Embedded Fingerprint Sensor Module With Galvanic Isolation in Smartcards
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Solution Overview
Problem
Existing smartcards face challenges in integrating biometric sensors due to manufacturing complexity and cost, particularly in providing mechanical and electrical protection for the sensors, which are exposed on the card's surface.
Innovation Solution
A smartcard with a galvanically isolated fingerprint sensor module embedded within the card, connected directly to an antenna layer for power and communication, eliminating the need for external electrodes and simplifying the manufacturing process by using a T-shaped module with contact pads directly connected to the antenna, and integrating additional components like secure elements and processing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fingerprint sensor module is exposed on the smartcard surface using mill and drill process, then the sensor can be integrated into the smartcard, but the sensor module is vulnerable to mechanical damage and electrical charge damage from user contact
Solution Approach 1:
The fingerprint sensor module is embedded within the smartcard structure, nesting the sensor inside protective layers of the card substrate. This embedding approach provides mechanical protection while maintaining integration, resolving the contradiction between ease of manufacture and sensor protection.
Solution Approach 2:
An antenna layer is introduced as an intermediary between the fingerprint sensor module and the external environment. The antenna serves as both a functional component for power/communication and a protective barrier that prevents direct electrical contact between the sensor and user-held charges, thereby protecting the sensor while enabling wireless operation.
2Reliability
If the fingerprint sensor module is embedded within the smartcard and galvanically isolated, then mechanical and electrical protection is provided, but the manufacturing complexity increases
Solution Approach 1:
The fingerprint sensor module and antenna layer are combined into a single integrated structure where the antenna serves dual purposes: providing wireless power/communication functionality and acting as a protective barrier. This merging reduces manufacturing steps compared to separate integration processes while achieving both protection and functionality.
Solution Approach 2:
The antenna layer performs multiple functions simultaneously: it provides electromagnetic coupling for power and data transmission, acts as a galvanic isolation barrier protecting the sensor from electrical damage, and serves as part of the structural assembly. This multi-functionality reduces overall device complexity while maintaining protection.
3Ease of operation
If the fingerprint sensor module is connected to external electrodes, then electrical connection is provided, but the sensor is vulnerable to damage from user-held electrical charges
Solution Approach 1:
The antenna layer acts as an intermediary between the fingerprint sensor module and the external environment, enabling electrical connection through electromagnetic coupling rather than direct physical contact. This intermediate approach provides the necessary electrical connection for power and communication while preventing direct exposure to harmful electrical charges from user contact.
Solution Approach 2:
The patent replaces direct mechanical electrical connections (external electrodes contacting the sensor) with an electromagnetic field-based connection through the antenna. This substitution eliminates the harmful direct electrical contact while maintaining the essential electrical connection functionality through wireless electromagnetic coupling.
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 provides enhanced mechanical and electrical protection for the sensor module, simplifies the manufacturing process, and ensures reliable operation without external electrical connections, facilitating biometric identification while minimizing the risk of damage from user-held charges.
Implementation Method 1
the fingerprint sensor module being configured to receive energy and communicate with a reading device via the antenna
Implementation Method 2
Capacitive fingerprint sensing devices, built based on CMOS technology for providing the fingerprint sensing elements
Data Source
AI summary
A smartcard comprising: a plurality of smartcard substrate layers; an antenna layer comprising an antenna; a fingerprint sensor module embedded in the smartcard and connected to the antenna layer, the fingerprint sensor module being configured to receive energy and communicate with a reading device via the antenna, and wherein the fingerprint sensor module is galvanically isolated from an outside of the smartcard.