Ultrasonic Fingerprint Sensor Anti-Spoofing via Echo Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fingerprint sensors are vulnerable to security breaches as they cannot distinguish between real and fake fingerprints, particularly those made from materials with similar sound wave impedance to human skin, leading to potential unauthorized access.
Innovation Solution
An ultrasonic fingerprint sensor that emits sound waves and analyzes the echo signals to differentiate between real and fake fingerprints by detecting the unique Time Of Flight (TOF) and impedance differences at multiple points on the finger, thereby enhancing security without compromising usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fingerprint sensors use reflection coefficients or electrical signal strength for recognition, then the recognition process is simple and fast, but fake fingerprints made from materials with similar impedance cannot be distinguished from real fingerprints
Solution Approach 1:
The patent replaces conventional optical or electrical fingerprint recognition systems with an ultrasonic acoustic system. The ultrasonic sensor emits sound waves that penetrate the fingerprint and reflect from subcutaneous structures, enabling detection of genuine biological characteristics that fake fingerprints cannot replicate. This mechanical wave-based approach substitutes the previous electromagnetic or optical fields, providing enhanced security through physical property differentiation.
Solution Approach 2:
The patent changes the recognition parameter from surface-level reflection coefficients or electrical impedance to the time of flight (ToF) of ultrasonic waves and acoustic impedance characteristics. By measuring how long it takes for sound waves to travel through and reflect from different fingerprint regions, the system captures depth information and subcutaneous structure characteristics that distinguish real fingerprints from fake ones made of rubber or other materials.
2Reliability
If ultrasonic sensors are used to detect subcutaneous structures, then security is improved by distinguishing real from fake fingerprints, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The ultrasonic sensor array is integrated into the existing fingerprint sensor module, allowing it to serve both conventional fingerprint recognition and advanced anti-spoofing functions simultaneously. The same sensor structure can operate in different modes (surface imaging vs. subcutaneous structure detection) by adjusting signal processing parameters, reducing the need for separate dedicated hardware and simplifying manufacturing.
Solution Approach 2:
The patent uses the existing fingerprint sensor architecture as a template and adapts it for ultrasonic operation. By copying the successful form factor, contact interface, and basic signal processing pipeline of conventional sensors, the design leverages proven manufacturing processes while incorporating the enhanced ultrasonic detection capability, thereby reducing overall manufacturing complexity.
3Productivity
If only surface fingerprint shape is recognized, then the recognition process is fast and simple, but security is compromised against copied fingerprints
Solution Approach 1:
The ultrasonic sensor performs preliminary detection of subcutaneous structures and acoustic impedance characteristics during the initial contact phase, before final authentication decisions are made. This preliminary action of gathering depth and tissue property information allows the system to quickly eliminate fake fingerprints without requiring extensive processing, thus maintaining fast recognition speeds while enhancing security.
Solution Approach 2:
The patent segments the fingerprint recognition process into multiple independent detection layers: surface ridge/valley pattern recognition and subcutaneous structure acoustic characterization. These segmented functions operate in parallel, with the surface recognition providing rapid initial verification and the ultrasonic subcutaneous detection providing security verification, allowing the system to maintain speed while improving reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively differentiates between real and fake fingerprints, improving security by accurately recognizing the unique biological characteristics of human skin, thus preventing unauthorized access.
Implementation Method 1
analyzes the echo signals to differentiate between real and fake fingerprints
Implementation Method 2
detecting the unique Time Of Flight (TOF) and impedance differences
Implementation Method 3
a sound wave impedance of human skin is 1.63, and a sound wave impedance of a material such rubber is 1.3
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for sensing a fingerprint, comprising: receiving, by an electronic device, a sound wave signal that is reflected from an object; detecting at least one echo signal that is associated with the object for each reception period in a plurality of reception periods, wherein the at least one echo signal is detected based on the sound wave signal; and detecting the fingerprint based on the at least one echo signal.