CMUT Ultrasonic Sensor Segmented Electrode Voltage Control
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Solution Overview
Problem
Existing capacitive micromachined ultrasonic transducers (CMUTs) face challenges in generating sufficient membrane vibration for effective ultrasound wave generation and reception, due to the inability to separately control DC and AC voltages applied to the same electrode, leading to distortion and insufficient signal amplitude.
Innovation Solution
The ultrasonic sensor employs a layered structure with separate metal layers for receiving DC and AC voltages, utilizing a thin-film transistor to control the application of DC voltage to the second metal layer, allowing for precise timing and separation of voltage applications during transmission and reception modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If both DC voltage and AC voltage are applied to the same electrode in the membrane to generate sufficient membrane vibration, then the membrane vibration amplitude is improved, but the control precision deteriorates because they cannot be controlled separately
Solution Approach 1:
The patent divides the electrode structure into multiple separate electrodes: a first electrode for applying DC voltage and a second electrode for applying AC voltage. This segmentation allows independent control of DC and AC voltages, resolving the contradiction between achieving sufficient membrane vibration and maintaining precise voltage control.
2Measurement precision
If DC voltage is applied to the electrode in the membrane during receive mode to generate sufficient membrane vibration, then the signal amplitude is improved, but the image quality deteriorates due to switching time causing distortion
Solution Approach 1:
By separating the DC voltage application electrode from the AC voltage application electrode, the patent enables independent control of voltage application timing. This allows the system to apply DC voltage during receive mode without the switching delays that occur in integrated designs, thereby maintaining both high signal amplitude and image quality.
Solution Approach 2:
The patent introduces a control circuit as an intermediary that independently manages the application of DC and AC voltages to different electrodes. This intermediary control mechanism eliminates switching delays and prevents image distortion while maintaining sufficient signal amplitude.
3Device complexity
If only AC voltage is applied to the electrode in the membrane, then the device complexity is reduced, but the membrane vibration is insufficient for effective ultrasound generation
Solution Approach 1:
The patent segments the voltage application function into two separate electrodes: one for DC voltage and one for AC voltage. This segmentation achieves sufficient membrane vibration without significantly increasing device complexity, as both electrodes can be integrated into the existing CMUT structure.
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 enables accurate control of membrane vibration, improving the generation and reception of ultrasound waves, thereby enhancing the signal-to-noise ratio and reducing distortion in ultrasonic imaging.
Implementation Method 1
A capacitive micromachined ultrasonic transducer (CMUT) is a type of ultrasonic transducer that uses the principle of capacitance to generate and detect ultrasound waves
Implementation Method 2
The AC voltage causes the membrane to vibrate, generating ultrasound waves
Implementation Method 3
The DC voltage causes the membrane to deflect towards the ground electrode
Implementation Method 4
The distance between the membrane and the ground electrode changes due to the ultrasound waves, which causes a corresponding change in the capacitance between the membrane and the ground electrode and the amount of charges stored on the electrode in the membrane
Data Source
AI summary
An ultrasonic sensor has a capacitance micromachined ultrasonic transducer (CMUT) with three metal layers and four insulating layers. A first metal layer receives a reference voltage, a second metal layer receives a direct current voltage, and a third metal layer receives an alternating current voltage. A cavity formed between the first metal layer and the second metal layer allows for mechanical vibration of the CMUT, which generates ultrasonic waves.