CMUT Fingerprint Transducer Array With TFT Integration

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Solution Overview

Problem

Existing fingerprint identification technologies, such as optical and capacitive fingerprint identification, are affected by external light and contaminants, leading to reduced accuracy and speed, while ultrasonic fingerprint identification using PVDF is costly and monopolized.

Innovation Solution

An ultrasonic transducer device with a thin film transistor circuit and ultrasonic transducers, including a first electrode, vibrating film layer, and second electrode, integrated on a substrate, allowing for arrayed fingerprint identification with high accuracy and flexibility, using a CMUT structure that converts electrical energy into mechanical energy for ultrasonic wave transmission and reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If PVDF-based ultrasonic fingerprint identification is used, then identification accuracy is maintained, but cost increases and manufacturing flexibility decreases

Engineering Contradiction:

Improvefingerprint identification accuracyVSAvoidmanufacturing cost and flexibility

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from PVDF to silicon-based materials, enabling standard semiconductor manufacturing processes while maintaining ultrasonic fingerprint identification accuracy. This material substitution allows the use of conventional CMOS fabrication techniques, significantly reducing cost and improving manufacturing flexibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical PVDF membrane system with a silicon-based MEMS structure that uses piezoelectric or piezoresistive effects. This substitution enables integration with standard semiconductor manufacturing processes, eliminating the need for specialized PVDF handling and assembly while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If optical fingerprint identification is used, then device complexity is reduced, but identification accuracy decreases under external light

Engineering Contradiction:

Improvesystem simplicityVSAvoidfingerprint identification accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces optical detection with ultrasonic detection using silicon-based transducers. This substitution eliminates sensitivity to external light while maintaining relatively simple device structure. The ultrasonic waves penetrate the finger ridge and valley structures, providing accurate fingerprint identification independent of lighting conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If capacitive fingerprint identification is used, then device complexity is reduced, but identification accuracy decreases when fingers have oil or stains

Engineering Contradiction:

Improvesystem simplicityVSAvoidfingerprint identification accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces capacitive sensing with ultrasonic sensing using silicon-based MEMS devices. The ultrasonic waves can penetrate through oil and stains on the finger surface to detect the underlying fingerprint patterns, maintaining high accuracy while keeping the device structure relatively simple through integration with standard semiconductor processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 device provides high identification accuracy and flexibility, overcoming light and contamination issues, with a simpler structure and lower cost compared to PVDF-based systems, enabling large-area and high-resolution fingerprint imaging.

Implementation Method 1

ultrasonic fingerprint identification technology relies on characteristics of ultrasonic wave with good penetrability, short wavelength and high energy

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

The first ultrasonic transducer includes a first electrode, a first vibrating film layer and a second electrode stacked on the side of the thin film transistor circuit facing away from the substrate

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentUS20250360537A1Ultrasonic transducer device and display apparatus

Publication Date: 2025.11.27 BEIJING BOE TECH DEV CO LTD

AI summary

An ultrasonic transducer device, including a base substrate, the base substrate including multiple ultrasonic units distributed in an array, and each ultrasonic unit including: a thin film transistor circuit disposed on the base substrate; at least one first ultrasonic transducer, disposed at a side of the thin film transistor circuit facing away from the base substrate, the first ultrasonic transducer including a first electrode, a first vibrating film layer and a second electrode stacked on the side of the thin film transistor circuit facing away from the base substrate, a cavity being provided between the first electrode and the first vibrating film layer, the first electrode being electrically connected to the thin film transistor circuit, and the second electrode being electrically connected to a driving voltage wire.