MEMS Charge Trapping via Breakable Link and Thermionic Emission
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Solution Overview
Problem
Microelectromechanical systems (MEMS) face challenges in retaining electrical charge due to leakage currents caused by contaminants within the chamber, which limits their operational duration without the need for power replacement.
Innovation Solution
The method involves encapsulating MEMS using thin film or wafer bonding techniques and employing mechanisms such as breakable links or thermionic electron sources to supply and store electrical charge within the device, ensuring isolation and prolonged charge retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS are sealed in a hermetically sealed metal container or bonded substrate chamber, then the mechanical structure is protected from contamination and inadvertent contact, but leakage currents caused by contaminants still occur and limit operational duration
Solution Approach 1:
The patent extracts the disturbing factor (contaminants) from the chamber environment by implementing enhanced sealing structures and contamination removal mechanisms. The encapsulation structure is designed to actively prevent contaminant ingress and remove existing contaminants, thereby eliminating the source of leakage currents that limit charge retention and operational duration.
Solution Approach 2:
The patent employs composite material structures for the encapsulation, combining multiple layers and materials with different properties to achieve both protection and contamination prevention. The encapsulation structure integrates various materials that work together to provide hermetic sealing while preventing contaminant accumulation that would cause charge leakage.
2Device complexity
If thin film encapsulation is used to encapsulate the mechanical structure, then the device size is reduced and integration is improved, but charge leakage due to contaminants within the chamber occurs
Solution Approach 1:
The patent utilizes thin film encapsulation structures that provide hermetic sealing while maintaining device miniaturization. The thin film encapsulation is designed with specific thickness and material properties to prevent contaminant ingress while preserving the mechanical structure's functionality and keeping the overall device compact.
Solution Approach 2:
The patent creates an inert or controlled atmosphere within the encapsulated chamber to prevent contaminant formation and accumulation. By maintaining a contaminant-free environment through inert gas filling or vacuum sealing, the system prevents charge leakage while using compact thin film encapsulation structures.
3Duration of action of moving object
If electrical charge is stored on the mechanical structure for extended periods, then operational autonomy is increased, but leakage currents from contaminants cause charge loss
Solution Approach 1:
The patent converts the harmful effect of contaminants into a benefit by implementing structures that actively detect and remove contaminants. The encapsulation design includes mechanisms that use the presence of contaminants as a trigger for activation of removal systems, thereby transforming the potential harm into a self-correcting feature that maintains charge retention over extended periods.
Solution Approach 2:
The patent employs parameter changes in the encapsulation environment, such as controlling pressure, temperature, and gas composition, to minimize charge leakage. By optimizing these parameters, the system extends charge storage duration while maintaining a environment that prevents contaminant-induced leakage currents.
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 enables MEMS to store electrical charge for extended periods, potentially up to ten years, by maintaining a contaminant-free environment and using specialized structures to prevent leakage, thereby extending the operational time of MEMS devices.
Implementation Method 1
employing mechanisms such as breakable links or thermionic electron sources to supply and store electrical charge within the device
Data Source
AI summary
Many inventions are disclosed. Some aspects are directed to MEMS, and/or methods for use with and/or for fabricating MEMS, that supply, store, and/or trap charge on a mechanical structure disposed in a chamber. Various structures may be disposed in the chamber and employed in supplying, storing and/or trapping charge on the mechanical structure. In some aspects, a breakable link, a thermionic electron source and/or a movable mechanical structure are employed. The breakable link may comprise a fuse. In one embodiment, the movable mechanical structure is driven to resonate. In some aspects, the electrical charge enables a transducer to convert vibrational energy to electrical energy, which may be used to power circuit(s), device(s) and/or other purpose(s). In some aspects, the electrical charge is employed in changing the resonant frequency of a mechanical structure and/or generating an electrostatic force, which may be repulsive.