A Comparison of Fingerprint Scanners

Fingerprint scanners offer businesses another level of security, whether used to perform an employee background check, secure facilities or protect confidential data. Numerous scanners provide this capability; however, you must consider how you intend to use the device before rushing to make a purchase. For example, you may not select the same scanner to authenticate access to a particular room as you would to fingerprint individuals away from the office.

There are two main ways to scan a fingerprint digitally. A static scanner requires the finger to lie stationary on the sensor to create the image of the print. Therefore, the scanning bed must be large enough to capture the entire image. This type of scanner provides the most accurate image creation. The other option is swipe technology, which requires you to slide your finger over the scanner to create the image. The device takes the multiple partial images created as the finger is swiped across the scanner and assembles a complete image of the print. This type of scanner doesn't offer the same level of accuracy as a stationary device; however, swipe scanners tend to cost less and come in smaller packages. One example of a swipe scanner is the fingerprint scanner included on certain laptop models.

Many fingerprint scanners require a USB connection to a computer to scan and store the fingerprint. This limitation may hinder you if you need to take the scanner into the field. Here, you would need a portable unit that allows you to scan and store the print for later download. Portable scanners often come with a heftier price tag, depending on the device you select.

One of the most common types of fingerprint scanners is the optical scanner. These scanners use an LED bulb to illuminate the finger while sensors detect and create the print image by determining the light and dark areas created by the ridges of your finger. Because optical scanners use light technology to create the image, certain external factors may reduce the accuracy of the print. For example, stray light from another source may render the print inaccurate.

Another type of fingerprint scanner is the thermal scanner. These scanners use heat to create the image of your fingerprint. As you press your finger on the scanner, the device measures the temperature of the ridges touching the sensors. The "valleys" formed between the ridges don't make contact with the scanner and aren't measured. The scanner creates the image by using the contrast between the temperature of these ridges and valleys. Because this type of scanner relies on heat, a temperature difference of at least one degree must exist between the surface of your finger and the ambient room temperature for it to operate properly.

A capacitive scanner generates the fingerprint image by using an array of capacitor plates. These plates interact with the physical ridges of the fingerprint, which act as electrical conductors to create the image. Although a static charge may interfere with this type of scanner, you cannot fool the device by using a high-quality photograph rather than an actual finger.