Optical Urea Concentration Sensing Without Source Aging Errors
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Solution Overview
Problem
Existing systems for measuring urea concentration in water are prone to errors due to ageing of the source of the light beam, and imprecise positioning, during assembly of the system, leading to unreliable and complex measurements.
Innovation Solution
A system using an emitter and receiver of electromagnetic waves with a duct containing the urea solution, where the receiver detects the variation in intensity over time, independent of the emitter's intensity, and a control unit determines concentration based on a pre-defined relation, using a Time-of-Flight sensor and optical elements, ensuring precise and repeatable measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intensity of the light beam emitted by the source is measured to compensate for source aging, then measurement reliability is improved, but device complexity increases due to requiring two lines for measuring light intensity with two distinct amplification lines and two different photodiodes
Solution Approach 1:
The patent combines the measurement of light intensity and loss of intensity along the optical fibre into a single measurement line. The control unit processes both the emitted light intensity and the transmitted light intensity through the urea solution, calculating the concentration based on the ratio of these two measurements. This eliminates the need for separate measurement lines and photodiodes, reducing device complexity while maintaining measurement reliability.
Solution Approach 2:
The single photodiode and amplification line are used for multiple purposes: measuring both the emitted light intensity (for compensation of source aging) and the transmitted light intensity (for concentration measurement). This multi-functional approach reduces the number of components required while achieving reliable concentration measurements that are independent of light source degradation.
2Measurement precision
If precise positioning between the source of the light beam and the optical fibre is ensured during assembly, then measurement precision is improved, but ease of manufacture deteriorates due to requiring complex alignment procedures
Solution Approach 1:
The system performs self-calibration by measuring the light intensity at the source and comparing it with the intensity after transmission through the urea solution. The control unit automatically compensates for any misalignment or assembly variations by using the ratio of the two measurements, eliminating the need for precise manual positioning during assembly.
Solution Approach 2:
The patent changes the measurement parameter from absolute loss of intensity to relative loss of intensity, expressed as a ratio between emitted and transmitted light intensities. This parameter transformation makes the measurement independent of assembly precision, allowing easy manufacture while maintaining measurement precision through automatic compensation by the control unit.
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 system provides precise and repeatable urea concentration measurements, unaffected by emitter aging or assembly errors, with a simplified structure and reliable control modalities.
Implementation Method 1
an optical fibre (22) made up of a core (22A) of transparent material and cladding (22B) constituted by the solution to be measured
Implementation Method 2
measurement of the losses of intensity of a light beam that is conveyed along an optical fibre immersed within the solution to be tested
Data Source
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Figure 3~4
Figure 5
AI summary
Described herein is a system (10) for measuring the concentration of urea in solution with water, comprising: - an emitter (2) of a beam of electromagnetic waves; - a receiver (4) of said beam of electromagnetic waves; - a duct (6) provided for containing said solution with water; - a first optical element (8) configured for optically coupling a first end (6A) of said duct (6) with said emitter (2); - a second optical element (12) configured for optically coupling a second end (6B), opposite to said first end (6A), of said duct (6) with said receiver (4); and - a control unit (20) configured for determining the concentration of urea in said solution as a function of the signal generated by said receiver.