Cotton-sealed pH test probe
The pH test probe with a cotton-sealed design uses foam as an electrolyte carrier, which solves the problems of insufficient conductivity and poor stability of the reference electrode, and achieves efficient storage and stable output of electrolyte, thus extending its service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG JINQIANG TECH CO LTD
- Filing Date
- 2025-05-20
- Publication Date
- 2026-05-19
AI Technical Summary
Existing pH test probes have insufficient conductivity of the reference electrode, poor pH stability, and short service life, mainly due to insufficient reference electrolyte filling and easy contamination and clogging of the diaphragm.
The design employs a cotton-sealed system, using foam as an electrolyte carrier to increase the reference electrolyte capacity. The reference space, formed by the foam, the outer shell, and the glass electrode, is filled with electrolyte, enabling slow exchange between the electrolyte and the test solution. This enhances conductivity and stability, and prevents contamination and clogging.
It improves the conductivity of the reference electrolyte, enhances pH stability, extends service life, prevents electrolyte penetration and leakage, and improves measurement reliability.
Smart Images
Figure CN224263179U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of pH test pen technology, and in particular relates to a cotton-sealed pH test probe. Background Technology
[0002] In numerous fields such as industrial production, environmental monitoring, medical and health care, food processing, and scientific research, the acidity or alkalinity (pH value) of a solution is an important monitoring indicator. Its accuracy is directly related to key aspects such as product quality control, process optimization, and environmental safety assessment. As the core component of pH measurement, the performance and structure of the pH test probe directly affect the reliability and stability of the measurement results.
[0003] Currently, most common pH test probes use glass electrodes as the sensing element, whose working principle is based on the selective response of the glass membrane to hydrogen ion concentration. Glass electrodes are typically used in combination with a reference electrode, calculating the pH value of the solution by measuring the potential difference between the two. The performance of the reference system directly affects the stability and lifespan of the measurement. The reference electrode is filled with a reference electrolyte (such as potassium chloride solution) and connected to the test solution through a reference diaphragm (such as a ceramic diaphragm). The diaphragm's function is to prevent direct mixing of the reference electrolyte and the test solution while allowing ion exchange to maintain potential stability. Because the diaphragm needs a certain thickness (a ceramic diaphragm acts like a "sieve," allowing liquid to pass through but making storage difficult) to prevent leakage, the internal space of the reference electrode is limited, resulting in a relatively small electrolyte filling volume (usually only a few milliliters). This leads to the following defects in the reference system:
[0004] (1) Insufficient conductivity:
[0005] The small amount of reference electrolyte leads to a large ion concentration gradient, which significantly increases the internal resistance when measuring high-impedance solutions or transmitting electrical signals over long distances, causing potential fluctuations. At the same time, the porosity and thickness of the membrane limit the ion diffusion rate, further reducing conductivity.
[0006] (2) Poor pH stability:
[0007] Insufficient electrolyte filling volume makes the electrolyte susceptible to permeation by the test solution (such as acidic or alkaline solutions slowly neutralizing the electrolyte through the diaphragm), leading to reference potential drift. When the temperature changes, the expansion / contraction of the electrolyte volume can easily cause diaphragm damage or electrolyte leakage, exacerbating pH instability.
[0008] (3) Short lifespan:
[0009] Prolonged immersion of the diaphragm can easily lead to contamination or blockage (such as the adhesion of proteins or colloidal particles), resulting in measurement interruption.
[0010] Therefore, the inventors dedicated themselves to designing a pH testing probe to solve the above problems. Utility Model Content
[0011] The purpose of this invention is to provide a cotton-sealed pH test probe that can increase the amount of reference electrolyte filling, thereby improving conductivity, enhancing pH stability, and extending service life.
[0012] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0013] A cotton-sealed pH test probe includes a housing and a glass electrode. The glass electrode is covered with foam, and the foam and the glass electrode are together covered with the housing. The test head of the glass electrode and the foam are both exposed on the test end face of the housing. A reference element is provided and filled with a reference electrolyte within the reference space formed by the housing, the glass electrode, and the foam. One end of the reference element is immersed in the reference electrolyte, and the other end of the reference element extends outside the reference space.
[0014] As an improvement of the cotton-sealed pH test probe of this utility model, the test head of the glass electrode extends out of the outer shell, the glass electrode, the foam and the outer shell are coaxially arranged, and the reference element is arranged along the axial direction of the outer shell.
[0015] As an improvement of the cotton-sealed pH test probe of this utility model, an annular positioning groove is provided on the inner wall of the outer shell near its test end face, and the foam is installed in the positioning groove.
[0016] As an improvement of the cotton-sealed pH test probe of this utility model, an arc-shaped protrusion is provided on the outer wall of the glass electrode near its test head, and the foam presses against the protrusion.
[0017] As an improvement of the cotton-sealed pH test probe of this utility model, the outer shell includes a fixing ring and a housing. The housing is long and cylindrical. The fixing ring is located inside the housing at one end away from the test head. Both the housing and the fixing ring are sleeved on the outside of the glass electrode.
[0018] As an improvement of the cotton-sealed pH test probe of this utility model, a limiting groove is provided on the inner wall of the housing away from the test head, and the fixing ring is located in the limiting groove.
[0019] As an improvement of the cotton-sealed pH test probe of this utility model, the fixing ring is provided with a perforation, the reference element passes through the perforation, and the fixing ring is fixedly and sealed to the reference element, the glass electrode, and the housing by applying glue.
[0020] As an improvement of the cotton-sealed pH test probe of this utility model, the glass electrode includes a glass tube, an internal reference electrode and an internal reference solution. The test end of the glass tube is conical and has a glass bulb to form the test head. The internal reference solution fills the glass tube. One end of the internal reference electrode is immersed in the internal reference solution, and the other end of the internal reference electrode extends outside the glass tube.
[0021] As an improvement of the cotton-sealed pH test probe of this utility model, a temperature sensor is provided at the bottom of the inner side of the glass tube. The temperature sensor is immersed in the internal reference solution. Two transmission lines of the temperature sensor extend to the outside of the glass tube. The opening of the glass tube is sealed and fixedly connected to the internal reference electrode and the two transmission lines by applying glue.
[0022] As an improvement of the cotton-sealed pH test probe of this utility model, a fixing block is provided inside the glass tube, the internal reference electrode passes through the through hole of the fixing block, and the fixing block uses elasticity to attach the two transmission lines to the inner wall of the glass tube.
[0023] Compared with the prior art, the cotton-sealed pH test probe of this utility model uses foam to seal the glass electrode and the outer shell. The reference space formed by the outer shell, glass electrode and foam is filled with reference electrolyte. The foam acts as an electrolyte carrier, allowing the reference electrolyte to communicate with the test liquid through the foam, thereby improving the conductivity of the reference electrolyte, enhancing the pH stability of the reference system and extending its service life. Attached Figure Description
[0024] Figure 1 This is a three-dimensional enlarged view of the cotton-sealed pH test probe of this utility model;
[0025] Figure 2 This is a three-dimensional exploded view of the cotton-sealed pH test probe of this utility model;
[0026] Figure 3 This is a cross-sectional enlarged view of the cotton-sealed pH test probe of this utility model;
[0027] Figure 4 yes Figure 3 Enlarged view of point A in the middle;
[0028] Figure 5 This is an enlarged cross-sectional view of the casing of this utility model;
[0029] Figure 6 This is a three-dimensional enlarged view of the casing of this utility model;
[0030] Figure 7 This is an enlarged cross-sectional view of the glass electrode of this utility model;
[0031] Figure 8 yes Figure 7 Enlarged view of point B in the middle;
[0032] Figure 9 This is an enlarged cross-sectional view of the glass electrode of this utility model at the location of the fixing block.
[0033] Illustration:
[0034] 1. Housing; 11. Positioning groove; 12. Limiting groove; 2. Glass electrode; 21. Glass tube; 211. Glass bulb; 212. Protrusion; 22. Internal reference electrode; 23. Internal reference solution; 3. Reference element; 4. Reference electrolyte; 5. Foam; 6. Temperature sensor; 61. Transmission line; 7. Fixing ring; 71. Limiting hole; 72. Perforation; 73. Fixing adhesive; 8. Fixing block; 9. Outer shell. Detailed Implementation
[0035] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. The drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of this utility model.
[0036] Reference Figures 1 to 9 A cotton-sealed pH test probe includes a housing 9, a glass electrode 2, a reference element 3, and a foam 5. The foam 5 is fitted over the glass electrode 2, and the housing 9 is fitted over both the foam 5 and the glass electrode 2. The test head of the glass electrode 2 and the foam 5 are both exposed on the test end face of the housing 9. The housing 9, the glass electrode 2, and the foam 5 together form a reference space. The reference element 3 is disposed in the reference space, and the reference space is filled with a reference electrolyte 4. One end of the reference element 3 is immersed in the reference electrolyte 4, and the other end of the reference element 3 extends out of the reference space.
[0037] Reference Figure 2 , Figure 3 , Figure 5 and Figure 6 The outer shell 9 includes a fixing ring 7 and a housing 1. Both the fixing ring 7 and the housing 1 are made of plastic material. The housing 1 is cylindrical, and the diameter of the upper end of the housing 1 is larger than the diameter of the lower end. The top and bottom of the housing 1 are open. The bottom end face of the housing 1 is its test end face. An annular positioning groove 11 is provided on the inner wall of the housing 1 near its test end face. A limiting groove 12 is provided on the inner wall of the housing 1 away from the test head (i.e., the upper inner wall of the housing 1). The fixing ring 7 is annular with a limiting hole 71 at its center. A through hole 72 is also provided eccentrically on the fixing ring 7. The fixing ring 7 is located at the end of the housing 1 away from the test head. Specifically, the fixing ring 7 is located in the limiting groove 12 at the upper end of the housing 1. The housing 1 and the fixing ring 7 are both sleeved on the glass electrode 2. The glass electrode 2, the fixing ring 7 and the housing 1 are coaxially arranged.
[0038] Reference Figure 2 , Figure 3 , Figure 4 and Figure 7 The glass electrode 2 is the sensitive electrode of the probe. The glass electrode 2, foam 5, and housing 9 are coaxially arranged. The lower end of the glass electrode 2 is its test head, which extends from the housing 1 to be immersed in the test liquid for detection. The glass electrode 2 includes a glass tube 21, an internal reference electrode 22, and an internal reference solution 23. The top of the glass tube 21 is its opening, and the test end (i.e., the lower end) of the glass tube 21 is conical and equipped with a glass bulb 211 to form the test head of the glass electrode 2.
[0039] The glass bulb 211 is made of silicate glass, which has a selective response to hydrogen ions. The outer surface of the glass bulb 211 is covered with an extremely thin glass film, which is the key interface for hydrogen ion exchange and potential generation. An arc-shaped protrusion 212 is provided on the outer wall of the glass tube 21 near the test head of the glass electrode 2. The internal reference solution 23 is filled in the glass tube 21. The internal reference solution 23 is usually a potassium chloride (KCl) solution with a fixed concentration to ensure the stability of the potential of the internal reference electrode 22. The internal reference electrode 22 is set along the axial direction of the glass tube 21. The lower end of the internal reference electrode 22 is immersed in the internal reference solution 23, and the upper end of the internal reference electrode 22 extends outside the glass tube 21. The common type of internal reference electrode 22 is the silver / silver chloride (Ag / AgCl) electrode, which is widely used because of its stable potential and good reproducibility.
[0040] Reference Figure 3 , Figure 4 and Figure 7 In order to automatically correct the effect of temperature on potential (temperature compensation) and ensure measurement accuracy, a temperature sensor 6 (such as an NTC thermistor) is provided at the bottom of the inner side of the glass tube 21. The temperature sensor 6 is immersed in the internal reference solution 23. The two transmission lines 61 of the temperature sensor 6 (one is the positive terminal and the other is the negative terminal) extend from the opening at the top of the glass tube 21 to the outside of the glass tube 21.
[0041] Reference Figure 3 , Figure 7 , Figure 8 and Figure 9To prevent the internal reference electrode 22 and the two transmission lines 61 inside the glass tube 21 from shifting, a fixing block 8 is provided inside the glass tube 21. The fixing block 8 is located outside the internal reference solution 23 (the internal reference solution 23 does not fill the glass tube 21). The fixing block 8 has a through hole through which the internal reference electrode 22 passes. The fixing block 8 uses elasticity to attach the two transmission lines 61 to the inner wall of the glass tube 21. To ensure the airtightness of the glass tube 21, the opening of the glass tube 21 is sealed and fixed to the internal reference electrode 22 and the two transmission lines 61 by applying glue to form a fixing glue 73.
[0042] Reference Figure 3 and Figure 4 The foam 5 is installed in the positioning groove 11 of the housing 1 and presses against the protrusion 212 of the glass tube 21. The reference element 3 is arranged along the axial direction of the housing 9. The lower end of the reference element 3 extends into the reference space and is immersed in the reference electrolyte 4. The upper end of the reference element 3 passes through the perforation 72 of the fixing ring 7 and extends out of the housing 9. The reference element 3 is usually composed of silver wire plated with a layer of silver chloride (Ag / AgCl). This structure provides a stable electrical...
[0043] For reference, the reference electrolyte 4 is generally a high-concentration potassium chloride (KCl) solution, used to maintain the stability of the electrochemical environment inside the reference electrode. The reference electrolyte 4 ensures the continuity of potential by contacting the test solution. The fixing ring 7 is fixedly and sealed to the reference element 3, glass electrode 2, and housing 1 by adhesive to prevent the reference electrolyte 4 from leaking out from the fixing ring 7. In this invention, the reference electrolyte 4, reference element 3, and foam 5 together constitute the reference electrode of the pH test probe of this invention. The reference electrolyte 4 can communicate with the test solution through the foam 5. The foam 5 allows ions in the reference electrolyte 4 to slowly diffuse into the test solution, thereby forming an electrical connection between the reference electrode and the test solution. At the same time, it prevents the test solution from entering the interior of the reference electrode, protecting the stability of the electrode.
[0044] Reference Figures 1 to 9 The working principle of the cotton-sealed pH test probe of this utility model is as follows:
[0045] The glass electrode 2 of the pH test probe and the reference electrode are simultaneously immersed in the test solution to form a closed electrochemical circuit.
[0046] The reference electrode undergoes an electrochemical reaction (e.g., AgCl + e) with the reference electrolyte 4 (e.g., saturated potassium chloride solution) via a reference element 3 (e.g., silver / silver chloride). - Ag+Cl - A stable potential is established as the measurement benchmark; its potential is determined by the ion concentration in the electrolyte and is not affected by changes in the external solution; foam 5 serves as the liquid junction, allowing the reference electrolyte 4 to slowly exchange ions (such as K+) with the test solution through its microporous structure.+ and Cl - At the same time, it prevents the components of the test liquid from interfering with the reference electrolyte 4, ensuring a stable potential output. The potential of the reference element 3 (Ag / AgCl) is directly transmitted to the main unit of the pH meter through a metal wire, serving as the reference potential for the measurement circuit.
[0047] The hydrated gel layer formed on the surface of the glass membrane on the glass bulb 211 reacts with H in the test solution. + Ion exchange occurs, forming a membrane potential (E1). The internal reference solution 23 also generates a membrane potential (E2) with the inner hydrated gel layer of the glass membrane. The potential difference across the glass membrane (ΔE = E1 - E2) is related to the H+ in the test solution. + The concentration (i.e. pH value) has a linear relationship, which conforms to the Nernst equation. The internal reference electrode 22 (such as Ag / AgCl) in the glass electrode 2 is in contact with the internal reference solution 23, and its potential is transmitted to the main unit of the pH meter through the metal wire. This potential and the potential of the reference electrode together constitute the potential difference of the measurement circuit.
[0048] Since the Nernst equation depends on temperature, temperature sensors 6 (such as NTC thermistors) automatically correct for the effect of temperature on potential, ensuring measurement accuracy.
[0049] This invention utilizes the three-dimensional porous structure of foam 5 to achieve distributed storage of reference electrolyte 4. The interior of foam 5 is composed of a large number of interconnected micropores, and the porosity can usually reach more than 90% (such as polyurethane foam), which is much higher than that of traditional ceramic diaphragms (40%-60%).
[0050] To address the structural deficiencies of traditional reference systems, this patent proposes a cotton-sealed pH testing probe. Its core innovation lies in achieving the following breakthroughs through the collaborative design of the foam 5 and the reference space:
[0051] I. Electrolyte capacity optimization and conductivity improvement
[0052] Foam 5 as an electrolyte carrier: Foam 5 has high porosity and liquid absorption, which can significantly increase the storage capacity of the reference electrolyte 4, reduce internal resistance and enhance conductivity.
[0053] II. Enhanced pH stability
[0054] Physical isolation and chemical buffering: Foam 5 serves as a buffer medium, reducing the direct penetration and contamination of the test liquid to the reference electrolyte 4; at the same time, its weak acidity / weak alkalinity can neutralize a small amount of intruding liquid and maintain the stability of the reference potential;
[0055] Thermal stress adaptability: The thermal buffering properties of foam 5 can balance the changes in electrolyte volume caused by temperature changes, preventing diaphragm rupture or electrolyte leakage.
[0056] III. Lifespan Extension
[0057] Self-cleaning and anti-fouling: The porous structure of Foam 5 can intercept particulate matter and reduce the risk of membrane blockage; its breathability helps to drain infiltrated liquid and extend the life of the reference system.
[0058] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of protection of the present utility model. Therefore, any equivalent changes made in accordance with the scope of the patent application of the present utility model shall still fall within the scope of the present utility model.
Claims
1. A cotton-sealed pH test probe, comprising a housing and a glass electrode, characterized in that, The glass electrode is covered with foam, and the foam and the glass electrode are together covered with a shell. The test head of the glass electrode and the foam are exposed on the test end face of the shell. The reference space formed by the shell, the glass electrode and the foam is filled with a reference element and reference electrolyte. One end of the reference element is immersed in the reference electrolyte, and the other end of the reference element extends out of the reference space.
2. The cotton-sealed pH testing probe according to claim 1, characterized in that, The test head of the glass electrode extends out of the housing, and the glass electrode, the foam and the housing are coaxially arranged, with the reference element arranged along the axial direction of the housing.
3. The cotton-sealed pH testing probe according to claim 1, characterized in that, The inner wall of the outer casing is provided with an annular positioning groove near its test end face, and the foam is installed in the positioning groove.
4. The cotton-sealed pH test probe according to claim 1, characterized in that, The outer wall of the glass electrode has an arc-shaped protrusion near its test head, and the foam presses against the protrusion.
5. The cotton-sealed pH test probe according to claim 1, characterized in that, The outer casing includes a retaining ring and a housing. The housing is cylindrical, and the retaining ring is located inside the housing at one end away from the test head. Both the housing and the retaining ring are sleeved on the outside of the glass electrode.
6. The cotton-sealed pH test probe according to claim 5, characterized in that, The inner wall of the housing is provided with a limiting groove at a position away from the test head, and the fixing ring is located in the limiting groove.
7. The cotton-sealed pH test probe according to claim 5, characterized in that, The fixing ring has a through hole through which the reference element passes. The fixing ring is fixedly and sealed to the reference element, the glass electrode, and the housing by applying adhesive.
8. The cotton-sealed pH test probe according to claim 1, characterized in that, The glass electrode includes a glass tube, an internal reference electrode, and an internal reference solution. The test end of the glass tube is tapered and has a glass bulb to form the test head. The internal reference solution fills the glass tube. One end of the internal reference electrode is immersed in the internal reference solution, and the other end of the internal reference electrode extends outside the glass tube.
9. The cotton-sealed pH test probe according to claim 8, characterized in that, A temperature sensor is installed at the bottom of the glass tube. The temperature sensor is immersed in the internal reference solution. Two transmission lines of the temperature sensor extend to the outside of the glass tube. The opening of the glass tube is sealed and fixedly connected to the internal reference electrode and the two transmission lines by applying glue.
10. The cotton-sealed pH testing probe according to claim 9, characterized in that, A fixing block is provided inside the glass tube, and the internal reference electrode passes through the through hole of the fixing block. The fixing block uses elasticity to attach the two transmission lines to the inner wall of the glass tube.