MEMS Filter Isolation Platform with Segmented Resilient Springs
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Solution Overview
Problem
Conventional RF filters in MEMS devices face a tradeoff between mechanical spring stiffness and actuation voltage, where stiffer springs require higher voltages to move the truss comb structure, making the system susceptible to external vibrations and occupying significant space, which is undesirable, especially in applications like in-vivo biomedical uses.
Innovation Solution
The implementation of a MEMS device with a mechanically suspended filter system using an isolation platform and resilient interconnections to absorb vibrations, allowing for reduced spring stiffness and lower actuation voltages, while maintaining mechanical stability and compactness by suspending the filter above a substrate with gas gaps and resilient interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring stiffness is increased to reduce susceptibility to external vibrations, then the mechanical stability is improved, but the actuation voltage required to move the truss comb structure increases dramatically
Solution Approach 1:
The resilient component is divided into multiple segments or sections along its length, with different stiffness characteristics in different regions. This allows the spring to provide adequate overall support and vibration resistance while having compliant sections that require lower actuation forces, thereby reducing the required actuation voltage while maintaining mechanical stability.
Solution Approach 2:
Different portions of the resilient component are designed with different mechanical properties - the root or support portions have higher stiffness to provide mechanical stability and vibration resistance, while the tip or actuation portions have lower stiffness to reduce the actuation voltage requirement. This local differentiation of properties resolves the contradiction between stability and energy consumption.
2Use of energy by moving object
If the spring stiffness is decreased to lower the actuation voltage, then the energy consumption is reduced, but the system becomes more susceptible to external vibrations
Solution Approach 1:
By segmenting the resilient component into multiple sections with varying stiffness, the system achieves low actuation voltage through compliant sections while the stiffer support sections provide vibration isolation. This segmentation allows the system to benefit from both low energy consumption and vibration resistance simultaneously.
Solution Approach 2:
The resilient component acts as an intermediary element that mediates between the fixed support structure and the movable truss comb. Its segmented design allows it to filter out high-frequency vibrations while still permitting the controlled displacement needed for low-voltage actuation, thus protecting the system from external vibrations while maintaining energy efficiency.
3Use of energy by moving object
If boost electronics are added to achieve desired high voltage, then the actuation voltage requirement is met, but the device complexity and occupied space increase
Solution Approach 1:
The segmented resilient component is designed to provide mechanical advantage and force multiplication through its geometry and material distribution. This allows the system to achieve the required actuation voltage capability through passive mechanical means rather than requiring active electronic boost circuits, thereby reducing device complexity and occupied space while still meeting the actuation voltage requirement.
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 solution achieves a significant reduction in insertion loss and improved vibration isolation, allowing for more compact and reliable RF filters with lower actuation voltages, enhancing performance and safety in various applications, including multi-band communication systems and biomedical uses.
Implementation Method 1
Once the voltage difference is reduced to zero, a resilient component (e.g., a spring) restores the position of the truss comb structure to the first interdigitating position
Implementation Method 2
An isolation platform is provided to absorb vibrations from the environment prior to reaching the MEMS filter device
Implementation Method 3
GCA varactors generally operate on the principle of electrostatic attraction between adjacent interdigitating fingers of a drive comb structure and a movable truss comb structure
Data Source
AI summary
Integrated Microelectromechanical System (“MEMS”) devices and methods for making the same. The MEMS devices comprise a substrate (200) and a MEMS filter device (100) mechanically suspended above a major surface of the substrate. A first gas gap (202) exists between the major surface of the substrate and the MEMS filter device. An isolation platform (600) is provided to absorb vibrations from an external environment prior to reaching the MEMS filter device. In this regard, the isolation platform comprises: a frame structure (610) framing a periphery of the MEMS filter device; and at least one resilient component (612-618) coupled between the frame structure and the MEMS filter device. The frame structure is mechanically connected to the substrate. Electronic circuitry is connected to the MEMS filter device via a resilient interconnection (204, 206) that is movable in at least one direction of the vibrations.