Electrochemical Sensor Flat Measuring Element Sealing
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Solution Overview
Problem
Conventional electrochemical sensors, particularly those with glass electrodes, face challenges in production complexity and sensitivity, while ISFET sensors lack stability and resistance to aggressive media, leading to measurement errors due to improper sealing of the measurement medium.
Innovation Solution
An electrochemical sensor with a precisely defined measurement surface is developed, featuring a flat, disc-shaped measurement element made of electrochemically active pH glass, combined with a ring-shaped sealing element and an insulator element, ensuring a secure seal and precise medium-touched area using wafer technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing element rests directly on the measuring surface of the measuring element to prevent medium penetration, then sealing effectiveness is improved, but measurement errors occur due to reduced slope and long response time
Solution Approach 1:
The patent divides the sensor structure into distinct functional zones: the measuring surface area is kept free of sealing elements, while the sealing element is positioned in a non-measuring area adjacent to the measuring surface. This segmentation allows the sealing element to prevent medium penetration without contacting the measuring surface, thus avoiding measurement errors while maintaining effective sealing.
2Reliability
If conventional glass electrodes are used to achieve high sensitivity and long-term stability, then measurement reliability is improved, but production complexity increases and individual production is required
Solution Approach 1:
The patent combines the advantages of glass electrodes (high stability) with the manufacturing benefits of ISFET sensors. A flat measuring element made of pH-sensitive glass is integrated with a planar structure that can be produced using wafer technology, enabling automated batch production while maintaining the reliability and stability characteristics of traditional glass electrodes.
Solution Approach 2:
The patent changes the geometric parameters of the measuring element from a traditional spherical or hemispherical glass electrode to a flat, planar structure. This parameter change enables compatibility with wafer-based manufacturing processes while preserving the electrochemical properties and measurement reliability of glass electrodes.
3Productivity
If ISFET sensors with flat measuring elements are used to enable wafer technology production, then productivity is improved, but stability and resistance to aggressive media deteriorate
Solution Approach 1:
The patent creates a composite structure combining a flat measuring element made of pH-sensitive glass with a planar support structure. This composite design enables the sensor to be manufactured using wafer technology for high productivity, while the glass material provides the necessary stability and resistance to aggressive media.
4Ease of manufacture
If the measuring element is designed as a flat measuring element for wafer technology production, then ease of manufacture is improved, but a precisely defined measuring surface area must be ensured to avoid measurement errors
Solution Approach 1:
The patent applies local quality by creating a specifically defined free area on the flat measuring element where the measuring surface is exposed and kept free of sealing elements. This localized design ensures that only the precise measuring area contacts the medium, while other areas can be sealed or structured for manufacturing purposes, thus maintaining both ease of manufacture and measurement precision.
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 solution provides improved long-term stability, reduced measurement errors, and enhanced reproducibility by ensuring a precise and secure interface between the sensor and the measurement medium, while being robust enough for use in harsh chemical environments.
Implementation Method 1
Depending on the pH value of the measuring medium, a potential difference develops across the glass membrane
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to an electrochemical sensor (1, 101) comprising a sensor element (15, 115) with a measuring surface (8, 108) facing a measuring medium (5) during use, said sensor element (15, 115) comprising a flat measuring element (2, 102). The electrochemical sensor (1, 101) is also provided with a sensor shaft (4, 104) comprising a window (13, 113) with a window jamb (11, 111), on the end thereof facing the measuring medium (5) during use, the sensor element (15, 115) being built into said sensor shaft (4, 104), in the region of the window (13, 113). The electrochemical sensor (1, 101) comprises an annular sealing element (9, 109) which is arranged between the sensor element (15, 115) and the window jamb (11, 111). An isolator element (10, 110) is connected to the measuring element (2, 102) of the sensor element (15, 115) in a fixed and inseparable manner, leaving the measuring surface (8, 108) free. The sealing element (9, 109), which protects the electrochemical sensor (1, 101) from the penetration of the measuring medium (5), is arranged between the isolator element (10, 110) and the window jamb (11, 111) in a sealing manner.