Here’s everything you need to know about Optical and Ultrasonic sensors!

Optical vs Ultrasonic sensor
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Fingerprint sensors are one of the most convenient ways to unlock your phone, but have you ever thought about the type of sensor inside your device? There are three main types of fingerprint sensors: Physical, Optical, and Ultrasonic. While physical sensors are easy to identify since they’re located on the exterior, Optical and Ultrasonic sensors are both in-display sensors, which can cause some confusion. Let me help you navigate the differences between the two.

Optical vs Ultrasonic sensors

Optical fingerprint

First, let’s define each type. Optical fingerprint sensors work by reflecting light off your finger. When you touch the scanner, the phone’s display lights up. Inside the display, there’s a small camera and a few LEDs that bounce light off the ridges of your fingerprint. The camera captures a 2D image of the pattern, which is then processed and compared to stored fingerprints. The phone unlocks if it finds a match.

fingerprint for security

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Ultrasonic fingerprint

On the other hand, Ultrasonic fingerprint sensors use sound waves to scan your fingerprint. These sensors are hidden behind the display and emit an inaudible sound wave when your fingertip makes contact. The waves hit the pattern of your fingerprint and return to the sensor.

fingerprint scanner in transparent screen

By analyzing the reflected waves, the sensor creates a 3D model of your fingerprint. Unlike optical sensors, ultrasonic sensors don’t rely on light, meaning they work well in any condition—rain, shine, or with wet and oily fingers. This makes them more accurate than optical sensors.

Which is the better choice?

While optical sensors are generally cheaper to develop, ultrasonic sensors offer significant advantages in terms of compatibility and security. They also provide better performance, especially in challenging conditions. However, it’s important to note that while ultrasonic sensors are more secure, they are not foolproof. For instance, a user managed to create a 3D print of their fingerprint and unlock their phone within just three attempts, highlighting that no sensor is entirely immune to security breaches.

  • Meanwhile, watch our recent video on how we 3D printed some stuff :