Many modern IoT (Internet of Things) apps rely on fingerprint sensors to identify users and for security and safety purposes. Fingerprint sensors have become commonplace in smartphones and wearable devices (as well as in smart home applications and the smart industry) for data security and entry identification. The importance of device fingerprinting is rising to protect our devices. However, when it comes to fingerprint sensors, two common types are in use today. These are capacitive sensors and optical sensors. Here is a look at how they work.

Optical Fingerprint Scanner versus Capacitive Fingerprint Scanner

Whether you want to identify yourself before entering a building or secure your phone, fingerprint sensors are a reliable way to add identification and security with ease. In the modern world, there are two common ways these sensors are being used, and that’s either through capacitive or optical sensors.

How Do Optical Fingerprint Scanners Work?

While optical fingerprint sensors might sound like new technology, it’s worth noting that they’ve been around for quite some time now. These scanners work by shining a bright beam of light over a user’s fingerprint after which a light-sensitive microchip takes a digital photo. The microchip makes a digital image of the fingerprint by looking at the print’s ridges and valleys, turning them into binary (0’s and 1’s). It then uses this information to create a code that’s unique to the user. The drawback of using this option, though highly improbable, is that digital photos can be reproduced.

How Do Capacitive Fingerprint Sensors Work?

Today, capacitive fingerprint scanners are quite common and are found on virtually all smartphones. Capacitive sensors measure a user’s fingerprint by using human conductivity to create an electrostatic field. It’s this field that helps create a unique digital image of the user’s fingerprint.

Let’s go a bit deeper. Capacitive fingerprint scanners use very small capacitor array circuits to track the details of a user’s fingerprint. The capacitive scanner features a conductive plate on which a user places their finger for scanning. When a user places their finger over the conductive plate, the ridges of their fingerprint alter the charge stored inside the capacitors – while the gaps/valleys leave the charge inside the capacitors unaffected. An amplifier integrator circuit inside the scanner then tracks these changes and records them using an analog to digital converter for analysis.

The technology behind capacitive fingerprint scanning is much more difficult to bypass since capacitive fingerprint sensors can’t read images while other types of materials will elicit varying changes in the charge inside the capacitor. While more expensive, capacitive sensors are also more secure and complex.

As technology advances and the Internet of Things continues to grow, accurate data collection via different sensors becomes even more important. Smartphones are a good example of how security sensors are rapidly changing how we go about things today. After all, it’s not so long ago that phones did not have fingerprint applications or touch screens on them.


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