Micromachined Ultrasonic Transducer Fingerprint ID System
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Solution Overview
Problem
Automated optical fingerprint scanning techniques are limited by their inability to sense beyond the epidermal layer, leading to errors due to finger contamination, and existing ultrasonic fingerprint scanners are large, costly, and require mechanical scanning, making them unsuitable for broad applications in consumer electronics.
Innovation Solution
The development of a micromachined ultrasonic transducer fingerprint identification system (MUT fingerprint ID system) that uses an array of ultrasonic transducers to detect fingerprints on both the epidermis and dermis layers, providing robust, small, and cost-effective 3D fingerprint analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fingerprint scanning is used, then the device is simple and low-cost, but it is prone to errors due to finger contamination and can only sense the epidermal layer
Solution Approach 1:
The patent replaces optical sensing with ultrasonic sensing to penetrate through contamination and sense both epidermal and dermal fingerprint layers. The ultrasonic transducer uses acoustic waves instead of light to detect fingerprint patterns, eliminating the problem of optical sensors being blocked by dirt, oil, or moisture on the finger surface.
Solution Approach 2:
The patent transitions from two-dimensional optical surface scanning to three-dimensional ultrasonic sensing that penetrates through the fingerprint layers. By using ultrasonic waves, the system can detect fingerprint patterns at multiple depths (epidermal and dermal layers), adding a depth dimension that improves reliability while maintaining compact form factor through electronic scanning.
2Reliability
If ultrasonic fingerprint scanners are used to analyze the dermal fingerprint, then contamination errors are reduced, but the device size becomes large and mechanical scanning is required
Solution Approach 1:
The patent replaces mechanical scanning with electronic scanning using a micromachined ultrasonic transducer array. Instead of physically moving a large ultrasonic transducer across the fingerprint surface, the system uses multiple small transducer elements that can be electronically activated in sequence or simultaneously with appropriate timing, eliminating mechanical movement and reducing overall device size.
Solution Approach 2:
The patent divides a single large ultrasonic transducer into multiple smaller micromachined transducer elements arranged in an array. Each element can be independently controlled with specific timing delays, allowing the system to scan the fingerprint area electronically without mechanical movement. This segmentation reduces the size of individual moving components and enables compact integration.
3Volume of moving object
If micromachined ultrasonic transducers are used, then device size is reduced and cost is lowered, but electronic scanning capability must be implemented
Solution Approach 1:
The patent segments the ultrasonic sensing function into multiple small micromachined transducer elements arranged in a grid array. Each element is connected to independent control circuitry that can apply timing delays to create focused beams at different angles and positions. This segmentation enables electronic scanning while keeping each individual transducer element small and inexpensive.
Solution Approach 2:
The patent implements dynamic control of the micromachined transducer array through electronic timing delays applied to each element. By dynamically adjusting the phase and timing of excitation signals to different transducer elements, the system can electronically steer and focus ultrasonic beams across the fingerprint surface without mechanical movement, achieving scanning functionality through dynamic signal processing.
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 MUT fingerprint ID system offers high fidelity and reliability, being insensitive to contamination and moist conditions, with a small size, fast electronic scanning, and low power consumption, enabling its use in consumer electronics and personal identification devices.
Implementation Method 1
ultrasonic fingerprint scanners... by analyzing the dermal fingerprint
Implementation Method 2
The MUT fingerprint ID system is a novel fingerprint sensor based on an array of ultrasonic transducers
Data Source
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AI summary
MEMS ultrasound fingerprint ID systems are provided. Aspects of the systems include the capabilty of detecting both epidermis and dermis fingerprint patterns in three dimensions. Also provided are methods of making and using the systems, as well as devices that include the systems.