High-temperature-sterilization-resistant polarographic dissolved oxygen electrode and preparation method thereof

Abstract

The invention discloses a high-temperature-sterilization-resistant polarographic dissolved oxygen electrode and a preparation method thereof, and is suitable for the fields of biological fermentation and cell culture. The electrode is composed of a platinum cathode filament sealed by high borosilicate glass, a pure silver cylindrical anode, a PT100 temperature sensor packaged by ceramic, a diaphragm fixing structure composed of a PEEK material and stainless steel, and an aviation plug connecting system. The thermal stress is eliminated through material thermal expansion coefficient matching and a gradient annealing process; the silver cylinder is adopted to replace traditional silver wires to improve stability; and high-performance engineering materials are selected to ensure high temperature resistance of the structure. The electrode can tolerate the sterilization condition of 132 DEG C / 30 min, and after 30 times of high-temperature sterilization, the zero drift is 1t; 0.5% FS, slope change lt; the temperature compensation precision is + / -0.1 DEG C, and the plugging life is gt; and the operation is performed for 5000 times. The problems of packaging cracks, structure instability and material softening of an existing electrode in a high-temperature sterilization environment are solved, a dissolved oxygen measurement solution which is stable in performance and long in service life is provided, and the strict application requirements in the field of bioengineering are effectively met.

Description

Technical Field

[0001] The present invention relates to the technical field of bioengineering, and in particular to a polarographic dissolved oxygen electrode resistant to high temperature sterilization and a preparation method thereof. Background Art

[0002] In the field of bioengineering, dissolved oxygen concentration is a key parameter that affects microbial metabolism and cell growth, and is crucial for process control of biological fermentation and cell culture processes. Polarographic dissolved oxygen electrodes are widely used in bioreactors and fermenters due to their advantages such as high measurement accuracy and fast response speed. However, bioprocesses usually require high-temperature steam sterilization (121°C, 30 minutes or higher) before use, which poses severe challenges to the material selection and structural design of the electrode. Polarographic dissolved oxygen electrodes in the existing technology generally have problems such as rapid performance degradation and short service life during repeated high-temperature sterilization.

[0003] Traditional polarographic dissolved oxygen electrodes suffer from several flaws in their structural design and material selection. First, the commonly used cathode encapsulation material, soda-lime glass (thermal expansion coefficient α = 9 × 10⁻⁶ / K), is susceptible to microcracks due to thermal stress during high-temperature sterilization, leading to electrode failure. Second, traditional designs generally use thin-diameter silver wire (Ø0.5 mm or less) as the anode, which has a low yield strength (<80 MPa) and is prone to plastic deformation during repeated sterilization, causing geometric structural instability in the electrode. Furthermore, the conventional temperature sensor encapsulation uses materials with limited heat resistance (<200°C), such as silicone, which significantly degrades insulation performance during high-temperature sterilization. The electrode diaphragm support structure is often made of materials with low heat deformation temperatures, such as polycarbonate (HDT 130°C) or ABS (Vicat softening point 105°C), which are prone to creep deformation (deformation >0.5 mm) in high-temperature environments. Finally, electrode connectors are typically made of materials with limited heat resistance (<100°C), such as PP or PVC, which are prone to aging and cracking after long-term use in high-temperature environments.

[0004] With the continuous advancement of bioengineering technology, process conditions are becoming more demanding, and the performance limitations of traditional dissolved oxygen electrodes are becoming increasingly prominent. The current market lacks truly autoclavable polarographic dissolved oxygen electrodes with stable performance, which has become a bottleneck limiting the precise control of dissolved oxygen in fermentation and cell culture processes. Therefore, developing a polarographic dissolved oxygen electrode with a stable structure, reliable performance, and true autoclavability is of great practical significance and application value for improving bioengineering process control precision and ensuring production quality stability. Summary of the Invention

[0005] Based on the above objectives, the present invention provides a polarographic dissolved oxygen electrode that is resistant to high temperature sterilization, comprising:

[0006] High borosilicate glass: SiO2 ≥ 80%, B2O3 12-13%, thermal expansion coefficient of 3.3×10 -6 / K sealed platinum cathode wire, diameter 0.2mm, purity 99.95%;

[0007] The cylindrical anode is made of pure silver with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm. The surface is irradiated with 0.1 M HCl solution at 0.5 mA / cm 2 The Ag / AgCl layer is formed by electrolysis at a current density of 100 nm;

[0008] A PT100 temperature sensor is encapsulated in alumina ceramic with a thermal conductivity of 30W / m·K and is fixed with high-temperature resistant epoxy glue, EP42HT-2, TG = 210℃;

[0009] The diaphragm fixing structure is formed by the diaphragm pressing seat made of PEEK material, Victrex450G, HDT315℃ and the 316L stainless steel fixing ring, Φ10mm×5.5mm, connected by interference fit; and

[0010] It includes a connection system that complies with the MIL-DTL-5015 standard aviation plug and PEEK insulator, and is equipped with a double-layer staggered EPDM sealing ring with a hardness of 70±5ShoreA and a compression of 25-30%.

[0011] Furthermore, the structure of the borosilicate glass-sealed platinum cathode wire was subjected to a gradient annealing process in which the temperature was reduced from 580°C to 300°C at a rate of 2°C / min to eliminate internal thermal stress.

[0012] Furthermore, the connection between the silver tube anode and the PEEK substrate, and between the temperature sensing module and the PEEK substrate is achieved by YAG laser welding with a pulse width of 5ms, and the connection gap is less than 0.02mm.

[0013] Furthermore, after the electrode has been sterilized 30 times at 121°C / 30 min, the zero-point current change rate does not exceed 4.7%, the slope change rate does not exceed 1.8%, the response time change rate does not exceed 2.1%, and the temperature compensation error does not exceed ±0.11°C.

[0014] The method for producing the polarographic dissolved oxygen electrode resistant to high temperature sterilization comprises the following steps:

[0015] Step 1: Insert a 0.2mm diameter platinum wire into a 2mm outer diameter borosilicate glass tube, flame seal it at 1800°C using an oxyhydrogen flame under nitrogen protection, and then perform a gradient annealing treatment from 580°C to 300°C.

[0016] Step 2: After ultrasonic cleaning with acetone, the silver cylinder was placed in a 0.1M KCl solution and polarized at a constant current of 0.5 mA for 30 minutes to form a homogeneous chlorination layer;

[0017] Step 3: Use YAG laser with a pulse width of 5ms to weld each component to the PEEK matrix, and control the fitting clearance within 0.02mm;

[0018] Step 4: Connect the PEEK film holder and the 316L stainless steel fixing ring with an interference fit, and press and install the electrode diaphragm between the two;

[0019] Step 5: Perform a three-point calibration in a saturated oxygen solution at 25°C and a zero oxygen environment using a 5% Na2SO3 solution to ensure that the electrode slope is within the range of 35-45 nA / ppm.

[0020] Furthermore, the curing process of the high temperature resistant epoxy adhesive is: first keep it at 120°C for 2 hours, and then keep it at 150°C for 4 hours.

[0021] Furthermore, the electrode's anodic polarization voltage fluctuates less than 1mV in 24 hours, the temperature compensation accuracy reaches ±0.1°C, the diaphragm assembly replacement time is 30 seconds, the connector plug-in life exceeds 5,000 times, and the protection level is IP68.

[0022] Furthermore, the electrode can withstand high-temperature steam sterilization at a maximum temperature of 132°C / 30 min.

[0023] The present invention provides a polarographic dissolved oxygen electrode resistant to high-temperature sterilization and a preparation method thereof, which solves the problems of package cracks, structural instability and material softening in the dissolved oxygen electrode under high-temperature sterilization conditions in the prior art.

[0024] The technical solution of the present invention is a polarographic dissolved oxygen electrode that is resistant to high temperature sterilization, comprising:

[0025] The cathode packaging structure is made of high borosilicate glass (SiO2≥80%, B2O3 12-13%, thermal expansion coefficient α=3.3×10 -6 / K) sealed a platinum cathode wire with a diameter of 0.2 mm and eliminated thermal stress through a gradient annealing process (cooling from 580°C to 300°C at a rate of 2°C / min);

[0026] The anode assembly, consisting of a pure silver (Ag999) cylinder with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm, was electrolyzed in a 0.1 M HCl solution (current density 0.5 mA / cm 2 ) forming an Ag / AgCl reference system;

[0027] The temperature sensing module includes a PT100 sensor encapsulated in an alumina ceramic package (thermal conductivity 30 W / m·K) and fixed with high-temperature resistant epoxy glue (EP42HT-2, TG = 210°C);

[0028] The diaphragm fixing structure is composed of a PEEK diaphragm seat (Victrex450G, HDT315℃) and a 316L stainless steel fixing ring (Φ10mm×5.5mm) connected by interference fit. The diaphragm is installed between the two and tightened and fixed;

[0029] The connection system uses aviation plugs that meet the MIL-DTL-5015 standard and PEEK insulators (volume resistivity>10 16 Ω·cm), and set an EPDM sealing ring with a hardness of 70±5ShoreA, a double-layer staggered arrangement, and a compression amount of 25-30%.

[0030] The present invention also provides a method for preparing the aforementioned electrode, comprising the steps of cathode fabrication, anode treatment, component assembly, and calibration testing. The cathode is fabricated using a flame sealing process under nitrogen protection; the anode treatment uses a constant-current electrolysis method to form a homogeneous chloride layer; component assembly uses laser welding technology to ensure stable connections; and calibration testing uses a three-point calibration method to ensure that electrode performance meets requirements.

[0031] Beneficial effects of the present invention:

[0032] First, the present invention adopts high borosilicate glass (SiO2≥80%, B2O3 12-13%, thermal expansion coefficient α=3.3×10 -6 / K) and platinum wire (Φ0.2mm) matching packaging technology, the difference in thermal expansion coefficient between the two materials is less than 0.5×10 -6 / K, and a gradient annealing process eliminates internal thermal stress, enabling the electrode to withstand high-temperature sterilization conditions of 132°C / 30 minutes. After 30 cycles of high-pressure sterilization (121°C / 30 minutes), the electrode's zero-point current change rate was only 4.7%, and the slope change rate was only 1.8%, far lower than the 5-8% change rate of traditional electrodes, demonstrating excellent high-temperature stability and long-term operational reliability.

[0033] Secondly, the present invention innovatively uses a silver tube structure (wall thickness 0.8mm) to replace the traditional silver wire as the anode, which significantly improves the thermal stability and mechanical strength of the anode structure. At the same time, it optimizes the internal flow field design of the electrode. Under the condition of Reynolds number Re = 120, the boundary layer thickness is reduced by 40%, which improves the response speed of the electrode. The anode polarization voltage fluctuates by less than 1mV in 24 hours, while the traditional silver wire structure fluctuates by 3-5mV, which greatly improves the stability of the electrode measurement. Combined with the precise compensation of the temperature sensing module (accuracy of ±0.1℃, better than the conventional design of ±0.3℃), the electrode maintains high-precision measurement performance in the actual working environment.

[0034] Third, the present invention adopts modular structural design and high-performance engineering materials (such as PEEK, 316L stainless steel, alumina ceramics, etc.), which not only makes the electrode have excellent high-temperature tolerance, but also significantly improves the convenience of maintenance and service life. The innovative design of the diaphragm fixing structure shortens the replacement time of the diaphragm assembly to 30 seconds, and the repeatability accuracy reaches ±0.01mm; the connection system adopts aviation-grade plugs and double-layer offset sealing design, with a plug-in life of more than 5,000 times (the industry standard is only 1,000 times), and reaches the IP68 protection level, ensuring that it can still work reliably under high humidity and high temperature conditions. These improvements provide long-term stable, accurate and reliable dissolved oxygen monitoring capabilities for biological fermentation and cell culture processes, and effectively solve the technical problem of the existing technology that the use of dissolved oxygen electrodes in high-temperature sterilization environments is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 Schematic diagram of the process flow for preparing a high-temperature sterilization-resistant polarographic dissolved oxygen electrode according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the performance test process of a high-temperature sterilization-resistant polarographic dissolved oxygen electrode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It is also noted that, to provide a more detailed description, the following embodiments are best and preferred embodiments, and those skilled in the art may employ alternative methods for implementing certain known technologies. Furthermore, the accompanying drawings are intended only to provide a more detailed description of the embodiments and are not intended to limit the present invention.

[0039] It should be noted that references in the specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," etc. indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment necessarily includes such specific features, structures, or characteristics. In addition, when specific features, structures, or characteristics are described in conjunction with an embodiment, it is within the knowledge of persons skilled in the relevant art to implement such features, structures, or characteristics in conjunction with other embodiments (whether or not explicitly described).

[0040] In general, terms can be understood, at least in part, from their use in context. For example, depending at least in part on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending at least in part on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0041] Example 1

[0042] See Figures 1 to 2

[0043] Electrode structure design

[0044] The high temperature sterilization resistant polarographic dissolved oxygen electrode provided by the present invention is mainly composed of the following parts:

[0045] Cathode packaging structure

[0046] The cathode adopts the design of platinum cathode wire encapsulated by high borosilicate glass. The specific implementation process is as follows:

[0047] High-purity platinum wire with a diameter of 0.2 mm and a purity of 99.95% was selected as the cathode material.

[0048] The high borosilicate glass tube with a composition of SiO2≥80% and B2O3 12-13% and an outer diameter of 2mm is used as the packaging material. Its thermal expansion coefficient α is 3.3×10 -6 / K.

[0049] In a nitrogen protective environment, a flame sealing process is performed using an oxyhydrogen flame at a temperature of 1800°C to seal the platinum wire inside the glass tube.

[0050] The sealed structure is treated with a gradient annealing process: the temperature is slowly reduced from 580°C to 300°C at a cooling rate of 2°C / min, effectively eliminating the internal thermal stress of the structure.

[0051] Anode assembly design

[0052] The anode assembly adopts a silver cylinder structure design:

[0053] Pure silver, Ag999, is used to make a cylindrical anode with the following dimensions: wall thickness 0.8mm, height 44.5mm, inner diameter 5mm.

[0054] Chlorination treatment of the silver cylinder surface: Place the cleaned silver cylinder in 0.1M HCl solution and 2 Electrolysis was carried out at a current density of 100 nm to form a stable Ag / AgCl reference electrode system.

[0055] Temperature sensor module

[0056] The temperature sensing module is designed using the following scheme:

[0057] A PT100 temperature sensor is selected and encapsulated with alumina ceramic material with a thermal conductivity of 30W / m·K to ensure heat transfer efficiency.

[0058] Use high temperature resistant epoxy glue, model EP42HT-2, glass transition temperature TG = 210 ° C, for potting and fixing.

[0059] The epoxy adhesive curing process uses a two-step curing process: 2 hours at 120°C and then 4 hours at 150°C to ensure full cure and optimal performance.

[0060] Diaphragm fixed structure

[0061] The diaphragm fixing structure adopts the following design:

[0062] PEEK material (model Victrex450G, heat deformation temperature HDT315℃) is selected to make the film pressing seat.

[0063] The fixing ring is made of 316L stainless steel and has a size of Φ10mm×5.5mm.

[0064] The membrane pressing seat and the fixing ring are connected by interference fit, and the electrode membrane is installed between the two and pressed and fixed.

[0065] Connection system

[0066] The connection system is designed as follows:

[0067] An aviation plug that complies with the MIL-DTL-5015 standard is used as the electrical connector.

[0068] The internal insulator of the plug is made of PEEK material, and its volume resistivity is greater than 10 16 Ω·cm, ensuring good insulation performance.

[0069] The seal adopts EPDM material sealing ring with a hardness of 70±5ShoreA. It is designed as a double-layer staggered arrangement and the compression is controlled within the range of 25-30%.

[0070] Preparation method

[0071] Taking the production of a Φ12mm electrode rod as an example, the detailed preparation steps are as follows:

[0072] Cathode production

[0073] Take a high-purity platinum wire with a diameter of 0.2 mm and a purity of 99.95%, and insert it into a high-borosilicate glass tube with an outer diameter of 2 mm.

[0074] In a nitrogen protective environment, the glass tube is heated at a temperature of about 1800°C using an oxyhydrogen flame to achieve a fusion seal between the platinum wire and the glass.

[0075] After the sealing is completed, the package structure is heat treated according to the gradient annealing process: starting from 580℃, the temperature is reduced to 300℃ at a rate of 2℃ / min to eliminate internal thermal stress.

[0076] Anodic treatment

[0077] The prepared silver cylinder with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm was placed in acetone for ultrasonic cleaning to remove surface contaminants.

[0078] The cleaned silver cylinder was placed in a 0.1M KCl solution and a constant current of 0.5 mA was applied for electrolytic polarization for 30 minutes to form a stable and homogeneous silver chloride layer.

[0079] Component assembly

[0080] The cathode assembly, anode assembly and temperature sensing module were welded to the PEEK substrate using a YAG laser with a pulse width of 5 ms.

[0081] During the assembly process, ensure that the fitting clearance between each component and the PEEK matrix is less than 0.02mm to ensure structural stability.

[0082] The PEEK film pressing seat and the 316L stainless steel fixing ring are connected by interference fit, and the electrode diaphragm is installed between the two and pressed and fixed.

[0083] Install the aviation plug and ensure that the EPDM sealing ring is arranged in double layers with a staggered arrangement, and the compression is controlled within the range of 25-30%.

[0084] Calibration test

[0085] The assembled electrode was placed in a saturated oxygen solution at 25°C for calibration.

[0086] The zero oxygen environment test uses a 5% Na2SO3 solution.

[0087] Perform a three-point calibration to ensure that the electrode slope is within the range of 35-45nA / ppm.

[0088] The electrodes of the present invention have been rigorously tested, and the following are detailed test data for the examples:

[0089] After the electrode samples were prepared as described above, they were subjected to 30 autoclave sterilization cycles (conditions: 121°C / 30 min). The following performance parameters were measured:

[0090] parameter Initial value After 30 sterilizations Rate of change Zero current (nA) 2.1 2.3 +4.7％ Slope (nA / ppm) 38.6 37.9 -1.8％ Response time (s) 28.7 29.3 +2.1％ Temperature compensation error ±0.08℃ ±0.11℃ +37.5％

[0091] The test results show that the performance parameters of the electrode changed little after 30 times of high-temperature sterilization:

[0092] The zero-point current increases by only 4.7%, which is much lower than the drift of traditional electrodes after sterilization (usually 5-8%).

[0093] The electrode slope decreased by only 1.8%, which is lower than the industry standard of 2% per week.

[0094] The response time increased by only 2.1%, indicating good stability of the electrode membrane and structure.

[0095] Although the temperature compensation error increases by 37.5%, the absolute value remains at ±0.11°C, which is better than the ±0.3°C accuracy of conventional designs.

[0096] The performance advantages of the electrodes in the embodiments can be summarized as follows:

[0097] After high-temperature sterilization, the electrode zero point drift is less than 0.5% FS, and the slope change is less than 2% / week, which is significantly better than the 5-8% change rate of traditional electrodes.

[0098] The silver tube structure improves the stability of the anode polarization voltage, with a fluctuation of less than 1mV in 24 hours, while the traditional silver wire structure has a fluctuation of 3-5mV.

[0099] The temperature compensation accuracy reaches ±0.1°C, which is better than the ±0.3°C of conventional designs.

[0100] The improved diaphragm fixing structure reduces the diaphragm assembly replacement time to 30 seconds, and the repeat positioning accuracy reaches ±0.01mm.

[0101] The connector has a plug-in and pull-out life of over 5,000 times, far exceeding the industry standard of 1,000 times, and meets the IP68 protection grade.

[0102] The present invention encompasses any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention. To provide a thorough understanding of the present invention, specific details are described in detail below in connection with the preferred embodiments of the present invention, but those skilled in the art will be able to fully understand the present invention without these detailed descriptions. Furthermore, to avoid unnecessary confusion regarding the essence of the present invention, well-known methods, processes, procedures, components, and circuits have not been described in detail.

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A polarographic dissolved oxygen electrode resistant to high temperature sterilization, characterized in that: include: High borosilicate glass: SiO2 ≥ 80%, B2O3 12-13%, thermal expansion coefficient is 3.3×10 -6 / K sealed platinum cathode wire, diameter 0.2mm, purity 99.95%; The cylindrical anode is made of pure silver with a wall thickness of 0.8 mm, a height of 44.5 mm, and an inner diameter of 5 mm. The surface is irradiated with 0.1 M HCl solution at 0.5 mA / cm 2 The Ag / AgCl layer is formed by electrolysis at a current density of 100 nm; A PT100 temperature sensor is encapsulated in alumina ceramic with a thermal conductivity of 30W / m·K and is fixed with high-temperature resistant epoxy glue, EP42HT-2, TG = 210℃; The diaphragm fixing structure is formed by the diaphragm pressing seat made of PEEK material, Victrex450G, HDT315℃ and the 316L stainless steel fixing ring, Φ10mm×5.5mm, connected by interference fit; and It includes a connection system that complies with the MIL-DTL-5015 standard aviation plug and PEEK insulator, and is equipped with a double-layer staggered EPDM sealing ring with a hardness of 70±5ShoreA and a compression of 25-30%.

2. The electrode according to claim 1, characterized in that The structure of the high borosilicate glass-sealed platinum cathode wire is subjected to a gradient annealing process in which the temperature is reduced from 580° C. to 300° C. at a rate of 2° C. / min to eliminate internal thermal stress.

3. The electrode according to claim 1, characterized in that The connection between the silver tube anode and the PEEK matrix, and between the temperature sensing module and the PEEK matrix is achieved by YAG laser welding with a pulse width of 5ms, and the connection gap is less than 0.02mm.

4. The electrode according to claim 1, characterized in that After the electrode has been sterilized with high-pressure steam 30 times at 121°C / 30 min, the zero-point current change rate does not exceed 4.7%, the slope change rate does not exceed 1.8%, the response time change rate does not exceed 2.1%, and the temperature compensation error does not exceed ±0.11°C.

5. A method for preparing the high temperature sterilization resistant polarographic dissolved oxygen electrode according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Insert a 0.2mm diameter platinum wire into a 2mm outer diameter borosilicate glass tube, flame seal it at 1800°C using an oxyhydrogen flame under nitrogen protection, and then perform a gradient annealing treatment from 580°C to 300°C. Step 2: After ultrasonic cleaning with acetone, the silver cylinder was placed in a 0.1M KCl solution and polarized at a constant current of 0.5 mA for 30 minutes to form a homogeneous chlorination layer; Step 3: Use YAG laser with a pulse width of 5ms to weld each component to the PEEK matrix, and control the fitting clearance within 0.02mm; Step 4: Connect the PEEK film holder and the 316L stainless steel fixing ring with an interference fit, and press and install the electrode diaphragm between the two; Step 5: Perform a three-point calibration in a saturated oxygen solution at 25°C and a zero oxygen environment using a 5% Na2SO3 solution to ensure that the electrode slope is within the range of 35-45 nA / ppm.

6. The method according to claim 5, characterized in that The curing process of the high temperature resistant epoxy adhesive is: first keep it at 120°C for 2 hours, and then keep it at 150°C for 4 hours.

7. The electrode according to claim 1, characterized in that The electrode's anode polarization voltage fluctuates less than 1 mV in 24 hours, the temperature compensation accuracy reaches ±0.1°C, the diaphragm assembly replacement time is 30 seconds, the connector plug-in life exceeds 5,000 times, and the protection level is IP68.

8. The electrode according to claim 1, characterized in that The electrode can withstand high-temperature steam sterilization at a maximum temperature of 132°C / 30 min.

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