Teeter-Totter MEMS Switch With Flexible Hinges
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Solution Overview
Problem
Conventional MEMS switches relying on spring force for opening often degrade when held in a closed state, especially at high temperatures, reducing their lifetime and reliability.
Innovation Solution
A teeter-totter MEMS switch design featuring a stiff beam and flexible hinges that actively open and close, minimizing mechanical stress and avoiding bending, with fabrication using electroplating techniques and reduced sacrificial layers to enhance robustness and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional cantilevered beam MEMS switch uses spring force to open the switch, then the switch can be opened without additional actuation, but the beam degrades when held in a closed state especially at high temperatures, reducing lifetime and reliability
Solution Approach 1:
The beam is divided into two functional segments: a stiff main beam portion for maintaining structural integrity and electrical connection, and a separate flexible hinge portion for providing the opening force. This segmentation allows each part to be optimized for its specific function without compromise.
Solution Approach 2:
Different regions of the beam structure have different mechanical properties: the main beam is made stiff to avoid degradation when held closed, while the hinge region is made flexible to provide the opening force. This local differentiation of mechanical properties resolves the contradiction between needing strength and needing flexibility.
2Strength
If a stiff beam is used to avoid bending and stress, then the beam maintains structural integrity, but the beam cannot actively open without additional mechanisms
Solution Approach 1:
The beam structure is segmented into a stiff main beam and a flexible hinge portion. The stiff beam maintains structural integrity while the separate flexible hinge provides the active opening capability through electrostatic actuation, resolving the contradiction between strength and operational capability.
Solution Approach 2:
The flexible hinge acts as an intermediary element between the stiff beam and the substrate. It transmits the electrostatic force to open the switch while allowing the main beam to remain stiff and structurally sound.
3Productivity
If electroplating techniques with reduced sacrificial layers are used, then manufacturing efficiency and robustness are enhanced, but fabrication precision requirements increase
Solution Approach 1:
The fabrication process parameters are changed by reducing the number of sacrificial layers and optimizing electroplating conditions. This allows for more efficient manufacturing while the design tolerances are adjusted to accommodate the simplified process, balancing productivity and precision requirements.
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 teeter-totter MEMS switch exhibits extended lifetime and improved robustness, maintaining effective electrical connections and reducing stress on the beam, outperforming conventional cantilevered beam switches in reliability and performance.
Implementation Method 1
fabrication using electroplating techniques
Implementation Method 2
application of an electric field generated by applying a voltage to an electrode on the substrate
Data Source
Figure 1A~1C
Figure 2
Figure 3A
AI summary
Microelectromechanical systems (MEMS) switches are described. The MEMS switches can be actively opened and closed. The switch can include a beam coupled to an anchor on a substrate by one or more hinges. The beam, the hinges and the anchor may be made of the same material in some configurations. The switch can include electrodes, disposed on a surface of the substrate, for electrically controlling the orientation of the beam. The hinges may be thinner than the beam, resulting in the hinges being more flexible than the beam. In some configurations, the hinges are located within an opening in the beam. The hinges may extend in the same direction of the axis of rotation of the beam and/or in a direction perpendicular to the axis of rotation of the beam.