Photo-acoustic Gas Sensor with Optical Detection on Silicon
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Solution Overview
Problem
Existing photo-acoustic gas sensors face limitations due to restricted material choices for micro-tuning forks, leading to sensitivity issues and interference from electrical signals, and have a bulky design that hinders mobile applications.
Innovation Solution
A compact photo-acoustic gas sensor is developed with a resonance body and oscillation detection device integrated on a single semiconductor substrate, utilizing silicon and incorporating interferometers and integrated electronic components for signal processing and light generation, allowing for improved sensitivity and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If piezoelectric materials are used for micro-tuning forks, then oscillation detection is enabled, but material choice is restricted and electrical interference occurs
Solution Approach 1:
The patent replaces the piezoelectric material-based oscillation detection with an optical detection system. A resonance body made of non-piezoelectric material (such as silicon) is optically illuminated, and oscillations are detected by measuring changes in reflected or transmitted light intensity or phase. This substitution eliminates the need for piezoelectric materials while maintaining oscillation detection capability, thereby expanding material choices and eliminating electrical interference issues.
Solution Approach 2:
The patent introduces light as an intermediary medium between the resonance body and the detection system. Instead of directly measuring piezoelectric voltage from the resonance body, the optical system mediates the detection process by converting mechanical oscillations into optical signal variations. This intermediary approach allows the use of non-piezoelectric materials while preserving the ability to detect oscillations reliably.
2Ease of operation
If separate components are used for light source, control electronics, and evaluation electronics, then functionality is complete, but device size is large and mobile application is not possible
Solution Approach 1:
The patent merges the resonance body, optical detection system, light source, control electronics, and evaluation electronics into a single integrated device. The resonance body is formed from a substrate with cutouts, and the optical detection components are positioned in close proximity, allowing all functional elements to work together in a compact configuration. This integration enables mobile applications while maintaining complete functionality.
Solution Approach 2:
The substrate serving as the resonance body also provides structural support and housing for the integrated components. The optical waveguides serve multiple functions by guiding light from the source to the interaction region and then to the detector. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure and enabling portability.
3Measurement precision
If piezo-voltage measurement is used for signal detection, then oscillation detection is achieved, but electrical interfering signals easily influence the measurement
Solution Approach 1:
The patent replaces electrical voltage measurement with optical measurement to detect oscillations. By using light intensity or phase changes instead of piezoelectric voltage, the system achieves comparable measurement precision while being immune to electrical interference. The optical detection method measures mechanical oscillations through their effect on light properties rather than through electrical signals.
4Measurement precision
If forked quartz crystal is used for high sensitivity detection, then photo-acoustic measurement sensitivity is high, but space requirement limits mobile application
Solution Approach 1:
The patent employs thin-film fabrication techniques to create the resonance body and optical components on a substrate. The resonance body is formed by cutting out portions of a thin substrate, creating a lightweight, compact structure with high surface-to-volume ratio that maintains detection sensitivity while minimizing overall device volume. This thin-film approach enables portable applications.
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 enhances measurement reliability and compactness, enabling more effective gas analysis with reduced interference and allowing for mobile and maintenance-free operation.
Implementation Method 1
the pressure fluctuations are generated by means of a laser diode which selectively excites the molecules of the gas phase by means of spectrally narrowband radiation
Implementation Method 2
a device for optically detecting the location of at least one partial area of the resonance body
Data Source
AI summary
A photo-acoustic gas sensor and methods for producing same, the gas sensor having a resonance body and a device for detecting a vibration of the resonance body, including a device for optically detecting the location of at least one partial surface of the resonance body, wherein the resonance body and the device for detecting a vibration are disposed on exactly one substrate, the resonance body is formed by at least one first recess of the substrate, and the substrate is a semiconductor material.