Dissolved Oxygen Sensor Phase Shift Correction
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Solution Overview
Problem
Existing methods for measuring dissolved oxygen using optical sensors face inaccuracies due to strong phase shifts greater than 2π, leading to potential confusion with weak phase shifts and incorrect measurements.
Innovation Solution
A method involving an optical sensor apparatus with a computing unit, performing two measurement sequences with different stimulation signals and calculating phase shifts and decay times to correct measurements, ensuring accurate dissolved oxygen measurement by adjusting for phase shifts and varying conditions like temperature and oxygen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single measurement sequence using one stimulation signal is used, then the measurement process is simple and fast, but measurement accuracy deteriorates due to inability to distinguish strong phase shifts from weak phase shifts
Solution Approach 1:
The measurement process is segmented into multiple distinct measurement sequences, each using different stimulation signals. The first measurement sequence uses a first stimulation signal to obtain a first phase shift, while the second measurement sequence uses a second stimulation signal to obtain a second phase shift. This segmentation allows the system to distinguish between strong and weak phase shifts by comparing results from different measurement sequences, thereby resolving the ambiguity in single-sequence measurements.
Solution Approach 2:
The invention changes the parameters of the stimulation signal between measurement sequences. By using different stimulation signals (different frequencies, amplitudes, or waveforms) in the first and second measurement sequences, the system creates different phase shift characteristics that enable accurate distinction between strong and weak phase shifts, improving measurement accuracy without excessive complexity.
2Measurement precision
If multiple measurement sequences with different stimulation signals are performed, then measurement accuracy improves by enabling phase shift distinction, but measurement time increases
Solution Approach 1:
The system performs multiple measurement sequences only when necessary. By comparing phase shifts from different measurement sequences and using correction algorithms, the system can achieve accurate measurements without always requiring the full multi-sequence approach. This partial application of excessive action (multiple sequences) optimizes the balance between accuracy and time.
Solution Approach 2:
The system uses feedback from the first measurement sequence to guide the second measurement sequence. By comparing the first phase shift with expected values and using correction algorithms, the system can determine whether additional measurement sequences are necessary, thereby reducing unnecessary measurement time while maintaining accuracy when needed.
3Reliability
If phase shift correction algorithms are applied, then measurement reliability improves by correcting strong phase shift errors, but computational complexity increases
Solution Approach 1:
The system creates a corrected phase shift value by copying and adjusting the measured phase shift based on comparison with reference values and correction algorithms. This copying approach allows the system to maintain measurement reliability through correction while keeping the computational process manageable by working with phase shift values rather than complex signal processing.
Solution Approach 2:
The correction algorithm changes the phase shift parameter by adjusting it based on the difference between measured and reference values. This parameter change approach simplifies the computational complexity by working directly with phase shift values and their differences, rather than requiring complex signal reconstruction or inversion processes.
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 enhances the accuracy, reliability, and quality of dissolved oxygen measurements by correcting for phase shift errors and optimizing measurement sequences based on predefined limits, thereby improving measurement certainty.
Implementation Method 1
measuring a phase difference between a stimulation signal and an oxygen-dependent response signal of a fluorescent spot stimulated by the stimulation signal
Implementation Method 2
an optical sensor with a light source, a sensitive layer, and a detector... the light source emitting a first stimulation signal onto the sensitive layer... the detector detecting a first detection signal emitted by the sensitive layer
Data Source
AI summary
A measuring method for measuring dissolved oxygen includes performing a first measurement sequence, including: emitting a first stimulation signal onto a sensor for a first period; detecting a first detection signal; determining a phase shift between the first stimulation signal and the first detection signal; and calculating a first measured value based on the determined phase shift. Performing a second measurement sequence, including a second stimulation signal onto the sensor for a second period, wherein the second stimulation signal is different than the first stimulation signal; detecting a second detection signal; determining a decay time of the second detection signal; calculating a second measured value based on the decay time. The method further includes comparing the first measured value to the second measured value and correcting the first measured value when a difference between the first measured value and the second measured value is greater than a first limit value.