Fingerprint Sensor Working and Applications

From the past few years, fingerprint detection utilization has existed for identification. Generally, the features of fingerprint recognition systems include faster speed, lower costs, as well as consistency is more comparing to other types of biometric devices. Every person has a separate model of the fingerprint which are made with ridges, which create whirls and loops that are unique to every person. Fingerprints are classified into five types namely whorl, right loop, left loop, tented and arch. In most of the recognition systems, troubles will occur while differentiating among the similar types of fingerprints. There are different recognition systems available which are used in neural networks to discover ends of the ridge, minutiae’s to match a fingerprint.

What is the Fingerprint Sensor?

The fingerprint sensor is one kind of sensor which is used in a fingerprint detection device. These devices are mainly inbuilt in the fingerprint detection module and it is used for computer safety. The main features of this device mainly include accuracy, better performance, robustness based on exclusive fingerprint biometric technology. Both fingerprint scanner otherwise reader are an extremely safe & suitable device for safety instead of a secret word. Because the password is easy to scan and also it is hard to keep in mind.


So, better to use USB based fingerprint reader or scanner using biometric software for verification, identification, and authentication, that allow your fingerprints to perform similar to digital passwords. These passwords cannot be forgotten, lost otherwise stolen.

R305 Fingerprint Sensor Module

There are different types of fingerprint modules available in the market like R305, R307. For a better understanding of this sensor, here we are going to discuss an overview of R305 fingerprint sensor module.


The R305 is one kind of fingerprint sensor module used in biometrics for security in fingerprint detection as well as verification. These devices are mainly used in safes where there is a high-powered DSP chip used in the rendering of image, feature-finding, searching and calculation by connecting it to any microcontroller with the help of TTL serial, & send data packets to get photos, notice prints, search and hash. The enrollment of new fingers can be stored directly within the flash memory of on board.

Features of Fingerprint Sensor

The features of this sensor include the following.

  • It includes image collection as well as chip algorithm
  • The fingerprint reader can perform lesser growth and can be fixed into a range of end products
  • Power use is low, excellent performance, small in size, and less cost
  • Optical technology which is used is professional, and exact module developed techniques
  • The capabilities of image processing are good, and can effectively capture pictures up to 500 dpi resolution

Fingerprint Sensor Working Principle

The working principle of the fingerprint sensor mainly depends on the processing. The fingerprint processing mainly includes two elements namely enrollment and matching. In fingerprint enrolling, every user requires to place the finger twice.

So that the system will check the finger images to process as well as to generate a pattern of the finger and it will be stored. When matching, a user places the finger using an optical sensor then the system will produce a pattern of the finger & compares it with the finger library templates.

For 1:1 fingerprint matching, the system will evaluate the exits finger with a precise pattern which is selected within the module. Similarly, for 1: N matching, the scanning system will look for the complete finger records for the finger matching. In both situations, the scanning system will go back to the corresponding result, success otherwise crash.


The specifications of this sensor include the following.

  • The fingerprint sensor is an optical type
  • The interface is USB1.1/ TTL logical level (UART)
  • The speed of scanning is 0.5 sec
  • The speed of verification is 0.3 sec
  • The capacity storage is 1000
  • The security level is 5
  • The baud rate of RS232 is 4800BPS ~115200BPS variable
  • Current is typical 50 mA, and peak 80mA
  • The corresponding technique is 1: N
  • Fixed indicators-15KV bright green backlight
  • The life of the sensor is 100 million times
  • The dimension is 44.1 X 20 X 23.5mm
  • The size of the character file is 256 bytes
  • The template size is 512 bytes
  • The FRR (False Rejection Rate) is <1.0%
  • The FAR (False Acceptance Rate) is 0.001%
  • Voltage is 4.2 to 6.0 VDC
  • Operating surroundings temperature is -20° C to 40° C

Fingerprint Sensor Arduino

In order to show a simple application of this sensor, here is a project namely fingerprint sensor using Arduino board. The required components of this project mainly include An Arduino Nano board, fingerprint sensor module, TFT display, small breadboard, connecting wires, and power bank.


Fingerprint sensor includes pins like DNC, VCC, TX, RX, and GND. These pins are connected through different colored connecting wires. Each color wire is used to indicate each pin of the sensor.

  • DNC pin is connected by a white wire
  • VCC pin is connected by a red wire
  • TX pin is connected by a blue wire
  • RX pin is connected by a green wire
  • GND pin is connected by a black wire

The connection of the fingerprint sensor module to an Arduino board can be done like the following.

  • The black wire is connected to the GND pin of the Arduino
  • The red wire is connected to the 5V of the Arduino
  • Green wire is connected to the digital pin-2 of the Arduino
  • The white wire is connected to the digital pin-3 of the Arduino

The connection of display to an Arduino board can be done like the following.

  • Vcc pin of the display is connected to the 5V pin of the Arduino
  • GND pin of the display is connected to the Arduino GND pin
  • CS pin of the display is connected to the Digital Pin-10
  • RST pin of the display is connected to the DIgital Pin-9
  • A0 pin of the display is connected to the Digital Pin-8
  • SDA pin of the display is connected to the Digital Pin-11
  • SCK pin of the display is connected to the Digital Pin-13
  • LED pin of the display is connected to the 3.3V pin of the Arduino

Project Code

First of all the project code of this project requires different libraries namely the Adafruit Fingerprint, the Adafruit GFX & the Sumotoy’s for the display.

Take an enroll example code and upload it into an Arduino board. Go to File  Examples Adafruit Fingerprint Sensor Library Enroll.

By using this code, the fingerprints can be stored within the FLASH memory of the device. Once the serial monitor opens then it asks to enter the credentials to register.

Pllace the finger over the sensor module twice then the fingerprint will be stored. So we can stock up many fingerprints in this way. The small portion of the code is shown below.

void loop()
fingerprintID = getFingerprintID(); //We scan the fingerprint here
if(fingerprintID == 1) //We have found a valid fingerprint with the id 1
if(fingerprintID == 2) //We have found a valid fingerprint with the id 2 {

Check the sensor as well as display by placing a finger over the sensor for every50ms, then the module checks the finger whether it is enrolled or not within the memory of the device. If it discovers in the memory then it go backs that finger prints identification. Finally, it shows a message like ‘WELCOME’ and after few seconds it will lock the screen automatically.

This is all about the fingerprint sensor module which is used for fingerprint detection and it is more accessible as well as very easy to use in projects. By using this we can make registration, fingerprint collection, search, and comparison. These modules are inbuilt with FLASH memory that stores the fingerprints. The fingerprint sensor applications include mobile, lock, unlock, in the display, on screen, security systems, time attendance systems, door locks, etc. Here is a question for you, what is the price of a fingerprint sensor?

Image Credits: Arduino