Thermal Finger Biometric Sensor for Eroded Print Verification
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Solution Overview
Problem
Conventional biometric verification methods using fingerprint sensors are ineffective for individuals with eroded fingerprints, such as cement or chemical workers, and are also hindered by contamination or moisture, which interferes with detection.
Innovation Solution
A biometric method utilizing a thermoelectric sensor for thermal imaging, which captures both fingerprint and vein images based on temperature differences, allowing for identity verification even without visible fingerprints, and distinguishing between real and fake fingers by sensing thermal infrared emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fingerprint sensors are used, then biometric verification is simple and convenient, but verification fails when fingerprints are eroded or the finger is wetted
Solution Approach 1:
The sensing member is designed to perform multiple functions: it can detect both conventional fingerprint patterns and alternative biometric features (finger-vein images, thermal distribution patterns) depending on the finger's condition. This multi-functionality allows the system to adapt to various scenarios including eroded fingerprints, wet fingers, and fingers with contamination.
Solution Approach 2:
The system changes the detection parameters by switching from detecting surface ridge patterns (conventional fingerprint mode) to detecting thermal radiation patterns and vein structures (thermal imaging mode). This parameter change enables verification reliability across different finger conditions by selecting appropriate detection modes based on the actual finger state.
2Reliability
If thermoelectric sensors for thermal imaging are used, then verification can be performed on fingers with eroded fingerprints or when wetted, but the device complexity increases
Solution Approach 1:
The patent merges the conventional fingerprint sensing function with thermal imaging capability into a single integrated sensing member. The sensing member includes both the fingerprint detection structure and thermoelectric elements (thermocouples or thermopiles) that detect thermal radiation, combining multiple functions in one device to reduce overall system complexity.
Solution Approach 2:
The sensing member acts as an intermediary that converts different types of biometric information (fingerprint patterns and thermal radiation) into electrical signals that can be processed by the same control unit. This intermediary structure allows diverse input types to be handled through a unified processing architecture.
3Reliability
If only fingerprint patterns are detected, then the verification process is fast, but it cannot distinguish between real and fake fingers or work with eroded fingerprints
Solution Approach 1:
The system performs preliminary detection of thermal radiation patterns and vein structures simultaneously with fingerprint pattern detection. By gathering multiple types of biometric data in advance during the same sensing operation, the system prepares comprehensive verification information without requiring additional separate detection steps, thus maintaining fast verification speed while enhancing anti-spoofing capability.
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
Enables reliable identity verification by extracting and comparing fingerprint and vein images from thermal data, ensuring accurate recognition even in cases where traditional fingerprint sensors fail due to erosion or moisture.
Implementation Method 1
The sensing member works based on the principle of sensing the contacted body heat conduction (temperature difference)... A temperature difference ΔT is generated between the hot junction 200 and the cold junction 300. The sensing member 10′ senses a voltage signal through the temperature difference ΔT
Implementation Method 2
the principle of sensing thermal infrared emitting from the finger to the sensing members in a small gap
Data Source
AI summary
A biometrics method based on a thermal image of a finger includes the steps of: acquiring the thermal image of the finger; and extracting a finger-print image or a finger-vein image from the thermal image and thus verifying a user's identity according to the finger-print image or the finger-vein image.