CMUT Electrode Layout for Dual-Mode Ultrasonic Actuation
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Solution Overview
Problem
Conventional capacitive micromachined ultrasonic transducers (CMUTs) face limitations in achieving high transmit bandwidth and efficient operation due to their design, particularly in medical imaging and other applications, where they struggle with dual out-of-plane and in-plane actuation and displacement.
Innovation Solution
The design incorporates a capacitive transducer with a plate and substrate configuration that includes a protruding center mass and depression, with specific electrode arrangements for direct current (DC) and alternative current (AC) signal application, enabling dual out-of-plane and in-plane actuation. This configuration allows for orthogonal and parallel actuation directions, enhancing electromechanical coupling and allowing operation in both conventional and mechanical collapse modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional CMUT design is used, then device simplicity is maintained, but transmit bandwidth is limited
Solution Approach 1:
The electrode structure is segmented into multiple independent electrodes (first electrode on center mass, second electrode on depression, third and fourth electrodes on horizontal surfaces) that can be independently controlled. This segmentation enables multiple actuation modes (conventional and mechanical collapse) and frequency operations, thereby increasing transmit bandwidth without requiring complete redesign of the device architecture.
Solution Approach 2:
The patent implements dynamic operation by allowing the CMUT to switch between two distinct actuation modes: conventional mode where the center mass oscillates above the depression, and mechanical collapse mode where the center mass contacts the depression bottom. This dynamic switching capability expands the operational bandwidth while maintaining a relatively simple underlying device structure.
2Reliability
If dual actuation modes are implemented, then electromechanical coupling is enhanced, but device structure becomes more complex
Solution Approach 1:
The CMUT device structure is designed to perform multiple functions through a single unified architecture. The same device can operate in both conventional actuation mode (for standard imaging) and mechanical collapse mode (for enhanced coupling applications), making the device universally applicable across different performance requirements without needing separate specialized devices.
Solution Approach 2:
The patent introduces a vertical dimension to the actuation mechanism by enabling the center mass to move from oscillating above the depression (conventional mode) to contacting the depression bottom (collapse mode). This dimensional transition adds operational versatility and enhances electromechanical coupling while utilizing the same physical structure.
3Adaptability or versatility
If mechanical collapse mode is enabled, then bandwidth is increased, but manufacturing precision requirements increase
Solution Approach 1:
The depression structure acts as a pre-designed mechanical cushion or stop that guides the center mass into proper contact during collapse mode operation. This pre-configured geometric feature ensures that even with variations in manufacturing precision, the center mass will reliably contact the depression bottom at the correct location, enabling mechanical collapse mode functionality without requiring extremely tight manufacturing tolerances.
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 solution enables higher transmit bandwidth and efficient operation in both conventional and mechanical collapse modes, improving the performance of CMUTs in medical imaging and other applications by optimizing actuation and displacement mechanisms.
Implementation Method 1
a first electrode coupled to a non-horizontal edge surface of the center mass and a second electrode coupled to a non-horizontal edge surface of the center depression
Implementation Method 2
a third electrode coupled to a horizontal edge surface of the center mass and a fourth electrode coupled to a horizontal edge surface of the center depression
Implementation Method 3
The capacitive transducer includes a plate including a protruding center mass and a substrate with a center depression configured to accept the center mass
Data Source
AI summary
A capacitive transducer is provided. The capacitive transducer includes a plate including a protruding center mass and a substrate with a center depression configured to accept the center mass. The capacitive transducer also includes a first electrode coupled to a non-horizontal edge surface of the center mass and a second electrode coupled to a non-horizontal edge surface of the center depression. The capacitive transducer further includes a third electrode coupled to a horizontal edge surface of the center mass and a fourth electrode coupled to a horizontal edge surface of the center depression. The plate is coupled to the substrate at least along an outer perimeter area of the plate and the substrate.