Wafer Stack Gas Sensor Using MEMS Photoacoustic Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas sensors have large thermal masses due to components in the millimeter to centimeter range, leading to high power requirements, sluggish operation, and restricted duty cycles, which limits quick calibration and measurement capabilities.
Innovation Solution
A miniaturized gas sensor using a MEMS membrane and emitter element connected in a wafer stack configuration, employing the photoacoustic effect to convert electromagnetic radiation into acoustic energy, allowing for reduced thermal masses, increased switching speeds, and a larger duty cycle, with a reference chamber to minimize cross-sensitivity and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional gas sensors use components in the millimeter to centimeter range, then the sensor structure is simple and easy to manufacture, but the thermal mass is large leading to high power requirements and sluggish operation
Solution Approach 1:
The patent transitions from conventional millimeter-to-centimeter-scale components to micro-scale components by applying MEMS technology. This dimensional reduction from macro to micro scale enables dramatically reduced thermal masses while maintaining manufacturability through established MEMS fabrication processes, thereby resolving the contradiction between manufacturing simplicity and power consumption.
Solution Approach 2:
The patent fundamentally changes the physical dimensions and thermal properties of the sensor components by adopting MEMS technology. This parameter change from macro-scale to micro-scale components results in reduced thermal mass and consequently lower power requirements, while the standardized MEMS manufacturing processes preserve ease of manufacture.
2Device complexity
If conventional gas sensors use components in the millimeter to centimeter range, then the sensor structure is simple, but the switching speed is slow and duty cycle is restricted
Solution Approach 1:
The patent applies dimensional reduction from macro-scale to micro-scale components through MEMS technology. This scaling effect inherently reduces thermal mass and increases thermal response time, enabling faster switching speeds and higher duty cycles while maintaining a relatively simple sensor structure through standardized MEMS architectures.
Solution Approach 2:
The patent enhances the dynamic response characteristics of the sensor by reducing component dimensions to the micro-scale. This enables the sensor to achieve faster switching speeds and higher operational duty cycles, transforming the static, sluggish conventional sensor into a dynamic, responsive measurement device while preserving structural simplicity.
3Use of energy by moving object
If the gas sensor is miniaturized using MEMS technology, then the thermal mass is reduced and switching speeds increase, but the device complexity increases due to wafer stack configuration
Solution Approach 1:
The patent employs vertical stacking of multiple MEMS wafers in the third dimension to achieve miniaturization. This vertical integration approach reduces the horizontal footprint while consolidating multiple functions (emitter, sensor, reference chambers) in a compact three-dimensional structure, thereby managing device complexity through spatial organization rather than increasing it.
Solution Approach 2:
The patent implements a nested wafer stack configuration where multiple functional layers (emitter wafer, sensor wafer, reference chamber wafer) are stacked and integrated vertically. This nesting approach allows compact integration of complex functionality while maintaining a small overall form factor, effectively managing device complexity through hierarchical organization.
4Productivity
If the measurement cycle is shortened due to higher switching speeds, then more measurements can be carried out in the same period, but calibration and measurement require quick response
Solution Approach 1:
The patent enhances the dynamic response characteristics through micro-scale MEMS components, enabling the sensor to perform both quick calibration and high-density measurements. The reduced thermal mass allows the sensor to rapidly respond to calibration inputs while maintaining the high switching speeds necessary for increased measurement density, effectively resolving the time trade-off.
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 miniaturized gas sensor achieves high switching speeds, extended service life, and increased measurement density, enabling more measurements in the same period while maintaining sensitivity and accuracy, surpassing the limitations of conventional sensors.
Implementation Method 1
The photoacoustic effect is a physical effect which optoacoustics makes use of. It describes the conversion of light energy into acoustic energy (sound). If a propagation medium, e.g. a gas, is irradiated with light, some of the light energy is received (absorbed) by the medium and converted into heat.
Implementation Method 2
There is, inter alia, an increase in volume as a result of the heat supply. There is periodic heating and cooling if the medium is irradiated by a sequence of light flashes or, in general, by pulses of electromagnetic radiation. This constant change in volume expansion and reduction constitutes a source of sound.
Data Source
AI summary
A gas sensor includes a multi-wafer stack of a plurality of layers and a measurement chamber. The plurality of layers includes a first layer comprising a sensor element that has a microelectromechanical system (MEMS) membrane; and a second layer comprising an emitter element configured to emit electromagnetic radiation. The measurement chamber is interposed between the first layer and the second layer. The measurement chamber is configured to receive a measurement gas and further receive the electromagnetic radiation emitted by the emitter element as the electromagnetic radiation travels along a radiation path from a first end of the measurement chamber to a second end of the measurement chamber that is opposite to the first end.