Flexible Poly-CMUT Arrays for X-Ray Compatible Ultrasound Imaging
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Solution Overview
Problem
Piezoelectric-based ultrasound transducers face challenges in fabricating large two-dimensional arrays due to interconnection and integration issues, and there is a mismatch in acoustic impedance between the transducers and target materials, necessitating additional layers that complicate the system.
Innovation Solution
Development of polymer-based capacitive micromachined ultrasonic transducers (poly-CMUTs) with a flexible substrate that are at least 77.4% transparent to ionizing radiation, featuring an array of transducers with electrical interconnections and walls to reduce acoustic cross-coupling, allowing for flexible and scalable manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric materials are used for ultrasound transducers, then mature technology and reliable performance are achieved, but fabrication of large two-dimensional arrays becomes difficult due to interconnection and integration challenges
Solution Approach 1:
The patent changes the fundamental material parameter from piezoelectric materials to capacitive micromachined ultrasonic transducer (CMUT) technology. This parameter change enables large two-dimensional arrays to be fabricated using standard semiconductor manufacturing processes, thereby improving ease of manufacture while maintaining reliable transducer performance through the mature CMUT fabrication infrastructure.
2Loss of energy
If piezoelectric crystals are used as transducer material, then effective acoustic power transfer is achieved, but acoustic impedance mismatch with target materials requires additional matching layers that complicate the system
Solution Approach 1:
The patent changes the transducer material parameter from piezoelectric materials to polymer-based CMUT membranes. This parameter change inherently reduces acoustic impedance mismatch with soft tissue and biological materials, eliminating or simplifying the need for acoustic matching layers and thereby reducing device complexity while maintaining effective acoustic power transfer.
Solution Approach 2:
The patent employs composite material structures in the CMUT design, combining polymer membranes with metallic electrodes and integrated circuitry. This composite approach enables direct coupling to target materials with reduced impedance mismatch, eliminating the need for separate matching layers and simplifying the overall system structure.
3Measurement precision
If traditional ultrasound transducers are used, then ultrasound imaging capability is achieved, but compatibility with x-ray imaging is limited due to lack of transparency to ionizing radiation
Solution Approach 1:
The patent changes the material composition parameter of the transducer from traditional opaque materials to polymer-based materials that are transparent to ionizing radiation. This parameter change enables the transducer to be compatible with both ultrasound imaging and x-ray imaging modalities, allowing for integrated multimodal imaging systems without compromising ultrasound imaging precision.
4Stability of the object's composition
If rigid substrates are used for transducer arrays, then structural stability is maintained, but flexibility and scalability for various applications are reduced
Solution Approach 1:
The patent employs flexible polymer substrates and thin-film CMUT structures instead of rigid substrates. This enables the transducer arrays to be conformally applied to curved surfaces and integrated into wearable devices while maintaining structural stability through the inherent mechanical properties of the polymer materials and the robustness of the CMUT design.
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 poly-CMUTs provide efficient ultrasound imaging with reduced manufacturing costs, flexibility, and compatibility with x-ray imaging, overcoming the limitations of piezoelectric transducers by minimizing impedance mismatch and enabling roll-to-roll fabrication.
Implementation Method 1
Capacitive Micromachined Ultrasound Transducers (CMUTs) are deemed to be an alternative technology to the current piezoelectric-based transducers
Implementation Method 2
alternately, ultrasound waves can be detected by measuring the variation in capacitance of the device while a DC voltage is applied in the presence of incoming ultrasound
Implementation Method 3
an array of polymer-based capacitive micromachined ultrasonic transducers positioned on the substrate, the array comprising a first row of the transducers and electrical interconnections electrically connecting the transducers of the first row in series; wherein the substrate is an underlying layer upon which the transducers are fabricated
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
An apparatus comprising an array of polymer-based capacitive micromachined ultrasonic transducers positioned on a substrate. The substrate may be at least substantially transparent to ionizing radiation, be flexible, and/or have walls positioned thereon to protect the transducers.