Turbidity Sensor Background Radiation Compensation

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Solution Overview

Problem

Conventional turbidity sensors face challenges in accurately measuring turbidity due to the need to account for varying background radiation, which is time-consuming and laborious, especially in uncontrolled environments, and require calibration with a nearly zero NTU sample that is difficult to obtain.

Innovation Solution

A turbidity sensor and method that uses a control fluid with known turbidity to determine a calibration factor by capturing reference and fluid signals with multiple optical settings, allowing for turbidity measurement of a sample fluid without needing to account for background radiation, using a controller to manage optical signals and detectors to calculate turbidity based on a regression line analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If background radiation is subtracted from the total measured signal to isolate the actual output from the light source, then measurement accuracy is improved, but measurement time and operational complexity increase

Engineering Contradiction:
Improveturbidity measurement accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing background radiation measurement and subtraction automatically as part of the measurement sequence. The controller pre-measures background radiation from the detection chamber and subtracts it from subsequent turbidity measurements, eliminating the need for manual background subtraction and reducing measurement time while maintaining accuracy.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If background radiation is measured and subtracted each time a measurement is taken in an uncontrolled environment, then measurement accuracy is improved, but operational complexity and labor increase

Engineering Contradiction:
Improveturbidity measurement accuracyVSAvoidoperational simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system applies self-service by automatically measuring background radiation and subtracting it from turbidity measurements without requiring user intervention. The controller autonomously manages the background radiation measurement, calculation, and subtraction process, making the system easy to operate while maintaining high measurement accuracy in uncontrolled environments.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If calibration is performed with a sample close to 0 NTU to minimize background light effects, then calibration accuracy is improved, but sample availability and measurement reliability worsen

Engineering Contradiction:
Improvecalibration accuracyVSAvoidsample availability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent converts the harmful effect of background radiation into a beneficial calibration method. Instead of requiring near-zero NTU samples to minimize background effects, the system measures background radiation separately and uses it to calibrate the measurement system. This approach allows calibration with more readily available samples while maintaining or improving calibration accuracy by explicitly accounting for background radiation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Measurement precision

If multiple optical signals with different settings are used to determine calibration factor, then measurement accuracy across wide turbidity range is improved, but device complexity increases

Engineering Contradiction:
Improveturbidity measurement accuracyVSAvoidoptical signal control complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system applies dynamics by using multiple optical signals with different settings (wavelengths, intensities, or polarization states) to probe the sample at varying conditions. The controller dynamically selects and switches between different optical signal configurations to optimize measurements across the full turbidity range, improving accuracy while managing complexity through automated control.

Inventive Principle:
Principle #15Dynamics

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 fast and accurate turbidity measurements by ignoring background radiation effects, allowing multiple measurements without recalibration and maintaining high accuracy across a wide range of turbidity levels.

Implementation Method 1

The turbidity sensor measures the amount of light scatter in the sample by the particles within the sample

Methodology Applied
Scientific EffectLight absorption and scattering: Absorption (EM radiation)

Implementation Method 2

measuring the response through the sample by a turbidity sensor. The turbidity sensor measures the amount of light scatter in the sample by the particles within the sample

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3472596B1Turbidity sensor and method for measuring turbidity
Publication Date: 2023.04.26 PROCESS INSTR UK
  • EP3472596B1 patent drawingFigure 1~2
  • EP3472596B1 patent drawingFigure 3
  • EP3472596B1 patent drawingFigure 4~5

AI summary

Sensor and Measurement Method A turbidity sensor and method of measuring turbidity is provided. The turbidity sensor (100) comprises first and second optical detectors for detecting a respective optical response of each optical signal. The first optical detector (20) may be arranged in direct view of the emitter (10) and the second optical detector (30) may be arranged in indirect view of the emitter (10). The two detectors collect light emitted from the emitter (10) when directed through a fluid sample during two optical tests run in very close succession. Firstly, a control sample is illuminated to determine a calibration factor for the control sample with known turbidity. Then, the calibration factor is used to determine the turbidity of a fluid sample with unknown turbidity. Advantageously, background radiation during the data collection process is ignored because the transient behaviour during each optical test is negligible. The approach is more convenient over known turbidity sensors and measurement methods, particularly in light of the calibration step.