Curved MEMS Membrane Spring With Preload for Large Deflection
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Solution Overview
Problem
Conventional MEMS sensors and actuators face challenges due to the small deflections of mechanically elastically deformable elements, leading to low electrical signals and limited force generation. Additionally, these components are prone to destruction during production or use due to their fineness.
Innovation Solution
The development of micromechanical membrane springs with a two-dimensional curvature, comprising a first membrane spring element with a linear characteristic curve and a second membrane spring element with a nonlinear characteristic curve. These elements are mechanically coupled to produce a resulting spring force suitable for MEMS components, and a preloading device is used to set a permanent elastic deflection, reducing stiffness and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional mechanically elastically deformable elements are used, then the structure is simple and easy to manufacture, but the deflection is small leading to low electrical signals and limited force generation
Solution Approach 1:
The membrane spring is divided into multiple independent membrane spring elements (first membrane spring element with linear characteristic and second membrane spring element with nonlinear characteristic) that are mechanically coupled together. This segmentation allows each element to contribute differently to the overall spring force, enabling enhanced force generation while maintaining manufacturability through standardized element designs.
Solution Approach 2:
The membrane spring combines different types of spring elements (linear and nonlinear characteristic curves) into a composite structure. This composite approach allows the system to exhibit complex spring behavior that cannot be achieved with a single element type, thereby increasing spring force output without proportionally increasing structural complexity.
2Force
If very soft beams or membranes are produced to achieve desired dimensions, then the deflection increases, but the structures are easily destroyed during production or use due to overload
Solution Approach 1:
The spring characteristic curve is modified by combining linear and nonlinear elements, creating a progressive spring behavior. This allows the membrane spring to be preloaded into a stiffness range with a small gradient, reducing the risk of overload destruction while maintaining the ability to generate sufficient spring force during operation. The parameter change in spring characteristic enables both softness for deflection and robustness against overload.
3Length of moving object
If the stiffness of the membrane spring is reduced to enable larger movement amplitudes, then the movement amplitude increases, but the spring force generation capability decreases
Solution Approach 1:
The membrane spring system dynamically adjusts its effective stiffness through the combination of linear and nonlinear elements. During operation, as the membrane deflects, the nonlinear elements engage progressively, maintaining force generation capability even at large movement amplitudes. This dynamic behavior allows large deflections without proportionally losing spring force capability.
Solution Approach 2:
The progressive engagement of different membrane spring elements during deflection creates a periodic contribution to spring force. As the membrane moves through its range, different elements become active, ensuring continuous force generation throughout the movement amplitude range rather than relying on a single stiffness characteristic.
4Ease of manufacture
If disk springs are mounted loosely to allow deformation, then the structure is simple, but friction occurs at mounting points which is undefined and excludes them from use in MEMS sensors or actuators
Solution Approach 1:
The mounting structure is extracted from the spring element itself. The membrane spring elements are designed to be integrated directly into the layer structure of the MEMS component, eliminating separate mounting points. This integration removes the source of undefined friction while maintaining ease of manufacture through direct structural incorporation rather than separate assembly steps.
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
The proposed solution enables MEMS sensors and actuators to achieve larger movement amplitudes and increased robustness against overload, while also reducing the stiffness of the membrane spring during operation, thus facilitating a wide range of applications.
Implementation Method 1
a first membrane spring element, preferably with a linear characteristic curve, and a second membrane spring element, preferably with a nonlinear characteristic curve
Implementation Method 2
The preloading device is configured to set a permanent elastic deflection of the membrane spring
Data Source
AI summary
A MEMS component. The MEMOS component includes a micromechanical membrane spring including first and second membrane spring elements with an at least regional two-dimensional curvature. The first membrane spring element is mechanically coupled to the second membrane spring element such that a resulting spring force of the membrane spring is imparted by the first and second membrane spring elements. The membrane spring is integrated into a layer structure of the MEMS component such that the resulting spring force of the membrane spring acts substantially in the layer sequence direction of the layer structure. A device for preloading the membrane spring is configured to set an operating point of the membrane spring with respect to the spring characteristic curve using permanent elastic deflection of the membrane spring, such that the operating point is in an approximately linear spring characteristic curve range of the membrane spring with a slight gradient.