How to Set Up Under-Display Fingerprint Scanner

The under-display fingerprint scanner is one of those technologies that seems like magic: you touch the screen and your phone unlocks. But for it to work well, you need to set it up correctly. In this article I’ll show you how to register your fingerprint on a phone with an under-display sensor, tricks to improve accuracy, and solutions to the most common problems.

Table of contents

How to register your fingerprint for the first time

Registering the fingerprint is the first thing you should do when setting up a phone with an under-display sensor. The process varies slightly by manufacturer, but the general steps are:

1. Open Settings > Security or Biometrics and security.
2. Tap Fingerprints.
3. Enter your PIN, pattern, or password as verification.
4. Tap Add fingerprint.
5. Place your finger on the indicated screen area and lift it repeatedly until registration is complete.

The phone will ask you to tap the sensor several times, slightly changing the angle each time. This captures different areas of your fingerprint so recognition is more accurate in varied positions.

Pro-tip: Register the fingerprint you use most to unlock the phone. If you’re right-handed, it will probably be your right thumb; if left-handed, your left thumb. But you can also register both for maximum convenience.

Tricks to improve sensor accuracy

The under-display sensor has inherent limitations compared to physical sensors. These tricks can significantly improve its performance:

Register the same fingerprint twice: You can add the same fingerprint as two different entries. The system stores more data about that fingerprint and improves the hit rate, especially if your hands are wet or cold.

Keep the screen clean: Grease and fingerprint marks over the sensor area can interfere with recognition. Clean the screen regularly with a microfiber cloth.

Moisture and temperature: Optical under-display sensors perform worse with very dry or very wet fingers. In winter, if your fingers are cold, rub them briefly before trying to unlock.

Cover the sensor fully: Make sure your finger covers as much of the sensor area as possible. A too-fast or partial tap can cause a failure.

Types of under-display sensors: optical vs ultrasonic

Not all under-display sensors work the same way. There are two main technologies:

Ultrasonic sensors, like those Samsung uses in its high-end phones, are notably more precise and secure because they create a three-dimensional map of your fingerprint ridges. Optical ones simply take a 2D photo, which is easier to fake.

How to use fingerprint for app unlocking and payments

Once your fingerprint is set up, it’s not just for unlocking the phone. You can also use it to:

Unlock individual apps: Many banking, messaging, and note apps allow fingerprint protection. Go to each app’s settings and look for the biometric security option.

Mobile payments: Google Pay, Samsung Pay, and Apple Pay (on iPhone) use the fingerprint as authentication for contactless payments. You need to register your card in the corresponding app, and the fingerprint serves as verification for each transaction.

Access secure folders: Samsung offers a “Secure Folder” protected by fingerprint. Xiaomi and other manufacturers have similar features for hiding photos, documents, and sensitive apps.

Pro-tip: For banking and payment apps, always use fingerprint instead of PIN. It’s faster and paradoxically more secure, since no one can “spy” on your fingerprint the way they can spy on a PIN you enter in public.

Solutions to common problems

The sensor doesn’t recognize my fingerprint: Try re-registering it from scratch. Over time, cuts, scrapes, or changes in skin can make the registered fingerprint no longer match.

The sensor is slow: Close background apps and restart your phone. Sometimes the security software slows down due to lack of memory.

Doesn’t work with screen protectors: Some thick or textured screen protectors affect the sensor. Use protectors compatible with under-display sensors, which are usually thinner and transparent in the sensor area.

Failure after a system update: Restart your phone, and if the problem persists, delete the registered fingerprints and re-register them. Software updates can change recognition algorithms.

Fingerprint vs face recognition: which to use

Many current phones offer both fingerprint and face recognition. The question is: which should you use as your primary method?

Face recognition:

• More convenient because you don’t have to touch anything
• Works well when your hands are busy or wet
• Can fail with sunglasses, masks, or in darkness
• On Android, most use the front camera (2D), which is less secure than Apple’s Face ID

Fingerprint:

• Works in any lighting condition
• Ultrasonic sensors are practically impossible to fool
• Faster in most cases
• Doesn’t depend on your face being visible

My personal recommendation: Use both. Set up fingerprint as the primary method because it’s faster and more reliable, and face recognition as a backup. That way, if one method fails, you have the other.

Pro-tip: If you use face recognition on an Android with a 2D camera (most of them), don’t use it for banking or sensitive apps. Fingerprint is significantly more secure on these devices.

How to maintain sensor performance long-term

Over time, the fingerprint scanner’s performance can degrade if you don’t maintain certain habits. Here’s what I recommend:

Update your system regularly: Manufacturers continuously improve recognition algorithms. An update can significantly improve your sensor’s speed and accuracy. Don’t postpone system updates.

Re-register your fingerprint every 6-12 months: Your fingerprint can change slightly over time due to scars, manual work, or skin changes. Delete the old fingerprint and register it again to maintain the best possible accuracy.

Avoid low-quality screen protectors: A thick protector or one with air bubbles over the sensor can drastically reduce effectiveness. Invest in a quality protector that’s compatible with under-display sensors.

Clean the sensor area: Once a day, wipe the sensor area with a microfiber cloth. Built-up grease is the number one cause of recognition failures.

FAQ: Frequently asked questions

How many fingerprints can I register?

Most phones allow between 4 and 5 fingerprints. I recommend registering at least two: your dominant thumb and the index finger of your other hand as a backup.

Is it safe to use fingerprint as an unlocking method?

Yes, very safe. Biometric data is stored in an isolated security chip (Secure Enclave or equivalent) and is never shared with apps or servers. The ultrasonic under-display sensor is practically impossible to fool with a photo or mold.

Does it work with screen protectors?

It depends on the protector. Standard tempered glass protectors usually work fine. Thicker protectors, privacy ones, or textured ones can reduce sensor sensitivity. Look for protectors that indicate fingerprint sensor compatibility.

Can I use the fingerprint instead of a password in all apps?

Not all apps support biometric authentication. Banking and financial services almost always do, but some older or less-known apps don’t include this option. In that case, you’ll have to use a password or PIN.

Conclusion

Setting up the under-display fingerprint scanner is one of the first things you should do with a new phone. It not only improves your security but makes unlocking much faster and more convenient than entering a PIN every time. Register your fingerprint twice for greater accuracy, keep the screen clean, and don’t hesitate to use the fingerprint to protect banking and payment apps. It’s one of those features that, once you get used to it, you won’t want to live without.