CMUT Array Fuse Segmentation for Cell Isolation
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Solution Overview
Problem
In ultrasonic transducer probes using micromachined ultrasonic transducers (MUTs), the failure of a single cell can short out hundreds or thousands of other cells due to high DC bias voltage, rendering the entire probe inoperative, and existing solutions complicate the array design and reduce sensitivity.
Innovation Solution
Each MUT cell in the array has a fuse coupled to its signal electrode that opens in case of an overcurrent condition, isolating the failed cell from the rest, allowing the remaining cells to operate without affecting their performance, and the fuses are formed on an application-specific integrated circuit (ASIC) to maintain high cell density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is placed at the end of a row or column of interconnected MUT cells to open when one cell shorts out, then the failed cell and its connected cells are removed from operation, but this removes a large number of functioning cells from operation and degrades the performance of the ultrasound probe
Solution Approach 1:
The patent segments the electrical connections so that each MUT cell has its own dedicated fuse and independent bias voltage supply, rather than sharing connections in rows or columns. This segmentation allows individual cell isolation without affecting other cells, resolving the contradiction between reliability and sensitivity by enabling failure containment to the single-cell level.
Solution Approach 2:
The patent applies local quality by providing each MUT cell with its own dedicated fuse and bias voltage supply, creating localized protection zones. This ensures that when one cell fails, only that specific local region is affected, while the rest of the array maintains full functionality, thus preserving overall transducer sensitivity while improving reliability.
2Reliability
If a fuse is provided for each row or column of interconnected MUT cells, then the complexity of providing bias voltages to all cells increases, but this also allows for simpler individual cell protection
Solution Approach 1:
The patent segments the bias voltage supply system so that each MUT cell receives its own dedicated bias voltage through separate supply circuits. This segmentation increases reliability by enabling independent cell protection, while the modular nature of the segmentation keeps the complexity manageable through systematic design.
Solution Approach 2:
Each MUT cell is equipped with its own fuse and bias voltage supply, making each cell self-protected and self-servicing. This self-service approach allows individual cells to be isolated upon failure without requiring complex centralized control systems, thereby improving reliability while keeping the overall system complexity distributed and manageable.
3Reliability
If a fuse occupies area on the MUT substrate, then individual cell protection is achieved, but this decreases the area available for MUT cells and hence reduces transducer sensitivity
Solution Approach 1:
The patent moves the fuse structures from the two-dimensional MUT substrate plane to the three-dimensional substrate cross-section by forming fuses in separate layers below or above the MUT cell array. This dimensional relocation preserves the宝贵 substrate area for MUT cells while still providing individual cell protection through vertically-integrated fuse structures.
Solution Approach 2:
The patent embeds the fuse structures within the substrate layers, nesting them beneath or above the MUT cell array. This nesting approach allows the fuses to occupy space in different vertical layers rather than competing for horizontal substrate area, thereby maintaining high MUT cell density while providing individual cell protection.
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 solution efficiently deactivates failed cells without affecting the operation of other cells, maintaining the high density and sensitivity of the MUT array, and minimizes the influence on the rest of the cells, thereby increasing the lifetime of the probe.
Implementation Method 1
The fuse is designed to melt when the current flow there through is great enough
Data Source
AI summary
An array of CMUT cells (10) has a DC bias voltage (VB) coupled to the top electrodes of the cells to bias the electrode to a desired collapsed or partially collapsed state. Fuses (200) are coupled in series with the bottom electrodes (22) of the cells which will open and isolate an individual cell from the other still-functional cells of the array in the event of a failure of the individual cell. In a preferred embodiment the cells are coupled to control integrated circuitry such as microbeamformer circuitry and the fuses are formed of semiconductor materials with the integrated circuitry, thereby leaving the MUT surface area available for high density MUT fabrication. Damage to the integrated circuitry due to short-circuiting of the DC bias current through a failed cell is prevented.