Qualcomm Second Gen Ultrasonic Fingerprint Sensor: What’s New

Yes, Qualcomm has unveiled its second-generation ultrasonic fingerprint sensor, the 3D Sonic Gen 2, and it brings a major speed upgrade and a larger scanning area compared to the original 3D Sonic Sensor. Announced in early 2021, the Gen 2 sensor is designed for flagship Android smartphones, offering faster unlocking and improved usability. This article explains what changed, how the technology works, and what it means for you.

Background: Why Ultrasonic Fingerprint Sensors Exist

Before ultrasonic sensors, most in-display fingerprint readers were optical. Optical sensors shine a bright light through the display to capture a 2D image of your finger. They work well but can be fooled by a high-resolution photo, and they struggle with wet or oily fingers. Ultrasonic sensors, by contrast, use sound waves to map the ridges and valleys of your fingerprint in 3D. This makes them more secure and more reliable in real-world conditions.

Qualcomm introduced its first ultrasonic sensor, the 3D Sonic Sensor, in 2019 with the Galaxy S10 series. That sensor had a small scanning area and was relatively slow, taking about one second to unlock. The second generation, unveiled in 2021, addresses those two main complaints.

Key Improvements in the Second Gen Sensor

The 3D Sonic Gen 2 offers two headline upgrades over the original:

• Faster unlocking: The Gen 2 is about 50% faster than the first generation, reducing unlock time from roughly 1 second to around 0.5 seconds.
• Larger scanning area: The new sensor is 77% larger, giving a scanning area of 8x8mm (64mm²) compared to the original 4x9mm (36mm²). This means you don’t have to be as precise when placing your finger.

These improvements make the sensor feel closer to a traditional capacitive fingerprint reader in terms of speed and ease of use. The larger area also allows for more accurate readings, which reduces failed attempts.

How Ultrasonic Fingerprint Sensing Works

Ultrasonic sensors work on the same principle as medical ultrasound. The sensor emits a high-frequency sound wave (around 20 MHz) through the display glass. When the wave hits your finger, it bounces back differently depending on the surface: the ridges of your fingerprint reflect a strong echo, while the valleys reflect a weaker one.

The sensor captures these returning echoes and builds a 3D map of your fingerprint. Because it reads the sub-surface layers of your skin, it is much harder to fool with a photo or a 3D-printed fake than an optical sensor. The sound waves also penetrate through common screen protectors and work with wet, dry, or oily fingers.

The Gen 2 sensor uses the same underlying technology but with a faster processing pipeline and a larger transducer array, which is why it can scan a bigger area in less time.

Which Phones Use the Second Gen Sensor?

The 3D Sonic Gen 2 was first used in the Samsung Galaxy S21 series (released January 2021). It has since appeared in other flagship devices, including the Galaxy S22 and S23 series, and several other Android flagships from brands like iQOO and Vivo.

If you are buying a new phone and want the fastest ultrasonic sensor, look for the “3D Sonic Gen 2” in the specs. Many mid-range phones still use older optical sensors, so the Gen 2 is a premium feature. Note that Qualcomm has also released a newer “3D Sonic Max” sensor with an even larger area (30x20mm), but that has not been widely adopted in phones.

Common Problems and Misconceptions

Misconception: Ultrasonic sensors work through any screen protector. While they work through most glass and plastic protectors, thick or air-gapped protectors can interfere. Tempered glass protectors with a solid adhesive layer usually work fine. If you have issues, try removing the protector or using a thinner one.

Problem: Slow or failed unlocks. Even with the Gen 2, users sometimes report failures. Common causes include:

• Dry or very rough fingers – the sensor needs a clear ridge pattern.
• Screen protector with an air gap.
• Finger not covering the sensor completely – the larger area helps, but you still need to hit it.
• Software glitches – a reboot often fixes temporary issues.

Misconception: Ultrasonic sensors are faster than optical. The Gen 2 is competitive, but some optical sensors in 2023-2024 are just as fast. The main advantage of ultrasonic is security and reliability, not raw speed.

Comparing Ultrasonic vs. Optical vs. Capacitive

Here is a quick comparison to help you understand where the Gen 2 fits:

• Capacitive (physical button): Fastest and most reliable, but requires a dedicated button. Used on older phones and some mid-rangers.
• Optical (in-display): Cheap and common. Works well with clean fingers, but can be fooled by photos and struggles with wet fingers.
• Ultrasonic (in-display): More secure, works with wet fingers, and now faster with Gen 2. Slightly more expensive, so found mainly in flagships.

For most users, the Gen 2 ultrasonic sensor is a clear upgrade over optical. The larger area alone makes it more convenient, and the speed improvement closes the gap with capacitive sensors.

Cost and Availability

The Gen 2 sensor itself is not sold separately to consumers; it is integrated into phones. You cannot buy it as an upgrade. The cost is bundled into the phone’s price, and it is typically found in devices above $600. If you are on a budget, you will likely get an optical sensor, which is still fine for most daily use.

There is no way to retrofit an older phone with a Gen 2 sensor. If you want the faster ultrasonic experience, you need to buy a new phone that includes it.

Safety and Security Considerations

Ultrasonic sensors are generally considered more secure than optical because they read a 3D map of your fingerprint, including sweat pores and sub-surface details. They are harder to spoof with a printed image. However, no fingerprint sensor is 100% secure – a determined attacker with a high-quality 3D mold could potentially fool it. For high-security situations, use a strong PIN or password instead.

There are no known health risks from ultrasonic fingerprint sensors. The sound waves are low-power and localized to the finger area, similar to medical ultrasound but much weaker. The sensor is safe for daily use.

Frequently Asked Questions

Is the second-gen ultrasonic sensor faster than the first?

Yes, Qualcomm claims it is about 50% faster, reducing unlock time from roughly 1 second to about 0.5 seconds. The larger scanning area also means fewer failed attempts, which makes it feel even faster in practice.

Does the Gen 2 sensor work with screen protectors?

Yes, it works with most glass and plastic screen protectors, as long as they are applied without air bubbles. Thick protectors or those with a gap can interfere. Samsung and other manufacturers often recommend specific protectors that are tested with the sensor.

Can I update my phone to get the Gen 2 sensor?

No. The sensor is hardware, not software. You would need to buy a new phone that includes the 3D Sonic Gen 2. Software updates can improve the sensor’s performance, but they cannot change the physical hardware.

Which phones have the 3D Sonic Gen 2?

The Samsung Galaxy S21, S22, and S23 series use it, as do several other flagships from brands like iQOO and Vivo. Always check the official specs before buying if this feature is important to you.

Is ultrasonic fingerprint sensing safe?

Yes. The sound waves are low-power and only active when you touch the sensor. It is safe for daily use and poses no known health risks.

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