Fingerprint readers
Introduction
A fingerprint sensor also known as fingerprint sensor or fingerprint reader is a device that is capable of reading, saving and identifying fingerprints generally from the thumb, although most have no problem accepting other fingers. All fingerprint sensors have at least one piece that is sensitive to touch. These devices have become popular because the latest smartphones, "Tablet (computer)" tablets and mobile devices in general have incorporated this system, as it is the one that provides the greatest security.
Nowadays, passwords provide some protection, but remembering and knowing where the different codes for each machine are stored is a problem in itself. Something similar happens with a smart card: we no longer have to memorize anything, but if we lose our card we will not be able to use the facilities it provides.
It would seem logical to use some identifier that could not be lost, changed or falsified. Biometrics techniques take advantage of the fact that the characteristics of the human body are unique and fixed. Facial features, the iris pattern of the eye, writing features, fingerprint, and many others are used for these functions, including DNA.
Reflective optics
They are based on the oldest technique, which consists of placing the finger on a glass surface or a prism that is illuminated by an LED diode. When the ridges of the fingerprints touch the surface, light is absorbed, while total reflection occurs between these ridges. The resulting light and dark areas are recorded on an image sensor.
In practice there are some difficulties with this technique: the images obtained with wet and dry fingers are very different and, in addition, the system is sensitive to dust and dirt on the surface. The unit is large in size, impractical and expensive. This system is easy to deceive and if the skin is deteriorated or damaged, the fingerprint is not recognized correctly. Fingerprint recognition of elderly people is also difficult to do since the skin is not elastic enough. In some circumstances this may produce a false recognition. If the stored fingerprint was taken with less pressure, false acceptances may occur.
This is mainly due to the type of fingerprint that the person or user has.