MEMS Gas Sensor With Sealed Capillaries and Stacked Substrates
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Solution Overview
Problem
Conventional gas sensors are large and costly, limiting their integration into portable devices and increasing the risk of gas detection failures due to evaporation and reduced accuracy.
Innovation Solution
A micro-electro-mechanical system (MEMS) based gas sensor design featuring electrolyte-sealed capillaries and electrodes on semiconductor substrates, allowing for compact, low-impedance gas detection with improved accuracy and extended lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional gas sensor designs are used, then gas detection functionality is achieved, but sensor size is large and cost is high
Solution Approach 1:
The sensor is divided into separate functional layers including semiconductor substrates, electrolyte layer, capillary layer, and membrane layer. Each layer is fabricated independently using MEMS processes and then stacked together, allowing for miniaturization while maintaining reliable gas detection functionality through proper separation of concerns.
Solution Approach 2:
The sensor transitions from planar electrode arrangements to a three-dimensional stacked configuration with capillaries extending vertically through the structure. This vertical integration reduces the footprint area while maintaining detection volume and reliability through enhanced gas transport pathways.
2Volume of moving object
If sensor size is reduced, then integration into portable devices is enabled, but manufacturing complexity increases
Solution Approach 1:
The sensor is divided into separate functional layers including semiconductor substrates, electrolyte layer, capillary layer, and membrane layer. Each layer is fabricated independently using MEMS processes and then stacked together, allowing for miniaturization while maintaining reliable gas detection functionality through proper separation of concerns.
Solution Approach 2:
The capillary structures are formed using self-aligned processes where the capillary holes are created through the substrate and automatically align with the electrolyte and membrane layers during stacking. This self-alignment mechanism reduces the need for complex external alignment tools and procedures.
3Duration of action of stationary object
If electrolyte is enclosed in sealed structure, then evaporation is minimized and lifespan extended, but gas diffusion path becomes more complex
Solution Approach 1:
The sensor utilizes capillary action through vertically extended holes to transport gas from the ambient environment to the enclosed electrolyte. This passive fluid transport mechanism eliminates the need for active pumping while maintaining extended sensor lifespan through effective evaporation prevention.
Solution Approach 2:
The sensor transitions from planar electrode arrangements to a three-dimensional stacked configuration with capillaries extending vertically through the structure. This vertical integration reduces the footprint area while maintaining detection volume and reliability through enhanced gas transport pathways.
4Volume of moving object
If MEMS fabrication technology is used, then sensor size is reduced and cost decreased, but manufacturing precision requirements increase
Solution Approach 1:
The capillary structures are formed using self-aligned processes where the capillary holes are created through the substrate and automatically align with the electrolyte and membrane layers during stacking. This self-alignment mechanism reduces the need for complex external alignment tools and procedures.
Solution Approach 2:
The sensor is divided into separate functional layers including semiconductor substrates, electrolyte layer, capillary layer, and membrane layer. Each layer is fabricated independently using MEMS processes and then stacked together, allowing for miniaturization while maintaining reliable gas detection functionality through proper separation of concerns.
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 MEMS design enables smaller, more accurate, and cost-effective gas sensors that can be integrated into portable devices, enhancing gas detection capabilities and extending sensor lifespan by minimizing evaporation and reducing size while maintaining functionality.
Implementation Method 1
one or more capillaries providing gaseous communication to the electrolyte from an external ambient environment
Implementation Method 2
Gas may diffuse into the sensor through a porous membrane to a working electrode where it is oxidized or reduced. This electrochemical reaction may result in an electric current
Implementation Method 3
the TSS and BSS joined with an adhesive seal around the electrolyte
Data Source
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AI summary
Apparatus and associated methods relate to a micro-electro-mechanical system (MEMS) based gas sensor including an electrolyte contacting one or more top electrode(s) arranged on the bottom surface of a top semiconductor substrate (TSS), and one or more bottom electrode(s) arranged on the top of a bottom semiconductor substrate (BSS), the TSS and BSS joined with an adhesive seal around the electrolyte, the sensor including one or more capillaries providing gaseous communication to the electrolyte from an external ambient environment. The electrodes may be electrically accessed by one or more vias to externally accessible bond pads. In some examples, an electrical connection may be made from an additional bond pad on top of the TSS to the electrolyte. Various embodiments may reduce the size of various gas sensors to advantageously allow their inclusion into portable electronic devices.