Dual-Frequency Ultrasonic Sensor With Frequency Splitting Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing biometric authentication systems, particularly those based on fingerprint recognition, are vulnerable to spoofing and lack reliability due to their inability to effectively differentiate between surface and sub-epidermal features, leading to potential security breaches.
Innovation Solution
An ultrasonic sensor system with a first layer stack and a second layer stack, separated by a frequency splitting layer, which transmits and receives ultrasonic waves of different frequencies to image both fingerprints and sub-epidermal features, reducing cross-talk and enhancing signal amplitude for sub-epidermal imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single ultrasonic frequency is used for imaging, then the device structure is simple, but it cannot simultaneously capture both surface fingerprint details and sub-epidermal features
Solution Approach 1:
The patent divides the ultrasonic imaging system into two separate frequency channels: a first ultrasonic transmitter/receiver pair operating at a first frequency for surface fingerprint imaging, and a second ultrasonic transmitter/receiver pair operating at a second frequency for sub-epidermal feature imaging. This segmentation allows each frequency to be optimized for its specific imaging target while maintaining a relatively simple overall device structure through the use of a shared piezoelectric layer and integrated circuit board.
2Measurement precision
If higher frequency ultrasonic waves are used, then surface fingerprint imaging resolution is improved, but penetration depth into sub-epidermal layers is reduced
Solution Approach 1:
The patent applies different ultrasonic frequencies to different imaging depths: a higher first frequency (e.g., 20-100 MHz) is used for high-resolution surface fingerprint imaging where fine detail is critical, while a lower second frequency (e.g., 1-10 MHz) is used for deeper sub-epidermal feature imaging where penetration is more important. This local optimization of frequency characteristics resolves the contradiction between resolution and penetration depth.
3Adaptability or versatility
If dual-frequency ultrasonic transmitters are used, then both surface and sub-epidermal features can be imaged, but cross-talk between frequencies increases
Solution Approach 1:
The patent introduces a frequency splitting layer positioned between the piezoelectric layer and the ultrasound coupling window. This intermediary layer is designed with specific acoustic impedance characteristics that allow it to transmit one frequency range while blocking or attenuating the other frequency range. The frequency splitting layer effectively separates the two ultrasonic frequency channels, preventing cross-talk while enabling dual-frequency imaging capability.
4Object-generated harmful factors
If frequency splitting layer is added, then cross-talk between frequencies is reduced, but device complexity increases
Solution Approach 1:
The patent designs the frequency splitting layer to serve multiple functions simultaneously: it acts as a frequency selective filter to separate ultrasonic frequency channels, provides an acoustic impedance transition between the piezoelectric layer and coupling window, and maintains structural integration with the existing device architecture. By making the frequency splitting layer multi-functional, the patent reduces cross-talk without proportionally increasing device complexity.
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 system provides enhanced security by reliably distinguishing between surface and sub-epidermal features, reducing the likelihood of spoofing and improving authentication accuracy through the use of frequency splitting layers that suppress higher frequencies for fingerprint imaging while passing lower frequencies for sub-epidermal feature detection.
Implementation Method 1
The first transmitter may be configured for transmitting a first ultrasonic wave including a first frequency
Implementation Method 2
first signals corresponding to reflections of the first ultrasonic wave from a surface of a portion of a target object
Implementation Method 3
The second transmitter may be configured for transmitting a second ultrasonic wave including a second frequency that is lower than the first frequency
Implementation Method 4
second signals corresponding to reflections of the second ultrasonic wave from an interior of the portion of the target object
Implementation Method 5
The frequency splitting layer may have a relatively lower acoustic impedance than that of a first adjacent layer of the first layer stack and a second adjacent layer of the second layer stack
Implementation Method 6
a thickness that corresponds to a half wavelength of the second frequency
Data Source
AI summary
An apparatus may include an ultrasonic sensor system having a first layer stack and a second layer stack. The first layer stack may include a first ultrasonic transmitter and the second layer stack may include a second ultrasonic transmitter. The first layer stack and/or the second layer stack may include an ultrasonic receiver. A frequency splitting layer may reside between the first layer stack and the second layer stack.