Biometric Skin Contact Sensing With Selective High-Resolution Scanning
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Solution Overview
Problem
Current biometric sensors, such as fingerprint sensors, face challenges in achieving high resolution and large area coverage due to limitations in pixel density and parasitic capacitance, leading to inefficiencies and vulnerabilities in authentication systems.
Innovation Solution
A biometric skin-contact sensor with a capacitive sensing array that switches between low and high resolution modes, using a controller to operate pixels efficiently, focusing energy consumption on sub-regions for accurate biometric data collection, and employing thin film transistors and capacitive sensing electrodes to minimize parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution scanning is applied across the entire sensor area, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The sensor area is divided into multiple sub-regions, and high-resolution scanning is applied only to the contacted sub-region rather than the entire sensor area. This segmentation allows the system to maintain high measurement precision where needed while reducing energy consumption in non-contacted areas.
Solution Approach 2:
The system applies different scanning resolutions to different spatial locations based on contact detection. The contacted sub-region receives high-resolution scanning for accurate biometric data, while non-contacted regions use lower resolution or no scanning, optimizing the balance between precision and energy usage.
2Measurement precision
If high resolution scanning is applied across the entire sensor area, then measurement precision is improved, but processing time increases
Solution Approach 1:
The sensor area is segmented into contacted and non-contacted sub-regions. High-resolution scanning is performed only on the contacted sub-region, significantly reducing the total number of pixels that need to be processed and thus reducing data acquisition time while maintaining biometric data precision.
Solution Approach 2:
The system performs high-resolution scanning only partially, specifically only in the contacted sub-region where biometric data is actually present. This partial action approach avoids the excessive time cost of scanning the entire sensor area while still achieving the required measurement precision for authentication.
3Device complexity
If parasitic capacitance is reduced by limiting pixels per column, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The system dynamically adjusts the number of pixels activated in each column based on contact detection. During low-resolution mode, fewer pixels are activated to reduce parasitic capacitance and simplify the circuit. During high-resolution mode, more pixels are activated to improve measurement precision, with the understanding that this is only needed in contacted sub-regions.
Solution Approach 2:
The system changes the operational parameters of the sensor by switching between different resolution modes. In low-resolution mode, the sensor uses fewer pixels per column to minimize parasitic capacitance. In high-resolution mode, the sensor increases pixel density in contacted regions to improve measurement precision, accepting higher parasitic capacitance only where necessary.
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 faster and more energy-efficient biometric data acquisition with higher resolution, particularly in large area sensors, while reducing noise sensitivity and improving authentication accuracy.
Implementation Method 1
capacitive sensing electrode for sensing contact
Implementation Method 2
each pixel comprising a thin film transistor and a capacitive sensing electrode
Data Source
AI summary
Disclosed herein is a biometric skin-contact sensor comprising: a contact sensing area comprising an array of pixels, each pixel comprising a thin film transistor and a capacitive sensing electrode for sensing contact; and a controller coupled to the contact sensing area and configured to operate the array of pixels to switch between a low resolution mode and a high resolution mode. In the low resolution mode the sensor is operable to obtain contact location data comprising an indication of a sub-region of the contact sensing area in which contact is sensed. In the high resolution mode the sensor is operable to obtain biometric data for skin interacting with the contact sensing area by identifying a difference in capacitance between valleys and ridges of the skin.