Buckled Flexure MEMS Actuator Electrical Bar Latching
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Solution Overview
Problem
Conventional low stiffness flexures face limitations in design due to fabrication constraints and conflicts with other system requirements, such as increased electrical resistance when made thin, which can lead to power wastage and failure in actuator systems like MEMS.
Innovation Solution
The integration of buckled flexures with an electrical bar latching mechanism in MEMS actuators, allowing the flexures to operate in a post-buckle regime with significantly reduced stiffness, achieved by compressing unbuckled flexures during assembly, thereby seamlessly integrating buckling into the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the flexure cross section is made as small as possible to reduce stiffness, then the force requirements on the actuator are reduced, but the electrical resistance increases which wastes power and can lead to failure
Solution Approach 1:
The patent applies parameter changes by transitioning the flexure from a straight configuration to a buckled configuration. This changes the mechanical properties of the flexure, reducing its stiffness by several orders of magnitude while maintaining its electrical conductivity. The buckled state is achieved through controlled compression during assembly, creating a new operational parameter state that simultaneously achieves low mechanical stiffness and maintains electrical performance
Solution Approach 2:
The patent implements preliminary action by pre-compressing the flexures to their buckled state during the assembly process. The electrical bars are designed with latching mechanisms that, when engaged, automatically compress the flexures to the desired buckled configuration. This preliminary action ensures the flexures start in their low-stiffness state before the actuator begins operation, eliminating the need for continuous compression forces
2Force
If the flexure is made thin to reduce stiffness, then the force requirements are reduced, but the handling and manufacturability are affected
Solution Approach 1:
The patent changes the mechanical state parameter of the flexure from straight to buckled, achieving ultra-low stiffness without requiring the flexure to be made extremely thin. The buckled configuration provides the low stiffness effect while the flexure can maintain a practical thickness for manufacturing and handling purposes
Solution Approach 2:
The patent applies preliminary compression during assembly to achieve the buckled state, allowing the flexure to be manufactured at standard thicknesses. The latching mechanism on the electrical bars provides the preliminary compression action needed to buckle the flexure, eliminating the need to manufacture excessively thin flexures
3Force
If the length of the flexure is made as long as possible to reduce stiffness, then the force requirements are reduced, but the system size increases
Solution Approach 1:
The patent changes the configuration parameter of the flexure from straight to buckled, achieving dramatic stiffness reduction without increasing the flexure length. The buckled state creates a mechanically softer structure that provides the same force reduction benefit as a much longer flexure, but within the existing spatial constraints
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 results in flexures that are several orders of magnitude softer than their normal state, reducing the force requirements on actuators and minimizing stiffness and stress, while maintaining electrical conductivity, thus enhancing the performance and reliability of MEMS actuator systems.
Implementation Method 1
low stiffness flexures
Implementation Method 2
buckled flexures coupling the inner frame to the outer frame
Implementation Method 3
a first of the plurality of latched bars includes a latch protrusion secured to a corresponding latch groove of a second of the plurality of latched bars
Implementation Method 4
the plurality of buckled flexures electrically and mechanically couple the inner frame to the outer frame
Data Source
AI summary
A MEMS actuator including buckled flexures and a method of assembling the actuator are described. The assembled MEMS actuator includes an inner frame; an outer frame including latched electrical bars, where a first of the latched bars includes a latch protrusion secured to a corresponding latch groove of a second of the latched bars; and buckled flexures coupling the inner frame to the outer frame. The flexures are buckled during assembly of the MEMS actuator by incorporating the electrical bar latching mechanism into the design of the outer frame of the MEMS actuator. In one implementation, the MEMS actuator is assembled by providing a MEMS actuator with unbuckled flexures coupling the outer frame of the MEMS actuator to an inner frame of the MEMS actuator, where the outer frame includes unlatched electrical bars, and latching the electrical bars of the outer frame, resulting in buckled flexures.