Offset MEMS Photoacoustic Sensor Design
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Solution Overview
Problem
Current photoacoustic sensors face challenges in providing cost-effective solutions with improved construction for detecting hazardous gases, particularly in ensuring worker safety, and existing production methods may not be efficient enough to meet these demands.
Innovation Solution
A photoacoustic sensor design comprising a first layer with an optical MEMS emitter, a second layer with a MEMS pressure pick-up and an optically transparent window arranged offset laterally, and a third layer with a cavity for a reference gas, where the optical MEMS emitter transmits radiation through the window and cavity, with the MEMS pressure pick-up outside the optical path, enhancing detection accuracy and reducing thermoacoustic disturbances. This design also allows for wafer-level bonding, a more cost-effective production method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the MEMS pressure pick-up is placed in the optical path for compact design, then device complexity is reduced, but thermoacoustic disturbances occur that degrade measurement precision
Solution Approach 1:
The patent resolves the contradiction by transitioning from a one-dimensional placement constraint to a two-dimensional spatial arrangement. The MEMS pressure pick-up and optically transparent window are positioned at different lateral locations (offset arrangement) within the same layer, allowing both components to coexist without optical interference while maintaining a compact multi-layer structure.
2Productivity
If conventional production methods are used, then manufacturing processes are simple, but production efficiency and cost-effectiveness are insufficient
Solution Approach 1:
The patent applies segmentation by dividing the photoacoustic sensor into three separate functional layers: first layer with optical MEMS emitter, second layer with MEMS pressure pick-up and optically transparent window, and third layer with reference gas cavity. This layered segmentation enables independent fabrication of each layer using standard MEMS processes, followed by precise stacking and bonding, thereby improving production efficiency and cost-effectiveness.
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 solution enables accurate detection of gases by minimizing thermoacoustic disturbances and offering a cost-effective production process through wafer-level bonding, improving the overall efficiency and reliability of photoacoustic sensors.
Implementation Method 1
an optical MEMS emitter designed to transmit optical radiation along an optical path
Implementation Method 2
a MEMS pressure pick-up arranged outside the course of the optical path
Data Source
AI summary
A photoacoustic sensor includes a first layer with an optical MEMS emitter; a second layer stacked over the first layer with a MEMS pressure pick-up and an optically transparent window, wherein the MEMS pressure pick-up and the optically transparent window are offset laterally with respect to one another; and a third layer stacked over the second layer with a cavity for a reference gas. The optical MEMS emitter transmits optical radiation along an optical path, wherein the optical path runs through the optically transparent window and the cavity for the reference gas, and wherein the MEMS pressure pick-up is outside the course of the optical path.