Sterile blood sampling device for large animals

Abstract

The utility model relates to the technical field of blood sampling devices for large animals, and discloses a sterile blood sampling device for large animals, which comprises a blood sampling needle, a blood sampling main pipe and a plurality of blood sampling branch pipes which are communicated in sequence, a peristaltic pump is arranged on the blood sampling main pipe, the blood sampling main pipe is communicated with a plurality of blood sampling branch pipes through a three-way pipe or a four-way pipe, the tail end of each blood sampling branch pipe is respectively connected with a blood sampling bottle, and a stop valve is arranged on each blood sampling branch pipe. According to the scheme, the peristaltic pump and the blood sampling branch pipes are combined, so that the blood sampling amount of a large animal in the end is ensured, meanwhile, the continuity of collecting blood for different project purposes is effectively improved, and the situation that the whole blood sampling amount is affected by blood coagulation and pipe blockage possibly caused by the fact that blood sampling bottles need to be switched and blood sampling is suspended in the midway is avoided.

Description

Technical Field

[0001] This invention relates to the field of blood collection devices for large animals, and specifically to a sterile blood collection device for large animals. Background Technology

[0002] In the field of serum product manufacturing, large animal blood is a crucial raw material. Especially when large animals are nearing the end of their lives, collecting as much blood as possible for serum sample production not only makes full use of resources but also provides vital support for medical research, disease diagnostic reagent development, and biopharmaceuticals. For example, in the development of diagnostic reagents for some rare diseases, specific antibody components in large animal serum are key to reagent effectiveness; in biopharmaceutical processes, certain large animal serums can be used for cell culture, ensuring the quality and yield of drug production. However, this process requires ensuring that blood collection is relatively painless and humane, while simultaneously collecting a sufficient amount of blood within a limited time, and ensuring that the collected blood can be used to produce high-quality serum samples, avoiding problems such as hemolysis that affect serum quality. This places extremely high demands on the blood collection equipment.

[0003] Currently, there are two main types of blood collection devices for large animals on the market: traditional manual and automated. Traditional manual blood collection generally uses syringes or simple blood collection tubes, relying on the operator's experience to collect blood. This method is simple to operate and has a low cost, but it has the problems of limited blood collection volume and low efficiency, making it difficult to meet the needs of large animals for large blood collection at the end of their lives. Automated blood collection equipment, such as the sterile blood collection device for negative pressure blood collection for large animals disclosed in patent publication number CN 217659882 U, uses a vacuum pump to continuously collect blood under negative pressure and control the flow rate to a certain extent. However, this method still has the following problems: (1) Although the existing technology can regulate the blood flow rate to a certain extent by adjusting the pressure of the vacuum pump, the cardiovascular function of large animals gradually declines at the end of their lives, and the blood pressure and blood flow rate are unstable. The continuous negative pressure blood collection of the vacuum pump is prone to triggering the stress response of large animals, which interrupts the blood collection and affects the blood collection volume; in addition, if the pressure of the vacuum pump negative pressure blood collection is too high, it may cause the blood vessels to collapse due to negative pressure, hindering the blood flow and affecting the blood collection volume. (2) During the rapid collection of large amounts of blood, hemolysis can easily occur in the blood as it flows through the pipeline due to factors such as pressure changes and uneven flow rates. This seriously affects the quality of serum samples and reduces their usability in production and research. (3) During long-term, large-volume blood collection, the existing equipment is unable to maintain a sterile environment throughout the process, which increases the risk of blood contamination. Once the blood is contaminated, the produced serum samples will not meet the strict quality standards.

[0004] Therefore, developing a sterile blood collection device for large animals can not only make up for the shortcomings of existing technologies, but also meet the requirements of collecting large amounts of blood at the end of life in large animals, which is of great significance for realizing the full utilization of blood resources of large animals. Summary of the Invention

[0005] The present invention aims to provide a sterile blood collection device for large animals to solve the technical problem that existing blood collection devices, which use continuous negative pressure to collect blood, are prone to causing stress reactions in animals and thus reducing the amount of blood collected.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a sterile blood collection device for large animals, comprising a blood collection needle, a blood collection main tube, and several blood collection branch tubes connected in sequence; the blood collection main tube is equipped with a peristaltic pump, and the blood collection main tube is connected to several blood collection branch tubes through a three-way or four-way tube, and the end of each blood collection branch tube is connected to a blood collection bottle, and a stop valve is provided on the blood collection branch tube.

[0007] The principle and advantages of this scheme are:

[0008] 1. Large animals experience cardiovascular function decline and unstable blood pressure and blood flow velocity during the terminal stage. Compared to existing technologies that use vacuum pumps for blood collection, which are prone to triggering stress responses in large animals due to continuous negative pressure, this method uses a peristaltic pump. On the one hand, the flow rate can be flexibly adjusted according to the animal's real-time physiological state, such as a decrease or increase in blood pressure, avoiding damage to blood vessels due to flow rate fluctuations and ensuring a continuous and stable blood collection process. On the other hand, the peristaltic pump gently pushes blood through the tube without generating excessive negative pressure, effectively preventing vascular collapse, ensuring continuous blood flow, and reducing blood residue in the blood collection tube, thus allowing more blood to be collected within a limited time.

[0009] 2. Compared to existing technologies where blood collection can only be used for one purpose, this solution designs several blood collection branches, with different types of blood collection bottles connected to the end of each branch. This facilitates blood collection for research on different projects. If a certain project requires a large amount of blood, the type of blood collection bottle at the end of the different blood collection branches can be adjusted in real time to meet different blood collection needs.

[0010] 3. This solution combines a peristaltic pump and multiple blood collection tubes, which can ensure the blood volume of large animals at the end of their lives while effectively improving the continuity of blood collection for different purposes, and avoid the impact on the overall blood volume caused by blood clotting and tube blockage that may occur when blood collection is interrupted due to the need to switch blood collection bottles.

[0011] 4. This solution involves installing a shut-off valve on the blood collection branch tube, which allows for the switching of different blood collection bottles connected to the main blood collection tube during continuous blood collection by adjusting the opening and closing of the shut-off valve. This enables the switching of different blood collection branch tube pathways, thereby ensuring continuous blood collection and increasing the amount of blood collected within a limited blood collection time.

[0012] Preferably, as an improvement, the blood collection bottle is a sterile procoagulant blood collection bottle, a sterile anticoagulant blood collection bottle, or a sterile ordinary blood collection bottle.

[0013] Beneficial effects: The above setup facilitates the preparation of appropriate blood collection bottle combinations for different animals and different blood research projects.

[0014] Preferably, as an improvement, the blood collection bottle is connected to a breathing tube, and the end of the breathing tube is provided with a sterile filter membrane.

[0015] Beneficial effects: This solution, with the above-mentioned setup, allows air to escape from the blood collection bottle during collection by squeezing the blood, thus maintaining pressure balance inside and outside the bottle. This prevents blood from clotting due to excessive pressure inside the bottle, which could affect the continuity of blood collection. Furthermore, the inclusion of a sterile filter membrane effectively prevents cross-contamination between the blood and harmful substances in the outside air, further enhancing the safety of blood collection.

[0016] Preferably, as an improvement, the breathing tube is provided with a one-way valve.

[0017] Beneficial effects: The above-mentioned setup facilitates the one-way discharge of air from the blood collection bottle, preventing outside air from entering the blood collection bottle and affecting the condition of the collected blood.

[0018] Preferably, as an improvement, the blood collection needle and the blood collection tube are threaded together.

[0019] Technical Benefits: This solution, employing the aforementioned design, enhances the stability and sealing of the connection between the blood collection needle and the main blood collection tube. Especially during blood collection from large animals, the blood collection device may experience shaking or displacement due to animal activity and the blood collection procedure. This solution utilizes a threaded connection between the blood collection needle and the main blood collection tube, creating a tighter and more stable connection structure compared to simple plug-in connections. This stability prevents accidental detachment of the blood collection needle and main blood collection tube during blood collection, avoiding blood leakage and contamination, and ensuring the continuity of blood collection. Furthermore, the excellent sealing prevents outside air from entering the blood collection system, reducing the chance of blood contact with air and lowering the risk of blood oxidation and contamination. Additionally, the threaded connection facilitates the installation and removal of the blood collection needle and main blood collection tube, allowing users to quickly disassemble, clean, disinfect, replace, or repair various components of the blood collection device as needed.

[0020] Preferably, as an improvement, the ratio of the inner diameter of the blood collection needle tube to the inner diameter of the blood collection tube is 0.3-0.4:0.5-0.6.

[0021] Beneficial Effects: This solution, with the aforementioned setup, not only easily adapts to different types of large animals but also enables continuous blood collection under the action of a peristaltic pump, improving collection continuity and increasing the blood volume. Specifically, by setting the inner diameter of the blood collection needle slightly smaller than the main blood collection tube, excessive fluctuations in blood flow velocity within the collection channel are avoided, effectively stabilizing the collection speed. The applicant's experiments revealed that if the inner diameter of the blood collection tube is too low, the blood flow velocity will decrease significantly after entering the tube from the needle, leading to uneven blood flow within the tube. In large animal blood collection, this uneven flow velocity may increase the risk of hemolysis. Conversely, if the inner diameter of the blood collection needle is too large, it will increase the animal's suffering, potentially causing stress and affecting the continuity of blood collection.

[0022] Preferably, as an improvement, the inner diameter of the blood collection needle tube is 0.3-0.4 cm, and the inner diameter of the blood collection tube is 0.5-0.6 cm.

[0023] Beneficial effects: The above settings are adopted in this scheme. Specifically, when the inner diameter of the blood collection needle is 0.35cm and the inner diameter of the blood collection tube is 0.5cm, the combination of the peristaltic pump has the following technical advantages: (1) High-efficiency blood collection: The needle with an inner diameter of 0.35cm is relatively thick, which can provide a larger blood flow channel. Combined with the stable pumping capacity of the peristaltic pump, a large amount of blood can be collected in a short time, which can meet the needs of large animals at the end of life to quickly collect enough blood for the production of serum samples, and greatly improve the blood collection efficiency. (2) Precise flow rate control: The peristaltic pump has the function of precisely adjusting the flow rate. When paired with the needle with an inner diameter of 0.35cm, the blood flow rate can be adjusted in real time according to the unstable cardiovascular state of large animals at the end of life. For example, when the blood pressure of large animals decreases, the flow rate is appropriately reduced to prevent damage to blood vessels due to excessive pressure difference; when the blood pressure is relatively stable, the flow rate is increased to speed up the blood collection process and ensure that enough blood is collected in a limited time. (3) Reduced risk of hemolysis: The peristaltic pump precisely controls the flow rate, allowing blood to flow smoothly through the larger inner diameter needle into the blood collection tube, reducing pressure fluctuations and uneven flow rates within the needle and tube, thus effectively reducing the risk of hemolysis and ensuring that the collected blood can be used to produce high-quality serum samples. (4) Adaptable to multiple scenarios: The combination of the peristaltic pump and the 0.35cm inner diameter needle is relatively flexible and easy to integrate into different types of blood collection equipment, from small portable devices to large fixed blood collection devices. This allows for rapid deployment and use in emergency blood collection scenarios for large animals at the end of their lives, whether in farms, zoos, or the wild, improving the applicability and portability of the equipment.

[0024] Preferably, as an improvement, the ratio of the inner diameter of the blood collection needle tube, the length of the blood collection needle, and the length of the blood collection needle tip is 0.3-0.4:5-7:1.2-1.4.

[0025] Preferably, as an improvement, the inner diameter of the blood collection needle tube is 0.3-0.4 cm, the length of the blood collection needle is 5-7 cm, and the length of the blood collection needle tip is 1.2-1.4 cm.

[0026] Beneficial Effects: This design, employing the aforementioned configuration, facilitates blood collection by inserting the lancet into the blood vessels of large animals. Specifically, when the lancet is 6cm long, has an inner diameter of 0.35cm, and a tip length of 1.3cm, the tip angle is approximately 15°. The 6cm lancet length provides sufficient penetration into the thicker skin and subcutaneous tissue of large animals, effectively reaching the blood vessel even with thicker subcutaneous fat and muscle tissue. The 0.35cm inner diameter provides a relatively large blood flow channel. When collecting large amounts of blood for serum sample production from large animals at the time of death, the larger inner diameter allows for smooth blood flow, preventing slow blood flow due to a small lancet diameter, thus improving collection efficiency. The 1.3cm tip length aids in precise vessel positioning, providing better guidance during puncture. Furthermore, the 15° tip angle facilitates easy penetration of the vessel wall, reducing damage to surrounding tissues and increasing the success rate of puncture. Furthermore, a suitable needle tip bevel angle and inner diameter design can maintain a relatively stable flow of blood as it flows out of the blood vessel and into the blood collection needle. When blood can smoothly enter the blood collection needle and pass through the subsequent blood collection tube, the risk of hemolysis caused by factors such as sudden changes in blood flow rate and pressure can be effectively reduced. This is crucial for obtaining high-quality blood samples for serum production.

[0027] Preferably, as an improvement, a fixed baffle is provided at the point where the blood collection main pipe enters the peristaltic pump head.

[0028] Beneficial effects: The above-mentioned setup in this scheme helps to prevent the blood collection tube from twisting inside the peristaltic pump, which would affect the quality of blood collection.

[0029] Preferably, as an improvement, the peristaltic pump head is provided with a groove, and a number of rolling balls are connected in a circumferential array within the groove.

[0030] Beneficial effects: The above settings in this scheme facilitate uniform blood collection by the rolling ball squeezing the blood in the blood collection tube after the peristaltic pump is started, thereby improving the continuity of blood collection.

[0031] Preferably, as an improvement, the groove diameter is 1.0 to 1.2 cm, the groove depth is 0.6 to 0.7 cm, and the diameter of the rolling ball is 0.5 to 0.6 cm.

[0032] Beneficial effects: This solution effectively avoids problems such as hemolysis that may occur due to excessive compression of blood collection tubes caused by excessively large balls in conventional peristaltic pumps by limiting the size of the pump head (groove, ball, etc.). Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a sterile blood collection device for large animals in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the installation structure of the peristaltic pump and the blood collection tube in an embodiment of the present invention.

[0035] Figure 3 for Figure 2 The left view of the peristaltic pump head shows the structure of the grooves and the rolling balls.

[0036] Figure 4 This is a schematic diagram of the installation structure of the peristaltic pump and the blood collection tube in other embodiments of the present invention. Detailed Implementation

[0037] The following detailed description illustrates the specific implementation method:

[0038] The reference numerals in the accompanying drawings include: blood collection needle 1, needle tube 11, needle tip 12, main blood collection tube 2, peristaltic pump 3, peristaltic pump head 31, groove 311, ball 32, triangular block 33, limiting block 34, first stop block 35, second stop block 36, pressure block 37, blood collection branch tube 4, shut-off valve 41, blood collection bottle 5, breathing tube 6, sterile filter membrane 61, and one-way valve 62.

[0039] Example

[0040] This solution provides a sterile blood collection device for large animals, as shown in the attached diagram. Figure 1 As shown: It includes a blood collection needle 1, a blood collection main tube 2 and several blood collection branch tubes 4 connected in sequence; for reference, in this scheme, the blood collection needle 1 and the blood collection main tube 2 are threadedly connected.

[0041] The ratio of the inner diameter of the tube 11 of blood collection needle 1, the length of blood collection needle 1, and the length of the needle tip 12 of blood collection needle 1 is 0.3–0.4:5–7:1.2–1.4. The ratio of the inner diameter of the tube 11 of blood collection needle 1 to the inner diameter of the main blood collection tube 2 is 0.3–0.4:0.5. As a reference, the inner diameter of the main blood collection tube 2 is 0.5 cm, the inner diameter of the tube 11 of blood collection needle 1 is 0.3–0.4 cm, the length of blood collection needle 1 is 5–7 cm, and the length of the needle tip 12 of blood collection needle 1 is 1.2–1.4 cm, thereby effectively ensuring the blood collection speed and volume.

[0042] The blood collection main pipe 2 is equipped with a peristaltic pump 3, which facilitates adjusting the blood collection speed according to the condition of large animals and increases the blood collection volume. This solution also provides a peristaltic pump 3, which includes a pump housing, a peristaltic pump head 31, and several rolling balls 32 rolledly connected to the peristaltic pump head 31. The peristaltic pump head 31 is fixedly connected to a motor (not shown in the figure) via a rotating shaft and connecting gears; rotation of the motor drives the peristaltic pump head 31 to rotate. Figure 2and Figure 3 As shown, the peristaltic pump head 31 has a circumferential groove 311, and the rolling balls 32 are located within the groove 311. Specifically, there are two or three rolling balls 32, all of which are arranged circumferentially within the groove 311. The groove diameter is 1.0–1.2 cm, the groove depth is 0.6–0.7 cm, and the rolling ball diameter is 0.5–0.6 cm. By limiting the size of the peristaltic pump head (grooves, rolling balls, etc.), problems such as hemolysis that may occur due to excessive compression of the blood collection tube caused by excessively large rolling balls in conventional peristaltic pumps are effectively avoided.

[0043] The pump casing has an inlet and an outlet for the blood collection tube 2 to pass through. A fixing baffle is installed where the blood collection tube enters the peristaltic pump head to prevent the blood collection tube from twisting inside the pump, thus affecting blood collection quality. For reference, the fixing baffle can be a set of triangular blocks 33 positioned near the inlet and outlet inside the pump casing to guide the blood collection tube 2. The set of triangular blocks 33 near the inlet forms a first channel for the blood collection tube 2 to pass through, and the set of triangular blocks 33 near the outlet forms a second channel for the blood collection tube 2 to pass through. A pressure block 37 is provided between the first and second channels, positioned opposite the groove 311 and with a gap between it and the ball bearing 32 smaller than the diameter of the blood collection tube 2. During installation, the blood collection tube 2 passes sequentially through the inlet, the first channel, the gap, the second channel, and the outlet, thus installing the blood collection tube 2 and the peristaltic pump 3. After the peristaltic pump 3 starts, the ball bearing 32 rotates and compresses the blood inside the blood collection tube 2, generating pumping power and propelling the blood forward in the blood collection tube 2. The first and second channels effectively guide and limit the blood collection main pipe 2, ensuring that the peristaltic pump head 31 rotates continuously to deliver blood continuously, thus achieving continuous blood collection.

[0044] In other embodiments, such as Figure 4 As shown, the fixed baffle can be an arc-shaped limiting block 34, a first baffle 35, and a second baffle 36 set on one side of the pump housing. The limiting block 34 has a limiting groove. The first baffle 35 and the second baffle 36 are respectively set on both sides of the limiting groove near the inlet and outlet. There is a gap between the ball 32 and the limiting block 34 that is smaller than the diameter of the blood collection tube 2. The limiting block 34, the first baffle 35, the ball 32, and the second baffle 36 together form a main tube channel for the blood collection tube 2 to pass through. In specific installation, the blood collection tube 2 passes through the inlet, the main tube channel, and the outlet to realize the installation of the blood collection tube 2 and the peristaltic pump 3. After the peristaltic pump 3 is started, the ball 32 rotates and squeezes the blood in the blood collection tube 2 to generate pumping power and push the blood in the blood collection tube 2 forward. The three balls 32 alternately squeeze the blood in the blood collection tube 2 to achieve continuous blood collection.

[0045] The main blood collection tube 2 is connected to several branch blood collection tubes 4 via a three-way or four-way connector. Each branch blood collection tube 4 is connected to a blood collection bottle 5 at its end, and a shut-off valve 41 is provided on the branch blood collection tube 4. For reference, in this embodiment, a four-way connector is used to connect the main blood collection tube 2 and the branch blood collection tubes 4. The blood collection bottle 5 at the end of each branch blood collection tube 4 can be a sterile procoagulant blood collection bottle 5, a sterile anticoagulant blood collection bottle 5, or a sterile ordinary blood collection bottle 5. In actual blood collection operations, different blood collection bottles 5 can be selected in combination or all the same blood collection bottles 5 can be used according to the needs of the research project.

[0046] To ensure the blood flow rate within the blood collection bottle 5, a breathing tube 6 is connected to the blood collection bottle 5, and a sterile filter membrane 61 is installed at the end of the breathing tube 6. During the blood collection process, blood flows into the blood collection bottle 5, squeezing out the air inside the bottle through the breathing tube 6. The sterile filter membrane 61 effectively prevents cross-contamination between the blood and harmful substances in the outside air, ensuring blood safety and thus obtaining large animal blood samples that meet the requirements of the project's testing / research.

[0047] In other embodiments, to further ensure the safety of blood collection, a one-way valve 62 is also provided at the end of the breathing tube 6. Specifically, a one-way valve 62 is provided outside the sterile filter membrane 61. On the one hand, this ensures that air in the blood collection bottle 5 can only be discharged in one direction, avoiding the possibility that outside air may enter the blood collection bottle 5, affecting the blood flow rate, or even causing hemolysis.

[0048] The specific implementation method is as follows:

[0049] Before the actual blood collection, depending on the large animal being collected and the type of research / testing project, prepare in advance a sterile blood collection needle 1, a peristaltic pump 3, a connected sterile blood collection main tube 2, a four-way blood collection branch tube 4, and a sterile blood collection bottle 5, etc., and ensure they are in a sterile state according to the instructions. Figure 1 Assemble the blood collection device in advance using the connection method shown. During the actual blood collection, use appropriate restraint equipment and methods to restrain the animal, ensuring it is in a quiet and stable state, preventing it from struggling or moving during the blood collection process, to ensure the smooth progress of the blood collection operation and the safety of personnel. If the animal is near death, simple restraint and protection are sufficient. Disinfect the blood collection site, and apply a tourniquet or manually compress the vein near the heart at the blood collection site to make the vein more engorged and visible. Then insert the needle to collect blood. After the bleeding stabilizes, start the peristaltic pump 3 to collect the blood one by one into the blood collection bottle 5.

[0050] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A sterile blood collection device for large animals, characterized by: The blood collection device comprises a blood collection needle, a blood collection main tube and a plurality of blood collection branch tubes connected in sequence; a peristaltic pump is arranged on the blood collection main tube; the blood collection main tube is connected with the plurality of blood collection branch tubes through a three-way tube or a four-way tube; the end of each blood collection branch tube is connected with a blood collection bottle; and a stop valve is arranged on the blood collection branch tube.

2. A sterile blood collection device for large animals as defined in claim 1, wherein: The blood collection bottle is a sterile coagulation blood collection bottle, a sterile anticoagulation blood collection bottle or a sterile general blood collection bottle.

3. The sterile blood collection device for large animals of claim 1, wherein: A breathing tube is connected to the blood collection bottle, and a sterilization filter membrane is arranged at the end of the breathing tube.

4. A sterile blood collection device for large animals as defined in claim 3, wherein: A one-way valve is arranged on the breathing tube.

5. The sterile blood collection device for large animals of claim 1, wherein: The blood collection needle and the blood collection main tube are threadedly connected.

6. The sterile blood collection device for large animals of claim 1, wherein: The ratio of the inner diameter of the needle tube of the blood collection needle to the inner diameter of the blood collection main tube is 0.3-0.4:0.5-0.6; the ratio of the inner diameter of the needle tube of the blood collection needle to the length of the blood collection needle to the length of the needle tip of the blood collection needle is 0.3-0.4:5-7:1.2-1.

4.

7. A sterile blood collection device for large animals as defined in claim 6, wherein: The inner diameter of the blood collection main tube is 0.5-0.6 cm; the inner diameter of the needle tube of the blood collection needle is 0.3-0.4 cm; the length of the blood collection needle is 5-7 cm; and the length of the needle tip of the blood collection needle is 1.2-1.4 cm.

8. The sterile blood collection device for large animals of claim 1, wherein: A fixed baffle is arranged at the position where the blood collection main tube is connected with the pump head of the peristaltic pump.

9. A sterile blood collection device for large animals as defined in claim 8, wherein: A groove is arranged in the pump head of the peristaltic pump, and a plurality of rolling balls are connected to the groove in a rolling manner, and the rolling balls are arranged in a circumferential array in the groove.

10. A sterile blood collection device for large animals as defined in claim 9, wherein: The diameter of the groove is 1.0-1.2 cm, the depth of the groove is 0.6-0.7 cm, and the diameter of the rolling ball is 0.5-0.6 cm.

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