Device for obtaining blood serum

Abstract

The invention relates to a device for obtaining blood serum from a whole blood sample, the device comprising at least one attachable sample container (1) which is designed to receive and dispense a whole blood sample. The device further comprises at least one housing (3), which is in the form of an elongate hollow body and has an upper opening (3a) and a lower opening (3b), and at least two membranes of different pore size (2). The at least one housing (3) is designed to be connected to the at least one attachable sample container (1) at the upper opening (3a) by means of a plug connection in such a way that pressure stability is maintained. The at least two membranes of different pore sizes (2) are arranged within the at least one housing (3) in such a way that their planar extent in each case runs perpendicularly to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body, the at least two membranes (2) being arranged one behind the other between the upper opening (3a) and the lower opening (3b) in a sequence of decreasing pore size. The device additionally has at least one attachable collection container (4), the at least one attachable collection container (4) having a pressure-reduced interior and being designed to receive blood serum. The at least one housing (3) is designed to be connected to the at least one attachable collection container (4) at the lower opening (3b) by means of a plug connection in such a way that pressure stability is maintained.

Description

[0001] Fraunhofer Society...eV

[0002] P150395PC00

[0003] Device for obtaining blood serum

[0004] The invention relates to a device and a method for obtaining blood serum from a whole blood sample. This method allows for the rapid extraction of blood serum from a sample container containing a previously drawn sample.

[0005] Whole blood sample isolated serum at the outlet side of the device, without the use of additional chemicals. The device can be used for processing human or animal blood samples or artificial blood-like fluids for research purposes. Without functionalized membrane layers, the device can also be used for the filtration of

[0006] Water samples are used.

[0007] Blood tests play an important role in clinical diagnosis, as they provide valuable information about the cause of a disease and its symptoms. Blood tests are also used for monitoring and

[0008] Testing is used to detect critical health changes before they develop into serious illnesses (heart disease, cancer, diabetes, etc.) or become the cause of disease. Point-of-care tests (POCTs) can play a crucial role in assessing a patient's immediate health status and assisting the physician in diagnosis and treatment. These tests often involve analyzing various components in the patient's blood, requiring the separation of plasma or serum from whole blood. Conventional blood separation requires milliliter-sized blood samples, anticoagulants, and centrifuges, or specialized blood separation membranes used for milliliter-sized samples.The separation of blood plasma (with clotting factors, from anticoagulant-treated blood) or serum (without clotting factors, from fresh blood) is therefore carried out in well-equipped laboratory environments by trained personnel and is thus one of the biggest challenges in the development of cost-effective and portable point-of-care blood diagnostic devices.

[0009] Currently, only technologies and expensive, bulky devices capable of processing large volumes of blood are used to separate serum from whole blood samples. Such solutions are unsuitable for point-of-care testing (POCT) due to their price, size, and the need for trained personnel. For POCT, there is a need for a fast, cost-effective, and simple approach to separating serum from a small, adjustable volume of whole blood.

[0010] Currently, there are many laboratory tests based on blood analysis. Many of these tests require the separation of plasma or serum from whole blood. Since most tests are performed in centralized laboratories, plasma separation is achieved through centrifugation or dialysis. Such equipment processes large volumes of blood and is not only expensive and bulky but can also only be installed in limited locations (laboratories, hospitals, etc.).

[0011] Furthermore, there are solutions for lateral plasma separation tests based on penetration through membranes made of various materials (glass, p-glass, cotton, or mixtures) and pore sizes. Such test strips often require additional buffer for proper execution, with a maximum blood filtration volume of 85 pl per cm³. 2Membrane material is reached within 230 seconds. The separated plasma is then no longer recoverable from the membrane, which is part of the lateral flow test. Methods for on-chip plasma separation based on a piezoacoustic approach, albeit with low yield, are also described in the scientific literature.

[0012] Solutions exist for mobile, portable serum separation using paper-based filtration. Such a solution can be used on-site and for point-of-care testing (POCT). However, the processed volume of separated serum is less than 100 pl and, since it is contained on the paper chip, cannot be transferred to another device for testing. This means the separating paper chip becomes bound to the assay (which remains on the same chip).

[0013] US 2024408 619 Al discloses a centrifuge with rotor attachment for preparing a small-format blood collection tube after blood collection for handling and analysis.

[0014] US 2024 382 949 A1 discloses a device and method for separating serum or plasma from blood cells in a whole blood sample. A cap with a reservoir is used, so that blood cells are drawn into the cap when the sample container is centrifuged. Upon removal of the cap, the blood cells are also removed, and the serum or plasma remains in the sample tube, from where it can be easily withdrawn with a pipette that reaches to the bottom of the sample tube, thus minimizing dead volume.

[0015] The invention is therefore based on the objective of proposing a device and a method that provides an efficient, cost-effective, mobile, and user-friendly means of obtaining blood serum from a whole blood sample with optimal filtration.

[0016] This problem is solved according to the invention by a device according to the main claim and a method according to the dependent claim. Advantageous embodiments and further developments are described in the dependent claims. A device for obtaining blood serum from a whole blood sample has at least one attachable sample container, wherein the at least one attachable sample container is configured to receive and dispense a whole blood sample. Furthermore, the device has at least one housing designed as an elongated hollow body with an upper opening and a lower opening, wherein the at least one housing is configured to be pressure-resistant when connected to the at least one attachable sample container by means of a plug connection at the upper opening.Furthermore, the device comprises at least two membranes of different pore sizes, wherein the at least two membranes are arranged within the at least one housing such that their planar extent is perpendicular to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body, wherein the at least two membranes are arranged one behind the other between the upper opening and the lower opening in a sequence of decreasing pore size. Finally, the device comprises at least one attachable collection container, wherein the at least one attachable collection container has a pressure-reduced interior and is configured to receive blood serum, wherein the at least one housing is configured to be pressure-resistant when connected to the at least one attachable collection container by means of a plug connection at the lower opening.

[0017] The advantages of this device include its high flexibility and ease of use at low cost. The device uses disposable consumables, namely the sample container and the collection container, and its compact size and simple operation allow for use by untrained personnel. The combination of membranes with different pore sizes and the housing diameter can be flexibly adapted to the required blood filtration volume. The decreasing pore size in the direction of flow provides optimal filtration. The device is portable and, due to the closed process column within the housing and the attached sample and collection containers, can be used under all environmental conditions and in any location.The reduced pressure within the collection container allows the device to operate without additional pumps and simultaneously offers the possibility of extracting the serum from the device within 1-5 minutes for further use and testing, for example, with a POCT measuring device based on a known approach (optical, electrochemical, lateral, etc.).

[0018] Pressure-stable means that the connection between the sample container and the housing, as well as between the collection container and the housing, is designed in such a way that the reduced pressure in the interior of the collection container, compared to the interior of the sample container and the housing, can act as a mechanical drive, drawing the whole blood sample from the sample container and through the housing, including all membranes. In particular, no pressure equalization may occur between the sample container and the external environment, nor between the collection container and the external environment, not even by making the respective connection, before the filtration process is completely finished and the collection container is disconnected from the housing, i.e., before the connection is released.

[0019] Typically, the at least two membranes of different pore sizes are arranged in an interchangeable column designed as a hollow cylinder, the column being designed to be connected to the at least one housing by insertion.

[0020] The advantage of this embodiment is the presence of an interchangeable disposable column in combination with a pressure-reduced collection container, which offers flexibility in terms of blood volume and the possibility of using the device for different patient samples after replacing the column and collection container.

[0021] Preferably, at least one of the at least two membranes with different pore sizes is functionalized with fibrin or another coagulation agent. The fibrin-functionalized membrane layers enable faster coagulation of the whole blood and lead to the formation of larger clots. This accelerates the filtration process and increases the filtration quality and thus the efficiency of the device. Preferably, exactly two of the at least two membranes are functionalized, with one functionalized membrane having a pore size of 60 µm and the other functionalized membrane having a pore size of 40 µm. In this way, the advantages of enhanced blood coagulation are best achieved, with the pore size being larger due to the formation of larger clots compared to that of non-functionalized membranes.

[0022] In another embodiment, the device further comprises at least one piezoelectric element, wherein the at least one piezoelectric element is configured to enhance the penetration of the at least two membranes and / or to reduce clogging of the at least two membranes.

[0023] The particular advantage of this embodiment lies in the fact that, in addition to the pressure-reduced interior of the collection container, there is a further mechanical drive for transporting the whole blood. The mechanical force acting on the sample is thus increased. This is due to the vibrations of the piezoelectric element. As a result, not only is the filtration rate increased, but also the filtration volume of the device, because the penetration of the membrane layers is enhanced. Furthermore, when using functionalized membrane layers that promote increased blood coagulation and larger clots, the risk of membrane clogging, which can occur due to larger clots, is reduced. The piezoelectric element is preferably battery-operated, so that there are no disadvantages regarding the flexibility of the device.

[0024] Typically, the at least two membranes each have a pore size of at least 5 pm and at most 60 pm. This has the advantage of optimal filtration quality.

[0025] In a typical embodiment, the at least two membranes are designed as exactly five membranes with pore sizes of 30 pm, 20 pm, 15 pm, 10 pm and 5 pm. Such a filter cascade exhibits particularly high efficiency.

[0026] The hollow volume of the housing, which is designed as an elongated hollow body, can be at least 150 pl and at most 7.5 ml. Within this range, the typically achievable serum volumes of 50 pl to 2.5 ml from a whole blood sample of 100 pl to 5 ml can be obtained, while simultaneously ensuring the smallest possible design of the device, i.e., an optimal volume of the cavity within the housing.

[0027] The at least one sample container, column, housing, or collection container preferably comprises polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), or polystyrene (PS), and / or the at least two membranes preferably comprises p-glass, nitrocellulose, or polyester. This makes the housing shatterproof, pressure-resistant, and lightweight. The membranes achieve optimal filtration performance in this way. In this context, p-glass refers to a glass fiber membrane, wherein the glass fibers have a diameter of less than 0.7 pm and the membrane has a pore size of 5 to 100 pm.

[0028] In a method for obtaining blood serum from a whole blood sample, in which a device according to one of the preceding embodiments is used, at least one attachable sample container contains a whole blood sample and is pressure-resistantly connected to at least one housing designed as an elongated hollow body with an upper opening and a lower opening by means of a plug connection at the upper opening. The at least one attachable sample container is opened as a result of the plug connection with the housing.At least one attachable collection container, which has a pressure-reduced interior and is pressure-resistantly connected to at least one housing by a plug connection at the lower opening, is opened as a result of the plug connection with the housing and the pressure equalization occurring thereby in the housing and the at least one connected sample container, the whole blood sample exits the at least one sample container and flows through the at least one housing, which has at least two membranes of different pore sizes, wherein the planar extent of the at least two membranes within the at least one housing is perpendicular to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body, wherein the at least two membranes are arranged one after the other between the upper opening and the lower opening in a sequence of decreasing pore size.The at least one attachable collection container collects the blood serum that emerges from the lower opening of the housing.

[0029] This method realizes the advantages of the device, enabling the efficient and cost-effective extraction of blood serum from a whole blood sample, flexibly according to the required filtration volume, and in a mobile and user-friendly manner.

[0030] Preferably, before introducing the whole blood sample into the layers, i.e., into the multiple layers, freeze-dried fibrin is introduced into at least one of the at least two membranes. In this way, functionalized membranes are produced particularly easily, and the advantages associated with functionalization are achieved.

[0031] An exemplary embodiment is shown in the drawing and is explained below with reference to Figure 1.

[0032] It shows:

[0033] Fig. 1 shows a schematic cross-sectional view of a device for obtaining blood serum from a whole blood sample.

[0034] Fig. 1 shows a schematic cross-sectional view of a device for obtaining blood serum from a whole blood sample. The housing 3, designed as an elongated hollow body, has an upper opening 3a and a lower opening 3b. A snap-on sample container 1, designed to receive and dispense a whole blood sample, is attached to the housing 3 at the upper opening 3a, and a snap-on collection container 4, designed to receive blood serum and featuring a pressure-reduced interior, is attached to the lower opening 3b, both in a pressure-resistant manner. A piezoelectric element 5 is arranged on the housing 3, designed to enhance the penetration of the membranes 2 and / or reduce clogging of the membranes 2.In this embodiment, the housing 3 contains an interchangeable column 2a, which in turn comprises a cascade of two membranes functionalized with fibrin or another coagulation agent, each with a different pore size 2, and five further, non-functionalized membranes, each with a different pore size 2. In the illustrated embodiment, the membranes 2 functionalized with a fibrin membrane layer have pore sizes of 60 pm and 40 pm. The non-functionalized membranes 2 have pore sizes of 30 pm, 20 pm, 15 pm, 10 pm, and 5 pm. The at least two membranes 2 are arranged within the housing 3 such that their planar extent is perpendicular to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body. The seven membranes 2 in total are arranged one after the other between the upper opening 3a and the lower opening 3b in a sequence of decreasing pore size.

[0035] The combination of the proposed technologies (piezoelectric element 5, cascade 2 of functionalized and non-functionalized membrane layers, and pressure-reduced collection vessel 4) aims to maximize both the speed and quality of the separation process while ensuring the flexibility of whole blood volume processing. The device is battery-operated, portable, and, due to its closed process column, can be used under all environmental conditions and in any location.

[0036] In a method for obtaining blood serum from a whole blood sample, comprising the device shown in Fig. 1, the attachable sample container 1 contains a whole blood sample and is pressure-resistant connected at its upper opening 3a to the housing 3, which is designed as an elongated hollow body, by a plug connection. The plug connection opens the sample container 1. At its lower opening 3b, an attachable collection container 4, which has a pressure-reduced interior, is pressure-resistant connected to the housing 3 by a plug connection. The plug connection opens the collection container 4, and the resulting pressure equalization in the housing 3 and the connected sample container 1 causes the whole blood sample to exit the sample container 1 and flow through the housing 3 and the two membranes 2 functionalized with fibrin or another coagulation agent, as well as the five non-functionalized membranes 2.The movement of the sample through the membrane cascade thus occurs through the reduced-pressure or pressureless interior of collection container 4. The collected blood serum is gathered in collection container 4. Both collection container 4 and sample container 1 can be designed as attachable vials.

[0037] In the embodiment shown in Fig. 1, after inserting the attachable sample container 1 into the housing 3, the planar or cylindrical piezoelectric vibration element 5 is activated. This ensures additional penetration of the plasma through the membranes 2 and reduces membrane clogging. A waiting period of 1–10 minutes, depending on the filtration volume, is then required. Finally, the collection container 4 containing the serum is removed and stored or transferred directly to a point-of-care testing (POCT) device. After each cycle, the disposable consumables 1, 2, 2a, 4 are replaced, and the process can then be repeated for the next whole blood sample (from the same or a different patient) using the same device.

[0038] This method allows for the mobile and user-friendly extraction of blood serum from a whole blood sample in a particularly efficient and cost-effective manner. The innovative aspect lies in the use of planar or cylindrical piezoelectric elements 5 in combination with the membrane cascade 2 to improve sample penetration (flow rate) through the membranes 2 and to increase the potential blood filtration volume. Also innovative is the introduction of freeze-dried fibrin or another clotting agent into the membrane layers to coagulate the entire blood volume and form larger clots, thus improving filtration. The collection container 4, with its reduced internal pressure, enables the device to operate without additional pumps and facilitates the transfer of serum material to the point-of-care testing (POCT) device.

[0039] The embodiment of the device shown in Fig. 1 consists of a hardware unit 3, 5 and disposable consumables 1, 2, 2a, 4. Its dimensions are approximately 3 cm x 3 cm x 20 cm, and its weight is between 100 and 150 g. Battery operation, particularly for powering piezoelectric elements 5, is achieved using AA or AAA batteries at 5 V. Depending on the selected size of the hardware 2, 3 and the containers 1, 4, the sample volume (whole blood) ranges from 100 µl to 5 ml, and the collected serum volume ranges from approximately 50 µl to 2.5 ml, directly dependent on the sample volume used. The estimated price of such a device is between €10 and €20 per run.

[0040] With this device and method, it is possible, unlike paper-based tests, to process the same or even higher volumes of whole blood anywhere in the world and to store or transfer the collected serum material for any other required use (no paper-based assay). Thus, the proposed device and method can facilitate the further development of various types of point-of-care testing (POCT) devices. The proposed solution offers maximum speed and quality for portable serum separation (flexible filter volume), allowing the collected serum to be handled even by unauthorized personnel (the device contains only 1-2 buttons).

[0041] The device's size and ease of use allow for operation by untrained personnel anywhere (portable). The flexibility of combining membranes with different pore sizes and housing diameters allows for adaptation to the required blood filtration volume. The presence of a piezoelectric element 5 enables faster blood flow through the membrane cascade 2 and reduces membrane clogging, thereby increasing the area of ​​blood volume that can be filtered. The membrane layers functionalized with fibrin or another clotting agent allow for faster coagulation of whole blood, accelerating the filtration process and increasing filtration quality. The collection container 4, with its reduced-pressure interior, eliminates the need for active pumping and allows for serum to be withdrawn from the device within 1-10 minutes for further use and testing.The most important advantage is that the device can be used for different patient samples after replacing column 2a and collection container 4. The device is not dependent on a specific method of further serum analysis, making it possible to adjust the required volume and use the serum sample in other diagnostic instruments based on any known approach (optical, electrochemical, lateral, etc.).

[0042] The specified parameters of the device and the method not only improve some of the parameters compared to existing solutions, but above all suggest new ways and applications of the device.

[0043] Only features of the various embodiments disclosed in the exemplary embodiments can be combined and claimed individually.

Claims

Fraunhofer Society...eV P150395PC00 Patent claims 1. Device for obtaining blood serum from a whole blood sample, comprising at least one attachable sample container (1), wherein the at least one attachable sample container (1) is designed to receive and dispense a whole blood sample; at least one housing (3) designed as an elongated hollow body with an upper opening (3a) and a lower opening (3b), wherein the at least one housing (3) is designed to be connected to the at least one attachable sample container (1) by means of a plug connection at the upper opening (3a) in a pressure-resistant manner;at least two membranes of different pore sizes (2), wherein the at least two membranes (2) are arranged within the at least one housing (3) such that their planar extent is perpendicular to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body, wherein the at least two membranes (2) are arranged one after the other in a sequence of decreasing pore size between the upper opening (3a) and the lower opening (3b); at least one attachable collection container (4), wherein the at least one attachable collection container (4) has a pressure-reduced interior and is designed to receive blood serum, wherein the at least one housing (3) is designed to be pressure-resistant when connected to the at least one attachable collection container (4) by a plug connection at the lower opening (3b).

2. Device according to claim 1, wherein the at least two membranes of different pore sizes (2) are arranged in an interchangeable column (2a) designed as a hollow cylinder are arranged, wherein the column (2a) is designed to be connected to the at least one housing (3) by insertion.

3. Device according to claim 1 or 2, wherein at least one of the at least two membranes (2) is functionalized with fibrin or another blood coagulation agent.

4. Device according to claim 3, wherein exactly two of the at least two membranes (2) are functionalized and one functionalized membrane has a pore size of 60 pm and the other functionalized membrane has a pore size of 40 pm.

5. Device according to one of the preceding claims, further comprising at least one piezoelectric element (5), wherein the at least one piezoelectric element (5) is configured to enhance the penetration of the at least two membranes (2) and / or to reduce clogging of the at least two membranes (2).

6. Device according to one of the preceding claims, wherein the at least two membranes (2) each have a pore size of at least 5 pm and at most 60 pm.

7. Device according to one of the preceding claims, wherein the at least two membranes (2) are designed as exactly five membranes with pore sizes of 30 pm, 20 pm, 15 pm, 10 pm and 5 pm.

8. Device according to one of the preceding claims, wherein the hollow volume of the at least one housing (3) designed as an elongated hollow body is at least 150 pl and at most 7.5 ml.

9. Device according to one of the preceding claims, wherein the at least one attachable sample container (1), the column (2a), the at least one housing (3) or the at least one attachable collection container (4) comprise polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC) or polystyrene (PS) and / or the at least two membranes of different pore sizes (2) comprise glass, nitrocellulose or polyester.

10. Method for obtaining blood serum from a whole blood sample, in which a device according to one of the preceding claims is used, wherein at least one attachable sample container (1) contains a whole blood sample and is pressure-resistant connected to at least one housing (3) designed as an elongated hollow body with an upper opening (3a) and a lower opening (3b) by means of a plug connection at the upper opening (3a), wherein the at least one attachable sample container (1) is opened as a result of the plug connection with the housing (3), wherein the housing (3) has at least two membranes of different pore sizes (2), wherein the planar extent of the at least two membranes (2) within the at least one housing (3) is perpendicular to the longitudinal axis of the hollow body and completely covers the inner cross-section of the hollow body.wherein the at least two membranes (2) are arranged one after the other in a sequence of decreasing pore size between the upper opening (3a) and the lower opening (3b), wherein at least one attachable collection container (4) has a pressure-reduced interior and is pressure-resistantly connected to the at least one housing (3) by a plug connection at the lower opening (3b), wherein the at least one attachable collection container (4) is opened as a result of the plug connection with the housing (3) and through the resulting opening in the housing (3) and the at least one connected, Upon pressure equalization in the sample container (1), the whole blood sample exits the at least one sample container (1) and flows through the housing (3) and the at least two membranes (2), with the at least one attachable collection container (4) collecting the blood serum exiting from the lower opening (3b) of the housing (3).

11. Method according to claim 10, wherein freeze-dried fibrin is introduced into the layers of at least one of the at least two membranes (2) prior to the introduction of the whole blood sample into the layers.

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