CMUT Charging Voltage Source for Dielectric Management
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Solution Overview
Problem
Capacitive micro-machined ultrasound transducer (CMUT) devices face limitations in acoustic pressure output and receive sensitivity due to dielectric layer charging effects, which reduce efficiency and reliability when excessive operating bias voltages are applied.
Innovation Solution
The solution involves intentionally applying a charging voltage with reverse polarity to the dielectric layers during non-operation phases to create a semi-permanent charge, which increases output pressure and receive sensitivity when combined with the operating bias voltage, and using a control unit to manage and monitor this charging effect for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If excessive operating bias voltage is applied to increase acoustic pressure output, then the acoustic pressure output is improved, but the dielectric layers become permanently charged which reduces device efficiency and reliability
Solution Approach 1:
The patent applies preliminary charging action by intentionally charging the dielectric layers before normal operation using a dedicated charging voltage source. This preliminary charging establishes the desired electric field distribution in advance, allowing the CMUT to achieve high acoustic pressure output during operation without requiring excessive operating bias voltage that would cause harmful permanent charging during operation.
Solution Approach 2:
The patent implements preliminary anti-action by applying a charging voltage with polarity opposite to the operating bias voltage. This opposite polarity charging counteracts the harmful permanent charging effect that would otherwise occur during high-voltage operation, thereby preventing efficiency degradation while still enabling high acoustic pressure output when needed.
2Stress or pressure
If excessive operating bias voltage is applied to increase acoustic pressure output, then the acoustic pressure output is improved, but the membrane may collapse to the substrate causing electrical contact between electrodes
Solution Approach 1:
The patent applies preliminary action by establishing the appropriate electric field in the dielectric layers through dedicated charging before operation. This preliminary field configuration provides the necessary electrostatic support to maintain membrane position during operation, enabling high acoustic pressure output without requiring excessive operating bias voltage that would cause membrane collapse.
3Object-affected harmful factors
If dielectric layers are used to prevent electrode contact, then membrane collapse is prevented, but the device efficiency is reduced due to permanent charge accumulation
Solution Approach 1:
The patent implements preliminary anti-action by applying charging voltage with opposite polarity to counteract the harmful permanent charge accumulation in the dielectric layers. This approach maintains the protective function of the dielectric layers in preventing electrode contact while simultaneously eliminating the efficiency-reducing charge accumulation through the opposite polarity charging process.
4Stress or pressure
If operating bias voltage is increased to improve acoustic pressure output, then the output pressure is improved, but receive sensitivity decreases due to dielectric layer charging
Solution Approach 1:
The patent applies preliminary action by establishing the optimal electric field distribution in the dielectric layers through dedicated charging before operation. This preliminary field setup enables the device to achieve both high output pressure during transmission and high receive sensitivity during reception, without the trade-off that occurs when relying solely on increased operating bias voltage.
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 approach significantly enhances the CMUT device's output pressure and receive sensitivity by leveraging trapped charges in the dielectric layers, allowing for higher effective forces on the membrane and improved reliability, while maintaining flexibility and cost-effectiveness.
Implementation Method 1
supplying an additional charging voltage between the first and second electrode, the second polarity being the reverse polarity of the first polarity
Implementation Method 2
leveraging trapped charges in the dielectric layers, allowing for higher effective forces on the membrane
Implementation Method 3
Capacitive micro-machined ultrasound transducer (CMUT) device for transmitting and/or receiving ultrasound
Data Source
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AI summary
The present invention relates to a capacitive micro-machined ultrasound transducer (CMUT) device (1) for transmitting and/or receiving ultrasound waves, comprising at least one CMUT cell (10). The CMUT cell (10) comprises a substrate (13) comprising a first electrode (22), a membrane (15) comprising a second electrode (20), at least one dielectric layer (21, 23) between the first electrode (22) and the second electrode (20), and a cavity (18) formed between the substrate (13) and the membrane (15). The CMUT device (1) further comprises an operating bias voltage source (25) for supplying an operating bias voltage (VB) of a first polarity between the first and second electrode (20, 22) during transmitting and/or receiving ultrasound waves, and a charging voltage source (30) for supplying an additional charging voltage (VC) between the first and second electrode (20, 22), the second polarity being the reverse polarity of the first polarity. The present invention further relates to a method of operating such a CMUT device.