Planar Dissolved Oxygen Sensor with Electrochemical Antifouling
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Solution Overview
Problem
Existing sensors for measuring conductivity, temperature, and dissolved oxygen in water face challenges such as high cost, complexity, fragility, flow sensitivity, and biofouling, which limit their accuracy and long-term performance, especially in marine environments.
Innovation Solution
A microfabricated apparatus with a dissolved oxygen sensor using a working and reference electrode, applying a conditioning waveform and wait time to minimize oxygen depletion, integrated with a conductivity and temperature sensor on a planar substrate, and employing electrochemical generation of chlorine for antifouling, allowing for robust, flow-insensitive, and accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high accuracy sensors for conductivity, temperature and dissolved oxygen are used, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines multiple sensing functions (conductivity, temperature, and dissolved oxygen measurement) into a single integrated sensor device. The sensor head integrates a conductivity sensor with parallel platinum electrodes, a temperature sensor, and a dissolved oxygen sensor with working and reference electrodes, all on one substrate. This merging reduces overall device complexity while maintaining high measurement precision for all three parameters simultaneously.
2Measurement precision
If conventional dissolved oxygen sensors are used, then measurement precision is improved, but reliability decreases due to flow sensitivity and fragility
Solution Approach 1:
The dissolved oxygen sensor employs a recessed electrode design where the working electrode is positioned in a recessed cavity rather than exposed on the surface. This localized structural modification creates a stable measurement environment that eliminates flow sensitivity while maintaining measurement precision. The recessed geometry confines the measurement zone, protecting it from external flow disturbances that would otherwise affect conventional exposed electrode sensors.
3Duration of action of stationary object
If sensors operate in natural water environments long-term, then duration of action is improved, but object-affected harmful factors increase due to biofouling
Solution Approach 1:
The patent employs an electrochemical conditioning waveform that generates chlorine species at the electrode surface during measurement cycles. This converts the electrical measurement process into a dual function: measuring dissolved oxygen while simultaneously generating biocidal chlorine that prevents biofouling. The harmful effect of biological contamination is counteracted by converting the measurement electricity into a protective chemical environment that cleanses the sensor surface.
Solution Approach 2:
The sensor applies periodic conditioning waveforms between measurement cycles to maintain the electrode surface. These periodic electrochemical treatments generate chlorine species that continuously prevent biofouling accumulation, enabling long-term operation in natural water environments. The periodic action ensures that biofouling does not have time to establish significant contamination layers between treatments.
4Manufacturing precision
If manufacturing processes use precision dicing, deposition and etching in three dimensions, then manufacturing precision is improved, but ease of manufacture worsens due to difficulty in automation
Solution Approach 1:
The patent transitions from complex three-dimensional microfabrication to planar two-dimensional fabrication processes. The sensor elements are fabricated on flat substrates using standard planar deposition and photolithography techniques, eliminating the need for complex 3D dicing and etching. This dimensional simplification maintains manufacturing precision while enabling automated mass production through established planar processing workflows.
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 apparatus achieves high accuracy and stability in measuring conductivity, temperature, and dissolved oxygen with reduced biofouling, enabling long-term operation in natural environments while minimizing power consumption and manufacturing costs.
Implementation Method 1
a dissolved oxygen sensor which is for sensing dissolved oxygen in the water and which has a working electrode and a reference electrode; and applying a voltage signal between the working electrode and the reference electrode
Implementation Method 2
the voltage signal provides a conditioning waveform, then a wait time that returns a perturbed local oxygen concentration at the working electrode to a bulk oxygen concentration value
Implementation Method 3
employing electrochemical generation of chlorine for antifouling
Data Source
AI summary
Apparatus (2) for sensing at least one parameter in water, which apparatus (2) comprises: (i) a dissolved oxygen sensor (4) for sensing dissolved oxygen in the water; and which apparatus (2) is such that: (ii) the dissolved oxygen sensor (4) has a working electrode and a reference electrode; and (iii) a voltage signal is applied between the working electrode and the reference electrode, and the voltage signal provides a conditioning waveform, then a wait time, and then a measurement function.