Types of Fingerprint Scanners: Optical vs. Capacitive vs. Ultrasonic vs. Thermal

There are various types of fingerprint scanners, each with strengths and weaknesses.

Optical Scanners

Optical scanners are the most traditional type. They take a digital fingerprint picture using a light source and a photodiode (a device that turns light into electrical current). Optical scanners are simple to use but can be easily fooled with a good-quality fingerprint image.

Capacitive scanners

Commonly found in smartphones, capacitive scanners use electrical current to sense and map the ridges and valleys of a fingerprint. They offer higher resolution and security than optical scanners but can be sensitive to temperature and electrostatic discharge.

Ultrasonic scanners

Ultrasonic scanners are considered more secure than optical and capacitive scanners. They use high-frequency sound waves to penetrate the epidermal layer of the skin. This allows them to capture both the surface and sub-surface features of the skin. This information helps form a 3D image of the fingerprint and makes the scanner less prone to spoofing.

Thermal scanners

This type of scanner is the least common of the four. Thermal scanners detect minutiae based on the temperature differences of the contact surface. However, their high costs and sensitivity to ambient temperature make them less popular choices.

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