Optochemical Sensor Aging Compensation via Multi-Frequency Phase Measurement
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Solution Overview
Problem
Optochemical sensors based on fluorescence principles face challenges in maintaining measurement accuracy due to aging effects, which cannot be completely suppressed by calibration or delayed replacement, leading to inaccurate results and process disruptions, especially in inaccessible process systems.
Innovation Solution
A measuring method using a radiation source with multiple excitation modulation frequencies, a detector, and a control unit to calculate an aging-compensated quencher concentration by accounting for frequency- and aging-dependent phase base values and Stern-Volmer constants, allowing for accurate measurements regardless of sensor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitive element is replaced to restore sensor functionality, then measurement accuracy is improved, but production process disruption and complexity increase
Solution Approach 1:
The patent applies parameter changes by using multiple excitation modulation frequencies to characterize sensor aging. Instead of replacing the sensitive element, the system changes the excitation frequency parameter to obtain aged phase measurements, which are then used to calculate compensation factors that restore measurement accuracy without physical replacement.
Solution Approach 2:
The patent substitutes the mechanical replacement of the sensitive element with a computational approach. By using phase measurements at multiple frequencies and calculating compensation factors through mathematical relationships, the system replaces the need for physical intervention with an information-processing solution.
2Measurement precision
If the sensitive element is replaced to restore sensor functionality, then measurement accuracy is improved, but time loss and productivity decrease
Solution Approach 1:
The patent performs preliminary action by obtaining aged phase measurements at multiple excitation frequencies before actual measurement. These preliminary measurements allow the system to calculate compensation factors in advance, so that when measurement is needed, the accurate compensated value can be immediately obtained without time-consuming replacement procedures.
3Measurement precision
If calibration is performed more frequently to compensate for aging, then measurement accuracy is improved, but time loss and productivity decrease
Solution Approach 1:
Instead of performing time-consuming calibration procedures, the patent changes the excitation frequency parameter to obtain aged phase measurements. This parameter-based approach allows the system to calculate compensation factors quickly through mathematical relationships, avoiding the need for frequent physical calibration while maintaining measurement accuracy.
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 method effectively compensates for aging effects, ensuring high accuracy and reproducibility of measurements for optochemical sensors, even in aged states, by using multiple excitation frequencies to adjust for changes in phase measurements and Stern-Volmer constants, thereby reducing the need for frequent sensor replacement.
Implementation Method 1
oxygen (O2) can be determined in a measurement medium, for example by means of fluorescence quenching. During fluorescence quenching, the molecules of the fluorescent dye are excited by irradiation with light of a suitable wavelength. When the excited molecules return to the ground state, they release the energy they have absorbed in the form of fluorescent radiation, which is quenched by interaction with a quencher in the measurement medium, here oxygen.
Implementation Method 2
the sensitive element is excited by radiation of a first excitation modulation frequency emitted by the radiation source and a first aged phase measurement value is recorded with the detector. This step is repeated for at least second and third excitation modulation frequencies
Implementation Method 3
The path difference between the signals of the fluorescence response and the radiation from the excitation radiation source or an identical second radiation source, which is directed directly onto the detector, is recorded by the detector as a phase measurement value or phase angle.
Data Source
AI summary
Measurement method for an optochemical sensor (1) for calculating an age-compensated quencher concentration taking into account a first and second aged phase measurement (φ(f1,t)). The optochemical sensor (1) comprises a radiation source (6) which can emit radiation with at least two excitation modulation frequencies (νi), a detector (7), a control unit (9), and a sensitive element (2, 202, 302) with a fluorescent dye (4, 204, 304). The measurement method comprises exciting the sensitive element (2, 202, 302) by radiation emitted from the radiation source (6) with a first and second excitation modulation frequency (f1) and acquiring a first and second aged phase measurement (φ(f1,t)) with the detector (7).