MEDICAL FLUID PUMP SYSTEM

Description

[0001] The invention relates to a medical fluid pump system for conveying a fluid during extracorporeal blood treatment, comprising a housing with a receiving area, a fluid cassette detachably mounted on the receiving area with a dimensionally stable base body and at least one elastic pump membrane which is fixed to the base body to form at least one pump volume, wherein the pump volume is variable by means of a deflection of the pump membrane for conveying the fluid, and comprising at least one actuator element which is configured to deflect the pump membrane.

[0002] Such a medical fluid pump system is known from US 2011 / 0015610 A1 and is designed as a dialysis machine for use in extracorporeal blood therapy. The known dialysis machine has a fluid cassette and a housing with a recess for receiving the fluid cassette, which can be closed with a lid. The fluid cassette has a base body and a pump diaphragm attached to the base body, forming a pump volume. The pump volume is intended for pumping a dialysis fluid and can be varied by means of a corresponding deflection of the pump diaphragm. For deflecting the pump diaphragm, a piston assembly integrated into the housing is provided, with a piston located in the recess and guided along the housing for movement.When the fluid cassette is inserted into the receiving recess, the pump diaphragm faces the piston, so that a stroke of the piston causes a deflection of the pump diaphragm and thus the pumping of the dialysis fluid.

[0003] A similar fluid pump system is known from US 2009 / 182262. Diaphragm pumps with a dielectric elastomer actuator are known from US 2003 / 117044.

[0004] The object of the invention is to provide a medical fluid pump system of the type mentioned above, which has a simple and robust design.

[0005] This problem is solved by providing at least one actuator element as a dielectric elastomer actuator that is operatively connected to the pump diaphragm and, under the influence of an electrical voltage, performs an actuating movement to deflect the pump diaphragm. The solution according to the invention makes it possible, in particular, to dispense with a piston arrangement for deflecting the pump diaphragm. Instead, the invention provides at least one dielectric elastomer actuator. Dielectric elastomer actuators, their basic structure, and the underlying operating principle for converting electrical energy into mechanical energy are known, at least in the field of drive technology. The basic structure of such a dielectric elastomer actuator comprises a passive elastomer film, the upper and lower surfaces of which are each coated with a flexible electrode.When an electrical voltage is applied to the opposing electrodes, they attract each other due to electrostatic forces. This compresses the elastomer film in the thickness direction and expands it laterally. In a de-energized state, the elastomer film returns to its original state, contracted laterally and expanded in the thickness direction. The actuating movement for deflecting the pump diaphragm is generated based on this operating principle. The elastomer film, which can also be referred to as the elastomer diaphragm, is preferably made of silicone or acrylic. The electrodes can be made of graphite powder, a silicone oil-graphite mixture, or gold.Based on the aforementioned basic structure, the at least one dielectric elastomer actuator can be designed, in particular, as a planar actuator, stacked actuator, bundled actuator, roller actuator, or shell actuator. The aforementioned designs are generally known, so further explanations are unnecessary. The solution according to the invention achieves a structurally simple, robust, and space-saving design. Furthermore, it has been shown that the solution according to the invention enables comparatively quieter pump operation of the medical fluid pump system. This is because, compared to solutions known from the prior art, the design of the actuator element as a dielectric elastomer actuator allows for a significant, and in particular a complete, elimination of friction-generating and thus noise-producing bearings, guides, or other functional elements for supporting or guiding the actuating movement.The receiving area is preferably arranged on an outer housing wall, in particular a housing front. Alternatively, the receiving area can be designed in the form of a receiving compartment, a receiving recess, or the like, which can be closed, in particular by means of a closing element. The fluid cassette is movable relative to the housing between a receiving state and a removal state. In the receiving state, the fluid cassette is held in the receiving area of ​​the housing. In contrast, in the removal state, the fluid cassette is removed from the receiving area and thus separated from the housing. Preferably, the fluid cassette has a fluid inlet and a fluid outlet. During pumping, the fluid preferably enters the pump volume through the fluid inlet and exits the fluid cassette through the fluid outlet.In other words, the pump volume is preferably fluid-conducting and connected to the fluid inlet and outlet. The base body of the fluid cassette is preferably made of a dimensionally stable plastic. The pump diaphragm is elastic, in particular soft-elastic, and preferably made of a silicone material. The at least one pump volume is partially enclosed by the pump diaphragm and / or partially by the base body. The fluid cassette can be assigned to an extracorporeal blood circuit, in which case it can be designated as a blood cassette and is intended for pumping blood. Alternatively, the fluid cassette can be assigned to a dialysis fluid circuit, in which case it can be designated as a dialysis fluid cassette and is intended for pumping dialysis fluid. The dielectric elastomer actuator is at least indirectly operatively connected to the pump diaphragm.Preferably, the dielectric elastomer actuator is associated with the housing or the fluid cassette. In the former case, the dielectric elastomer actuator is arranged on the housing side in the receiving area and is therefore stationary. In the latter case, the dielectric elastomer actuator is arranged on the cassette side and, together with the fluid cassette, can be moved relative to the housing between the receiving and dispensing states. The positioning movement of the dielectric elastomer actuator can be transmitted directly or indirectly to the pump diaphragm. For direct transmission, the dielectric elastomer actuator and the pump diaphragm can be in contact to transmit force and motion.For indirect transmission, a coupling device can be provided which is operatively connected to both the dielectric elastomer actuator and the pump membrane, so that the force and motion transmission from the dielectric elastomer actuator to the pump membrane takes place via the coupling device.

[0006] In this embodiment of the invention, the at least one dielectric elastomer actuator is integrated into the housing. This allows for a particularly simple design of the fluid cassette. As a result, it can be manufactured very cost-effectively, especially as a disposable item for single use. In this embodiment of the invention, the pump diaphragm is preferably fixed externally to the base body, such that an outer surface of the pump diaphragm facing away from the pump volume is oriented towards the receiving area. Furthermore, the dielectric elastomer actuator is preferably arranged at least partially externally on the receiving area and is thereby at least indirectly, and preferably directly, contactable with the external pump diaphragm.

[0007] In a further embodiment of the invention, the at least one dielectric elastomer actuator is a planar actuator arranged in the receiving area. The planar actuator can also be referred to as a dielectric membrane actuator or dielectric actuator membrane and has a planar extent with an actuating movement oriented perpendicular to this extent. This allows the planar actuator to be integrated into the housing in a particularly space-saving manner.

[0008] In a further embodiment of the invention, a coupling device is provided on the housing and / or the fluid cassette, by means of which the at least one dielectric elastomer actuator and the pump diaphragm are coupled to each other in a force- and / or motion-transmitting manner – in a state of the fluid cassette received at the receiving area. The coupling device serves in particular to indirectly transmit the actuating movement and the actuating forces resulting therefrom from the dielectric elastomer actuator to the pump diaphragm. This allows the dielectric elastomer actuator and the pump diaphragm to be spaced apart from each other – in the receiving state of the fluid cassette – and in particular to be arranged inside the housing and / or the base body. Such an internal arrangement particularly prevents damage to the dielectric elastomer actuator and / or the pump diaphragm. The coupling device preferably effects a mechanical coupling.Alternatively or additionally, magnetic coupling can be achieved.

[0009] In a further embodiment of the invention, the coupling device comprises a coupling spring that is supported at one end by the dielectric elastomer actuator and at the other end by the pump diaphragm. The coupling spring provides an elastically compliant coupling in the direction of the positioning movement of the dielectric elastomer actuator and / or in the direction of the deflection of the pump diaphragm. This serves in particular to compensate for tolerances, so that the positioning movement is transmitted into a deflection of the pump diaphragm with as little backlash as possible, and in particular, a free stroke of the dielectric elastomer actuator is avoided. The coupling spring can also be referred to as a tolerance spring. The coupling spring is preferably designed as a helical, leaf, or disc spring.

[0010] In a further embodiment of the invention, the fluid cassette comprises several elastic pump membranes, each fixed to the base body to form a pumping volume, and several dielectric elastomer actuators are provided, each operatively connected to one of the multiple pump membranes. Such a design with multiple pump membranes and multiple dielectric elastomer actuators particularly allows for alternating pumping, in which the multiple pumping volumes are emptied and filled sequentially and / or alternately. This enables a more consistent pumping flow.

[0011] In a further embodiment of the invention, the at least one dielectric elastomer actuator is integrated into the fluid cassette and detachably mounted together with it at the receiving area. This allows the housing of the fluid pump system to be designed in a particularly simple, compact, and cost-effective manner. At the same time, the design of the actuator element as a dielectric elastomer actuator enables a comparatively simple, compact, and cost-effective design of the fluid cassette. In other words, such integration is only made technically feasible and economically viable by designing the actuator element as a dielectric elastomer actuator. In contrast, a corresponding integration of, for example, a reciprocating piston arrangement is not possible for design and / or economic reasons.To supply the at least one dielectric elastomer actuator, the fluid cassette preferably has at least one electrical contact element which – in the receiving state of the fluid cassette – is electrically contacted with a complementary contact element of the housing. Such contacting advantageously eliminates the need for a separate electrical connector and instead creates a virtually automatic electrical connection when the fluid cassette is attached to the receiving area.

[0012] In a further embodiment of the invention, the at least one dielectric elastomer actuator is designed as a planar actuator, wherein the planar actuator is integrated into the pump membrane or vice versa. This allows for a further simplified and particularly compact design. The planar actuator preferably comprises an elastomer film or an elastomer layer, the upper and lower surfaces of which are each coated with a flexible electrode. Preferably, at least the elastomer film or the elastomer layer and the electrodes are embedded in the pump membrane and / or together with the pump membrane form a membrane assembly.

[0013] In a further embodiment of the invention, the pump diaphragm is fixed to the base body, forming a first pumping volume and a second pumping volume. The first and second pumping volumes are fluid-tightly separated from each other by means of the pump diaphragm and are alternately variable. Depending on the direction of deflection of the pump diaphragm, the first pumping volume is reduced and the second pumping volume is increased, or vice versa. This design enables a simple and continuous pumping of the fluid. At the same time, compared to a design in which two separate pump diaphragms are fixed to the base body to form two pumping volumes, installation space can be saved. This embodiment of the invention is particularly advantageous in combination with a dielectric elastomer actuator designed as a planar actuator integrated into the pump diaphragm.

[0014] In a further embodiment of the invention, the at least one dielectric elastomer actuator is configured for capacitive detection of the actuator's position and thus also functions as a sensor element. The actuator movement, performed under the influence of an electrical voltage, is caused by the previously described change in the geometry of the dielectric elastomer actuator. This change in geometry simultaneously causes a change in capacitance, which can be used for sensory purposes, for example, for measuring displacement and / or pressure. In this embodiment of the invention, the at least one dielectric elastomer actuator therefore has a particularly advantageous multiple function. Consequently, a separate sensor element for detecting the actuator's position can be dispensed with, resulting in a further simplified design.By recording the position, it is also possible to indirectly determine the deflection position of the pump diaphragm and, consequently, the prevailing fluid pressure in the pump volume.

[0015] In a further embodiment of the invention, an emergency drive device operatively connected to the pump diaphragm is provided, which has a drive element that can be actuated for manually driven deflection of the pump diaphragm. Manual actuation of the drive element causes the emergency drive device to move, deflecting the pump diaphragm. The emergency drive device ensures emergency operation of the medical fluid pump system, in which fluid delivery can be maintained even in the event of a failure of the dielectric elastomer actuator and / or an interruption of the electrical power supply. The drive element can be designed, in particular, as a crank, handwheel, or the like.

[0016] In a further embodiment of the invention, a detection device is provided which is configured to detect the receiving state of the fluid cassette, in which the fluid cassette is received as intended at the receiving area. For this purpose, the detection device can have at least one sensor element and / or an electrical contact device formed between the receiving area and the fluid cassette, which is electrically conductive in the receiving state and electrically disconnected in the ejection state. Detecting the receiving state particularly prevents incorrect operation of the medical fluid pump system and increases patient safety.

[0017] In a further embodiment of the invention, the receiving area is arranged on an outer housing wall, and a fastening device formed on the housing wall and / or the base body is provided, by means of which the fluid cassette – in a state received by the receiving area – is detachably fastened to the housing wall. The fastening device is preferably designed as a snap-fit ​​device with several snap-fit ​​elements or as a clip device with several clips. Due to the external arrangement of the receiving area, the fluid cassette can be attached to and removed from the housing particularly easily. The fastening device prevents the fluid cassette from unintentionally coming loose.

[0018] In a further embodiment of the invention, the fluid cassette is designed as a disposable item for single use. This eliminates the need for costly sterilization of the fluid cassette before reuse, thus saving the associated costs. Furthermore, the disposable design offers hygienic advantages over sterilizing and reusing the fluid cassette.

[0019] The invention further relates to a medical fluid cassette for a medical fluid pump system according to the preceding description, comprising a dimensionally stable base body and at least one elastic pump diaphragm, which is fixed to the base body to form at least one pump volume, wherein the pump volume is variable by means of a deflection of the pump diaphragm for pumping the fluid, wherein a dielectric elastomer actuator operatively connected to the pump diaphragm is provided, which performs an actuating movement to deflect the pump diaphragm under the influence of an electrical voltage. The at least one dielectric elastomer actuator is integrated into the fluid cassette. To avoid repetition, reference is made to the description of the medical fluid pump system according to claim 7. What has been said there concerning the fluid cassette applies preferably mutatis mutandis to the medical fluid cassette according to the invention.The same applies to embodiments of the medical fluid cassette according to the invention.

[0020] Further advantages and features of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. Fig. 1 shows a highly simplified schematic representation of a section of a medical device with an embodiment of a medical fluid pump system according to the invention, comprising a housing and a fluid cassette detachably mounted on a receiving area of ​​the housing. Fig. 2 shows a highly simplified schematic detail view of the receiving area of ​​the housing, equipped with two actuator elements, in a front view, with the fluid cassette removed from the receiving area. Fig. 3 shows a further detailed view of the receiving area with the fluid cassette mounted on it in a highly simplified schematic sectional view along a section line III-III. Fig. 2 , Fig. 4 a simplified detailed view of the fluid cassette along a section line IV-IV according to Fig. 3 , wherein the fluid cassette has two pump diaphragms, Fig. 5 a further detailed view of the fluid cassette along a section line VV according to Fig. 4 , Fig. 6, 7 highly simplified schematic representations of the principle based on Fig. 2 Fig. 8 shows the actuator elements in different states, Fig. 8 shows a further enlarged schematic representation of the fluid pump system in the area of ​​one of the actuator elements, Fig. 9 shows a highly simplified schematic representation of the principle in the area of ​​a coupling device, and Fig. 10 shows a detailed representation of a further embodiment of a medical fluid pump system according to the invention.

[0021] According to Fig. 1 A medical device V for extracorporeal blood treatment is shown section by section and is designed in the form of a dialysis machine. Fig. 1 Figure 1 shows, in a highly simplified schematic representation, essentially the entire extracorporeal blood circulation of medical device V. This circulation includes an arterial blood line 1, through which blood to be treated is conveyed from a patient (not shown) to a fluid pump system 2 of medical device V. An arterial pressure sensor 3 is provided upstream of the fluid pump system 2, measuring the pressure in the arterial blood line 1 upstream of the fluid pump system 2. This pressure can also be referred to as the low-pressure side pressure. Downstream of the fluid pump system 2 – and thus on the high-pressure side – a high-pressure blood line 4 leads to an arterial air trap 5. A supply line 6 is arranged at an outlet of the fluid pump system 2 and is connected to a pump 7.Additives, such as heparin for blood thinning, can be added via line 6. From the arterial air trap 5, a line 8 carries the blood to be treated to a dialyzer 9, which is supplied with dialyzer fluid via a dialyzer fluid inlet line 10. In the dialyzer 9, the blood is treated with the dialyzer fluid in a known manner. Used dialyzer fluid, which can also be called dialysate, is drained from the dialyzer 9 via a dialyzer fluid outlet 11 and sent for disposal or reprocessing (not shown). The treated blood is then conveyed from the dialyzer 9 to a venous air trap 13 for air removal via a blood drain 12. Downstream of the air trap is an air detector 14, which detects whether there is any air in the system that could be hazardous to the patient.A venous pressure sensor 15 is provided at the venous air trap 13, by means of which the venous pressure can be detected. From the venous air trap 13, via the air detector 14, the treated blood is returned to the patient via a venous blood line 16. A control and monitoring device 17 is also provided for controlling and monitoring the medical device V.

[0022] The fluid pump system 2 serves to pump the blood through the aforementioned extracorporeal blood circulation of the medical device V and has a housing G and a fluid cassette F detachably attached to the housing G.

[0023] In the illustrated embodiment, the fluid pump system 2 is integrated into the medical device V insofar as the housing G is simultaneously assigned to the medical device V. In an embodiment not shown, the fluid pump system instead has a separate housing, so that the fluid pump system is designed as a separate functional unit that is nevertheless assigned to the medical device.

[0024] The housing G has a recording area A ( Fig. 2 ), which is provided for the detachable mounting of the fluid cassette F. In the illustrated embodiment, the mounting area A is arranged on a housing front 100 of the housing G.

[0025] The Fluidcassette F is based on the Fig. 1 and 3shown in a recording state recorded at the recording area A and has a dimensionally stable base body 18 and at least one elastic pump membrane 19 which is fixed to the base body 18 forming at least one pump volume 20 ( Fig. 4, 5 The pump volume 20 forms a fluid-carrying section of the extracorporeal blood circulation. For this purpose, the pump volume 20 is connected to a fluid inlet 21 and a fluid outlet 22 of the fluid cassette F. The fluid cassette F has a fluid inlet 23 extending between the fluid inlet 21 and the pump volume 20, and a fluid outlet 24 extending between the pump volume 20 and the fluid outlet 22. A check valve 25 is assigned to each of the fluid inlet 23 and fluid outlet 24.

[0026] The pumping of blood takes place with reference to Fig. 5 The operation is essentially as follows: To draw blood in through the fluid inlet 21, the pump diaphragm 19 is deflected to the left – and thus towards an outer surface of the base body 18. This increases the pump volume 20. The resulting negative pressure opens the check valve 25 associated with the fluid supply line 23, so that blood is drawn through the fluid inlet 21 via the fluid supply line 23 into the pump volume 20. The check valve 25 associated with the fluid outlet 24 remains closed. To expel the previously drawn-in blood from the pump volume 20, the pump diaphragm 19 is deflected to the right – and thus towards an inner surface of the base body 18. This decreases the pump volume 20. The resulting overpressure opens the check valve 25 associated with the fluid drain 24, so that the previously aspirated blood is pumped from the pump volume 20 through the fluid outlet 22 via the fluid drain 24.The check valve 25 associated with the fluid supply line 23 remains closed.

[0027] For deflection of the pump membrane 19, the fluid pumping system 2 has at least one actuator element in the form of a dielectric elastomer actuator 26 ( Fig. 2, 3 ). In the embodiment according to the Fig. 1 bis 9 The dielectric elastomer actuator 26 is integrated into the housing G. The dielectric elastomer actuator 26 is located in the housing, which is characterized in particular by the Fig. 1 and 3 The fluid cassette F shown in the recording state is connected to the pump diaphragm 19 and, under the influence of an electrical voltage, performs an actuating movement S to deflect the pump diaphragm 19 ( Fig. 3 ).

[0028] Based on the Fig. 6 und 7 A possible embodiment of the dielectric elastomer actuator 26 is shown. Fig. 6 und 7 The following are to be understood as highly simplified schematic diagrams illustrating the operating principle and basic structure of the dielectric elastomer actuator 26. In the embodiment shown, the dielectric elastomer actuator 26 has a passive elastomer membrane 27, which can also be referred to as an elastomer film. The elastomer membrane 27 is designed in the shape of a circular disk and is fixedly mounted on the housing side at unspecified bearing points on its outer circumference U. Furthermore, the dielectric elastomer actuator 26 has a support element 28, which is coupled to an inner circumference of the elastomer membrane 27 in a manner known to those skilled in the art. The support element 28 is designed as a circular plate. An actuating spring 29 engages an unspecified underside of the support element 28. At its other end, the actuating spring 29 is supported on the housing side.An electrode E is arranged on both a top and a bottom surface of the elastomer membrane 27. The electrodes E are designed in a manner known to those skilled in the art and are connected to a voltage source Q. In the following, based on... Fig. 7 In the depicted state, an electrical voltage is applied to the electrodes E. These attract each other due to electrostatic forces. This compresses the elastomer membrane 27 in its thickness direction, leading to a planar expansion in the radial direction. Starting from the point shown Fig. 6 In the tensionless state shown, the elastomer membrane 27 is deflected by the adjusting spring 29 due to its planar expansion and the associated loss of mechanical preload. If the electrical connection to the voltage source Q is interrupted ( Fig. 6 ), the elastomer membrane 27 returns to its radially contracted and thickness-expanded state. The radial mechanical preload of the elastomer membrane 27 compensates for the spring force of the actuating spring 29. The actuating movement S of the dielectric elastomer actuator 26 is generated based on the aforementioned operating principle, which is known as such, so that further explanations in this regard are unnecessary.

[0029] In the embodiment shown, the dielectric elastomer actuator 26 is designed as a planar actuator P arranged flat within the receiving area A. In embodiments not shown in the drawing, the dielectric elastomer actuator is instead designed as a stacked actuator, bundled actuator, roller actuator, or shell actuator. The aforementioned designs of dielectric elastomer actuators are known as such, so further explanations in this regard are unnecessary.

[0030] In an embodiment not shown in the drawing, several dielectric elastomer actuators are arranged in series in the direction of flow and coupled to the pump diaphragm in a manner similar to linear peristalsis. In this case, the pump diaphragm is fixed to the base body, forming a pump volume extending longitudinally along the direction of flow. To pump the blood, the series-arranged elastomer actuators perform wave-like positioning movements, thereby pumping the blood along the pump volume. With this design, check valves can be omitted, resulting in a further simplified construction.

[0031] Based on Fig. 3 The planar actuator P is shown in an upper end position of the positioning movement S (cf. Fig. 7 In this state, the elastomer membrane 27 is convexly bulged outwards from the receiving area A with respect to the housing front 100. In contrast, the elastomer membrane 27 is in the lower end position ( Fig. 6 ) flush with the front of the housing 100 and / or the recording area A.

[0032] Based on the Fig. 1 bis 9 In the illustrated embodiment, the planar actuator P – in the receiving state of the fluid cassette F – acts directly on the pump diaphragm 19 mechanically. In other words, an outer surface of the pump diaphragm 19 facing away from the pump volume 20 contacts an outer surface of the planar actuator P facing away from an interior space I of the housing G.

[0033] To ensure a tolerance-compliant coupling of the dielectric elastomer actuator 26 to the pump membrane 19, a coupling device is preferably provided. A possible embodiment of a coupling device is schematically simplified, in particular by reference to Fig. 9 shown. The coupling device K has a coupling spring 30 which is supported at one end by the dielectric elastomer actuator 26 and at the other end by the pump diaphragm 19. The coupling spring 30 is not to be confused with the actuating spring 29 of the dielectric elastomer actuator 26 ( Fig. 6, 7 The coupling spring 30 creates a preload oriented along the positioning movement S and thus along the deflection L between the dielectric elastomer actuator 26, more precisely: its elastomer membrane 27, and the pump membrane 19. This preload reduces backlash. The coupling spring 30 is supported on both sides and designed to transmit tensile and compressive forces. The coupling device K according to Fig. 9 is assigned to the fluid cassette F. In an embodiment not shown, a coupling device associated with the housing is provided.

[0034] What next based on Fig. 4 As shown, the fluid cassette F has several pump diaphragms 19, 19' and, accordingly, several pump volumes 20, 20'. In the illustrated embodiment, exactly two pump diaphragms 19, 19' and, accordingly, two pump volumes 20, 20' are provided, which can also be referred to as the first pump diaphragm 19, first pump volume 20, second pump diaphragm 19', and second pump volume 20'. In embodiments not shown, three, four, five, and / or more pump diaphragms and thus pump volumes are provided. The second pump diaphragm 19' is fixed to the base body 18, forming the second pump volume 20'. The second pump volume 20' is fluidly connected to the fluid inlet 21 and the fluid outlet 22 of the fluid cassette F, respectively, by means of a fluid inlet 23' and a fluid outlet 24', in a manner corresponding to the first pump volume 20. To control the fluid or...In turn, non-return valves 25' are provided for the blood flow and are assigned to the fluid supply line 23' and the fluid outlet 24'.

[0035] On the housing side, the fluid pump system 2 accordingly has several dielectric elastomer actuators 26, 26', which can also be referred to as the first elastomer actuator 26 and the second elastomer actuator 26'. The second elastomer actuator 26' is identical in construction to the first elastomer actuator 26 and is therefore also designed as a planar actuator. The two elastomer actuators 26, 26' are arranged in the receiving area A in a manner dimensionally adapted to the arrangement of the pump diaphragms 19, 19' on the fluid cassette F. The second elastomer actuator 26' is connected, like the first elastomer actuator 26, by means of a further coupling device not shown, as in Fig. 8 or alternatively Fig. 9 shown, coupled to the second pump diaphragm 19'.

[0036] The aforementioned configuration with multiple pump volumes 20, 20' is particularly advantageous with regard to stabilizing the pump delivery and avoiding pressure peaks. For this purpose, the elastomer actuators 26, 26' can be controlled alternately to cause the two pump diaphragms 19, 19' to deflect alternately. However, such a configuration is not mandatory. In an embodiment not shown, the fluid pumping system has exactly one pump volume and exactly one dielectric elastomer actuator.

[0037] A fastening device B is provided for attaching the fluid cassette F to the housing G, which is based on the Fig. 1 and 2The diagram is shown in a highly simplified schematic representation. The fastening device B is preferably designed as a snap-fit ​​or clip-on device and allows the fluid cassette F to be detachably fastened to the housing G, more precisely to the housing front 100, without the need for tools. The fastening device B preferably has housing-side fastening sections or elements and complementary cassette-side fastening sections or elements, which (without reference numerals) are arranged in Fig. 9 shown schematically.

[0038] In the embodiment shown, the fluid pump system 2 also has an emergency drive device 31 with a manually operated drive element 32. The emergency drive device 31 is shown schematically in a highly simplified form. Fig. 1 shown, where the dashed connection to the housing G symbolizes a functional connection with the pump diaphragms 19, 19'. The drive element 32 can, for example, be designed as a crank or handwheel. By means of the emergency drive device 31, the pumping operation can also be maintained if the voltage source Q ( Fig. 6, 7 ) fail or the elastomeric actuators 26, 26' should otherwise be impaired in their function.

[0039] Furthermore, the fluid pump system 2 includes a detection device 33, which is designed to detect when the fluid cassette F is properly inserted and / or attached to the insertion area A. The detection device 33 may have electrical contact elements, sensors, or the like on the housing and / or cassette side for this purpose. The detection device 33 is connected to the control and monitoring unit 17 via a signal connection. As soon as the detection device 33 detects that the fluid cassette F is properly inserted, a corresponding signal is transmitted to the control and monitoring unit 17, and the medical device V is enabled for operation. If this signal is not received, operation may be blocked by the control system. Alternatively or additionally, a visual or audible warning signal may be issued to an operator of the medical device V.

[0040] In the illustrated embodiment, the dielectric elastomer actuators 26, 26' simultaneously function as unspecified sensor elements for capacitively detecting the position of the respective actuating movement. Based on the Fig. 6 und 7 The resulting change in the geometry of the elastomer membrane 27 simultaneously causes a change in capacitance, which can be used for sensory purposes, for example, for the aforementioned position determination. The capacitive detection of the position allows conclusions to be drawn about the position of the deflection L of the respective pump membrane 19, 19'. Based on the deflection position, the prevailing fluid pressure in the respective pump volume 20, 20' can be deduced using fundamentally known physical relationships. This is particularly advantageous because separate sensor elements designed for this purpose can be dispensed with. Such simultaneous use as both an actuator and a sensor is also referred to as "self-sensing".

[0041] What next based on Fig. 8 As indicated, the dielectric elastomer actuator 26 can alternatively or additionally be provided with another dielectric elastomer membrane M, which functions as a sensor element based on the principles described above.

[0042] Based on Fig. 10 Figure 2a shows a further embodiment of a fluid pumping system 2a according to the invention, in a highly simplified schematic form. To avoid repetition, only the essential differences compared to the previously described fluid pumping system 2 are discussed. Otherwise, reference is made to the descriptions of the fluid pumping system 2 according to the above. Fig. 1 bis 9 Reference is made to the above. What is said there regarding the basic functionality and structure also applies mutatis mutandis to the embodiment according to... Fig. 10 .

[0043] Fluid pump system 2a differs essentially from fluid pump system 2 in that the at least one dielectric elastomer actuator 26a is integrated into the fluid cassette Fa and detachably mounted together with it on the receiving area A of the housing Ga, which is not shown in detail. Consequently, the housing Ga has no actuator components for deflecting the pump diaphragm 19a. All components required for this purpose are instead integrated into the fluid cassette Fa. This offers numerous advantages, particularly with regard to the simplest possible design of the housing Ga.

[0044] The fluid cassette Fa, in turn, has a dimensionally stable base body 18a. The pump diaphragm 19a is fixed to this base body, forming at least one pumping volume 20a. The pumping volume 20a is fluid-conductingly connected to an unspecified fluid inlet and outlet of the fluid cassette Fa in a manner corresponding to the pumping volume 20. Unspecified check valves are assigned to the fluid lines provided for this purpose.

[0045] In the based Fig. 10 In the illustrated embodiment, the elastomeric actuator 26a is also designed as a planar actuator and is furthermore integrated into the pump membrane 19a, or vice versa. In other words, the pump membrane 19a and the dielectric elastomeric actuator 26a form a membrane arrangement 19a, 26a. This is fixed to the base body 18a, forming the pump volume 20a.

[0046] The fluid cassette Fa has two pump volumes 20a, 20'a, which can also be referred to as the first pump volume 20a and the second pump volume 20'a. These are separated from each other fluid-tight by means of the membrane arrangement 19a, 26a. Depending on the direction of the actuating movement S or deflection L of the membrane arrangement 19a, 26a, the first pump volume 20a is enlarged for aspiration of blood and the second pump volume 20'a is reduced for expulsion of blood, or vice versa.

[0047] To supply the dielectric elastomer actuator 26a with electrical operating energy, the fluid cassette Fa has electrical contact elements 34 which, in the recording state, are electrically contacted with complementary contact elements of the housing Ga which are not shown in detail.

[0048] A detection device 33a is provided to record the recording status of the fluid cassette Fa. In the illustrated embodiment, the detection device 33a is associated with the fluid cassette Fa, as symbolized by the dashed line connecting the two parts. Alternatively, the detection device 33a can be arranged on the housing side and associated with the housing Ga.

[0049] Furthermore, an emergency operating device 31a associated with the fluid cassette Fa is provided, along with a drive element 32a. Alternatively, the emergency operating device 31a can be arranged on the housing side and associated with the housing Ga.

[0050] The fluid cassette Fa is designed as a disposable item for single use. The same applies to the fluid cassette F of the embodiment according to the Fig. 1 bis 9 .

Claims

1. Medical fluid pump system (2a) for delivering a fluid for extracorporeal blood treatment, comprising - a housing (Ga) which has a receiving portion (A), - a fluid cassette (Fa), which is detachably received on the receiving portion (A) and has a dimensionally stable main body (18a) and at least one elastic pump membrane (19a) that is fixed to the main body (18a) with formation of at least one pump volume (20a, 20'a), - wherein the pump volume (20a, 20'a) is variable by means of a deflection (L) of the pump membrane (19a) for the purpose of delivering the fluid, - and comprising at least one actuator element configured to deflect the pump membrane (19a), - characterized in that the at least one actuator element is a dielectric elastomer actuator (26a) which is operatively connected to the pump membrane (19a) and, under the influence of an electrical voltage, performs an actuating movement (S) for deflecting the pump membrane (19a), - wherein the at least one dielectric elastomer actuator (26a) is integrated in the fluid cassette (Fa) and together therewith is detachably received on the receiving portion (A).

2. Medical fluid pump system (2a) according to Claim 1, characterized in that the at least one dielectric elastomer actuator (26a) is in the form of a planar actuator (P), wherein the planar actuator (P) is integrated in the pump membrane (19a) or vice versa.

3. Medical fluid pump system (2a) according to Claim 1 or 2, characterized in that the pump membrane (19a) is fixed to the main body (18a) with formation of a first pump volume (20a) and a second pump volume (20'a), wherein the first pump volume (20a) and the second pump volume (20'a) are alternately variable and are fluid-tightly separated from one another by means of the pump membrane (19a).

4. Medical fluid pump system (2a) according to one of the preceding claims, characterized in that the at least one dielectric elastomer actuator (26a) is configured for capacitive detection of an actuating position of the actuating movement and thus additionally acts as a sensor element.

5. Medical fluid pump system (2a) according to one of the preceding claims, characterized in that an emergency drive device (31a), which is operatively connected to the pump membrane (19a) and has a drive element (32a) that can be actuated for manually driven deflection of the pump membrane (19a), is provided.

6. Medical fluid pump system (2a) according to one of the preceding claims, characterized in that a detection device (33a), which is configured to detect a receiving state of the fluid cassette (Fa) in which the fluid cassette (Fa) is received as intended on the receiving portion (A), is provided.

7. Medical fluid pump system (2a) according to one of the preceding claims, characterized in that the receiving portion (A) is arranged on an external housing wall (100) of the housing (Ga), and in that a fastening device (B), which is formed on the housing wall (100) and / or the main body (18a) and by means of which the fluid cassette (Fa) - in a state in which the latter is received on the receiving portion (A) - is fastened detachably to the housing wall (100), is provided.

8. Medical fluid pump system (2a) according to one of the preceding claims, characterized in that the fluid cassette (Fa) is in the form of a disposable article for one-time use.

9. Medical fluid cassette (Fa) for a medical fluid pump system (2a) according to one of the preceding claims, comprising a dimensionally stable main body (18a) and at least one elastic pump membrane (19a), which is fixed to the main body (18a) with formation of at least one pump volume (20, 20'a), wherein the pump volume (20a, 20'a) is variable by means of a deflection of the pump membrane (19a) for the purpose of delivering the fluid, characterized in that there is provided at least one dielectric elastomer actuator (26a) which is operatively connected to the pump membrane (19a) and, under the influence of an electrical voltage, performs an actuating movement (S) for deflecting the pump membrane (19a), wherein the at least one dielectric elastomer actuator (26a) is integrated in the fluid cassette (Fa) and together therewith can be detachably received on a receiving portion (A) of a housing (Ga) of the medical fluid pump system (2a).