Air-Coupled cMUT Ear Canal Transducer for Fluid Detection
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Solution Overview
Problem
Conventional ultrasound transducers face challenges in achieving sufficient intensity, spatial coherence, small divergence, and phase stability when used in air-coupled applications, particularly for characterizing fluids behind biological membranes, due to impedance mismatch and scattering issues.
Innovation Solution
Development of a capacitive micro-machined ultrasound transducer (cMUT) with a small base size, capable of operating through air, featuring an angular beam spread greater than 15 degrees and attenuation loss greater than 10 dB, and comprising multiple capacitive ultrasound elements with specific design features such as openings and hexagonal packing, to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid structure is used to maintain transducer array geometry, then structural stability is improved, but the ability to conform to curved surfaces or accommodate motion is worsened
Solution Approach 1:
The patent employs a flexible membrane structure that can conform to curved surfaces while maintaining transducer array geometry. The membrane acts as a flexible shell that provides mechanical support and maintains the relative positions of transducers, yet allows the array to adapt to different surface geometries and accommodate motion between the transducer array and the surface being scanned.
2Manufacturing precision
If individual piezoelectric elements are used, then manufacturing precision and element control are improved, but device complexity and manufacturing cost are worsened
Solution Approach 1:
The patent divides the piezoelectric material into multiple discrete elements within a single integrated membrane structure. This segmentation allows precise control of individual elements while maintaining a unified manufacturing process. The membrane can be manufactured as a single component with pre-positioned elements, reducing assembly complexity while preserving the benefits of individual element control for focused ultrasound beamforming.
3Manufacturing precision
If a fixed transducer array is used, then manufacturing precision is improved, but adaptability to different scanning scenarios is worsened
Solution Approach 1:
The patent transitions from a fixed rigid array to a dynamic flexible membrane structure. The membrane can deform and adapt its shape while maintaining the relative geometric relationships between transducer elements. This dynamic capability allows the array to conform to different surface geometries and accommodate relative motion between the transducer array and the surface being scanned, while manufacturing precision is maintained through controlled fabrication processes.
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 cMUT achieves improved signal-to-noise ratio, fractional bandwidth, and projected intensity, enabling effective characterization of fluids behind membranes with high precision and stability, suitable for applications like otitis media diagnosis.
Implementation Method 1
The ultrasound transducer array includes a flexible membrane including a plurality of piezoelectric elements arranged in a two-dimensional array on the membrane
Implementation Method 2
generating an ultrasound wave having a frequency above the audible range of human hearing
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
An ultrasound transducer may include: a plurality of capacitive ultrasound transducer elements; and a base having a largest dimension sized and shaped to be disposed with an external ear canal, wherein the plurality of capacitive ultrasound transducers is mounted on the base. Each capacitive ultrasound transducer element and the ultrasound transducer are specifically constructed to achieve select desired performance characteristics. The ultrasound transducer may have an angular beam spread through a gaseous medium of greater than 15 degrees and an attenuation loss through the gaseous medium of greater than 10 dB measured at a distance 12.5 mm to 25 mm along a primary transmission axis of the ultrasound transducer. The ultrasound transducer may be particularly useful for characterizing fluid behind an ear drum to diagnose otitis media.