Microfabricated Glass Substrate Water Sensor with Electrochemical Biofouling Control
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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
The development of a microfabricated apparatus on a glass substrate using photolithography and etching to produce multiple conductivity and dissolved oxygen sensors as open cell sensors with platinum microelectrodes, integrated with a temperature sensor, which enables cost-effective, flow-insensitive, and stable measurements, and incorporates electrochemical generation of chlorine for biofouling reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensors are used for measuring conductivity, temperature, and dissolved oxygen, then measurement accuracy can be achieved, but the sensors are large, power hungry, and require regular recalibration
Solution Approach 1:
The patent replaces conventional mechanical/electrochemical sensor systems with a microfabricated planar sensor that uses integrated circuits and microelectrodes. The conductivity measurement uses a four-electrode configuration with AC excitation to eliminate polarization effects, while dissolved oxygen is measured using a microelectrode array with recessed electrodes. This substitution reduces size, power consumption, and calibration requirements while maintaining measurement accuracy.
2Measurement precision
If conventional sensors are used, then measurement capability is provided, but they are fragile and difficult to mass-manufacture
Solution Approach 1:
The patent changes the manufacturing parameters from conventional sensor fabrication to standard microfabrication processes including photolithography, sputter deposition, and wet etching. These are well-established semiconductor manufacturing techniques that enable mass production. The sensor elements are fabricated as planar structures on a substrate, with conductive traces and electrodes defined by photolithographic patterning, making them compatible with automated manufacturing and assembly.
3Device complexity
If microfabricated sensors are used, then miniaturisation and cost reduction are achieved, but manufacturing precision and mass production capability are limited
Solution Approach 1:
The patent segments the sensor into distinct functional regions fabricated in sequence: conductivity electrodes, temperature sensor, and dissolved oxygen microelectrode array. Each region is defined by separate photolithographic masking steps, allowing precise control of dimensions and positions. The recessed microelectrodes are formed by controlled etching to specific depths, ensuring consistent geometry across multiple sensors. This segmented approach enables high manufacturing precision using standard microfabrication techniques.
4Measurement precision
If sensors operate in natural waters, then measurement data is obtained, but biofouling negatively impacts long-term performance
Solution Approach 1:
The patent converts the harmful effect of biofouling into a beneficial self-cleaning mechanism by applying a periodic bipolar waveform to the electrodes. During the anodic phase, electrochemical oxidation generates reactive oxygen species that oxidize and remove organic fouling deposits. During the cathodic phase, reduction reactions regenerate the electrode surface. This alternating electrochemical treatment continuously cleans the electrode surfaces, maintaining measurement performance in biofouling-prone environments without external intervention.
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 results in high accuracy measurements with reduced biofouling, increased frequency of valid measurements, and long-term stability, while minimizing manufacturing costs and complexity, making it suitable for oceanographic and freshwater applications.
Implementation Method 1
incorporates electrochemical generation of chlorine for biofouling reduction
Implementation Method 2
sensing at least one parameter in water. The sensed parameter may be one or more of conductivity, temperature, and dissolved oxygen
Implementation Method 3
The measurement of dissolved oxygen concentration or partial pressure in water is required for a wide range of industrial and environmental applications
Data Source
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AI summary
Apparatus (2) for sensing at least one parameter in water, which apparatus comprises: (i) a conductivity sensor (6) for sensing conductivity in the water; (ii) a dissolved oxygen sensor (4) for sensing dissolved oxygen in the water; (iii) a glass substrate (14); and (iv) the conductivity sensor (6) and the dissolved oxygen sensor (4) are fabricated on the glass substrate (14) using photolithography and etching.