Ceramic Conductivity Cell for Low TOC Water Analysis
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Solution Overview
Problem
Conductivity measurement devices struggle with precision at low impurity levels in ultra-pure water due to temperature variations and material leaching, especially when measuring total organic carbon (TOC) below 500 ppb, as existing designs are prone to contamination and have inefficient UV irradiation setups.
Innovation Solution
A conductivity measuring device with a UV-transparent window and a ceramic hydraulic body, featuring a measuring chamber with inlet and outlet channels positioned outside the UV exposure area, minimizing the active surface area and maximizing the sampling volume, and using machinable ceramic materials to reduce leaching, along with a thermistor integrated into the measuring electrode for temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the surface area of materials exposed to UV rays is minimized to reduce leaching, then measurement precision is improved, but the sampling volume is reduced which decreases measurement yield and efficacy
Solution Approach 1:
The patent transitions from a planar chamber design to a three-dimensional configuration where UV rays irradiate the liquid sample from the side through a transparent window, rather than from above. This dimensional change allows the UV irradiation path to be separated from the liquid sampling volume, enabling the chamber to be designed with optimized S/V ratio while maintaining both precision and productivity.
Solution Approach 2:
The patent divides the measuring chamber into distinct functional zones: a UV irradiation path defined by a transparent window on one side, and a liquid sampling volume defined by inlet and outlet channels on the opposite side. This segmentation allows independent optimization of the irradiation surface area and the sampling volume, resolving the contradiction between minimizing leaching surface and maximizing sampling capacity.
2Ease of operation
If holes are made in the substrate for fluid inlet and outlet, then hydraulic function is improved, but mechanical strength is weakened and design complexity increases
Solution Approach 1:
The patent extracts the hydraulic function from the substrate by providing separate inlet and outlet channels that are independent of the substrate structure. The substrate remains intact without holes, maintaining its mechanical strength, while the hydraulic function is achieved through external channel connections to the measuring chamber.
Solution Approach 2:
The patent separates the hydraulic function (inlet and outlet channels) from the substrate structure. The channels are positioned on the opposite side of the substrate from the UV irradiation window, allowing the substrate to maintain its structural integrity while the hydraulic function is achieved through separate, non-intrusive channel connections.
3Ease of operation
If the chamber is designed with inlet and outlet channels facing UV rays, then hydraulic function is improved, but the sampling volume is difficult to determine due to uncertainty about irradiated volumes
Solution Approach 1:
The patent repositions the inlet and outlet channels from facing the UV irradiation window to being on the opposite side of the chamber. This spatial reconfiguration in another dimension allows clear separation between the UV irradiation path and the hydraulic flow path, enabling precise determination of the sampling volume as the region between the channels, while maintaining effective hydraulic function.
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 device achieves precise conductivity measurements at low TOC levels with reduced leaching and improved UV irradiation efficiency, allowing for accurate detection of organic compounds down to 5 ppb, while maintaining mechanical integrity and reducing contamination sources.
Implementation Method 1
a sample of theoretically ultra-pure water is subjected to photo-oxidation by means of ultraviolet (UV) rays, which makes it possible to measure the amount of organic carbon present in the water from the decrease in resistivity resulting from the ultraviolet oxidation of the organic substances present in the water sample subjected to the measurement
Implementation Method 2
A temperature sensor, which is in practice in the form of a thermistor, is generally intended to be placed either upstream or downstream of the conductivity measuring cell or, better still, placed under one of the electrodes
Implementation Method 3
conductivity is the measurement of the flow of electrons passing through a substance. It is directly proportional to the ion concentration, to the charge borne by each of these ions (valency) and to their mobility
Data Source
AI summary
The present patent application relates to a device (1) for measuring the conductivity of a liquid, which comprises a measuring chamber for containing a sampling volume to be irradiated with UV rays formed in a hydraulic body (4) which comprises an inlet channel for feeding the measuring chamber with liquid to be measured and an outlet channel for removing the measured liquid from the measuring chamber, the inlet channel and the outlet channel emerging on either side beyond a surface exposed to the UV rays, such that only the sampling volume contained in the measuring chamber is irradiated. The present patent application is also directed towards a use of such a device and to a purification system comprising such a device.