Fingerprint scanners, once used for biometric logging systems and attendance capture, are now routinely used as part of smartphones and other devices. The unique method of personal identification is by leaving fingerprints. Compared to other biometric identification such as Face ID or retina scanning, fingerprints provide a seamless way to identify any individual. It may not unlock your mobile phone and its applications. Many IoT applications such as intelligent home automation, door automation IIoT, and modern security applications are already using fingerprint scanners wherever user identification is required without proof of use.
The use case shows that the electronics behind the fingerprint scanner also work together. This article will explore different types of fingerprint scanners based on their electronics.
Fingerprints are unique identification.
The pattern of tiny ridges and valleys on the skin of the fingers are called fingerprints. A wonder of nature, human fingerprints are identified as unique markers. Presumably, during human evolution, fingerprints were tissues used to hold things tightly.
Interestingly, fingerprints are formed during the seventh month of fetal development in the mother’s womb. The pattern formed by fingerprints is determined by the genetic code as well as external environmental factors. In addition to the genetic code that determines the structure of the skin of the developing fetus, the location of the embryo, the development of each part of the fingerprint in the womb, the composition and density of the surrounding amniotic fluid, and other fetal development factors are among the factors. All these events and factors are so random that it is unlikely that two people, even if they are twins, will have identical fingerprints. we can get more information from Farman IT Firm
What is more interesting is that the fingerprints set in the mother’s womb remain unchanged throughout life. No doubt, fingerprints are unique identifiers of people
How do fingerprint scanners work:
Any fingerprint scanner scans a digital image of the fingerprint with the embedded electronics device. The sample image is stored in memory and used for comparison with future scan data.
Comparative analysis of complete fingerprint images is often unique. This is why most scanning systems look for unique patterns in fingerprint images. The unique characteristics of a fingerprint sample are called minutiae. The scanner looks for points where ridges end or split into two ridges and separate. The scanning software records the absolute positions of the minutes on the scanned image and maps them to find their relative positions to each other. This results in unique shapes and features within minutes.
Like fingerprints, the resulting shapes and dimensions are always unique. After a sufficient number of minutes, their exact position and relative pattern in the scan is extracted, a scanner uniquely identifies a particular fingerprint. All of these involve complex image processing algorithms.
Many fingerprint scanners have additional sensors such as pulse sensors or heat sensors to determine whether the scanned image is of a live finger. A fingerprint scanner relies on scanning a digital image of the fingerprint. It is sometimes possible to duplicate fingerprints using print images, fingerprint molds, or cloning from residual fingerprints. The use of additional sensors helps the mesh detect mishaps.
Types of fingerprint scanners:
- Optical scanners
- Capacitive scanners
- Ultrasonic scanners
- In-display scanners
In embedded applications and optical and capacitive scanners are most common. Mobile devices and wearables mostly have capacitive or in-display image scanners.
Optical scanners are older models of fingerprint scanners. As the name suggests, these scanners use CCD or CMOS image sensors. An optical image of the fingerprint is captured. They are similar to camera sensors, although they are designed to capture higher-contrast images than any regular camera. The sensor has an array of LEDs that CCD/CMOS sensors illuminate the finger area and reflect light waves to produce a clear image. The sensor is packed with a high density of diodes to get all detailed images of the fingerprint. The captured image is a 2D image of the scanned fingerprint. The latest models are as small as 1 mm in size and can scan even wet fingers As costs are gradually decreasing, optical-capacitive hybrid scanners capable of live finger detection are trending.
Capacitive scanners use completely different technology to read fingerprints. It uses an array of billions of tiny capacitors to detect the capacitance between finger ridges and valleys for the capacitor plates. Wherever there is a ridge, its distance from the capacitor plate is less, resulting in a slightly lower capacitance. Wherever there is a valley its distance from the capacitor plate is greater than the intervening air gap. This results in large capacitance. The capacitance signal from each capacitor in the array is sent to an operational amplifier and recorded by an analog-to-digital converter. It captures data by doing a digital scan of the fingerprint according to the capacitive touch sensing.
Ultrasonic scanner is the latest and most sophisticated fingerprint scanner that operates 3D scanning of fingerprints. Currently, this technology is only being used in some high-end smartphone devices. In an ultrasonic scanner, there is an array of ultrasonic transmitters and receivers devices. The transmitters emit ultrasonic pulses of light that reflect off the ridges, valleys, and pores of the fingerprint. An array of receivers senses the reflected pulse given. Receivers are actually sensors that measure pressure due to the intensity of reflected ultrasonic pulses at different points. This results in a 3D map of the fingerprint scanners.
An ultrasound scanner is a 3D scan. Currently, this technology is only used in a few high-end smartphones. An Atarsone scanner consists of an array of transmitter and receiver parts. The transmitters emit ultrasonic pulses above the light reflected from the fingerprint rock. An array of receivers works to sense reflected pulses. The receiver is the actual sensor that measures the pressure due to the intensity of the data scanning the reflected accents at different points. This results in a 3D image map of the fingerprint scan.
Fingerprint scanners for Arduino, Raspberry Pi, and embedded prototyping platforms
Optical and capacitive scanners are used for embedded applications. An example of an optical scanner is the R305 model. R303 is a popular capacitive scanner. These scanners usually interface data with a microcontroller or microcomputer through a UART interface. It is easy to interface with instructions to record, scan and compare fingerprints. All these instructions are communicated to the scanner through the UART protocol.
Fingerprint scanners are an all-around convenient device. Integrate with biometric or authentication methods to implement a foolproof person identification system. Retina scanning, iris scanning, ‘what-you-know’ systems like PIN codes or biometric identification systems like RFID tags, or smart cards like fingerprint scanners are helpful in designing IIoT logging and presence applications, smart homes, and security applications.