Flexible Acoustic Sensor Stack for Curved-Surface Signal Fidelity
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Solution Overview
Problem
Existing acoustic sensors in flexible devices, such as foldable displays, suffer from reduced signal transmission and reception due to their inflexible nature, leading to suboptimal performance in fingerprint sensing and other biometric applications.
Innovation Solution
A flexible acoustic sensor system comprising a polyimide substrate and a stack of materials including a piezoelectric layer and acoustic transmitter/receiver elements, allowing the sensor to conform to curved surfaces and enhance signal propagation and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid acoustic sensors are used in flexible devices, then the sensor structure is simple and manufacturing is easy, but signal transmission and reception are reduced due to inflexibility
Solution Approach 1:
The patent employs flexible substrates made of polyimide or polyester materials that can bend and conform to curved surfaces while maintaining structural integrity. These flexible substrates support the acoustic sensor elements and enable the sensor to adapt to various device configurations without compromising signal transmission or reception capabilities.
Solution Approach 2:
The acoustic sensor system integrates multiple materials with complementary properties: piezoelectric materials for acoustic signal generation and detection, flexible substrates for mechanical support and bending, and acoustic coupling materials for efficient signal transmission. This composite structure resolves the contradiction by combining rigidity for signal fidelity with flexibility for adaptability.
2Adaptability or versatility
If the sensor is made flexible to conform to curved surfaces, then adaptability to flexible devices is improved, but manufacturing precision and assembly difficulty increase
Solution Approach 1:
The sensor system is divided into modular components including separate piezoelectric elements, flexible substrates, and acoustic coupling layers. This segmentation allows each component to be manufactured and tested independently with standard precision techniques, then assembled into the final flexible sensor system, reducing overall assembly complexity while maintaining conformability.
Solution Approach 2:
The sensor design incorporates dynamic flexibility where the flexible substrate and acoustic coupling materials can adapt their shape and stiffness characteristics during manufacturing and operation. This dynamic property allows the sensor to conform to curved surfaces without requiring ultra-precise manufacturing, as the flexible components can accommodate variations in shape and geometry.
3Adaptability or versatility
If acoustic sensor elements are integrated into flexible substrates, then device flexibility is improved, but signal sensitivity and fidelity are reduced
Solution Approach 1:
The patent introduces acoustic coupling materials as intermediaries between the piezoelectric elements and the flexible substrate. These coupling materials serve as a mediator that efficiently transmits acoustic signals while accommodating the flexibility of the substrate. The coupling materials compensate for potential signal loss by providing acoustic impedance matching and maintaining good acoustic contact even when the substrate is bent or deformed.
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 flexible sensor system maintains high resolution and reliability on curved surfaces, improving signal sensitivity and fidelity, enabling effective fingerprint sensing and biometric authentication in flexible devices.
Implementation Method 1
a piezoelectric layer disposed adjacent to the acoustic receiver element
Implementation Method 2
an acoustic transmitter element configured to transmit one or more acoustic signals through the flexible substrate
Implementation Method 3
an acoustic receiver element configured to detect one or more acoustic signals received through the flexible substrate
Data Source
AI summary
Flexible sensing apparatus and various configurations of sensor stacks associated therewith are disclosed. In some embodiments, an acoustic sensing system may include: a flexible substrate comprising polyimide and having a thickness between 5 and 80 μm; and a flexible acoustic sensor element disposed adjacent to the flexible substrate, and including a stack of materials, the stack of materials including: an acoustic receiver element configured to detect one or more acoustic signals received through the flexible substrate; a piezoelectric layer disposed adjacent to the acoustic receiver element; and an acoustic transmitter element configured to transmit one or more acoustic signals through the flexible substrate. The flexible substrate and the flexible acoustic sensor element may be configured to conform to a curvature of a surface that is constructed to contact a body part of a user from which the one or more acoustic signals transmitted from the acoustic transmitter element are reflected.