How to build a fingerprint scanner in Xiaomi phones: technology, configuration and security secrets

The fingerprint scanner in Xiaomi smartphones has long ceased to be a luxury — today it is a standard security element that is found even in budget models. But how exactly does this technology work? Why is the sensor hidden under the screen on some devices, and on others it is located on the back or on the side? And most importantly, how secure is it to protect your data?

In this article, we will discuss the principles of different types of scanners (optical, ultrasonic and capacitive), explain which Xiaomi models are equipped with what sensors, and give step-by-step instructions for setting up. You will also learn why sometimes the scanner refuses to recognize the finger, how to fix it, and what hidden functions can be activated through the engineering menu (spoiler: this does not work on all firmware!).

If you've ever wondered if you can fool a fingerprint scanner or why it doesn't work with wet fingers, the answers are below. And for those who like to experiment, we've prepared a comparative table of recognition speeds across Xiaomi and Redmi models.

Types of fingerprint scanners in Xiaomi: how they differ

Xiaomi smartphones use three main types of fingerprint sensors, each with its own features, pros and cons. Let's take a look at them in detail.

Capacitive sensors are the most common in budget and mid-budget models (e.g. Redmi Note 10 or POCO X3 Pro) and work by measuring the electrical capacity of the skin: when you touch the sensor, it reads the unique relief of papillary lines.

• ⚡ Low power consumption – almost no effect on battery life.
• 💰 Cheap – This is why it is found in most devices.
• 🔒 Reliability – it is difficult to cheat by fake (unlike first-generation optical scanners).

Minus – does not work with wet or dirty fingers, and also requires physical contact with the sensor.

2 Optical sensors are used in models with a scanner under the screen (for example, Xiaomi Mi 11 or Redmi K50 Pro). Here the principle of operation is different: the sensor illuminates the finger with infrared light and takes it "photo", which is then analyzed.

• 🖥️ Convenience – the sensor is hidden under the display, does not take up space on the body.
• 🌧️ It works with wet fingers (but not always perfect).
• 🎨 Visual aesthetics – no protruding elements.

Disadvantages: higher power consumption, lower recognition speed compared to capacitive sensors, and some models can be fooled by high-quality fingerprint photography.

3. Ultrasonic sensors are the most advanced, but so far rare in the Xiaomi lineup (e.g., Xiaomi Mix 4). 3D-- I'm a print card:

• 🔍 High accuracy – it is almost impossible to cheat.
• 💧 Works with wet/dirty fingers.
• 🛡️ Security – creates a three-dimensional model, not a flat image.

The disadvantage is the high price and complexity of production, so it is found only in flagships.

Where is the scanner in different Xiaomi models: comparison table

The location of the fingerprint sensor depends on the model and year of release, for example, in older smartphones (Xiaomi Mi 5, Redmi 4X) it was on the back, and in new flagships (Xiaomi 13 Ultra, Redmi K60 Pro) – under the screen.

Note that recognition speeds are not only dependent on the type of sensor, but also on firmware optimization, for example, after the MIUI 14 update, many users reported a 10-15 percent acceleration in the scanner.

⚠️ Warning: If your smartphone has fallen or been repaired, the scanner under the screen may not work properly. Optical sensors are particularly sensitive to display damage - even microcracks can interfere with reading.

How to set up a fingerprint scanner on Xiaomi: step-by-step instructions

Adding a fingerprint to Xiaomi is possible through the settings menu. the process takes no more than a minute, but there are a few nuances that will help avoid problems in the future.

Open the Settings. → Passwords and security → If you're setting up the scanner for the first time, the system will ask you to ask PIN-A code or a pattern lock is a prerequisite for biometrics to work:

Make sure your finger is clean and dry.|

Remove the case if it interferes with access to the sensor |

Choose the finger you will use most often.|

Don’t press too hard – the sensor should scan, not “press” the finger.-->

1. Place your finger on the scanner and wait until the system starts reading. Don't tear your finger off until there's a vibration or a beep.
2. Raise your finger and put it back at a different angle, so the sensor will record more details.
3. Repeat the process 3-5 times until the fill scale reaches 100%.
4. Name the print (for example, "Indicative right") and save.

Tip: Add at least two fingerprints (for example, the index and thumb of one hand) and this will come in handy if one finger is busy or damaged.

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If the scanner doesn't recognize the finger the first time, try registering it again by sliding your finger slightly to the sides with each touch, which will help the system remember more options for position.

Why the fingerprint scanner doesn’t work: Common problems and solutions

Even the most reliable sensors sometimes fail, so let's look at the typical causes and ways to fix them.

1.The sensor doesn't respond to touch.

• 🔋 Battery discharge – at a charge level below 5%, some models turn off the scanner to save energy.
• 🧴 Dirt or fat on the sensor - wipe it with a soft cloth soaked in alcohol.
• 📱 Software glitch – restart your phone or reset the scanner settings in Settings → Passwords and security → Fingerprint. → Delete all prints.

2.The scanner recognizes the finger once in a while.

• 💦 Wet or sweaty fingers – wipe your hands and sensor.
• 🩹 Skin damage (cuts, calluses) – temporarily use another finger.
• 🔄 Update firmware – sometimes after the update you need to re-register fingerprints.

Error "Can't add a fingerprint"

• 📲 Removing your finger too quickly – hold it on the sensor until it vibrates.
• 🛠️ Damaged sensor – if you fall or water, contact the service.
• 🔒 Disabled biometrics in the developer settings - check Settings → The phone. → Version. MIUI (Press 7 times, then Developer Settings → Fingerprint.

⚠️ Note: If you use unofficial firmware (such as LineageOS or custom recovery), the fingerprint scanner may not work due to the lack of drivers. MIUI.

Hidden features of the fingerprint scanner in Xiaomi: what does biometrics besides unlocking

Many users think that the fingerprint scanner is only for unlocking the screen, but in fact, MIUI has a few additional features related to biometrics.

1. Authorization in annexes

You can use a fingerprint instead of a password in banking apps, instant messengers, and even some games.

1. Open the desired application and find the "Security" or "Entry" section in the settings.
2. Select the "Fingerprint" option (if supported).
3. Confirm access through biometrics.

2.Hidden folder in the Gallery

MIUI has a Protected Albums feature where you can hide personal photos and videos to set up fingerprint access:

1. Open the gallery → Albums → Protected albums.
2. Click on the lock icon and select "Fingerprint".
3. Add files you want to hide.

3. Quick action (only for some models)

For example, in Xiaomi Mi 10T Pro, you can assign a double tap of the scanner to launch the camera or other application. The settings are in Settings → Additional → Buttons and gestures.

Can you cheat a fingerprint scanner in Xiaomi? security tests

The security of biometrics is a concern for many: How realistic is it to hack a fingerprint scanner at Xiaomi?

First-generation optical sensors (e.g., Xiaomi Mi 8 Explorer Edition) can be fooled by:

• 📸 High-quality print photos on special film.
• 🖨️ 3D-printing by casting (requires professional equipment).

However, modern optical scanners (such as the Xiaomi 13 Pro) use live detection – they check the pulse and temperature of the skin, making cheating almost impossible.

Capacitive sensors are more difficult to crack, but theoretically possible with:

• 🧪 gel pastes with conductive particles (original imprint required).
• ⚡ Electrical pulses (the method requires direct access to the sensor).

In practice, such attacks are unlikely – an attacker needs to physically take possession of your phone and have special equipment.

Ultrasonic sensors are by far the most secure, and they can only be fooled by:

• 🦾 The real finger of the owner (forced application).
• 🧬 Genetic cloning (scientifically possible, but highly unlikely in the home).

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No scanner gives 100% protection. Use a combination of fingerprints for maximum security. + PIN-code + data-encryption MIUI.

FAQ: Frequent questions about the fingerprint scanner in Xiaomi