CMUT Probe Support Layer Isolates Reflection Stress
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Solution Overview
Problem
In photoacoustic imaging, the direct placement of a light reflection layer on a capacitive micromachined ultrasonic transducer (CMUT) causes stress that alters the spring constant and deformation of the vibration membrane, leading to decreased sensitivity and bandwidth due to noise generation from incident light.
Innovation Solution
A probe configuration with a capacitive transducer, an acoustic matching layer, and a support layer is used, where the light reflection layer is positioned on the support layer rather than directly on the transducer, minimizing its impact on the vibration membrane and maintaining sensitivity and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light reflection layer is arranged directly on the receive surface of the element, then the acoustic wave generated at the receive surface is restricted, but the stress of the light reflection layer causes a change in spring constant of the vibration membrane and a variation in deformation
Solution Approach 1:
A support layer is introduced as an intermediary component between the light reflection layer and the vibration membrane. The support layer carries the light reflection layer, preventing direct contact with the vibration membrane while still allowing the light reflection layer to fulfill its function of reflecting incident light. This mediator structure isolates the stress-inducing light reflection layer from the sensitive vibration membrane, thereby maintaining element reliability.
Solution Approach 2:
The probe structure is segmented into distinct functional layers: the vibration membrane for acoustic wave reception, the acoustic matching layer for acoustic impedance matching, and the support layer with integrated light reflection layer for light reflection. This segmentation separates the functions of light reflection and acoustic reception, allowing each component to optimize its performance without interfering with the other, thus resolving the contradiction between noise reduction and sensitivity maintenance.
2Object-affected harmful factors
If the light reflection layer is arranged directly on the receive surface, then light incident on the receive surface is prevented, but the deformation of the vibration membrane varies
Solution Approach 1:
The support layer serves as a mediator that carries the light reflection layer at a position separated from the vibration membrane. This intermediary structure prevents the stress from the light reflection layer from directly affecting the vibration membrane's deformation characteristics, thereby maintaining consistent deformation behavior while still preventing light-induced noise.
Solution Approach 2:
The probe is segmented into functionally independent layers where the light reflection layer is integrated into the support layer rather than being directly applied to the vibration membrane. This segmentation allows the vibration membrane to maintain its original deformation characteristics while the support layer with integrated light reflection layer performs the light reflection function, thus maintaining manufacturing precision.
3Object-affected harmful factors
If the light reflection layer is placed on the element, then the acoustic wave from incident light is restricted, but the bandwidth decreases
Solution Approach 1:
The support layer acts as an intermediary that enables the light reflection layer to be positioned near the receive surface without directly contacting the vibration membrane. This intermediary arrangement restricts acoustic wave noise while maintaining the vibration membrane's original mechanical properties and bandwidth characteristics, as the stress from the light reflection layer is isolated by the support layer.
Solution Approach 2:
The probe structure is segmented into distinct layers with the light reflection layer integrated into the support layer. This segmentation allows the light reflection function to be performed without the light reflection layer being directly coupled to the vibration membrane, thereby preventing bandwidth degradation while still restricting noise-generating acoustic waves from incident light.
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 effectively restricts the influence of the light reflection layer on the transducer, maintaining high sensitivity and bandwidth while preventing noise generation, allowing for effective photoacoustic wave reception.
Implementation Method 1
a light reflection layer (6) provided at a position near the object with respect to the element and configured to reflect light
Implementation Method 2
a vibration membrane (7) having one of a pair of electrodes formed with a gap arranged therebetween is supported so that the vibration membrane can be vibrated by the acoustic wave
Implementation Method 3
a capacitive transducer (33), in which a vibration membrane (7) having one of a pair of electrodes formed with a gap arranged therebetween is supported so that the vibration membrane can be vibrated
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A probe configured to receive an acoustic wave from an object including an element (1) having a cell structure (2), in which a vibration membrane (7) having one of a pair of electrodes formed with a gap arranged therebetween is supported so that the vibration membrane can be vibrated by the acoustic wave; a light reflection layer (6) provided at a position near the object with respect to the element and configured to reflect light; and a support layer (10) provided between the element and the light reflection layer and configured to support the light reflection layer.