Double-Sided Fingerprint Sensor Module for Smart Card Anti-Spoofing
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Solution Overview
Problem
Current fingerprint sensors face challenges in providing effective anti-spoof protection without degrading ease of use, particularly in smart card applications, where they can be easily spoofed by fake fingerprints, leading to increased false rejections and manufacturing complexities when trying to implement dual sensing capabilities.
Innovation Solution
A double-sided fingerprint sensor module is designed using a flexible substrate wrapped around a core, with two sensing areas connected to separate ASICs, allowing for simultaneous detection of two fingerprints in a pinching motion, enhancing security and ease of use while being cost-effective and robust enough to pass ISO stress tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional security measures such as live finger detection are implemented, then anti-spoof protection is improved, but false rejection rate increases and ease of use deteriorates
Solution Approach 1:
The fingerprint sensor is divided into two separate sensing areas (first and second sensing areas) that can independently detect fingerprints. This segmentation allows the system to require two distinct fingerprints for authentication, making spoofing attacks more difficult while maintaining ease of use through a simple pinching motion gesture.
Solution Approach 2:
The patent transitions from single-sided fingerprint sensing to double-sided sensing by adding a second sensing area on the opposite side of the substrate. This dimensional change enables simultaneous detection of two fingerprints in a pinching gesture, enhancing security without complicating the user interaction model.
2Reliability
If dual sensing capabilities are implemented to improve security, then anti-spoof protection is enhanced, but device complexity and manufacturing complexity increase
Solution Approach 1:
Two separate fingerprint sensing areas are integrated onto a single flexible substrate, sharing common structural elements and manufacturing processes. This merging approach enables dual sensing capability while simplifying manufacturing compared to using two separate sensor modules.
Solution Approach 2:
The flexible substrate serves multiple functions: it provides the structural base for both sensing areas, enables the pinching gesture detection, and facilitates integration into smart cards. This multi-functionality reduces overall device complexity while achieving enhanced security.
3Stability of the object's composition
If a rigid substrate is used for the fingerprint sensor, then structural stability is improved, but adaptability to different device integrations deteriorates
Solution Approach 1:
The patent employs a flexible substrate instead of a rigid one, allowing the fingerprint sensor to be bent and adapted to various device form factors including smart cards. This flexibility maintains structural integrity while enabling widespread integration across different electronic devices.
Data Source
AI summary
A sensor assembly includes a flexible substrate with conductive traces formed on opposed sides of the substrate and oriented transversely to each other. The substrate is wrapped around a core so that the traces formed on opposed sides of a first part of the substrate form a first sensor surface on one surface of the core, and the traces formed on opposed sides of a second part of the substrate form a second sensor surface on an opposed surface of the core. The core may comprise an encapsulant overmolded onto the conductive traces on a surface of the first part of the substrate, and the second part of the substrate is folded over the encapsulant. The sensor assembly may include an integrated circuit disposed on the flexible substrate, wherein one or more of the conductive traces are electrically connected to each integrated circuit.