Staggered CMUT Array on Flexible Foil for Catheter Imaging

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Solution Overview

Problem

Intra-cardiac ultrasonic imaging catheters face challenges in achieving high resolution and deep penetration due to limited acoustic penetration and the need for high-density transducer arrays, which are hindered by the discontinuity between neighboring CMUT arrays and the rigidity of rectangular silicon islands.

Innovation Solution

A CMUT transducer array is designed with staggered rows of cells on flexible silicon islands, connected by a flexible foil with conductive interconnects, allowing for a continuous, curved array that can be wrapped around a catheter without discontinuities, enhancing image quality and reducing grating lobes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If CMUT arrays are arranged in a standard grid pattern on rigid silicon islands, then manufacturing is simplified, but the array cannot be wrapped around a catheter and creates discontinuities between neighboring arrays

Engineering Contradiction:

Improvearray fabricationVSAvoidarray flexibility and continuity

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The silicon substrate is divided into multiple separate silicon islands, each carrying a portion of the CMUT array. This segmentation allows each island to be independently handled and positioned, enabling the array to be wrapped around the catheter in a curved configuration while maintaining electrical connections through the flexible foil substrate.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A flexible foil substrate is used to mount the silicon islands and provide electrical interconnections. This flexible film allows the rigid silicon islands to be positioned in a curved arrangement around the catheter while maintaining structural integrity and electrical continuity, resolving the contradiction between rigidity for manufacturing and flexibility for catheter integration.

Inventive Principle:

Principle #30Flexible shells and thin films

2Measurement precision

If the pitch between CMUT cells is reduced to improve resolution, then image quality improves, but the array becomes more complex and difficult to manufacture

Engineering Contradiction:

Improveimaging resolutionVSAvoidarray structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The array transitions from a two-dimensional grid pattern to a curved three-dimensional arrangement around the catheter. This dimensional change allows the pitch between cells to be effectively reduced in the radial direction without proportionally increasing the complexity of the manufacturing process, as the curved geometry naturally provides better cell spacing and acoustic performance.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If discontinuities between neighboring arrays are eliminated to improve imaging, then image quality and continuity improve, but the structural complexity of the array increases

Engineering Contradiction:

Improveimaging qualityVSAvoidarray structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple silicon islands carrying CMUT elements are merged into a single integrated curved array structure through the flexible foil substrate. This merging eliminates the discontinuities between separate arrays while distributing the structural complexity across multiple manageable silicon islands, making the overall system both continuous and manufacturable.

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration enables improved imaging performance with reduced image artifacts and increased flexibility, allowing for both near and far-field imaging with enhanced structural integrity and flexibility, facilitating the generation of high-quality ultrasound images.

Implementation Method 1

This invention relates to medical diagnostic ultrasonic imaging and, in particular, to ultrasonic imaging catheters which use capacitive micromachined ultrasonic transducers (CMUTs)

Methodology Applied

Scientific EffectCapacitive micromachined ultrasonic transducer (CMUT):

Implementation Method 2

a flexible foil retaining the respective silicon islands, the flexible foil comprising conductive interconnects

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10555722B2Catheter transducer with staggered columns of micromachined ultrasonic transducers

Publication Date: 2020.02.11 KONINKLIJKE PHILIPS NV

AI summary

A CMUT transducer array comprising a first column (58) of spaced CMUT cells on at least one silicon island, a second column (58) of spaced CMUT cells on at least one further silicon island, the second column being staggered in alignment with the first column such that cells of the second column are partially located in spaces between successive cells of the first column, the first column and the second column being spaced apart by a gap, and a flexible foil retaining the respective silicon islands, the flexible foil comprising conductive interconnects.