Transparent Semiconductor Substrate for Photoacoustic Gas Sensor
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Solution Overview
Problem
The miniaturization trend in gas sensors requires the development of more compact photo-acoustic gas sensors with improved detector modules that can effectively detect hazardous gases while minimizing thermal impacts and maintaining high sensitivity.
Innovation Solution
A detector module comprising a semiconductor substrate with a recess forming an airtight cell filled with a reference gas, where a pressure-sensitive element with a membrane is exposed to light pulses, and the module is constructed using transparent materials to minimize thermal effects, with options for bonding techniques like anodic bonding or glass frit bonding, and incorporating MEMS technology for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the detector module uses opaque materials for substrate construction, then mechanical strength and sealing are improved, but thermal effects increase and light transmission is blocked
Solution Approach 1:
The patent changes the optical parameter (transparency) of the substrate materials to be transparent at the wavelength of the light pulses used in the photo-acoustic sensor. This allows light transmission while the substrate still provides mechanical support, resolving the contradiction between mechanical strength and thermal effects by selecting materials with appropriate optical properties rather than relying on opaque materials.
Solution Approach 2:
The patent employs composite material construction where the detector module uses transparent substrates (such as transparent ceramics or glasses) that combine mechanical strength with optical transparency. These composite materials provide both the structural integrity needed for sealing and the optical properties required to minimize thermal effects and allow light transmission.
2Volume of moving object
If the detector module size is reduced for miniaturization, then compactness is improved, but sensitivity and signal quality may deteriorate
Solution Approach 1:
The patent segments the detector module into functionally optimized components including a light source unit, a measurement cell with transparent windows, and a detector unit. This segmentation allows each component to be miniaturized independently while maintaining optimal performance, enabling compact overall size without sacrificing sensitivity.
Solution Approach 2:
The patent utilizes thin-film technologies for the transparent substrates and optical components, allowing miniaturization of the detector module while maintaining sufficient light transmission and mechanical integrity. The thin-film construction enables compact design without compromising the optical path quality or measurement sensitivity.
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 the creation of compact, thermally stable, and highly sensitive photo-acoustic gas sensors capable of detecting gases effectively, with the ability to perform differential measurements and maintain signal integrity by using transparent substrates and MEMS pressure-sensitive elements.
Implementation Method 1
An infrared (IR) pulse, which is chopped with audio-frequency, is absorbed by a gas and is provoking a local pressure increase which can be sensed by a pressure sensitive element
Implementation Method 2
at least a part of the first substrate is transparent at the wavelength of the light pulses
Data Source
AI summary
A detector module is disclosed. In one example, the detector module is for a photo-acoustic gas sensor and comprises a first substrate made of a semiconductor material and comprising a first surface and a second surface opposite to the first surface, a second substrate comprising a third surface, a fourth surface opposite to the third surface, and a first recess formed in the fourth surface. The second substrate is connected with its fourth surface to the first substrate so that the first recess forms an airtight-closed first cell which is filled with a reference gas and a pressure sensitive element comprising a membrane disposed in contact with the reference gas. The detector module is further configured such that a beam of light pulses passes through the first substrate and thereby enters the first cell.