Flexible PMUT Array for Implantable Ultrasonic Imaging
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Solution Overview
Problem
Conventional ultrasonic transducer devices are rigid and large, making them unsuitable for implantable or ingestible non-invasive imaging applications, and existing solutions fail to provide a flexible ultrasonic transducer array that can be packaged into small devices for such uses.
Innovation Solution
A flexible piezoelectric micromechanical ultrasonic transducer (PMUT) array is developed, which includes a method of forming PMUTs with a carrier, release layer, laminating polymer layers for support, depositing sacrificial materials to create cavities, and forming electrodes and piezoelectric layers to enable flexible and adjustable frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ultrasonic transducer devices are used, then ultrasonic imaging function is provided, but the devices are rigid and large in size making them unsuitable for implantable or ingestible applications
Solution Approach 1:
The patent applies this principle by replacing rigid transducer structures with flexible polymer layers and thin-film piezoelectric membranes. The PMUT device uses a flexible substrate with laminated polymer layers that provide both structural support and flexibility, enabling the device to conform to curved surfaces and be suitable for implantable or ingestible applications while maintaining ultrasonic imaging functionality
Solution Approach 2:
The patent divides the ultrasonic transducer into multiple discrete PMUT elements arranged in an array on a flexible substrate. Each PMUT element consists of separate functional layers (piezoelectric layer, electrodes, cavity structure) that can be independently fabricated and then integrated. This segmentation allows the large functional area to be distributed across multiple small elements on a flexible platform, reducing overall device rigidity and size
2Adaptability or versatility
If tube/wire based ultrasonic transducer insertion methods are used, then transducer insertion is achieved, but the devices require external support structures making them unsuitable for implantable or ingestible applications
Solution Approach 1:
The patent merges the ultrasonic transducer elements directly onto a flexible polymer substrate, eliminating the need for separate tube or wire support structures. The flexible substrate itself provides the mechanical support and flexibility needed for insertion, combining the functions of structural support and transducer mounting into a single integrated flexible platform that can be easily inserted or implanted without external assistance
Solution Approach 2:
The flexible polymer substrate acts as an intermediary between the rigid piezoelectric elements and the human body environment. This flexible intermediate layer allows the rigid transducer elements to be mounted on a flexible platform that can navigate through body passages or conform to tissue surfaces, eliminating the need for rigid tube/wire support structures
3Adaptability or versatility
If flexible PMUT array is developed for implantable or ingestible devices, then adaptability for non-invasive imaging is improved, but manufacturing complexity increases due to multiple deposition and lamination steps
Solution Approach 1:
The patent uses a sacrificial layer that is deposited and patterned before the final device assembly. This sacrificial layer defines the cavity structure in advance, and is subsequently removed to create the acoustic cavity. This preliminary action simplifies the overall manufacturing process by establishing the three-dimensional cavity structure during the planar fabrication process, avoiding complex post-assembly cavity formation steps
Solution Approach 2:
The patent extracts and removes the sacrificial layer after it has served its purpose of defining the cavity structure. This removal step cleanly separates the cavity formation from the device assembly process, allowing the flexible PMUT array to be manufactured using standard thin-film deposition techniques followed by a simple sacrificial layer removal, thereby managing manufacturing 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 flexible PMUT array can be adapted for implantable, ingestible, or wearable devices, offering improved flexibility and frequency response, suitable for non-invasive imaging and monitoring applications.
Implementation Method 1
a piezoelectric layer configured to separate the first electrode and a second electrode
Implementation Method 2
the membrane being configured to undergo one or both of flexural motion and vibration when the PMUT receives or transmits ultrasonic signals
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 1F~1G
AI summary
Embodiments of a flexible PMUT array and methods for manufacturing the same are disclosed. In one embodiment, a piezoelectric micromechanical ultrasonic transducer (PMUTs) array comprises a plurality of PMUTs, where each PMUT in the flexible array of PMUTs includes: a first polymer layer configured to support the PMUT, a mechanical layer configured to provide planarization to the PMUT, a first electrode, a second electrode, a piezoelectric layer configured to separate the first electrode and the second electrode, patterns on the first electrode, the piezoelectric material, and the second electrode configured to route electrical signals, and a cavity configured to adjust a frequency response of the PMUT.