phones you know in a possible future iPhone or a Samsung phone down the road, then it's worth exploring now.

So I have my fingerprint registered here my right thumb and I'll go ahead and register my left thumb as well so you can see how it works but it's pretty similar to any other fingerprint reader like touch ID you press down over and over again and it gets multiple reads of the same finger it's a little slower and more deliberate right now but it learns it, it saves it and then you do the edges too so you're nice and thorough and that's it so now it has two fingers it's got the right thumb that's fingerprint number one and the left is fingerprint two, so obviously a fingerprint reader doesn't work when your fingers are covered like with a glove on or something like that but what if your fingers just slightly covered, so all right without water on my hands it works perfectly, but we've all been sweaty or been in the rain for a minute or had our hands wet and we go to unlock our phone and it can get interesting here it's not rejecting me it's just having a hard time my finger, it's saying you know pressed deeper it's not getting a very good read I'm actually not surprised though like if I bring out the iPhone 8 here with touch ID you're going to see the same thing actually it works perfectly right now, but if I get a little water on my hand here it doesn't work as well so there's no real advantage or disadvantage with water here but being underneath the display glass I'm sure doesn't help anything water has always been a nemesis of displace, but you're going to have to wipe your finger and get it a little more dry and then it'll go through no problem.

All right here's a little bit of a spicier test so let's say you're eating some hot wings maybe here maybe right at lunch with someone and you want to answer your phone you get a phone call, but you don't have time to wipe your fingers but you still got to unlock now I would guess that this would also not work basically for the same reason that water doesn't work, but also because if your finger is dirty in any way the sauce or the dirt or whatever it is that's on your hand it'll kind of fill in the gaps in your fingerprint and it'll look different to the optical sensor and sure enough saucy fingers do not work, I'll try it on the iPhone as well for good measure but yeah as you can see it doesn't go through phones just don't like saucy fingers and this new under glass fingerprint reader won't get you out of this one, but we have another idea which was it's just dusty fingers so we got the Sun shifts out and basically I'm going to get enough dust on my fingers to like when you're getting to the end of the bag we've all been there let's see how it holds up so the English fingerprint reader it's not seeing me okay so that's a negative and if I tried touch ID actually touch ID on the iPhone does unlock, so okay touch ID saw enough info on that first swipe to verify it's my fingerprint but the under glass vivo didn't, but then actually after a couple more tries it does work.

Another question that actually came up in the comments of the article is screen protector, will an in glass fingerprint reader work with a screen protector on your phone? Well I can already actually answer that yes. I know that because actually I have two of these and they come in the box with the screen protector on by default, it's a standard fingerprint reader cuts around the notch and everything you can see that right so that goes over the glass it doesn't affect the optical sensor because it can still see through that thing a permit or no problem it doesn't obscure the optics in any way, but that got me of course thinking about all the screen protectors you can get all types of other screen protectors you can get tempered glass screen protectors and the final level which is the glass privacy shield, so it's basically polarized so you can't in view it off access it's one of those maximum security screen protectors, confirmed you can use a tempered glass screen protector with this reader, the privacy shield though it's getting pretty intense but believe it or not as much as I hate them a lot of people use these on the daily you know got to keep that person behind you on the train from being able to read your messages so there you go fully protected, but does your in glass fingerprint reader still work yes it does.

So that just leaves us with my final experiment which is simulated extreme wear and tear you see micro scratches these things happen right you take this thing in and out of your pocket hundreds of times a week maybe even hundreds of times a day there's going to be wear and tear there's going to be little things in your pocket little abrasions from the part circles around you it's unavoidable it's painful to make them by myself on purpose with a box cutter, but it's every phone I've ever had has gotten these scratches on the screen so here's where we're at and if we give that a shot no problem, right the knife is a little harder and the scratches are a little more real this might be more like a year of wear and tear like a year later type of scenario if you take pretty good care of your phone, but still no problem.

You're probably noticing this whole time that the reader isn't quite as fast as touch ID that's for sure it's still just where the technology is right now no doubt it's going to be getting faster with time like touch ID did, anyway I got to say that's some pretty solid results with everything we just threw at it nothing exceedingly great or way better but also nothing exceedingly bad it's kind of in this like middle ground, but that has me pretty pumped about it for its development and the future of smartphones, if you remember the first generation of fingerprint in smart phones the first gen touch ID, it wasn't that great, but it's had time to develop and turn into the gold standard that it is now for both speed and accuracy and I kind of see that for the feature of this if this gets worked on from all angles by a bunch of different companies I could eventually see this finding its way into a future iPhone, a future Samsung phone and maybe even flagships in the next couple years.