Low Power Amperometric Probe for Remote Chlorine Monitoring

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Solution Overview

Problem

Current methods for analyzing chlorine in water require chemical reagents and are time-consuming and expensive, making them unsuitable for rapid, in-field testing by mobile personnel in the water supply industry, which seeks remote, automated, and low-maintenance systems for monitoring chlorine levels.

Innovation Solution

An amperometric system with a probe comprising a reference electrode, counter electrode, working electrode, and thermistor, powered by a low-power DC supply, using a species-selective membrane and electronic components optimized for low power consumption, including a charge pump inverter and micro-power shunt voltage reference, to measure chlorine levels with temperature compensation and gain adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional amperometric probes with multiple amplifiers and voltage references are used, then measurement capability is achieved, but power consumption is excessive for battery-operated remote systems

Engineering Contradiction:
Improvepower consumptionVSAvoidmeasurement reliability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent combines multiple voltage reference functions into a single low-power voltage reference that can provide both the reference potential for the amperometric measurement and the bias voltage for the field effect transistor amplifier. This merging eliminates the need for separate voltage references, reducing power consumption while maintaining measurement reliability through the stabilized gate potential.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional operational amplifier-based measurement circuits with a field effect transistor-based amperometric probe that uses voltage-controlled current regulation. This substitution eliminates the need for high-power operational amplifiers and their associated voltage references, achieving reliable measurement with minimal power consumption suitable for battery-operated systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Extent of automation

If remote automated monitoring systems are deployed, then continuous chlorine level monitoring is achieved, but power supply requirements increase system complexity

Engineering Contradiction:
Improveautomated monitoringVSAvoidpower supply system complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The patent implements a self-regulating amperometric probe where the field effect transistor automatically adjusts its channel conductivity based on the measured chlorine concentration, maintaining a stable measurement current without requiring external power regulation circuits. The single voltage reference self-provides all necessary bias potentials, eliminating the need for complex power supply management in automated remote systems.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If traditional chemical reagent methods are used for chlorine analysis, then accurate measurement is achieved, but the process is time-consuming and requires laboratory infrastructure

Engineering Contradiction:
Improvechlorine concentration accuracyVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces chemical reagent-based chlorine analysis with an electrochemical amperometric method that directly measures chlorine concentration through ionic current. This substitution eliminates the need for time-consuming chemical reactions, reagent preparation, and laboratory infrastructure, enabling rapid on-site measurement while maintaining accuracy through the selective response of the field effect transistor to chlorine ions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enables reliable, remote, and automated chlorine monitoring with minimal power consumption, allowing continuous operation for extended periods without frequent maintenance, suitable for in-field use by the water supply industry.

Implementation Method 1

The probe is rendered selective to species of interest by an species-selective barrier (e.g. an ion selective membrane, not shown) between the working electrode and the sample solution. The current flowing in the working electrode 4 is converted to a voltage by a current to voltage conversion module 7. Said voltage is then adjusted for temperature of the sample by temperature correction module 8 with reference to thermistor 5.

Methodology Applied
Scientific EffectThermistor: Thermistor

Implementation Method 2

The probe is rendered selective to species of interest by an species-selective barrier (e.g. an ion selective membrane, not shown) between the working electrode and the sample solution.

Methodology Applied
Scientific EffectIon selective membrane separation: Semipermeable Membrane

Implementation Method 3

The determination of analyte concentration in a solution by amperometry is well known. In such analyses, the electric current generated in a suitable chemical reaction involving the analyte is measured and used as an indication of analyte concentration.

Methodology Applied
Scientific EffectAmperometry:

Data Source

PatentEP2235515B1Low power amperometric probe
Publication Date: 2016.10.19 EVOQUA WATER TECHNOLOGIES LLC
  • EP2235515B1 patent drawingFigure 1
  • EP2235515B1 patent drawingFigure 2
  • EP2235515B1 patent drawingFigure 3~4

AI summary

An amperometric probe suitable for monitoring chlorine levels in water is described. The probe has low power consumption and maintenance requirements rendering it particularly suitable for long periods of operation in remote locations with portable power supplies.