Piezoelectric MEMS Actuation for Linear Deformation
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Solution Overview
Problem
MEMS devices face limitations in design flexibility and performance due to susceptibility to high actuation voltage and micro-fabrication complexity, especially as devices are miniaturized, affecting the accuracy of devices like Coriolis-effect-based vibratory gyroscopes, which require precise structural deformation for sensing functions.
Innovation Solution
The use of piezoelectric slabs with controlled electric fields applied through electrodes to induce desired stress on a base layer, allowing for controlled in-plane and out-of-plane deformation, enabling precise movement and sensing of a proof mass without the need for high actuation voltage or complex microfabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic forces are used to detect or actuate proof mass movement, then sensing or actuation function is achieved, but high actuation voltage and non-linearity over travel distances occur
Solution Approach 1:
The patent replaces electrostatic actuation and sensing mechanisms with piezoelectric mechanisms. The piezoelectric film converts electrical signals to mechanical deformation for actuation, and mechanical stress to electrical signals for sensing, eliminating the high voltage and non-linearity issues inherent in electrostatic systems.
Solution Approach 2:
The patent changes the physical mechanism from electrostatic to piezoelectric, fundamentally altering how actuation and sensing are achieved. This parameter change enables linear response characteristics and eliminates the pull-in effect and high voltage requirements of electrostatic systems.
2Reliability
If comb drive or parallel plate designs are used, then actuation and sensing are achieved, but micro-fabrication process complexity increases
Solution Approach 1:
The patent replaces complex electrostatic structures (comb drives, parallel plates) with a simpler piezoelectric film layer integrated into the beam structure. This substitution dramatically reduces micro-fabrication complexity while maintaining actuation and sensing functions.
Solution Approach 2:
The patent uses a composite structure where a piezoelectric film is integrated with the mechanical beam structure. This composite approach combines structural and actuation/sensing functions into a single integrated component, reducing the number of separate elements and fabrication steps required.
3Volume of moving object
If device size is miniaturized, then integration and portability are improved, but performance decreases
Solution Approach 1:
The patent changes the actuation mechanism to piezoelectric, which provides higher force density and more linear response compared to electrostatic mechanisms. This enables miniaturized devices to maintain or improve performance as size decreases, reversing the typical scaling trend.
Solution Approach 2:
The integrated piezoelectric film-structure composite enables miniaturization while maintaining performance by combining structural support and actuation/sensing functions in a single lightweight component, improving the performance-to-size ratio.
4Measurement precision
If specialized structural deformation is required for sensing functions, then sensing accuracy is improved, but design flexibility is reduced
Solution Approach 1:
The patent makes the beam structure dynamic and adaptable by using piezoelectric actuation to achieve precise controlled deformations. The same piezoelectric mechanism can produce different deformation modes (transversal bending, longitudinal bending, torsional bending) by changing the actuation pattern, enabling a single structure to serve multiple sensing functions.
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 allows for high-efficiency transduction with linear input voltage and output stress, reducing manufacturing complexity and avoiding non-linearity issues, thereby enhancing the performance and adaptability of MEMS devices, especially in smaller scales.
Implementation Method 1
a first piezoelectric film on the first bottom electrode... a second piezoelectric film connected to the first piezoelectric film... applying a voltage to the first and second piezoelectric films causes the beam to bend
Implementation Method 2
applying a voltage to the first and second piezoelectric films causes the beam to bend
Data Source
Figure 1~8
Figure 4~6
Figure 9~15
AI summary
In one embodiment, a method of deforming a MEMS structure includes providing a base layer (102), providing a first piezoelectric slab (106, 108, 110, 112) operably connected to a surface of the base layer (102), determining a desired deformation of the base layer, applying a first potential to a first electrode operably connected to the first piezoelectric slab, applying a second potential to a second electrode operably connected to the first piezoelectric slab (106, 108, 110, 112), and deforming the base layer (102) with the first piezoelectric slab (106, 108, 110, 112) using the applied first potential and the applied second potential based upon the determined desired deformation.