Oxide Semiconductor Biometric Pixels for Thermal Spoof Detection
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Solution Overview
Problem
Existing biometric sensors, such as fingerprint sensors, face limitations in accuracy due to the physical principles used for reading fingerprint patterns and are susceptible to environmental variables, leading to issues with spoofing and inconsistent performance.
Innovation Solution
A biometric sensor utilizing a pixel matrix with micro temperature sensors and micro heaters made of oxide semiconductor material, specifically indium gallium zinc oxide (IGZO) or modified IGZO, that operates on active thermal sensing principles, combined with capacitive touch sensing elements, enhancing anti-spoofing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fingerprint sensing principles are used, then basic fingerprint pattern reading is achieved, but measurement precision and reliability are limited due to susceptibility to environmental variables and spoofing
Solution Approach 1:
The patent employs a dual-material sensing approach combining oxide semiconductor materials (for thermal sensing) and conductive polymer materials (for capacitive sensing). This composite material strategy enables simultaneous thermal and capacitive measurements, creating a multi-parameter verification system that significantly improves both measurement precision and reliability by making spoofing extremely difficult while maintaining environmental stability
Solution Approach 2:
The patent utilizes the temperature-dependent electrical properties of oxide semiconductor materials, where the material's resistance changes predictably with temperature. By applying controlled heat pulses and measuring the resulting electrical parameter changes, the system achieves precise thermal sensing that is inherently resistant to environmental variables and spoofing attempts
2Reliability
If active thermal sensing with heat pulses is implemented, then anti-spoofing performance is enhanced, but device complexity increases due to integration of micro heaters and temperature sensors
Solution Approach 1:
The oxide semiconductor material serves multiple functions simultaneously: it acts as the active heating element, the temperature sensing element, and the signal processing element. This multi-functionality is achieved because the material's electrical resistance changes with temperature, allowing the same component to both generate heat and measure temperature, thereby reducing device complexity while maintaining enhanced anti-spoofing performance
Solution Approach 2:
The patent merges the micro heater and micro temperature sensor into a single integrated pixel structure using oxide semiconductor material. This consolidation combines previously separate components into one unified element, reducing the overall device complexity while maintaining the active thermal sensing capability for anti-spoofing verification
3Measurement precision
If oxide semiconductor material is used for micro temperature sensors and micro heaters, then measurement precision and anti-spoofing are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies oxide semiconductor material selectively in specific regions where thermal and capacitive sensing is required, rather than uniformly across the entire device. This localized application allows for optimized manufacturing processes in critical areas while reducing overall manufacturing complexity and precision requirements in non-critical regions
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 sensor achieves high-resolution biometric pattern detection with extremely low false rejection and acceptance rates, providing robust anti-spoofing capabilities and improved immunity to environmental factors.
Implementation Method 1
a micro heater and a micro temperature sensor, which may comprise an oxide semiconductor material
Implementation Method 2
The oxide semiconductor material may have a temperature coefficient in a suitable range, for example, from −2 mV/° C. and −200 mV/° C.
Data Source
AI summary
A sensor, a device, a system, and a method, for biometric sensing, are provided. Such a device or system includes a micro heater and a micro temperature sensor for at least active thermal sensing, which may comprise an oxide semiconductor material. The micro heater and the micro temperature sensor may be separate or combined in one pixel. The present disclosure also provides an out-cell type or an in-cell type of biometric sensor on display device, for example, an out-cell type or an in-cell type fingerprint sensor on display (FoD) device. The pixels for active thermal sensing include an oxide semiconductor material. The methods of making and the methods of using the sensors, the devices, or the system are also provided.