Piezoelectric Sensor Array for Fingerprint Detection
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Solution Overview
Problem
Existing fingerprint scanners, particularly optical and silicon-based systems, are costly and prone to durability issues due to their complex optical components and large silicon transducer geometries, leading to high maintenance costs and reduced structural integrity.
Innovation Solution
A fingerprint sensor utilizing Acoustic Impediography with an array of piezoelectric ceramic elements arranged in rows and columns, connected to an Application Specific Integrated Circuit (ASIC), which generates mechanical resonations to detect fingerprint ridges and valleys based on impedance differences, offering a durable and cost-effective solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical components (lenses, illumination source, imaging camera) are used to capture fingerprint images, then image quality and resolution are improved, but device cost and structural complexity increase
Solution Approach 1:
The patent replaces the optical mechanical system (lenses, illumination sources, cameras) with a solid-state piezoelectric sensor array that directly contacts the fingerprint. The piezoelectric elements detect mechanical stress and electrical impedance changes caused by fingerprint ridges and valleys, eliminating the need for complex optical components while maintaining measurement precision.
Solution Approach 2:
The invention extracts and eliminates the unnecessary optical components (lenses, illumination sources, imaging cameras) from the fingerprint scanning system, retaining only the essential sensing function through piezoelectric elements that directly measure fingerprint characteristics through contact.
2Measurement precision
If mechanical structures are added to maintain alignment of optical components, then measurement precision is improved, but manufacturing and maintenance costs increase
Solution Approach 1:
The patent replaces the mechanical alignment system with a direct-contact piezoelectric sensor array that inherently maintains proper positioning through physical contact with the fingerprint. The sensor elements are arranged in a fixed matrix that naturally aligns with fingerprint ridges and valleys, eliminating the need for additional mechanical alignment structures.
3Area of stationary object
If large-area silicon transducers (1 inch x 1 inch, 50 microns thick) are used to detect rolled fingerprints, then sensing coverage is improved, but device cost and structural integrity worsen
Solution Approach 1:
The patent divides the sensing area into multiple small piezoelectric elements arranged in a matrix array. Each element is small and mechanically robust, yet collectively they cover the required sensing area. This segmentation allows the sensor to detect rolled fingerprints across large areas while maintaining the structural integrity of individual sensor elements.
Solution Approach 2:
The invention uses piezoelectric ceramic materials with superior mechanical strength and durability compared to brittle silicon. The piezoelectric elements can withstand repeated contact and pressure without cracking or deforming, providing long-term structural integrity while maintaining sensing coverage.
4Measurement precision
If silicon transducers are positioned within a few microns of the fingerprint sensing circuit, then measurement precision is improved, but durability and reliability decrease
Solution Approach 1:
The patent replaces the close-positioned silicon transducer system with piezoelectric elements that directly contact the fingerprint surface. This direct contact approach maintains high measurement precision while eliminating the fragility associated with sub-micron positioning, as the piezoelectric elements are mechanically robust and can withstand repeated contact without degradation.
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 piezoelectric sensor array provides a durable, low-maintenance, and cost-effective means of capturing high-resolution fingerprints, meeting quality standards while reducing physical and operational risks, suitable for secure biometric applications.
Implementation Method 1
an array of piezoelectric ceramic elements arranged in rows and columns, connected to an Application Specific Integrated Circuit (ASIC), which generates mechanical resonations
Implementation Method 2
A fingerprint sensor utilizing Acoustic Impediography with an array of piezoelectric ceramic elements arranged in rows and columns
Data Source
AI summary
Provided is a Fingerprint sensor using Acoustic Impediography. The sensor includes an Application Specific Integrated Circuit (ASIC or IC) and an array of mechanical resonator used as sensing elements. The array of sensing elements contains multiple sensing elements arranged in rows and columns.