Stacked-Membrane Ultrasonic Transducer with Electrostatic Coupling
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Solution Overview
Problem
Existing ultrasonic transducers face limitations in power and efficiency, particularly in membrane-based designs, due to suboptimal force transfer and potential damage from high actuation voltages.
Innovation Solution
A stack of membranes with electrodes configured to apply varying electric signals during vibration cycles, utilizing electrostatic and piezoelectric forces to enhance vibration amplitude and power, with asymmetry in displacement improving bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the actuation signal is matched to the resonance frequency of the membrane or the amplitude of the electrical signal is increased to increase vibration amplitude, then the vibration amplitude increases, but the actuation mechanism may be damaged due to maximum voltage limits and force transfer may be suboptimal
Solution Approach 1:
The patent combines piezoelectric and electrostatic actuation mechanisms into a single transducer system. The piezoelectric layer provides primary actuation while the electrostatic interaction between membranes provides additional force amplification, achieving higher vibration amplitudes without exceeding voltage limits on individual actuation mechanisms.
Solution Approach 2:
The transducer uses a composite structure with piezoelectric material layers integrated between flexible membranes. This composite design allows the system to leverage both the high strain capability of piezoelectric materials and the mechanical amplification of flexible membranes, achieving high vibration amplitudes with reduced stress on individual components.
2Power
If a single piezoelectric transducer is used to actuate the membrane, then the structure is simple, but the force transfer to effect vibration is suboptimal and power is limited
Solution Approach 1:
The patent merges piezoelectric and electrostatic actuation in a single integrated device. Multiple membranes with electrodes create electrostatic interactions that amplify the force generated by the piezoelectric transducer, resulting in higher power output without requiring a fundamentally more complex actuation architecture.
Solution Approach 2:
The patent introduces electrostatic interaction as an additional dimension of force generation alongside piezoelectric actuation. By applying voltages to electrodes on opposing membranes, the system creates electrostatic attraction/repulsion forces that act in conjunction with piezoelectric deformation, effectively adding another force vector to the actuation mechanism.
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
Enhances vibration amplitude and power in ultrasonic transducers, potentially increasing bandwidth and efficiency by leveraging electrostatic and piezoelectric interactions between membranes.
Implementation Method 1
actuation can be effected by a piezoelectric transducer coupled to the membrane. Depending on the electrical signal, the piezoelectric material may expand or contract which can result in vibration of the membrane
Implementation Method 2
The first electrode on the first membrane is configured to interact with the second electrode on the second membrane by a varying electrostatic force during the respective vibration cycle depending on the varying voltage
Data Source
AI summary
An ultrasonic transducer is described that includes a stack of at least two membranes attached to a substrate. An electric circuit is coupled to the electrodes with a controller configured to apply a first electric signal to a first electrode on the first membrane, and a different, second electric signal to a second electrode on the second membrane. The first and second electric signals are configured to apply a varying voltage between the first electrode and the second electrode during a respective vibration cycle of the membranes. The first electrode on the first membrane is configured to interact with the second electrode on the second membrane by a varying electrostatic force during the respective vibration cycle depending on the varying voltage.