3D Biometric Sensor Using Acoustic Microscopy for Subsurface Fingerprint Imaging
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Solution Overview
Problem
Conventional fingerprint imaging methods are not foolproof and can be deceived by surface replicas, lacking the necessary detail and depth for secure identification.
Innovation Solution
A biometric sensor using high-frequency acoustic microscopy to scan both surface and subsurface tissue layers of a finger, generating a three-dimensional representation that includes unique features such as dermis and blood vessel networks, thereby providing a more robust and accurate identification system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fingerprint imaging methods (ink blotting or 2D scanning) are used, then the identification process is simple and fast, but the system can be deceived by surface replicas and lacks reliability
Solution Approach 1:
The patent transitions from two-dimensional fingerprint imaging to three-dimensional subsurface imaging by introducing acoustic wave propagation through tissue layers. This dimensional change enables visualization of subsurface features (dermis, blood vessels, nerve endings) that are invisible in conventional 2D images, thereby preventing spoofing by surface replicas while maintaining system manageability through automated acoustic scanning.
Solution Approach 2:
The patent replaces conventional optical imaging systems with an acoustic imaging system that uses sound wave propagation through tissue. Acoustic waves penetrate subsurface layers and reflect off different tissue densities, creating detailed 3D representations of subsurface structures. This substitution fundamentally changes the imaging mechanism from surface-optical to subsurface-acoustic, enabling reliable identification that cannot be replicated by surface molds.
2Measurement precision
If conventional 2D fingerprint imaging is used, then the device complexity is low, but the measurement precision of subsurface features is insufficient
Solution Approach 1:
The system adds the depth dimension to fingerprint imaging by measuring acoustic wave travel time and intensity at multiple depths. This enables precise localization of subsurface features such as the dermis layer, blood vessel networks, and nerve endings. The acoustic transducer scans through the tissue, capturing reflectivity data at different depths to construct a three-dimensional map of subsurface structures with high measurement precision.
Solution Approach 2:
The patent changes the physical parameters measured from surface optical properties to subsurface acoustic properties. By measuring acoustic wave intensity, travel time, and frequency shifts as waves propagate through tissue, the system obtains precise information about subsurface tissue density, composition, and structure. These parameter changes enable detection of features at depths of 0.5-2mm below the skin surface with high precision.
3Measurement precision
If high-frequency acoustic microscopy is used to scan surface and subsurface tissue layers, then the identification accuracy is enhanced, but the scanning time and device complexity increase
Solution Approach 1:
The patent uses periodic acoustic pulse transmission through the tissue, where each pulse generates a reflected signal that is detected and processed. By repeating this process at high frequency with systematic variation of pulse parameters (frequency, amplitude, timing), the system efficiently collects three-dimensional acoustic data from different tissue depths. This periodic scanning approach balances detailed subsurface imaging with reasonable scanning time by optimizing the pulse repetition rate and acquisition sequence.
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 enhances the accuracy of fingerprint identification by providing a detailed three-dimensional representation, making it more difficult to deceive and reducing false positives and negatives, thus creating a more secure access control system.
Implementation Method 1
A biometric sensor uses high frequency acoustic microscopy to scan both surface and subsurface tissue layers of a finger
Implementation Method 2
a first transducer arranged around the platen that receives acoustic waves after the acoustic waves reflect off of the finger and outputs signals based upon the received acoustic waves
Data Source
AI summary
One embodiment includes a biometric sensor for generating a three-dimensional representation of a portion of a finger, the finger comprising a three-dimensional structure including a surface tissue layer and a subsurface tissue layer, the biometric sensor comprising: a platen; a first transducer; a drive system; a controller; and a software module. The platen is configured to receive the finger. The first transducer is arranged about the platen, configured to scan at least a portion of the finger by transmitting ultrasound waves toward the finger and receiving the ultrasound waves after the waves reflect off of the finger, and further configured to output signals based upon the received ultrasound waves. The drive system is configured to motivate the set of transducers accurately about a central axis substantially parallel to the length of the finger to be scanned. The controller is configured to control the motion of the drive system. The software module is configured to receive a form of the signals from the first transducer and to compose the form of the signals into a three-dimensional representation of at least a portion of the surface tissue layer of the finger.