Optical Spectroscopy System Multiplexing Sensor Channels
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Solution Overview
Problem
Conventional optical spectroscopy systems for measuring material concentration values are inefficient due to the need for multiple data acquisition channels, complex signal processing, and limited detection sensitivity, especially when dealing with multiple sensor channels and harmonic frequencies.
Innovation Solution
A high-speed data acquisition system that multiplexes signals from multiple sensors, using Fourier frequency analysis to process all channels simultaneously, and a customized modulation waveform to enhance signal intensity at the sensor's peak response frequency, allowing for improved detection sensitivity and reduced system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple data acquisition channels are used to measure multiple sensor channels, then measurement capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent combines multiple sensor output channels into a single data acquisition channel by time-multiplexing the sensor outputs. The sensor outputs are switched in sequence to share one data acquisition channel, reducing the number of channels needed while maintaining the ability to measure multiple sensors. This directly addresses the contradiction by merging multiple channels into one.
Solution Approach 2:
The patent employs periodic switching of sensor outputs to a single data acquisition channel. The switch sequentially connects different sensor outputs to the shared channel in periodic intervals, allowing time-multiplexed measurement of multiple sensors through one channel. This periodic action enables resource sharing while maintaining measurement capability.
2Device complexity
If time-multiplexing method is used to connect multiple sensor output to the same data acquisition channel, then system cost is reduced, but measurement efficiency decreases due to dead measurement time
Solution Approach 1:
The patent dynamically adjusts the switching frequency and timing of sensor outputs to optimize measurement efficiency. The switch operates at high speed to minimize dead measurement time between sensor channel transitions, and the system dynamically manages the timing to ensure continuous effective measurement across all channels. This dynamic operation reduces the impact of time-multiplexing on measurement efficiency.
3Measurement precision
If lock-in amplifier is used to measure sensor signal at specified modulated frequency, then detection sensitivity is improved, but total measurement time increases as sum of each sensor channel measurement time
Solution Approach 1:
The patent merges the measurement of multiple sensor channels into a single time-multiplexed measurement process. Instead of sequentially measuring each sensor channel separately with individual lock-in amplifier cycles, the system combines all sensor outputs into one shared measurement channel, allowing simultaneous extraction of multiple signals through frequency analysis. This reduces total measurement time while maintaining detection sensitivity.
Solution Approach 2:
The patent performs preliminary frequency analysis on the combined sensor signals to identify and extract signals from multiple channels simultaneously. By analyzing the frequency spectrum of the time-multiplexed output, the system can extract information from all sensors in parallel rather than sequentially, reducing total measurement time while maintaining the sensitivity benefits of lock-in amplification.
4Ease of manufacture
If sinusoidal waveform is used to modulate light source, then signal generation is simplified, but detection sensitivity is limited because sensor with one resonant frequency cannot detect harmonic frequencies
Solution Approach 1:
The patent changes the modulation waveform parameters from simple sinusoidal to multi-frequency or swept-frequency waveforms. This allows the light source to modulate at multiple frequencies simultaneously, enabling the sensor to detect signals across a broader frequency range including harmonics. The parameter change from single-frequency to multi-frequency modulation improves detection sensitivity without significantly complicating the signal generation.
Solution Approach 2:
The patent employs periodic modulation of the light source at multiple frequencies or frequency sweeps. Instead of a single continuous sinusoidal frequency, the system uses periodic variations that sweep through or include multiple frequencies, allowing the sensor to detect both fundamental and harmonic frequency components. This periodic multi-frequency action maintains ease of implementation while improving detection capability.
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
This approach enables higher detection sensitivity and efficiency by processing multiple sensor channels in parallel, capturing harmonic frequencies, and optimizing signal intensity, thereby reducing system costs and improving measurement accuracy.
Implementation Method 1
Optical instruments for highly sensitive gas sensing are being developed for use in future environmental, industrial, and health monitoring applications
Implementation Method 2
photoacoustic gas sensor comprising a ring array of acoustic sensors
Implementation Method 3
A trans-impedance amplifier (TA) is attached to each sensor to convert the tiny piezoelectric current signal generated by the sensor into a voltage signal
Data Source
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AI summary
A system capable of highly sensitive measurement of material concentration values in a sample using an optical spectroscopic method is disclosed. The system utilizes high-speed data acquisition and high resolution sampling of the raw signals output by the sensors with reduced total channel counts, and performs frequency analysis of the signals using the Fourier transform method to process all sensor channels in parallel. When each sensor is targeting the detection of some certain materials at some certain frequencies, the system is capable of simultaneous detection of multiple materials of interest in the sample with high measurement sensitivity and high speed.