When it comes to scanning in Xiaomi devices, many users only think of the fingerprint sensor under the screen. However, scanning technologies in the brand ecosystem are much broader, from infrared sensors for facial recognition to laser modules in robot vacuum cleaners and 3D- scanners in flagship smartphones. This article will reveal all the types of scanners that Xiaomi integrates into its equipment, explain their principles and show how to use them correctly, from basic functions to hidden capabilities.
It is important to understand that the scanner in the context of Xiaomi is not one device, but a whole range of technologies. For example, Xiaomi 13 Ultra uses a state-of-the-art Time-of-Flight (ToF) sensor for 3D- scanning objects with millimeter accuracy, and in the budget Redmi Note - a classic optical fingerprint scanner. We will analyze what tasks each type of scanner solves, how they affect the experience and what to do if the scanner stops working. Particular attention will be paid to security issues: how reliable biometric data is stored and the system can be fooled.
What is a scanner in Xiaomi devices: the main types
The term Xiaomi scanner* refers to several different technologies, each with unique functions, which can be divided into three categories:
- 👆 Biometric scanners: fingerprints, facial recognition, iris, used to unlock devices and log in to applications.
- 📱 Optical scanners: QR-codes, barcodes, documents, found in smartphone cameras and specialized devices (e.g., Xiaomi Mi Band for pulse scanning).
- 🤖 3D- scanners and LiDAR: used in Xiaomi Mi Robot Vacuum, drones and flagship smartphones to create three-dimensional models of the environment.
The most common are fingerprint scanners, which have evolved from mechanical buttons (like the Redmi 4X) to ultrasonic sensors under the display (like the Xiaomi Mix 4), which not only fire faster, but also work with wet or dirty fingers, while infrared facial scanners (like the Xiaomi Mi 11) use structured light to build a 3D- face model, making them more reliable than traditional front-facing cameras.
Special attention should be paid to scanners in smart devices of the Mi Home ecosystem. For example, the Xiaomi Mi Robot Vacuum-Mop 2 Pro robot vacuum cleaner is equipped with a laser scanner (LiDAR), which builds a map of the room with an accuracy of 5 cm, and the Xiaomi Mi LED Desk Lamp can scan the illumination of the room for automatic brightness adjustment.
How fingerprint scanners work in Xiaomi smartphones
The fingerprint scanners in Xiaomi devices are divided into three generations, each of which has its own characteristics:
- Mechanical (button): used in early models (e.g. Xiaomi Mi 5), based on a capacitive sensor that reads the skin's relief upon physical contact.
- Optical under-screen: debuted in the Xiaomi Mi 8 Explorer Edition, using LED backlighting to create a fingerprint image, which is then analyzed by algorithms.
- Ultrasonic: the most advanced (e.g., Xiaomi 13 Pro) uses sound waves to create the 3D- print model, making it more accurate and reliable.
The main difference between ultrasonic scanners and optical scanners is the ability to work in any conditions: with wet fingers, wearing gloves (if they are thin), or when the display is dirty. For example, the Xiaomi Mix 4 uses the Qualcomm 3D Sonic Sensor Gen 2 sensor, which scans the finger to a depth of 0.4 mm, which practically eliminates reading errors. Optical scanners, in turn, are cheaper to manufacture, but require a clean finger and display.
It is important to note that the fingerprint data in Xiaomi smartphones is stored in a Trusted Execution Environment (TEE) chip and never transmitted to the company’s servers, which ensures that even when a device is hacked, attackers will not be able to extract biometric information.
⚠️ Warning: If you use third-party launchers or custom firmware (like LineageOS), the fingerprint scanning feature may not work properly or may be disabled altogether due to the lack of drivers.
Face and iris scanners: safety and limitations
The facial recognition technology in Xiaomi smartphones is implemented in two ways:
- 📸 2D- scanning (via front camera): Used in budget models (Redmi 9A) facial recognition by key points, but vulnerable to photos or masks.
- 🔦 3D- scanning (infrared sensor + point projector): used in flagships (Xiaomi Mi 11 Ultra) to create a deep face map, making the system more reliable.
Three-dimensional scanning works on the principle of Time-of-Flight (ToF): infrared LED illuminates the face, and the sensor measures the time of reflection of rays from different points. This allows you to build an accurate 3D- model that can not be fooled by a flat image. For example, the Xiaomi 13 Pro uses the module 3D Face Unlock, which recognizes the face even in the dark and from different angles.
However, this technology has limitations:
| Type of scan | Level of security | Works in the dark? | Vulnerabilities |
|---|---|---|---|
| 2D (camera) | Low. | No. | Photos, videos, twins |
| 3D (ToF) | High-pitched | Yes. | Complex masks (rarely) |
| Iris shell | Very tall. | Yes. | Practically not. |
The iris scanner is rare, such as the Xiaomi Mi 5s Plus, which uses infrared light to read a unique iris pattern that cannot be faked, but because of the high cost of the technology, Xiaomi has abandoned its mass adoption in favor of the 3D- facial scanning.
⚠️ Warning: If you wear darkened glasses or contact lenses, the iris scanner may not work smoothly, in which case an alternative method of unlocking (PIN or print is recommended.
QR- Scanners and Optical Sensors: Where to Use in Xiaomi
Optical scanners in Xiaomi devices are most commonly associated with reading QR- codes, but their scope is much broader.
- 🔗 QR-codes: Quick authorization to Mi Account, payment via Mi Pay, Wi-Fi connection.
- 📄 Document scanning: The Mi Scanner app converts photos to PDF with perspective correction.
- 💳 Face Payment: In China, Xiaomi smartphones support facial recognition for contactless payments.
- 🩺 Medical Measurements: Xiaomi Mi Band 7 scans pulse and blood oxygen levels.
To scan the QR- codes, you don’t need to install additional applications — the function is built into a standard camera. Just point the lens to the code, and the system automatically prompts you to perform an action (open a link, connect to the network, etc.). In the latest versions of the MIUI, you can scan the codes even in lock mode, which speeds up access to frequently used services.
The Mi Scanner app (available from the Mi App Store) extends the optical scanning experience:
☑️ What Mi Scanner can do
Especially useful is the OCR (Optical Character Recognition) feature, which allows you to copy text from photos or documents. For example, you can take a picture of a book page and then edit the text in any text editor. Mi Scanner's recognition accuracy is 98% for printed text in Russian and English.
3D- Scanners and LiDAR: The Smart Device Revolution
Three-dimensional scanning technologies in Xiaomi devices are represented by two main solutions:
- LiDAR (Light Detection and Ranging): Used in Xiaomi Mi Robot Vacuum-Mop 2 Pro to map a room. A laser beam scans 360° of the surroundings at a frequency of 2,000 times per second.
- ToF sensors: Integrated into smartphones (Xiaomi Mi 10 Pro) to enhance bokeh photos and create 3D- object models.
LiDAR in robot vacuum cleaners allows you not only to avoid obstacles, but also to remember the location of furniture, determine the type of coating (carpet, laminate, tile), and even detect lost things on command from the Mi Home app. For example, if you say in your voice, "Find my phone," the vacuum cleaner will scan the room and show on the map where the device lies.
In smartphones, ToF sensors are used to:
- 📸 Portrait photography: the exact separation of the subject from the background for a realistic bokeh.
- 🎮 AR- Games: Scanning environments to host virtual objects.
- 🛒 Visual Search: Sizes of furniture when you buy at IKEA Place.
ToF sensor in Xiaomi 13 Ultra is able to scan objects at a distance of up to 5 meters with an error of less than 1%, which allows you to use the smartphone to create professional 3D- models. This feature is especially in demand among designers and architects who can quickly digitize real objects for further work in AutoCAD or Blender.
How to enable 3D- scanning in Xiaomi 13 Ultra?
Problems with Xiaomi scanners: causes and solutions
Despite being reliable, the scanners in Xiaomi devices sometimes fail, and let’s look at the typical problems and ways to fix them:
| Problem. | Possible cause | Decision |
|---|---|---|
| The fingerprint scanner doesn't recognize the finger. | Dirt on the sensor or finger, damage to the display | Wipe the sensor and finger, reboot the device, re-register the fingerprint |
| Facial recognition works slowly | Poor lighting, changes in appearance | Add an alternate face in the settings or use an infrared sensor |
| QR- codes are not scanned | Low resolution camera, dirty lens | Clean the camera, turn on the Improved Scan mode in the camera settings |
| LiDAR in vacuum cleaner builds inaccurate map | Interference from sunlight or mirror surfaces | Close the curtains, remove reflective objects, restart the map in Mi Home |
If the fingerprint scanner stopped working after the MIUI update, try resetting the security settings:
- Go to Settings → Passwords and Security → Fingerprint settings.
- Delete all the fingerprints you saved.
- Reset the device.
- Add the print again.
For ultrasonic scanners (such as the Xiaomi 13 Pro), it is important to consider that they are sensitive to pressure; pressing too much or too little can lead to an error; optimal pressure is as with light touching of the screen.
⚠️ Warning: If the fingerprint scanner stopped working after the smartphone fell, don't try to disassemble the device yourself. 90% of the time, the problem is caused by damage to the flexible plume of the sensor, and professional repair is required.
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If the face scanner is not working in the dark, check if the infrared ports are turned off in the battery saving settings. Go to Settings → Battery → Power Saving Mode and add the Camera app to exceptions.
The future of scanners in Xiaomi devices: what to expect next
Xiaomi is investing heavily in scanning technology, and we expect the following innovations in the coming years:
- 🧬 DNA scanners: Xiaomi’s patent describes a genome-based authentication technology that could be available in smartphones by 2026.
- 👁️ Palm vein scanning: Already being tested in prototypes for enterprise devices.
- 🚗 LiDAR for cars: Xiaomi’s SU7 electric cars will use laser scanners for autonomous driving.
- 🌍 Global 3D- mapping: Robot vacuum cleaners will be able to scan not only apartments, but also streets for navigation in smart cities.
One of the most anticipated innovations is a subscreen camera with an integrated iris scanner. Xiaomi patents describe a device where a front-facing camera and infrared sensor are hidden under the display, allowing for smartphones without cutouts and droplets. The technology could debut in the Xiaomi Mix 5 or Xiaomi 15 Ultra.
Also worth noting is the development of medical scanners in wearable devices, such as the Xiaomi Watch 3 will be able to scan blood glucose levels without punctures, and the Mi Band 8 Pro will be able to analyze the composition of sweat to determine stress and fatigue.
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Xiaomi’s scanning technologies are developing in three key areas: biometrics (DNA, veins), 3D- mapping (LiDAR for cars and robots), and medical diagnostics (blood and sweat analysis).