Blood pump with encapsulated actuator

Abstract

A system and method for generating blood flow using a blood pump comprising a membrane and an encapsulated actuator is described. The pump may be implantable and may comprise a stator assembly, an electromagnetic assembly supported by the stator assembly, a magnetic assembly, one or more springs attached to the stator and magnetic assembly, and an encapsulation portion connecting the magnetic assembly to the stator assembly. The magnetic assembly may further be coupled to a membrane assembly comprising a flexible membrane. The electromagnetic assembly may be selectively activated to reciprocate the magnetic assembly, thereby reciprocating the membrane assembly and inducing undulations in the flexible membrane to pump blood from the inlet to the outlet of the pump. The encapsulation portion may prevent blood from interacting with the inner moving parts of the pump, thereby reducing the risk of hemolysis.

Description

[Technical field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 363,635, filed April 26, 2022, and European Patent Application No. 22315090.5, filed April 26, 2022, the entire contents of each of which are incorporated herein by reference.

[0002] FIELD OF THEINVENTION The present invention relates generally to blood pumps. For example, by way of example, systems and methods are provided herein including an implantable heart pump with improved hydraulic performance designed to reduce hemolysis and platelet activation by encapsulating an actuator assembly. [Background technology]

[0003] (background) The human heart is composed of four major chambers, including two ventricles and two atria. Generally, the right heart receives oxygen-poor blood from the body into the right atrium and pumps it to the lungs via the right ventricle. The left heart receives oxygen-rich blood from the lungs into the left atrium and pumps it to the aorta via the left ventricle for distribution to the entire body. Due to any of a number of conditions, including coronary artery disease, high blood pressure (hypertension), valvular regurgitation and calcification, damage to the heart muscle as a result of infarction or ischemia, myocarditis, congenital heart disease, heart rhythm abnormalities, or various infectious diseases, the left ventricle may become less effective and therefore unable to pump oxygenated blood to the entire body.

[0004] The American Heart Association estimates that approximately 6 million people in the United States suffer from some form of heart failure. Heart failure is generally categorized into four different stages, the most serious of which is end-stage heart failure. Patients with end-stage heart failure may experience heart failure symptoms at rest despite medical treatment. Patients at this stage experience heart failure characterized by a reduced ejection fraction. The normally thick walls of the ventricles in healthy patients become thin and weakened in patients with systolic heart failure. As a result, reduced volumes of oxygenated blood are ejected into the circulatory system during systole, a situation that continues in a downward spiral until death. Patients diagnosed with end-stage heart failure have a one-year mortality rate of approximately 50%.

[0005] For patients who reach end-stage heart failure, treatment options are limited. In addition to continued use of drug therapy commonly prescribed during earlier stages of heart failure, treatment options are heart transplantation and implantation of mechanical assist devices. Heart transplantation can significantly extend a patient's lifespan, but due to a shortage of available donor organs, only 3,000-3,500 transplants are performed in the United States. Thus, patients often remain on transplant waiting lists for months to years, waiting for a compatible donor heart. Currently, one alternative to heart transplantation is circulatory assist devices. Although circulatory assist device designs have improved in recent years, typically such implants extend a patient's lifespan by several years at best and are associated with several comorbidities.

[0006] One type of circulatory support device available for patients with end-stage heart failure is the left ventricular assist device (LVAD). The LVAD is a surgically implanted pump that draws oxygenated blood from the left ventricle and pumps it directly into the aorta, thereby relieving (relieving) the left ventricle of its pumping work. LVADs are typically used as either "bridge to transplant," "bridge to recovery," or "definitive therapy." When used as bridge to transplant, LVADs are used to extend the life of patients awaiting heart transplant. In bridge to recovery, the patient's natural heart regains sufficient function during the period of mechanical circulatory support, and the device can be removed from the patient or "decommissioned" partially left in place. When a patient is not suitable for heart transplant, LVADs can be used as definitive therapy to extend the patient's life or improve their quality of life, but generally such extension is only for a few years.

[0007] In general, an LVAD comprises an inlet cannula, a pump, and an outlet cannula, and is coupled to an extracorporeal battery and control unit. The inlet cannula is typically connected directly to the left ventricle, e.g., at the apex, and delivers blood from the left ventricle to the pump. The outlet cannula is typically connected to the aorta distal to the aortic valve and delivers blood from the pump to the aorta. Typically, the pump outlet cannula is extended using a hose-type structure, such as a Dacron graft, to reach the appropriate delivery location on the aorta. Early LVAD designs were of the reciprocating type, but more recently, rotary and centrifugal pumps have been used.

[0008] U.S. Patent No. 4,277,706 to Isaacson, entitled "Actuator for Heart Pump," describes an LVAD having a reciprocating pump. The pump described in the Isaacson patent includes a housing having an inlet and an outlet, a cavity inside the pump connected to the inlet and outlet, a flexible diaphragm extending across the cavity, a plate affixed to the diaphragm, and a ball screw configured to reciprocate to drive the plate and connected diaphragm from one end of the cavity to the other to simulate systole and diastole. The ball screw is actuated by a DC motor. Isaacson's patent also describes a controller configured to manage the rotation of the ball screw to control starting, stopping, and redirection to control blood flow into and out of the pump.

[0009] Previously known reciprocating pump LVADs have several disadvantages. Such pumps are often bulky, heavy, and may require removal of tissue in the chest for implantation. They also require a significant amount of energy to displace blood by compressing the cavity. Furthermore, the pumps subject blood to significant pressure fluctuations as it passes through the pump, as well as high shear forces and the risk of hemolysis (e.g., due to valves and / or flow structures). These pressure fluctuations may be exacerbated at higher blood flow rates. Furthermore, depending on the pump geometry, areas with little or no flow may result in flow stagnation, which may lead to clot formation and, in some cases, fatal medical conditions such as stroke. Furthermore, blood flowing through such devices may be damaged when it comes into contact with moving components. For example, shear-induced damage may contribute to hemolysis. Finally, many positive displacement pumps, such as those described in the Isaacson patent, are unable to achieve pulsatility similar to that of the natural heart, e.g., about 60-100 beats / min, while maintaining physiological pressure gradients.

[0010] LVADs utilizing rotary and centrifugal configurations are also known. For example, U.S. Patent No. 3,608,088 to Reich, entitled "Implantable Blood Pump," describes a centrifugal pump for assisting a failing heart. The Reich patent describes a centrifugal pump having an inlet connected to a rigid cannula coupled to the left ventricular cavity and a Dacron graft extending from the pump diffuser to the aorta. The pump includes an impeller that rotates at high speed to accelerate the blood, and simulates the pulsation of a natural heart by varying the rotation speed or introducing a fluid oscillator.

[0011] Golding's U.S. Pat. No. 5,370,509, entitled "Sealless Rotodynamic Pump with Fluid Bearing," describes an axial-flow blood pump that can be used as a heart pump. One embodiment described involves an axial-flow blood pump having impeller blades aligned with the axes of the blood inlet and blood outlet. Taylor's U.S. Pat. No. 5,588,812, entitled "Implantable Electrical Axial-Flow Blood Pump," describes an axial-flow blood pump similar to that of the Golding patent. The pump described in the Taylor patent has a pump housing that defines a cylindrical blood conduit through which blood is pumped from an inlet to an outlet, and rotor blades that rotate along the axis of the pump to accelerate the blood flowing through the blood conduit.

[0012] Although previously known LVAD devices have improved, their pump designs are not without problems. Like reciprocating pumps, rotary and centrifugal pumps are often bulky and difficult to implant. Rotary pumps are mechanically different from volumetric pumps, but they also present undesirable characteristics. Like volumetric pumps, rotary pumps exert significant shear forces on the blood, thereby presenting the risk of hemolysis and platelet activation. The very nature of the disks or blades rotating about an axis results in areas of high and low speeds and vibration and heat generation. Areas near the leading and trailing edges of the blades and the gap between the blade tips and the housing experience the highest shear forces. In addition, stagnation or low flow rates near the axis of rotation can result in thrombus formation.

[0013] Centrifugal pumps may be able to generate pulsatile flow by varying the rotational speed of the associated disks or blades, but this only exacerbates the problems resulting from steep radial velocity profiles and high shear forces. Conventionally, the output of currently available rotary pumps, measured as flow rate for a given head pressure, is controlled by varying the rotational speed of the pump. Given the mass of the rotating members, their angular velocity, and the resulting inertia, the change in rotational speed is likely not instantaneous, but rather may be gradual. Thus, while centrifugal pumps may mimic pulsatile flow with speed changes, the resulting pulsations may cause physiological pressure changes.

[0014] Furthermore, rotary pumps typically result in non-physiological pressure changes being applied to the blood: if the pump rotational speed is varied to simulate pulsatile flow or to increase flow rate, the rotary pump is unlikely to be operated at its optimal operating point, reducing efficiency and increasing energy losses and heat generation.

[0015] LVADs can also be configured to increase blood flow to match patient demand. Numerous publications and patents describe methods for adjusting LVAD pump flow to match that required by the patient. For example, U.S. Patent No. 7,520,850 to Brockway, entitled "Feedback control and ventricular assist devices," describes a system and method for controlling a ventricular assist device employing pressure feedback. The system described in the Brockway patent attempts to maintain constant filling of the ventricle by measuring ventricular pressure and / or ventricular volume. Although such systems can achieve flow rates as high as 8 or 9 liters / minute, these flow rates are generally outside the efficient operating range of current rotary pumps, which are typically tuned to operate within the range of 4-6 liters / minute. Thus, increasing the flow rate in a rotary pump to match patient demand results in non-optimum pump performance.

[0016] Pumps for displacing fluids other than rotary and positive displacement types are also known in the art. For example, U.S. Patent Nos. 6,361,284 and 6,659,740, both to Drevet, entitled "Vibrating Membrane Fluid Circulator," describe pumps that vibrate a deformable membrane to force fluid through a pump housing. In these patents, a vibratory motion applied to the deformable membrane creates wave-like undulations in the membrane that force fluid along a channel. Different flow rates can be achieved by controlling the stimulus applied to the membrane.

[0017] U.S. Patent No. 7,323,961 to Drevet, entitled "Electromagnetic Machine with a Deformable Membrane," describes a device in which a membrane is coupled to an electromagnetic device that is positioned to rotate around the membrane along its outer edge under tension. As the electromagnetic device rotates, the outer edge of the membrane is slightly distorted in a direction normal to the plane of the membrane. These distortions induce wave-like undulations in the membrane that can be used to move fluids in contact with the membrane.

[0018] Drevet's U.S. Pat. No. 9,080,564, entitled "Diaphragm Circulator," describes a tensioned deformable membrane in which undulations are generated by electromechanically moving a magnetized ring attached to the outer edge of the deformable membrane over a coil. Axial displacement of the magnetized ring produces undulations in the membrane. As in the '961 patent, the undulations in the membrane can be controlled by manipulating magnetic attractive forces. Drevet's U.S. Pat. No. 8,714,944, entitled "Diaphragm Pump with a Crinkle Diaphragm of Improved Efficiency," and Drevet's U.S. Pat. No. 8,834,136, entitled "Crinkle Diaphragm Pump," teach similar types of vibrating membrane pumps.

[0019] None of the above-mentioned patents to Drevet describe a vibrating membrane pump that is suitable for use in a biological setting or capable of pumping blood for extended periods of time that present a low risk of flow stagnation leading to clot formation.

[0020] US Patent Nos. 2017 / 0290966 and 2017 / 0290967 to Botterbusch, the entire contents of each of which are incorporated herein by reference, describe an implantable cardiovascular blood pump having a flexible membrane coupled to an electromagnetic actuator assembly that propagates wave-like undulations along the flexible membrane to force blood through the pump while avoiding clot formation, hemolysis, and / or platelet activation. The Botterbusch pump generates fluid power, i.e., flow and pressure, by transferring the linear motion of an electromagnetic actuator to a flexible membrane that deforms through interaction with the blood and transfers energy to the blood. The flexible membrane is oriented at a 90° angle to the motion of the linear actuator such that the outer edge of the membrane is the first element to engage the blood. As a result, there is a risk of energy loss at the inlet to the membrane, which negatively impacts fluid power generation by the pump.

[0021] What is needed is an energy efficient implantable pump that is lightweight, compact, and has fast start and stop response that can operate efficiently over a wide range of flow rates and with improved hydraulic performance and minimal blood damage. Summary of the Invention

[0022] (Summary of the invention) Provided herein are systems and methods for providing a blood pump for circulatory support. The pump system herein may be implanted in a patient's body or used externally. The pump system may be used for circulatory support, for example, in the atria, ventricles, and / or blood vessels, for example. The pump system may be an implantable pump system. The pump system may have a wavy membrane capable of applying low shear forces to the blood, thereby producing a wide range of physiological flow rates while reducing hemolysis and platelet activation compared to previously known systems. The pump system may include a stator assembly, an electromagnetic assembly, a magnetic assembly, and a membrane assembly, as well as one or more encapsulation device parts that encapsulate the electromagnetic assembly and avoid damaging the blood with the moving components of the pump. The pump system herein may also minimize areas within the pump that may be prone to clot formation.

[0023] According to one aspect of the invention, a blood pump may include a housing having an inlet and an outlet and designed to be implanted in a patient's heart, a membrane disposed within the housing, an actuator disposed within the housing, the actuator designed to reciprocate the membrane to pump blood, and an encapsulation assembly designed to encapsulate the actuator such that blood does not contact the actuator, the encapsulation assembly disposed within the housing and defining a flow channel between the housing and the encapsulation assembly. During operation, blood may enter the inlet and flow between the housing and the encapsulation assembly in the flow channel and may be forced across the membrane to the outlet to pump the blood. The pump may further include a magnetic assembly designed to move relative to the actuator assembly. The magnetic assembly is annular and disposed around the actuator. Additionally, the blood pump may include at least one spring coupled to the magnetic assembly and to the actuator. The encapsulation assembly may include the magnetic assembly, which also encapsulates the at least one spring. The encapsulation assembly may isolate the actuator from the passage of blood, reducing exposure of the blood to higher shear conditions in the actuator. The flow channel may be configured to minimize damage to von Willebrand factor multimers in the blood. The flow channel may be sized and configured to promote blood flow towards the outlet and resist blood flow towards the inlet and / or may be configured to reduce recirculation of blood. The flow channel may be sized and configured to reduce the risk of shear conditions of the blood within the flow channel.

[0024] According to another aspect of the invention, a blood pump may include a housing having an inlet and an outlet and designed to be implanted in a heart, an actuator disposed within the housing, the actuator comprising an electromagnetic assembly designed to generate a magnetic field, an upper stator coupled to a first side of the actuator, a lower stator coupled to a second side of the actuator, a magnetic assembly comprising at least one magnet, the magnetic assembly designed to reciprocate in response to the magnetic field, a first encapsulation portion coupled to the upper stator and the magnetic assembly, a second encapsulation portion coupled to the lower stator and the magnetic assembly, and a flexible membrane coupled to the magnetic assembly and configured to reciprocate in response to the magnetic assembly. The first encapsulation portion, magnetic assembly, and second encapsulation portion may encapsulate the actuator such that during operation, blood enters the inlet, flows between an inner wall of the housing and the first encapsulation portion, the magnetic assembly, and the second encapsulation portion, and is forced across the flexible membrane to the outlet.

[0025] According to another aspect of the invention, a blood pump may include a housing having an inlet and an outlet designed to be in fluid communication with a patient's left ventricle, an actuator assembly including a stator assembly and an electromagnetic assembly designed to generate a magnetic field; the actuator assembly disposed within the housing, a magnetic assembly designed to reciprocate in response to the magnetic field, and an encapsulation assembly coupled to the magnetic assembly and the stator assembly, the encapsulation assembly encapsulating the actuator, and a flexible membrane coupled to the magnetic assembly and designed to reciprocate in response to the magnetic assembly. During operation, blood may enter the inlet and flow between the inner wall of the housing and the magnetic assembly, the stator assembly, and the encapsulation assembly, and may be forced across the flexible membrane to the outlet.

[0026] According to another aspect of the invention, a method of pumping blood with a blood pump is provided. The method of pumping blood may include providing a blood pump designed to be placed in a ventricle of a patient, and sending an electrical signal to the actuator to excite the electromagnetic assembly and generate the magnetic field. The blood pump may include an actuator comprising a housing having an inlet and an outlet designed to be in fluid communication with the ventricle of a patient, a stator assembly, and an electromagnetic assembly designed to generate a magnetic field, the actuator assembly being disposed within the housing, a magnetic assembly configured to reciprocate in response to the magnetic field, an encapsulation assembly coupled to the magnetic assembly and the stator assembly, the encapsulation assembly designed to encapsulate the actuator, and a flexible membrane coupled to the magnetic assembly and configured to reciprocate in response to the magnetic assembly. The magnetic field can cause the flexible membrane to reciprocate, thereby propagating waves along the flexible membrane and moving blood from the inlet, between the inner wall of the housing and the magnetic assembly, stator assembly, and encapsulation assembly, throughout the flexible member, and out the outlet. [Brief description of the drawings]

[0027] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] FIG. 1 depicts an exemplary embodiment of a pump system of the present invention comprising a blood pump, a controller, a battery, a programmer, and a mobile device according to some embodiments of the present invention.

[0028] [Diagram 2] FIG. 2 is a perspective view of the blood pump of FIG.

[0029] [Diagram 3] 3A and 3B are a perspective view and a schematic diagram, respectively, of the electronic components of an exemplary embodiment of a controller of the present invention.

[0030] [Figure 4] FIG. 4 is a plan view of an extracorporeal battery for use in the pump system of the present invention.

[0031] [Diagram 5] 5A and 5B are a perspective view and a schematic diagram, respectively, of the electronic components of an exemplary embodiment of a programmer of the present invention.

[0032] [Figure 6] FIG. 6 is a perspective view of a pump assembly of the present invention.

[0033] [Figure 7] FIG. 7 is a perspective cutaway view of a blood pump of the present invention.

[0034] [Figure 8] FIG. 8 is an exploded view of the blood pump of the present invention.

[0035] [Figure 9] FIG. 9 is a perspective cross-sectional view of a pump assembly of the present invention.

[0036] [Figure 10] FIG. 10 is a perspective cross-sectional view of a membrane assembly of the present invention.

[0037] [Figure 11] FIG. 11 is a perspective cross-sectional view of the moveable components of a pump assembly according to a first embodiment of the present invention.

[0038] [Figure 12] FIG. 12 is a cross-sectional view of a blood pump of the present invention.

[0039] [Figure 13] FIG. 13 is a cross-sectional view of the lower portion of the blood pump depicting the flow channel and membrane assembly in the rest position.

[0040] [Figure 14] FIG. 14 is a cross-sectional view of the lower portion of the blood pump depicting the flow channels and the membrane assembly with undulating membranes.

[0041] [Figure 15] Figure 15A is a cross-sectional view of another exemplary embodiment of a blood pump of the present invention having improved hydraulic performance for use in the pump system of Figure 1. Figure 15B is a perspective view of the blood pump of Figure 15A.

[0042] [Figure 16] Figure 16A illustrates blood flow across a planar ring membrane carrier, Figure 16B illustrates blood flow using a pump assembly with a skirt according to one embodiment of the invention, Figure 16C illustrates a blood pump with an integrated portion incorporating a magnetic assembly featuring linear bearing elements and magnets within a housing, and Figure 16D illustrates a blood pump with an integrated portion incorporating a magnetic assembly featuring a mechanical spring.

[0043] [Figure 17] FIG. 17 is a cross-sectional view of a blood pump with an encapsulated actuator assembly.

[0044] [Figure 18] FIG. 18 is an exploded view of a blood pump with an encapsulated actuator assembly.

[0045] [Figure 19] FIG. 19 is an exploded view of the moving magnet assembly.

[0046] [Figure 20] Figures 20A and 20B are perspective views of a membrane assembly and an actuator assembly, and Figure 20C is a cross-sectional view of a portion of the actuator assembly and membrane assembly.

[0047] [Figure 21]21A-21C are cross-sectional views showing the movement of the membrane assembly.

[0048] [Figure 22] Figures 22A and 22B are cross-sectional and top perspective views of a blood pump with an encapsulated actuator assembly, showing the surfaces that contact the blood.

[0049] [Diagram 23] FIG. 23 is an exploded view of a membrane assembly with several sensor targets.

[0050] [Figure 24] FIG. 24 is a cross-sectional view of a blood pump with an encapsulated actuator assembly illustrating the main cavity of the present invention.

[0051] [Diagram 25] FIG. 25 is a perspective view of an actuator assembly with grooves on its outer surface that prevent eddy current circulation within the stator.

[0052] [Figure 26] Figure 26A is a cross-sectional view of the inlet block, and Figure 26B is a top view of the inlet with three flow channels.

[0053] [Figure 27] Figure 27A is a cross-sectional view of a blood pump having a spring external to the actuator assembly, and Figure 27B is a cross-sectional view of a blood pump having a bearing external to the actuator assembly.

[0054] [Figure 28] FIG. 28 is a cross-sectional view of a blood pump with an encapsulated actuator assembly having a bellows.

[0055] [Figure 29]29A and 29B are cross-sectional and perspective views of a blood pump including a flexure spring assembly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] (Detailed Description) The blood pump system of the present invention is particularly well suited for use as an implantable left ventricular assist device (LVAD) and includes a pulsating membrane pump suitable for chronic implantation in patients with end-stage heart failure. A blood pump system constructed according to the principles of the present invention includes a blood pump, an extracorporeal battery, a controller, and a programmer. The blood pump system of the present invention may be implantable and / or may be a heart pump (e.g., an LVAD). The blood pump includes a housing having an inlet and an outlet, a flexible membrane, and an encapsulated actuator assembly. When configured as an LVAD, the housing includes an inlet cannula that is inserted into the patient's left ventricle near the apex of the heart, and an outlet cannula that is surgically placed in fluid communication with the patient's aorta. By activating the actuator assembly in the blood pump, the membrane is induced to pulsate, thereby drawing blood into the pump through the inlet cannula and ejecting it through the outlet cannula into the aorta. The flow rate and pulsatility may be manipulated by varying one or more of the frequency, amplitude, and duty cycle of the actuator assembly.

[0057] For improved hydraulic performance, the blood pump may include a membrane assembly including a membrane and a skirt disposed within the housing to direct blood flow from the inlet to the outlet of the pump. The skirt may be located within the housing such that upon actuation of the pump, blood flows across opposing sides of the skirt and toward the undulating membrane. For enhanced protection of blood flowing through the blood pump, the actuator assembly may be encapsulated with an encapsulation assembly such that a blood flow channel between the inlet and outlet cannulas of the blood pump is defined by the encapsulation assembly of the blood pump and an interior surface of the housing.

[0058] Referring now to FIG. 1, a pump system 10 constructed in accordance with the principles of the present invention is described. The blood pump system 10 comprises a pump 20, a controller 30, a battery 40, a programmer 50, and optionally software modules programmed to run on a mobile device 60. The pump 20 is configured to be implanted within a patient's chest such that an inlet cannula 21 is coupled to the left ventricle LV of a heart H. An outlet cannula 22 of the pump 20 is configured to be coupled to an aorta A. The inlet cannula 21 is preferably coupled to the apex of the left ventricle LV, while the outlet cannula 22 is coupled to the aorta A near the ascending aorta above the level of the aorta of the heart. The pump 20 may be affixed within the patient's chest using ring sutures or other conventional techniques. The outlet cannula 22, which may comprise a Dacron graft or other synthetic material, is coupled to an outlet 23 of the implantable pump 20.

[0059] 2, pump 20, in a preferred embodiment, consists of an upper housing portion 24 that is joined, for example by thread or welding, along interface 26 to a lower housing portion 25 to form a liquid-tight pump housing 27, which may have a cylindrical shape. Upper housing portion 24 includes inlet cannula 21 and conduit 28 for receiving electrical wires from controller 30 and battery 40. Lower housing portion 25 includes outlet 23, which couples to outlet cannula 22, as shown in FIG. 1. Pump housing 27 is made of a biocompatible material, such as stainless steel or titanium, and is sized to be implanted within a patient's chest.

[0060] Referring again to FIG. 1, in one embodiment, the controller 30 and battery 40 are external and sized to be placed on a belt or clothing worn by the patient. Both the controller 30 and battery 40 are electrically coupled to the pump 20, for example, via a cable 29 that extends through a percutaneous opening in the patient's skin and into a conduit 28 of the pump housing 27. Illustratively, the battery 40 is electrically coupled to the controller 30 via a cable 41 integrated into a belt 42. In another embodiment, the controller 30 may be enclosed in a biocompatible housing and sized to be implanted subcutaneously in the patient's abdomen. In this alternative embodiment, the controller 30 may include a wireless transceiver for bidirectional communication with an external programming device, and includes a battery that is persistently and inductively charged via the external battery 40 and an external charging circuit. As will be appreciated, the above alternative embodiment avoids the use of a percutaneous cable 29, thus eliminating a frequent source of infection associated with conventional LVAD devices.

[0061] Battery 40 preferably comprises a rechargeable battery capable of powering pump 20 and controller 30 for a period of several hours, e.g., 4-12 hours, before needing to be recharged. Battery 40 may include separate charging circuitry, not shown, as is conventional for rechargeable batteries. Battery 40 is preferably disposed in a housing suitable for carrying on a belt or holster so as not to interfere with the patient's daily activities.

[0062] Programmer 50 may consist of a conventional laptop computer that is programmed to execute preprogrammed software routines for use by a clinician or medical professional to set and provide operating parameters to controller 30. The setting and operating parameter data is stored in a memory associated with controller 30 and used by the controller to control the operation of pump 20. As described in more detail below, controller 30 instructs pump 20 to operate with particular parameters determined by programmer 50. Programmer 50 is preferably coupled to controller 30 via cable 51 only when the pump's operating parameters are initially set or periodically adjusted, e.g., when the patient sees the clinician.

[0063] In accordance with another aspect of the invention, the mobile device 60, which may be a conventional smartphone, may be equipped with an application program for bidirectionally and wirelessly communicating with the controller 30, for example via WiFi or Bluetooth communication. The application program on the mobile device 60 may be programmed to enable the patient to send instructions to the controller to modify or adjust a limited number of operating parameters of the pump 20 that are stored within the controller 30. Alternatively or in addition, the mobile device 60 may be programmed to receive from the controller 30 and display on the screen 61 of the mobile device 60 data related to the operation of the pump 20 or alerts or status messages generated by the controller 30.

[0064] 3A and 3B, the controller 30 will be described in more detail. As depicted in FIG. 1, the controller 30 may be sized and configured to be worn externally to the patient's body or may be incorporated into clothing such as a belt or vest. The controller 30 includes an input port 31, a battery port 32, an output port 33, an indicator light 34, a display 35, a status light 36, and buttons 37.

[0065] The input port 31 is configured to periodically and removably receive a cable 51 to establish an electrical connection between the programmer 50 and the controller 30, for example, via a USB connection. In this manner, a clinician may couple to the controller 30 and set or adjust operating parameters stored within the controller 30 to control operation of the pump. In addition, when the programmer 50 is coupled to the controller 30, the clinician may also download data related to operation of the pump, such as operational statistics, from the controller 30 for processing and display on the display 55 of the programmer 50, as illustrated in FIG. 5A. Alternatively or additionally, the controller 30 may include a wireless transceiver for wirelessly communicating such information with the programmer 50. In this alternative embodiment, wireless communications between the controller 30 and the programmer 50 may be encrypted with an encryption key associated with a unique identification number of the controller, such as a serial number.

[0066] The battery port 32 is configured to removably receive the cable 41, which is illustratively shown in FIG. 1 as being integrated with the belt 42 such that the cable 41 is routed through the belt and extends around the patient's back until it couples to the controller 30. In this manner, the battery 40 may be removed from the belt 42 and disconnected from the controller 30, allowing the patient to periodically replace the battery with a fully charged battery. It is anticipated that the patient will have at least two batteries available to them, such that one battery is coupled to the controller 30 to power the controller and pump, and the other battery may be connected to a recharging station. Alternatively or in addition, the battery port 32 may be configured to receive a cable that couples directly to a power source, such that a substantially larger battery / charger combination would allow the patient to remove the battery 40 while lying supine in bed, for example, for sleep.

[0067] The output port 33 is electrically coupled to a cable 29, which in turn is coupled to the pump 20 through a conduit 28 in the pump housing 27. The cable 29 provides both energy to power the pump 20 according to configuration settings and operating parameters stored in the controller 30 and to receive data from sensors disposed within the pump 20. In one embodiment, the cable 29 may comprise an electrical cable having a biocompatible coating and is designed to extend percutaneously. The cable 29 may be impregnated with a medicinal agent to reduce the risk of infection, transmission of potentially dangerous substances, or promote healing if it extends through the patient's skin and tissue.

[0068] As previously mentioned, the controller 30 may include indicator lights 34, a display 35, a status light 36, and buttons 37. The indicator lights 34 may visually display information related to the operation of the system, such as the remaining charge of the battery 40. The display 35 may be a digital liquid crystal display that displays real-time pump performance data, patient physiological data, such as heart rate, or pump operating parameters, such as target pump pressure or flow rate. If a parameter condition is determined to exceed a preprogrammed threshold, an alarm may be generated, an alert may be displayed on the display 35, and / or an internal vibration element may vibrate the controller 30 to provide a tactile stimulus. The status light 36 may include a light emitting diode (LED) that is turned on or off to indicate whether a certain function of the controller or pump is active. The button 37 may be used to wake up the display 35, set or silence an alarm, etc.

[0069] With reference to FIG. 3B, components of an illustrative embodiment of the controller 30 of FIG. 3A are described. In addition to the components of the controller 30 described in relation to FIG. 3A, the controller 30 further comprises a microprocessor 38, a memory 39, a battery 43, an optional transceiver 44, and an amplifier circuit 45. The microprocessor may be a general-purpose microprocessor for which programming for controlling operation of the pump 20 is stored in the memory 39. The memory 39 may also store configuration settings and operating parameters for the pump 20. The battery 43 provides power to the controller 30 to provide continuity of operation as the battery 40 is periodically replaced. The optional transceiver 44 (e.g., a communication unit) facilitates wireless communication with the programmer 50 and / or a mobile device 60 via any of several well-known communication standards, including any IEEE 802.11 wireless standard such as BLUETOOTH™, ZigBee, and / or Wi-Fi or Wi-Fi Direct. The controller 30 may further include an amplifier circuit 49 for amplifying the electrical signals transmitted between the controller 30 and the pump 20 .

[0070] 4, the battery 40 is described. The battery 40 provides power to the pump 20 and may also provide power to the controller 30. The battery 40 may consist of a single battery or multiple batteries disposed within a housing, and is preferably sized and configured to be worn externally to the patient's body, such as on a belt 42. A battery level indicator 46 may be provided on the exterior of the battery 40 to indicate the remaining charge of the battery. A cable 41 may have one end that is removably coupled to the battery 40 and the other end that is removably coupled to a battery port 32 of the controller 30 to provide power and energize the pump 20. In one embodiment, the battery 40 may be rechargeable using a separate charging station, as known in the art of rechargeable batteries. Alternatively or additionally, the battery 40 may include a port 47 that may be removably coupled to a transformer and cable to allow the battery to be recharged using a conventional residential power outlet, e.g., a 120V, 60Hz AC power source.

[0071] 5A and 5B, the programmer 50 will be described. The programmer 50 may be a conventional laptop or tablet computer into which programmed software routines are loaded for configuring the controller 30 and for setting the operating parameters that the controller 30 uses to control the operation of the pump 20. As previously mentioned, the programmer 50 is typically installed in a clinician's office or hospital and coupled to the controller 30 via a cable 51 or wirelessly to initially configure the controller 30 and then periodically thereafter on demand to adjust the operating parameters as needed. The operating parameters of the controller 30 that are set using the programmed routines of the programmer 50 may include, but are not limited to, pump operating mode, applied voltage, pump frequency, pump amplitude, target flow rate, pulsatility, etc. When first implanted, the surgeon or clinician may use the programmer 50 to communicate the initial operating parameters to the controller 30. After implantation, the patient may periodically return to the clinician's office for adjustments to the operating parameters, which may again be made using the programmer 50.

[0072] The programmer 50 may be any type of conventional personal computing device, such as a laptop or tablet computer, having touch screen capabilities. As illustrated in FIG. 5B, the programmer 50 preferably comprises a processor 52, a memory 53, an input / output device 54, a display 55, a battery 56, and a communication unit 57. The memory 53 may include an operating system for the programmer and programmed routines required to communicate with the controller 30. The communication unit 57 may include any of a number of well-known communication protocols, such as BLUETOOTH™, ZigBee, and / or any IEEE 802.11 wireless standard, such as Wi-Fi or Wi-Fi Direct. As shown in FIG. 5A, the programmed routines used to program and communicate with the controller 30 may also provide data for display on the screen of the programmer 50 identifying the operating parameters with which the controller 30 will control the pump 20. The programmed routines may also enable the programmer 50 to download operational or physiological data transmitted by the pump from the controller 30 and display that information in real time while the programmer is coupled to the controller via a wired or wireless connection. The transferred data may then be processed and displayed on the screen of the programmer 50.

[0073] 6 and 7, a preferred embodiment of pump assembly 70 and pump 20 is illustrated. However, it should be understood that pump assembly and pump and components contained therein may have shapes and sizes different from those shown in FIG. 6 and FIG. 7 without departing from the invention described herein. As illustrated in FIG. 7, pump assembly 70 is configured to fit within pump housing 27. To secure pump assembly 70 within pump housing 27, pump assembly 70 may include a locking ring 71, which may extend from and around stator assembly 72 and may be captured between upper housing portion 24 and lower housing portion 25 when the housing portions are assembled, as illustrated in FIG. 7. In this manner, stator assembly 72 may be suspended within the pump housing in a tight-fitting relationship with the inner wall of the pump housing. Locking ring 71 is preferably a rigid annular structure concentrically disposed around stator assembly 72, having a larger diameter than stator assembly 72. The retaining ring 71 may be rigidly coupled to the stator assembly 72 via struts 73. The struts 73 may create a gap 74 between the retaining ring 71 and the stator assembly 72, which is preferably about 0.05 mm at its maximum limiting point.

[0074] 7, pump assembly 70 may be disposed within pump housing 27 such that retaining ring 71 is captured on a step 75 formed between upper housing portion 24 and lower housing portion 25. In this manner, stator assembly 72 may be suspended within pump housing 27 and prevented from moving therein. Pump housing 27 is preferably sized and configured to conform to pump assembly 70 such that stator assembly 72 does not contact the interior of the pump housing anywhere other than at retaining ring 71.

[0075] 8 is an exploded view of pump 20 depicting the arrangement of internal components of pump assembly 70 arranged between upper housing portion 24 and lower housing portion 25. In particular, pump assembly 70 may include stator assembly 72, magnetic ring assembly 76, first electromagnetic coil 77, second electromagnetic coil 78, stationary ring 71, first suspension ring 79, second suspension ring 80, pillars 81, and membrane assembly 82. Stator assembly 72 may include tapered section 83, electromagnetic coil holder portions 84, 85, and 86, and flanged portion 87. Magnetic ring assembly 76 may include magnetic ring 88, and magnetic ring holder portions 89 and 90. First and second electromagnetic coils 77 and 78, together with electromagnetic coil holder portions 84, 85, and 86, may form electromagnetic assembly 91. The electromagnet assembly 91 together with the stator assembly 72 form an actuator assembly which together with the magnetic ring assembly 76 thus form the actuator system of the pump 20.

[0076] The first electromagnetic coil 77 and the second electromagnetic coil 78 may be concentrically sandwiched between the electromagnetic coil holder portions 84, 85, and 86 to form an electromagnetic assembly 91. The tapered section 83, which may be coupled to the fixed ring 71 and the first suspension spring 79, may be concentrically located on top of the electromagnetic assembly 91. The magnetic ring 88 may be positioned with the magnetic ring holder portions 89 and 90 to form the magnetic ring assembly 76, which may be concentrically positioned for reciprocating motion across the electromagnetic assembly 91. The second suspension ring 80 may be concentrically positioned below the electromagnetic assembly 91. The flanged portion 87 may be concentrically positioned below the second suspension ring 80. The post 81 may engage the first suspension ring 79, the magnetic ring assembly 76, and the second suspension ring 80 at equally spaced locations around the circumference of the actuator assembly. The membrane assembly 82 may be concentrically disposed below the flanged portion 87 and engaged with the post 81 .

[0077] Further details of the pump assembly 70 are provided with respect to FIG. 9. Specifically, the actuator assembly 95 includes a stator assembly 72 and an electromagnetic assembly 91 including first and second electromagnetic coils 77 and 78. During use of the pump 20, the actuator assembly 95 remains stationary relative to the pump housing 27. The first electromagnetic coil 77 and the second electromagnetic coil 78 may be separated by an electromagnetic holder portion 85. The controller 30 and the battery 40 are electrically coupled to the electromagnetic coils 77 and 78 via a cable 29 that extends through a conduit 28 of the pump housing 27 and supplies electrical current to the electromagnetic coils 77 and 78. The first electromagnetic coil 77 and the second electromagnetic coil 78 may be in electrical communication with each other, or may be configured to operate independently and have separate wired connections to the controller 30 and the battery 40 via the cable 29.

[0078] The electromagnetic coils 77 and 78 may be made of any conductive metallic material, such as copper, and may further comprise one or more smaller metallic wires wound into a coil. The wires of the electromagnetic coils are insulated to prevent shorting to adjacent conductive materials. Other components of the pump assembly 70, such as the stator assembly 72, are also preferably insulated and / or made of non-conductive materials to reduce undesired transmission of electrical signals.

[0079] The actuator assembly 95 may be surrounded by a first suspension ring 79 and a second suspension ring 80. The suspension rings 79 and 80 may be annular in shape and fit concentrically around the actuator assembly 95. The first suspension ring 79 is preferably rigidly affixed to a tapered section 83 near the top of the stator assembly 72 via posts 73 that extend from the suspension ring to the stator assembly. As mentioned above, the posts 73 may also affix the retaining ring 71 to the stator assembly 72. The retaining ring 71 and the first suspension springs 79 may be sized and positioned such that a gap of 0.5 mm or more exists between the first suspension ring 79 and the retaining ring 71. The second suspension ring 80 may similarly be rigidly affixed via posts near the bottom of the stator assembly 72 below the electromagnetic assembly 91. The suspension rings 79 and 80 are preferably sized and shaped so that when the suspension rings 79 and 80 are positioned around the actuator assembly 95, a gap of 0.5 mm or greater exists between the actuator assembly 95 and the suspension rings 79 and 80.

[0080] The first and second suspension rings 79, 80 may comprise stainless steel, titanium, or cobalt chrome alloys that have elastic properties and exhibit a spring force when deflected normal to the plane of the spring. The first and second suspension rings 79, 80 may be substantially rigid against forces applied tangentially to the suspension rings. Thus, the first and second suspension rings 79, 80 may exhibit a spring tension when deflected up and down relative to the vertical axis of the actuator assembly, but may rigidly resist movement along any other axis, e.g., tilting or twisting movement.

[0081] The magnetic ring assembly 76 may be annular in shape and concentrically surround the actuator assembly 95. The magnetic ring 88 may include one or more materials that exhibit magnetic properties, such as iron, nickel, cobalt, or various alloys. The magnetic ring 88 may be made from a single integral component or may comprise several magnetic components bonded together. The magnetic ring assembly 76 may be sized and shaped such that when it is concentrically positioned over the actuator assembly 95, a gap of 0.5 mm or more exists between the outer lateral surface of the actuator assembly 95 and the inner surface of the magnetic ring assembly 76.

[0082] The magnetic ring assembly 76 may be concentrically disposed around the actuator assembly 95 between the first suspension ring 79 and the second suspension ring 80 and may be rigidly coupled to the first suspension ring 79 and the second suspension ring 80. The magnetic ring assembly 76 may be rigidly coupled to the suspension rings by two or more posts 81 that are uniformly spaced around the actuator assembly 95 and configured to extend parallel to the central axis of the pump assembly 70. The suspension rings 79 and 80 and the magnetic ring assembly 76 may be engaged such that the magnetic ring assembly 76 is suspended equidistantly between the first electromagnetic coil 77 and the second electromagnetic coil 78 when the suspension rings are in their undeflected configuration. Suspension rings 79 and 80 and magnetic ring holder portions 89 and 90 may each include a post receiving area for engaging post 81 or may be affixed to post 81 in any suitable manner that rigidly affixes suspension rings 79 and 80 and magnetic ring assembly 76 to post 81. Post 81 may extend beyond suspension rings 79 and 80 to engage other components, such as flanged portion 87 and membrane assembly 82.

[0083] The first electromagnetic coil 77 may be activated by the controller by applying an electrical signal from the battery 40 to the first electromagnetic coil 77, thus inducing a current in the electromagnetic coil and generating a magnetic field surrounding the electromagnetic coil 77. The direction of the current in the electromagnetic coil 77 and the polarity of the magnetic ring assembly 76 nearest the electromagnetic coil 77 may be configured to cause the first electromagnetic coil to magnetically attract or repel the magnetic ring assembly 76 as desired. Similarly, a magnetic field may be generated in the second electromagnetic coil 78 by directing a current in the second electromagnetic coil 78. The direction of the current in the second electromagnetic coil 78 and the polarity of the magnetic ring assembly 76 nearest the second electromagnetic coil may also be configured to cause the first electromagnetic coil 77 to magnetically attract or repel the magnetic ring assembly 76 when an appropriate current is induced in the second electromagnetic coil 78.

[0084] The magnetic ring assembly 76 may be rigidly affixed to the post 81, which in turn may be rigidly affixed to the first suspension ring 79 and the second suspension ring 80, such that the elastic properties of the suspension rings allow the magnetic ring assembly 76 to move upward toward the first electromagnetic coil 77 or downward toward the second electromagnetic coil 78, depending on the polarity of the magnetic field generated by the electromagnetic rings. Thus, when the magnetic ring assembly 76 is subjected to an upward magnetic force, the magnetic ring assembly 76 deflects upward toward the first electromagnetic coil 77. As the post 81 moves upward with the magnetic ring assembly 76, it elastically deforms the suspension rings 79 and 80, which creates a spring force opposite to the direction of movement. When the current stops and the magnetic field generated by the first electromagnetic coil decays, this downward spring force causes the magnetic ring assembly to return to its neutral position. Similarly, when the magnetic ring assembly 76 is magnetically attracted downwards, it deflects downwards towards the second electromagnetic ring 78. As the pillars 81 move downwards with the magnetic ring assembly 76, they impose elastic deformations on the first and second suspension rings, thus generating a spring force in the opposite direction. When the current stops and the magnetic field generated by the second electromagnetic ring weakens, this upward spring force causes the magnetic ring assembly to return to its neutral position again.

[0085] The electromagnetic coils 77 and 78 may be energized separately or, alternatively, may be connected in series to activate the electromagnetic coils simultaneously. In this configuration, the first magnetic coil may be configured to have a current flow direction opposite that of the second magnetic coil. Thus, when a current is induced in the first magnetic coil 77 to attract the magnetic ring assembly 76, the same current is applied to the second magnetic coil 78 to induce a current in the second magnetic coil 78 that repels the magnetic ring assembly 76. Similarly, when a current is induced in the second magnetic coil 78 to attract the magnetic ring assembly 76, the current applied to the first magnetic coil 77 causes the first magnetic coil to repel the magnetic ring assembly 76. In this manner, the electromagnetic coils 77 and 78 cooperate to cause a deflection of the magnetic ring assembly 76.

[0086] By manipulating the timing and strength of the electrical signal applied to the electromagnetic coils, the frequency at which the magnetic ring assembly 76 deflects towards the first and second electromagnetic coils may be altered. For example, by alternating the current induced in the electromagnetic coils more frequently, the magnetic ring assembly may be caused to rise and fall more times in a given period of time. Increasing the amount of current may cause the magnetic ring assembly to deflect faster and travel a greater distance.

[0087] Alternatively, the first electromagnetic coil 77 and the second electromagnetic coil 78 may be independently energized. For example, the first electromagnetic coil 77 and the second electromagnetic coil 78 may be excited with varying intensities, i.e., one may be coordinated to decrease in intensity while the other increases in intensity. Thus, as the strength of the signal applied to the first electromagnetic coil 77 causes a decreasing upward magnetic attractive force, the strength of the signal applied to the second electromagnetic coil 78 to cause a downward magnetic attractive force may simultaneously be increased.

[0088] According to one aspect of the invention, movement of the magnetic ring assembly 76 may be translated to a membrane assembly 82, which may be concentrically disposed below the stator assembly 72. The membrane assembly 82 is preferably rigidly attached to the magnetic ring assembly 76 by posts 81. In the embodiment depicted in FIG. 9, the posts 81 may extend beyond the second suspension ring 80 and be coupled to the membrane assembly 82.

[0089] 10, one embodiment of the membrane assembly 82 will be described in more detail. The membrane assembly 82 may comprise a rigid membrane ring 96 and a membrane 97. The rigid membrane ring 96 exhibits rigid properties under typical forces encountered during the full range of operation of the present invention. Post receiving sites 98 may be formed in the rigid membrane ring 96 to engage the membrane assembly 82 with the posts 81. Alternatively, the posts 81 may be attached to the rigid membrane ring 96 in any other manner that directly transfers the motion of the magnetic ring assembly 76 to the rigid membrane ring 96. The rigid membrane ring 96 may be affixed to the membrane 97 to hold the membrane under tension. The membrane 97 may be directly molded onto the rigid membrane ring 96 or may be affixed to the rigid membrane ring 96 in any manner that holds the membrane 97 under tension uniformly around its circumference. Membrane 97 may alternatively comprise a flexible pleated structure, which is attached to rigid membrane ring 96 to increase the ability of the membrane to move where it is affixed to rigid membrane ring 96. Membrane 97 may further comprise a circular opening 99 located in the center of the membrane.

[0090] In a preferred embodiment, the membrane 97 is made of an elastomer, having a thin planar shape, elastic properties and good durability. Alternatively, the membrane 97 may have a uniform thickness from the membrane ring to the circular opening. As a still further alternative, the membrane 97 may vary in thickness and assume a more complex geometric shape. For example, as shown in FIG. 10, the membrane 97 may have a thickness that decreases as the membrane extends from the rigid membrane ring 96 to the circular opening 99. Alternatively or in addition, the membrane 97 may incorporate a metal element, such as a spiral spring, to enhance the spring force of the membrane normal to the plane of the membrane, which may vary radially along the membrane. In yet another embodiment, the membrane 97 may be preformed with an undulating shape.

[0091] FIG. 11 depicts the moving parts of the embodiment of pump assembly 70 shown in FIGS. 6-9 as non-gray elements. The non-moving parts of the pump assembly, including actuator assembly 95 and electromagnetic assembly 91 (partially shown), may be fixed to pump housing 27 by a fixed ring 71. The moving parts of pump assembly 70 may include a post 81, a first suspension spring 79, a magnetic ring assembly 76, a second suspension spring 80, and a membrane assembly 82. As the magnetic ring assembly 76 moves up and down, the movement is rigidly transferred by the post 81 to the membrane assembly 82. Given the rigidity of the post, when the magnetic ring assembly 76 travels upwards or downwards a certain distance, the membrane assembly 82 may travel the same distance. For example, as the magnetic ring assembly 76 travels 2 mm from a position adjacent the first electromagnetic coil 77 to a position adjacent the second electromagnetic coil 78, the membrane assembly 82 may also travel 2 mm in the same direction. Similarly, the frequency at which the magnetic ring assembly 76 traverses the space between the first and second electromagnetic coils may also be the same frequency at which the membrane assembly 82 travels the same distance.

[0092] 12, in the embodiment of pump 20 illustrated in FIGS. 6-9, blood may enter pump 20 from the left ventricle through inlet cannula 21 and flow downward along pump assembly 70 into delivery channel 100 defined by the interior surface of pump housing 27 and the exterior of pump assembly 70. Delivery channel 100 begins at the top of stator assembly 72 and extends between tapered section 83 and the interior of pump housing 27. As blood travels down tapered section 83, it is directed through gap 74 into the vertical portion of delivery channel 100 in the region between pump housing 27 and actuator assembly 95, including in the gap between magnetic ring assembly 76 and electromagnet assembly 91. Delivery channel 100 extends downward to flanged portion 87 of stator assembly 72, which routes blood into flow channel 101 in which membrane assembly 82 is suspended. Delivery channel 100 delivers blood to membrane assembly 82 by directing blood from inlet cannula 21 through delivery channel 100 to flow channel 101. By actuating electromagnetic coils 77 and 78, membrane 97 may be made to ripple within flow channel 101, inducing wave-like formations in membrane 97 that move from the edges of the membrane toward circular opening 99. Thus, as blood is delivered from delivery channel 100 to membrane assembly 82, it may be forced radially along both the top and bottom of membrane 97 toward circular opening 99 and from there out to outlet 23.

[0093] According to one aspect of the invention, the undulating membrane pump described herein reduces clot formation by placing moving parts directly in the primary flow path, thereby reducing the risk of flow stagnation. Specifically, the moving components depicted in FIG. 11, including the magnetic ring assembly 76, the suspension rings 79 and 80, the pillars 81, and the membrane assembly 82, are all located in the delivery channel 100 and the flow channel 101. Flow stagnation can be further avoided by eliminating the secondary flow path, which can have significantly lower flow rates. The width of the fluid passages, i.e., the delivery channel 100 and the flow channel 101, may be optimized to minimize exposure of the blood to shear conditions. The flow channels may be sized and shaped to optimize hydraulic performance. Specifically, the flow channel 101 may be sized and configured to promote blood flow toward the outlet and resist blood flow toward the inlet. It is understood that the size and shape of the flow channel may affect blood flow through the pump, and the optimal size and shape may be selected to optimize hydraulic performance. For example, the size and shape of the flow channels may be optimized to resist backflow and recirculation while allowing flow in the forward direction; thus resisting backflow without impeding forward flow.

[0094] 13 and 14, the lower portion of pump 20 is shown, including flanged portion 87, membrane assembly 82, and lower housing portion 25. A delivery channel 100 may be in fluid communication with membrane assembly 82 and a flow channel 101 defined by a bottom surface of flanged portion 87 and an inner surface of lower housing portion 25. Flanged portion 87 may include a feature 102 that extends downward as the bottom of flanged portion 87 transitions radially inward. The inner surface of lower housing portion 25 may also slope upward as it extends radially inward. The combination of the upward slope of the inner surface of lower housing portion 25 and the downward movement of the bottom surface of flanged portion 87 narrows flow channel 101 as the channel transitions radially inward from delivery channel 100 to a circular opening 99 in membrane 97 that is centered about pump outlet 23.

[0095] As explained above, membrane assembly 82 may be suspended by posts 81 within flow channel 101 below the bottom surface of flanged portion 87 and above the interior surface of lower housing portion 25. Membrane assembly 82 may be free to move vertically up and down within flow channel 101, constrained only by suspension rings 79 and 80. Membrane assembly 82 may be constrained by rigid posts 81 and the suspension rings from twisting, tilting, or moving in any direction within flow channel 101 other than up and down.

[0096] Flow channel 101 is divided into an upper flow channel by membrane 97 and a lower flow channel by membrane 97. The geometry of membrane 97 may be angled such that the top surface of membrane 97 is parallel to the bottom surface of flanged portion 87 and the bottom surface of membrane 97 is parallel to the opposing surface of lower housing portion 25 when membrane assembly 82 is at rest. Alternatively, membrane 97 may be sized and shaped such that the upper and lower flow channels narrow as they move radially inward from delivery channel 100 to circular opening 99 in membrane 97 when membrane assembly 82 is at rest.

[0097] 14 , as the rigid membrane ring 96 is moved up and down within the flow channel 101 by the posts 81, the outermost portion of the membrane 97 closest to the rigid membrane ring 96 moves up and down with the rigid membrane ring 96. The membrane 97 being flexible and having elastic properties causes the up and down movement of the membrane portion closest to the rigid membrane ring 96 to move gradually along the membrane 97 towards the circular opening 99. This movement across the flexible membrane 97 creates a wave-like deformation in the membrane that may propagate inward from the rigid membrane ring 96 towards the opening 99.

[0098] The waves formed in the wave membrane may be manipulated by varying the frequency at which the rigid membrane ring 96 moves up and down as well as the distance that the rigid membrane ring 96 moves up and down. As explained above, the amplitude and frequency at which the rigid membrane ring 96 moves up and down is determined by the amplitude and frequency at which the magnetic ring assembly 76 moves back and forth across the electromagnetic assembly 91. Thus, the waves formed in the wave membrane may be adjusted by varying the frequency and amplitude at which the magnetic ring assembly 76 is moved back and forth.

[0099] As blood is introduced into the flow channel 101 from the delivery channel 100, undulations in the membrane 97 urge the blood towards the circular opening 99 and out of the pump housing 27 via the outlet 23. The transfer of energy from the membrane to the blood is directed radially inward along the length of the membrane towards the opening 99, forcing the blood along both sides of the membrane 97 along the flow channel towards the outlet 23.

[0100] For example, as the rigid membrane ring 96 moves downward in conjunction with the magnetic ring assembly 76, the upper portion of the flow channel 101 near the delivery channel 100 expands, allowing blood from the delivery channel 100 to fill the upper portion of the flow channel near the outer region of the membrane 97. As the rigid membrane ring 96 moves upward, the upper portion of the flow channel 101 begins to narrow near the rigid membrane ring 96, moving a wave-like deformation across the membrane. As the wave propagates across the membrane 97, blood in the upper portion of the flow channel 101 is forced towards the circular opening and eventually forced out of the pump housing 27 through the outlet 23. At the same time, as the rigid membrane ring 96 moves upward, the lower portion of the flow channel 101 nearest the outer portion of the membrane 97 begins to expand, allowing blood from the delivery channel 100 to flow into this region. Subsequently, as the rigid membrane ring 96 is again forced downward, the area of ​​the lower portion of the flow channel 101 closest to the outer portion of the membrane 97 begins to narrow, moving a wave-like deformation across the membrane, which forces blood toward the outlet 23.

[0101] By manipulating the waves formed in the wave membrane by varying the frequency and amplitude with which the magnetic ring assembly 76 moves up and down, the pressure gradient in the flow channel 101 and ultimately the rate of flow of blood moving through the flow channel 101 may be adjusted. Proper control of the movement of the magnetic ring assembly 76 allows oxygen-rich blood to be effectively and safely pumped from the left ventricle to the aorta and, if desired, to the entire body.

[0102] In addition to simply pumping blood from the left ventricle to the aorta, the pump 20 of the present invention may be operated to accurately mimic physiological pulsatility without loss of pump efficiency. In the embodiment detailed above, pulsatility may be achieved nearly instantaneously by varying the frequency and amplitude at which the magnetic ring assembly 76 moves to produce a desired flow output, or by stopping the movement of the magnetic ring assembly for a period of time to produce a period of low or no flow output. Unlike a typical rotary pump, which requires a period of time to achieve a set revolutions per minute to achieve the desired fluid displacement and pulsatility, the pump 20 may achieve the desired flow output nearly instantaneously, as well as stop output nearly instantaneously due to the very low inertia generated by the small moving mass of the moving components of the pump assembly. The ability to start and stop on demand allows for fast changes in pressure and flow. Along with frequency and amplitude, the duty cycle, defined by the percentage of time the membrane 97 is excited relative to a set period of time, may also be adjusted to achieve the desired flow output and pulsatility without loss of pump efficiency. The flow rate can be varied by manipulating the duty cycle from 0 to 100%, while holding the frequency and amplitude constant.

[0103] According to another aspect of the invention, the controller 30 may be programmed by the programmer 50 to operate at selected frequencies, amplitudes, and duty cycles to achieve a wide range of physiological flow rates with physiological hemodynamics. For example, the programmer 50 may instruct the controller 30 to operate the pump 20 at a given frequency, amplitude, and / or duty cycle during periods when the patient is normally asleep, and may instruct the controller 30 to operate the pump 20 at a different frequency, amplitude, and / or duty cycle during periods when the patient is normally awake. The controller 30 or pump may also be equipped with an accelerometer or position indicator to determine if the patient is supine or ambulatory, the output of which may be used to transition from one set of pump operating parameters to another. If the patient experiences some discomfort or the physician determines that the parameters are not optimized, the physician may modify at least one or more of the frequency, amplitude, and duty cycle to achieve the desired function. Alternatively, the controller 30 or mobile device 60 may be configured to vary one or more of the frequency, amplitude, and duty cycle to suit the needs of the patient.

[0104] The pump 20 may further comprise one or more additional sensors for adjusting the flow output and pulsatility according to the patient's needs. The sensors may be integrated into the pump 20 or, alternatively or additionally, may be embedded elsewhere in or on the patient. The sensors are preferably in electrical communication with the controller 30 and may monitor operating parameters that measure the performance of the pump 20, or physiological sensors that measure physiological parameters of the patient, such as heart rate or blood pressure. The one or more physiological sensors may be used to synchronize the pulsatile flow with the patient's cardiac cycle, for example, by monitoring blood pressure or muscle contractions and synchronizing the duty cycle according to the sensed output.

[0105] The controller 30 may compare the physiological sensor measurements to the current pump output. If, by analyzing the sensor measurements, it is determined that the demand exceeds the current output, then the frequency, amplitude, and / or duty cycle may be automatically adjusted to meet the current demand. Similarly, the controller may determine that the current output exceeds the demand and vary the output accordingly by varying the frequency, amplitude, and / or duty cycle. Alternatively, or in addition, if it is determined that the demand exceeds the current output, then an alarm may be issued by the controller 30. Similarly, the performance measurements from the performance sensors may be compared against predefined thresholds and an alarm may be issued by the controller 30 if the measurements exceed the predefined thresholds or if a fault is detected.

[0106] The pump 20 is sized and shaped to produce physiological flow rates, pressure gradients, and pulsatility at operating points where maximum efficiency is achieved. In particular, the pump 20 may be sized and shaped to produce physiological flow rates ranging from 2 to 15 liters / minute with pressure gradients below the threshold associated with hemolysis. Also, to mimic a typical physiological pulsation of 60 beats / minute, the pump 20 may pulsate approximately once per second. To achieve such pulsatility, for example, a 20-50% duty cycle may be utilized with an "on" or "high" period of 0.2-0.5 seconds and an "off" or "low" period of 0.5-0.8 seconds (wherein the "high" setting represents an operating point of frequency and amplitude that results in increased blood flow as opposed to physiological pressure, and the "low" setting represents an operating point of frequency and amplitude that results in low blood flow as opposed to physiological pressure). For a given system, maximum efficiency at a particular operating frequency, amplitude, and voltage may be achieved while producing a flow rate of 2-15 liters / min at a duty cycle of 20-50% by manipulating one or more of the shape and size of the blood flow channel, the elastic properties of the suspension ring, the mass of the moving parts, the geometry of the membrane, and the elastic and frictional properties of the membrane. In this manner, pump 20 may be designed to produce a desired physiological output while continuing to function at optimal operating parameters.

[0107] By adjusting the duty cycle, pump 20 can be configured to generate a wide range of output flows at physiological pressure gradients. For example, for an exemplary LVAD system configured to generate 2-15 liters / minute with a duty cycle of 20-50%, the optimal operating frequency may be 25-70 Hz, or even 120 Hz. For this system, the flow output may be increased to 10 liters / minute or decreased to 4 liters / minute, for example, by varying only the duty cycle. Because the duty cycle and frequency operate independently of one another, the duty cycle may be operated from 0-100% without affecting the frequency.

[0108] The pump system described herein, which is tuned to achieve physiological flow rates, pressure gradients, and pulsatility, also avoids hemolysis and platelet activation by subjecting the blood to low to moderate shear forces similar to those faced by blood components in a normal, non-diseased vasculature. In the embodiment detailed above, the delivery channel 100 may also be sized and configured to avoid friction between the moving magnetic ring assembly 76, the suspension rings 79 and 80, the posts 81, and the lower housing portion 25 by sizing the channel such that a clearance of at least 0.5 mm is maintained between all moving components. Similarly, the magnetic ring assembly 76, the suspension rings 79 and 80, and the posts 81 may all be offset from the stator assembly 72 by at least 0.5 mm to avoid friction between the stator assembly and the moving parts.

[0109] 15A and 15B, another exemplary embodiment of a pump assembly of the present invention is described. The pump 20′ is configured similarly to the pump 20 described in FIGS. 7, 8, and 12, and similar components are identified with similar numerals with a prime symbol. The pump 20′ is distinguished from the pump 20 in that the membrane assembly 82′ includes a skirt 115 coupled to the membrane 97′. The skirt illustratively includes a first portion 115a and a second portion 115b. The first portion 115a of the skirt 115 extends upwardly within the delivery channel 100′ toward the inlet 21′ in a first direction, for example, parallel to the longitudinal axis of the stator assembly 72′ and / or the central axis of the pump housing 27′. The second portion 115b of the skirt 115 curves toward the outlet 23' such that the second portion 115b is coupled to the membrane 97' and the membrane 97' faces in a second direction, e.g., perpendicular to the first portion 115a of the skirt 115. For example, the skirt 115 may have a J-shaped cross-section such that the first portion 115a forms a cylindrical ring around the stator assembly 72' and the second portion 115b has a predetermined radius of curvature that allows blood to flow smoothly from the delivery channel 100' throughout the skirt 115 to the outer edge of the membrane 97' and into the flow channel 101' while reducing blood stagnation. The skirt 115 improves the fluid dynamics generated for a given frequency while preventing blood recirculation within the delivery channel 100' and minimizing blood damage. Additionally, the J-shape of the skirt 115 around the stator assembly 72' may be stiffer than a planar rigid membrane ring, thereby reducing flexure and fatigue and drag as blood moves across the membrane 97'.

[0110] The skirt 115 exhibits rigidity characteristics under typical forces encountered during the full range of operation of the present invention and may be made of a biocompatible metal, such as titanium. The skirt 115 is preferably impermeable so that blood cannot flow through the skirt 115. Post receiving sites 98' may be formed in the skirt 115 to engage the membrane assembly 82' with the posts 81'. Alternatively, the posts 81' may be attached to the skirt 115 in any other manner that directly translates the motion of the magnetic ring assembly 76' to the skirt 115.

[0111] When the magnetic ring assembly 76' moves up and down, the movement is rigidly transferred by the pillars 81' to the J-shape of the skirt 115 of the membrane assembly 82'. Considering the rigidity of the pillars, when the magnetic ring assembly 76' moves a certain distance upwards or downwards, the membrane assembly 82' can move the same distance. For example, if the magnetic ring assembly 76' moves 2 mm from a position near the first electromagnetic coil 77' to a position near the second electromagnetic coil 78', the membrane assembly 82' can also move 2 mm in the same direction. Similarly, the frequency at which the magnetic ring assembly 76' crosses the space between the first and second electromagnetic coils can be the same frequency as the frequency at which the membrane assembly 82' moves the same distance.

[0112] Skirt 115 may be affixed to membrane 97' and hold it under tension. Membrane 97' may be molded directly onto skirt 115 or may be affixed to skirt 115 in any manner that holds membrane 97' uniformly under tension around its circumference. For example, skirt 115 may be coated with the same material used to form membrane 97', and this coating on skirt 115 may be formed integrally with membrane 97'.

[0113] Blood may enter pump 20' from the left ventricle through inlet cannula 21' and flow downward along the pump assembly into delivery channel 100'. As blood travels down tapered section 83', it is directed through gap 74' into the vertical portion of delivery channel 100' in the region between pump housing 27' and actuator assembly 95'. As shown in FIG. 15A, skirt 115 divides delivery channel 100' into upper delivery channel 100a and lower delivery channel 100b, where flow channels 101a and 101b are separated by membrane 97', such that blood flow through delivery channel 100' is divided into flow channel 101a through upper delivery channel 100a and flow channel 101b through lower delivery channel 100b. As will be appreciated by one of ordinary skill in the art, the volume of blood flow through each of delivery channels 100a and 100b may depend on the diameter of first portion 115a of skirt 115. For example, the larger the diameter of first portion 115a of skirt 115, the larger the volume of delivery channel 100a and the smaller the volume of delivery channel 100b. The ratio of the volume of delivery channel 100a to the volume of delivery channel 100b may be, for example, 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, 4:1, etc., depending on the amount of blood flow desired on each surface of membrane 97'.

[0114] By directing blood from inlet cannula 21' in delivery channel 100' over skirt 115, blood flow is divided in delivery channels 100a and 100b and into flow channels 101a and 101b, respectively, so that blood flows over the entire upper and lower surfaces of membrane 97' of membrane assembly 82'. For example, as shown in FIG. 16A, blood flow through a pump having a planar rigid membrane ring spaced a relatively small distance from the pump housing allows unrestricted blood flow over the entire upper surface of the flexible membrane while restricting blood flow over the entire lower surface of the flexible membrane. On the other hand, blood flow through a pump having a J-shaped skirt or integral portion, as shown in FIGS. 16B and 16C, can be distributed in a desired ratio over both the upper and lower sides of the flexible membrane.

[0115] The second portion 115b of the skirt 115 curves toward the outlet 23' such that the second portion 115b is coupled to the membrane 97' and the membrane 97' faces in a second direction, e.g., perpendicular to the first portion 115a of the skirt 115. For example, the skirt 115 may have a J-shaped cross-section such that the first portion 115a forms a cylindrical ring around the stator assembly 72' and the second portion 115b has a predetermined radius of curvature that allows blood to flow smoothly from the delivery channel 100' throughout the skirt 115 to the outer edge of the membrane 97' and into the flow channel 101' while reducing blood stagnation. The skirt 115 improves the fluid dynamics generated for a given frequency while preventing blood recirculation in the delivery channel 100' and minimizing blood damage. Additionally, the J-shape of the peripheral skirt 115 of the stator assembly 72' may be stiffer than a planar rigid membrane ring, thereby reducing bending and fatigue as well as drag as blood moves across the membrane 97'.

[0116] 15A, by actuating electromagnetic coils 77' and 78', membrane 97' may be caused to ripple within flow channels 101a and 101b, inducing wave-like formations within membrane 97' that move from the edges of membrane 97' toward circular opening 99'. Thus, as blood is delivered from delivery channel 100' to membrane assembly 82', it may be forced radially along both the upper and lower surfaces of membrane 97' toward circular opening 99' and from there out of outlet 23'. Distribution of blood flow across the upper and lower surfaces of membrane 97' reduces recirculation of blood within delivery channel 101' and reduces repeated exposure of blood to high shear stress regions, resulting in a significant improvement in the hydraulic performance of pump 20'.

[0117] 16C, a pump 400 similar to pump 20 is illustrated, comprising a pump housing 402, an integrated assembly 406, a membrane 416, and an actuator assembly 404, which may be the same as or similar to actuator assembly 95. The integrated assembly 406 may be disposed around the actuator assembly 404 and may comprise a magnetic assembly 408 and a transition portion 410. The magnetic assembly 408 may be similar to the magnetic ring assembly 76 and / or may comprise one or more magnets 422 and / or an iron portion 420. It is understood that the magnetic assembly 408 may comprise a Halbach array. The integrated assembly 406 may further comprise an outer cover 418 that allows sealing of the components (e.g., magnetic assembly 408) within the integrated assembly 406, and a magnet liner 424 that facilitates alignment and assembly of the magnets. The integrated assembly 406 may also comprise one or more bearing portions 419.

[0118] The integrated assembly 406 may be similar in function to the skirt 115, except that the integrated assembly 406 may incorporate a magnetic assembly 408. The integrated assembly 406 may further include a transition portion 410 that may extend upwardly within the delivery channel 405 and toward a membrane 416, which may be the same as or similar to the membrane 97. The transition portion 410 may attach the integrated assembly 406 to the membrane 416. The integrated assembly 406 may define a first blood channel 412 between the integrated assembly 406 and the pump housing 402, and may further define a second blood channel between the integrated assembly 406 and the actuator assembly 404. Similar to the skirt 115, the integrated assembly 406 may redirect blood into the first blood channel 412 and the second blood channel 414 and ultimately to the membrane 416.

[0119] The pump housing 402 may include one or more magnets 413 and one or more bearing portions 417. The bearing portion 417 may be in fluid communication (e.g., via blood in the first blood channel 412) with the bearing portion 419, which together may form a bearing that resists radial motion of the moving assembly 406. The bearing portions 417 and 419 may be constructed of biocompatible materials such as ceramics, alumina, zirconia, or zirconia-reinforced alumina, or engineering plastics such as poly-ether-ether-ketone (PEEK) and Delrin, or metallic alloys coated with anti-friction coatings such as titanium coated with titanium nitride (TiN) or zirconium nitride (ZrN). The magnets 413 and the magnetic assembly 408 may interact to resist axial motion and return the moving assembly to a neutral position axially.

[0120] One or more magnets of the magnetic assembly 408 may be enlarged to increase the second blood channel 414 while maintaining the attractive force between one or more coils (e.g., coil 411) of the actuator assembly 404 and the magnetic assembly 408. The increased second blood channel 414 may reduce the risk of shear-induced damage and / or thermal damage to the blood. As shown in FIG. 16C, the pump 400 may have a single moveable assembly (e.g., integral assembly 406) in addition to the membrane 416.

[0121] 16D, a pump 450 is illustrated that includes an inlet spring 458 and an outlet spring 460. The pump 450 may be similar to the pump 400 and may include an actuator assembly 452 that may be similar to the actuator assembly 404, a pump housing 456 that may be similar to the pump housing 402, and an integration assembly 454 that may be similar to the integration assembly 406. As shown in FIG. 16, the integration assembly 454 may be coupled to the inlet spring 458 and the outlet spring 460. The inlet spring 456 and the outlet spring 460 may be coupled to the integration assembly 454 on one end and to the pump housing 456 on the other end. The inlet spring 458 and the outlet spring 460 may be, for example, a monoblock spring or any other known spring. The inlet spring 458 and the outlet spring 460 may be constructed of a biocompatible metal, such as, for example, stainless steel, titanium, or cobalt chrome, and / or may be processed by methods to remove surface defects or cold work the material to increase durability and hemocompatibility. The inlet spring 458 and / or the outlet spring 460 may be made by cutting a shape from a flat sheet of the biocompatible metal. Alternatively, the inlet spring 458 and / or the outlet spring 460 may be machined from a solid block of material, thus allowing for a smoother and / or more three-dimensional design. In a preferred embodiment, the solid block of material is stainless steel or titanium. The inlet spring 458 and the outlet spring 460 may resist both radial and axial movement of the moving assembly 456 and may return the moving assembly 456 to a neutral position. It is understood that either the inlet spring 458 and / or the outlet spring 460 are optional (e.g., the pump 450 may include the inlet spring 458 and / or the outlet spring 460). Also, as shown in FIG. 16D, a damping structure 462 may be coupled to and / or extend from the actuator assembly 452 and may facilitate damping vibrations of the pump 450 (e.g., caused by the moveable assembly 454). The damping structure 462 may be composed of a polymeric material, such as, for example, a biocompatible polyurethane having a Shore hardness value of 20-80A.It is understood that the inlet spring 458 and the outlet spring 460 may be the same as or similar to the suspension springs. Alternatively, an active damping structure may be used. The active damping structure may comprise or otherwise employ one or more moving masses or tuned mass dampers to reduce vibrations. In one example, an active damping structure, such as vibration damping assembly 523 in FIG. 17, may be located on an exterior surface of the pump.

[0122] 17, a pump 500 is illustrated that includes an encapsulation assembly. The pump 500 is similar to the pump 20 described above with respect to FIGS. 7, 8, and 12. For example, the pump 500 may include an inlet cannula 501, which may be similar to the inlet cannula 21, an outlet cannula 502, which may be similar to the outlet cannula 22, an upper housing portion 515, which may be similar to the upper housing portion 24, and a lower housing portion 517, which may be similar to the lower housing portion 25. The upper housing portion 515 may be coupled to the lower housing portion 517 and the outlet cannula 502. The lower housing portion 517 may be coupled to the outlet cannula 502. The upper housing portion 515 and / or the inlet cannula 501 may be coupled to a stator assembly 511, which may include an upper stator portion 521 and a lower stator portion 520, and a core stator portion 545. The core stator portion 545 may be coupled to both the upper stator portion 521 and the lower stator portion 520 and may support the electromagnetic coils (e.g., the first electromagnetic coil 504 and the second electromagnetic coil 505).

[0123] 17, upper stator portion 521 and lower stator portion 520 may form stator assembly 511 and may be designed to house and securely fasten electromagnetic assembly 503, which may be similar in structure and / or function to electromagnetic assembly 91. For example, electromagnetic assembly 503 may comprise a first electromagnetic coil 504 and a second electromagnetic coil 505. It is understood that electromagnetic assembly 503 may be any electromagnetic assembly described herein and / or may comprise more or less than two electromagnetic coils. Electromagnetic assembly 503 together with stator assembly 511 form an actuator assembly.

[0124] A magnetic assembly 513, which may be similar in structure and function to the magnetic ring assembly 76, may be suspended around the electromagnetic assembly 503. For example, the magnetic assembly 513 may be the magnetic assembly illustrated in FIG. 19. The magnetic assembly 513 may also be coupled to a first spring 534, which may be similar to the first suspension spring 79, and a second suspension spring 535, which may be similar to the second suspension spring 80. The first suspension spring 534 may also be coupled to the upper stator portion 521, and the second suspension spring 535 may also be coupled to the lower stator portion 520. The first suspension spring 534 and the second suspension spring 535 may bias the magnetic assembly 513 toward a neutral position between the first suspension spring 534 and the second suspension spring 535 and / or may offset the magnetic assembly 513 from the actuator assembly 503. It is further understood that the first suspension spring 534 and the second suspension spring 535 may resist twisting and / or tilting motion of the magnetic assembly 513 and / or provide a restoring force that returns the magnet assembly 513 toward a central position. Specifically, the first suspension spring 534 and the second suspension spring 535 may help keep the axial centerlines of the stator and the magnetic ring parallel.

[0125] The upper stator portion 521 may further be coupled to a top encapsulator 532, and the lower stator portion 520 may be coupled to a bottom encapsulator 531. The top encapsulator 532 and the bottom encapsulator 531 may each be coupled to the magnetic assembly 513. The top encapsulator 532 and the bottom encapsulator 531 may be elastic membranes made of any known elastic or stretchable material and / or structure. For example, the top encapsulator 532 and / or the bottom encapsulator 531 may be made of any known elastic and / or thermoplastic material and / or viscoelastic material (e.g., silicone) and / or any ribbed material that forms a structure designed to stretch (e.g., a metallic structure with bellows). The top encapsulator 532 and the bottom encapsulator 531 may exert a spring force on the magnetic assembly 513 due to their respective elastic properties. The top encapsulator 532 and the first suspension spring 534 may together act to apply a spring force to the magnetic assembly 513 as a whole, and similarly the bottom encapsulator 531 and the second suspension spring 535 may together act to apply a spring force to the magnetic assembly 513. The first suspension spring 534 and / or the second suspension spring 535 may be sized and otherwise designed to accommodate the spring force of the top encapsulator 532 and / or the bottom encapsulator 531. For example, the first suspension spring 534 and / or the second suspension spring 535 may be sized and otherwise shaped to achieve a desired neutral position of the magnetic assembly 513 based at least in part on the elastic properties of the top encapsulator 532 and the bottom encapsulator 531.

[0126] The magnetic assembly 513, the top encapsulation device 532 and the bottom encapsulation device 531, and the stator assembly 511 may collectively form an encapsulation assembly 525 that may form a continuous surface, thereby encapsulating the actuator assembly 503, the first suspension spring 534, and the second suspension spring 535. In this manner, a blood flow channel 537 may be defined between the magnetic assembly 513, the top encapsulation device 532 and the bottom encapsulation device 531, and the stator assembly 511 (i.e., the encapsulation assembly 525) on one side and the interior surface of the upper housing portion 515 and the lower housing portion 517 on the other side.

[0127] The encapsulation assembly 525 may provide several advantages. For example, because the actuator assembly 503, the first suspension spring 534, and the second suspension spring 535 are encapsulated, blood is prevented from interacting with the actuator assembly 503, the first suspension spring 534, and the second suspension spring 535, and thus such encapsulation may prevent damage to the blood (e.g., hemolysis) that may occur when these components interact with the blood and the magnetic assembly 513 during operation of the pump 500. Additionally, the blood passage may be more fluid-dynamically smooth with fewer areas of stagnation and turbulence, thereby reducing the risk of clot formation. The blood passage may be optimized to minimize exposure of the blood to shear conditions that may cause damage to blood components, such as the adhesion protein von Willebrand factor.

[0128] The membrane assembly 538 may be coupled to the magnetic assembly 513 such that the membrane assembly 538 moves with the magnetic assembly 513. The membrane assembly 538 may include a skirt 550 and a membrane 507, which may be similar to the skirt 115 and membrane 97′, respectively, as described above with respect to FIG. 16B. The membrane 507 may be circular in shape and may include a circular opening in the center. For example, the skirt 550 may be disposed around the encapsulation assembly 525 and may extend vertically within the delivery channel 537 and may be curved toward the membrane 507, which may be oriented horizontally. For example, the skirt 550 may have a J-shaped cross section such that a portion of the skirt 550 forms a cylindrical structure around the stator assembly and may have a predetermined radius of curvature that allows blood to flow smoothly from the delivery channel 537, all the way through the skirt 550, to the membrane 507, reducing stagnation of blood flow.

[0129] The skirt 550 may reduce or eliminate blood recirculation in the delivery channel 537, improving the fluid dynamics generated for a given frequency while minimizing blood damage. Additionally, the J-shape of the skirt 550 may be stiffer than the membrane 507, thereby reducing flexing and fatigue as well as drag as blood moves across the membrane 507. The membrane assembly 538 may be rigidly coupled to the magnetic assembly 513 via a number of rigid pins and / or via surface contacts that may be welded. As the magnetic assembly 513 moves up and down (e.g., reciprocates), so does the skirt 550, thereby creating undulations in the membrane 507 that push blood above and below the membrane 507, splitting the blood flow passage 537, including the blood flow passage 506, toward the outlet cannula 502 of the pump 500.

[0130] The upper housing portion 515 may include a vibration damping assembly 523 that may be designed to damp vibrations of the pump 500 as the magnetic assembly 513 reciprocates during operation. For example, the vibration damping assembly 523 may be a tuned mass damper tuned to oscillate 180 degrees out of phase with the primary motion of the actuator. The vibration damping assembly 523 may include a mass 540 suspended by one or more vibration springs 541. For example, the mass 540 may be an annular mass. The vibration damping assembly 523 may be disposed around and / or located on the outer surface of the upper housing portion 515 or may be otherwise integrated into the upper housing portion 515. The mass 540 and vibration springs 541 may be sized and shaped to reduce vibration levels of the pump 500 caused by the reciprocating magnetic assembly 513.

[0131] Referring now to Figure 18, an exploded view of the actuator assembly, magnetic assembly, and membrane assembly is illustrated. As shown in Figure 18, inlet block 601 may include an inlet cannula 621, which may be similar to inlet cannula 501 of Figure 17, and an upper stator portion 622, which may be similar to upper stator portion 521 of Figure 17. A first suspension spring 603, which may be similar to first suspension spring 534 of Figure 17, may be coupled to upper stator portion 622.

[0132] The core assembly 602 may be coupled to the upper stator portion 622 and may be disposed below the first suspension springs 603. The core assembly 602 may include an electromagnetic assembly 605, which may be similar to the actuator assembly 503 of FIG. 17, and a core stator portion 624, which may be identical to the core stator portion 545 of FIG. 17. The core stator portion 624 may support the electromagnetic assembly 605. The core assembly 602 may include an encapsulation portion 626, which may be a flexible membrane (e.g., silicone) that may cover all or a portion of the electromagnetic assembly 605 and / or the core stator portion 545. A magnetic assembly 607, which may be similar to the magnetic assembly 513 of FIG. 17, may be disposed around the core assembly 602 and may be coupled to the inlet block 601 via the first suspension springs 534. The magnetic assembly 607 may include a pin receiving portion 619 sized and designed to receive and engage the pin 615 .

[0133] A second suspension spring 609, which may be similar to the second suspension spring 535 of FIG. 17, may also be coupled to the magnetic assembly 607 and may also be coupled to the lower stator portion 611, which may be similar to the lower stator portion 520 of FIG. 17. Thus, the magnetic assembly 607 may be concentrically located between the first suspension spring 603 and the second suspension spring 609 such that the magnetic assembly 607 may oscillate between the first suspension spring 603 and the second suspension spring 609. The first suspension spring 603 and the second suspension spring 609 may further be coupled to the core assembly 602. The lower stator portion 611 may further include a protrusion 628, which may extend upwardly relative to the lower stator portion 611. For example, protrusions 628 may extend through core stator portion 624 and engage upper stator portion 622 to couple lower stator portion 611 and core stator portion 624 to upper stator portion 622. In one example, the engagement between protrusions 628 and upper stator portion 622 may be a threaded engagement.

[0134] The membrane assembly 645 may comprise a skirt 613 and a membrane 640. The skirt 613 may be similar to the skirt 550 of FIG. 17, and the membrane 640 may be similar to the membrane 507 of FIG. 17. The skirt 613 may further comprise a plurality of pin receiving portions 617, which may be openings extending through the skirt 613, and may be sized and shaped to receive the pins 615. The pins 615 may be any type of known pin that may extend through the skirt 613 and couple the skirt 613 to the magnetic assembly 607. In this manner, the membrane assembly 645 may be rigidly coupled to the magnetic assembly 607. It is understood that the magnetic assembly 607 may alternatively be coupled to the skirt 613 using any other known coupling technique (e.g., adhesives, threaded coupling, etc.).

[0135] 19, a magnetic ring assembly 700 is illustrated. As shown in FIG. 19, the magnetic ring assembly 700 may comprise magnet 701, magnet 705, and magnet 709, each of which may comprise one or more magnet portions forming a ring and / or having a common radius of curvature. It is understood that the magnet portions 701, 705, and 709 may comprise one or more magnets and / or iron portions (e.g., iron-cobalt). In an embodiment, the magnetic portions 701, 705, and 709 are iron-cobalt. In an embodiment, the magnetic ring assembly 700 may comprise three magnets, for example, iron, neon, and / or boron, with an iron-cobalt back iron cover. It is further understood that the magnetic portions 701, 705, and / or 709 may be or comprise a Halbach array. Further, the magnetic ring assembly 700 may include an inner housing 706 that may house or otherwise support the movable magnet portions 701, 705, and 709. An outer housing 707 may be disposed over the inner housing 706 and the magnet portions 701, 705, and 709 and may be coupled to the inner housing 706 to securely secure and seal the magnet portions 701, 705, and 709 to the inner housing 706. Although three magnet portions 701, 705, and 709 are illustrated in FIG. 19, it is understood that more or fewer magnet portions may be included in the magnetic ring assembly 700. It is understood that the magnetic ring assembly 700 may include magnetic segments such as the magnet portions 701, 705, and 709 arranged in series. Alternatively, the magnetic ring assembly 700 may include a single unbroken cylindrical magnet or a set of magnets.

[0136] 20A-20C illustrate pump 800, encapsulation assembly 850, and membrane assembly 817. Referring now to FIG. 20A, encapsulation assembly 850 may be identical to encapsulation assembly 525 of FIG. 17. Specifically, encapsulation assembly 850 may include upper stator assembly 801, upper encapsulator 815, magnetic assembly 805, bottom encapsulator 816, and lower stator assembly 803, which may be similar to upper stator portion 521, upper encapsulator 519, magnetic assembly 513, bottom encapsulator 521, and lower stator portion 520, respectively, of FIG. 17. Upper stator assembly 801 may be coupled to inlet cannula 855. Magnetic assembly 805 may include pin receiving portion 821.

[0137] As shown in Figure 20A, magnetic assembly 805 may be located between and coupled to top encapsulator 815 and bottom encapsulator 816. Top encapsulator 815 may be engaged with upper stator portion 801. Encapsulation assembly 850 may be axially and concentrically aligned with membrane assembly 817, which may be similar to membrane assembly 538 of Figure 17. For example, membrane assembly 817 may include skirt 807 and membrane 818, which may be similar to skirt 550 and membrane 507 of Figure 17.

[0138] FIG. 20B illustrates how the membrane assembly 817 may be concentrically located around or offset from the magnetic ring assembly 805. As shown in FIG. 20B, the membrane assembly 817 may be rigidly coupled to the magnetic ring assembly 805 via a pin 811 that may extend through the membrane assembly 817 and engage with the magnetic assembly 805. Referring now to FIG. 20C, the connection between the membrane assembly 817 and the magnetic assembly 805 is illustrated. As shown in FIG. 20C, the membrane assembly 817 may include an opening 820 through which the pin 811 may be inserted into and engage with a pin receiving portion 821 of the magnetic assembly 805 that is sized and designed to receive the pin 811.

[0139] 21A-21C, the movement of the membrane 901 during operation of the pump is illustrated. As shown in FIG. 21A, the magnetic assembly 903, which may be similar to the magnetic assembly 513 of FIG. 17, is moved to an uppermost position relative to the stator assembly 909, which may be similar to the stator assembly 511. As a result, the membrane assembly 907, which may be similar to the membrane assembly 538, may also move upward, causing the membrane 901, which may be similar to the membrane 507, to move upward. However, the free-standing portion 905 of the membrane 905 may remain in a lower position while the membrane assembly 907 moves upward. As illustrated in FIG. 21B and FIG. 21C, the membrane assembly 907 may move downward to second and third positions, respectively, where the membrane assembly 907 is lowered while the free-standing end 901 of the membrane 901 is raised. In this manner, a wave-like undulation may be created toward the free-standing end 905, which urges blood toward the free-standing end 905. This process repeats, with the membrane 901 moving upward and back to the first position as shown in Figure 21A, and then moving again to the second and third positions as shown in Figures 21B and 21C.

[0140] 22A and 22B, pump 1000 may be similar to pump 500 of FIG. 17. As shown in FIG. 22A, pump 1000 may include encapsulation assembly 1001, upper housing portion 1002, lower housing portion 1003, and membrane assembly 1004, which may be similar to encapsulation assembly 525, upper housing portion 515, lower housing portion 517, and membrane assembly 535. Encapsulation assembly 1001 on one side and upper housing portion 1002 and lower housing portion 1003 on the other side may form a blood flow passage 1005. As shown in FIG. 22A, blood may enter the components shown in red, and thus may enter inlet cannula 1006, travel along membrane assembly 1004 within blood flow passage 1005, and exit through outlet cannula 1007.

[0141] 22B is a top view of pump 1000 illustrating encapsulation assembly 1001, membrane assembly 1004, and partial upper housing portion 1002. As shown in FIG 22B, a blood passageway 1005 is defined by the interior surfaces of encapsulation assembly 1001 and upper housing portion 1002 and is divided into two blood flow passageways by membrane assembly 1004. Additionally, upper housing portion 1002 may include a position adjustment sensor 1008 that may determine certain operational information regarding the pump and / or the position of membrane assembly 1005.

[0142] The membrane assembly 1004 is illustrated in more detail in FIG. 23. As shown in FIG. 23, the membrane assembly 1004 may include one or more sensor targets 1301. The sensor target 1301 may be a permanent magnet that is a target for a sensor that is attached to the outside of the pump housing and can generate a moving field for the sensor. The sensor target 1301 may be used in conjunction with a position adjustment sensor 1008 illustrated in FIG. 22B to determine information regarding the position of the membrane assembly 1004 relative to the pump. Such information may be used to control the movement of the membrane in a closed loop circuit, thereby increasing the range of operation and preventing excessive oscillations that may damage the springs. In one embodiment, the sensor target may be similar in structure to that described in more detail in U.S. Pat. No. 10,799,625, which is incorporated herein by reference. The membrane assembly 1004 may include one or more sensor receiving portions 1303 that may be sized and shaped to receive the sensor target 1301. The sensor receiving portion 1303 may be sealed with a sealing portion 1302 that may cover the sensor receiving portion 1303 and the sensor target 1301 .

[0143] 24, a cross-sectional view of a pump 1100 with various isolated portions is illustrated. The pump 1100 may be similar to the pump 500 of FIG. 17 and may include a stator assembly 1103, an electromagnetic assembly 1108, a magnetic assembly 1107, a top encapsulator 1109, and a bottom encapsulator 1111, an encapsulation assembly 1113. The magnetic assembly 1107 may include an isolated portion 1124 that may include gaps and / or empty spaces within the magnetic assembly 1107 that may be filled with epoxy backfill 1124. Similarly, the electromagnetic assembly 1108 may include an isolated portion 1126 that may include gaps and / or empty spaces within the electromagnetic assembly 1108 that may be filled with epoxy backfill. Such epoxy backfilling of the isolated portions 1124 and 1126 may protect metallic components and / or wires and / or provide locking properties to prevent back-off of the screws. Epoxy backfill may be applied under vacuum before such components are hermetically closed. For example, the actuator assembly 1106, which may include the core stator portion 1104 and the electromechanical assembly 1108, may be hermetically sealed (e.g., by welding of seams). The core stator portion 1104 may support the electromechanical assembly 1108.

[0144] Referring now to FIG. 25, a perspective view of the actuator assembly 1106 is illustrated. As shown in FIG. 25, the actuator assembly 1106 may include several grooves 1130 located on the outer surface of the actuator assembly 1106. The grooves 1130 may be sized and arranged to prevent eddy current circulation within the stator. The grooves 1130 may also provide a wiring path for connection to the coil. In FIG. 25, a wiring path 1132 is shown in one of the circular grooves for connection to the coil. The grooves 1130 may be sized to facilitate backfilling of the stator from the inner diameter where epoxy may be used to enter the actuator assembly outer diameter.

[0145] Referring again to FIG. 24, the isolated portion 1122 may be filled with an encapsulation fluid. For example, the encapsulation fluid may be a perfluorocarbon, such as perfluorodecalin. The isolated portion 1122 may be defined, for example, by the space between the actuator assembly 1106 and the stator assembly 1125, the top encapsulator 1109, the magnetic assembly 1107, and the bottom encapsulator 1111. The encapsulation fluid may be an inert fluid that may prevent the movement of air, water, and other dissolved components. The encapsulation fluid may be silicone oil, saline, and / or deionized water. The encapsulation fluid may be added to the pump 1100 by the following process. First, a two-way stopcock may be connected to the pump 1100 (e.g., through an inlet block). Then, the pump core may be placed under vacuum as the connector may be switched to a liquid path. Once the encapsulation fluid has filled the isolated portion 1122, the chamber pressure may be returned to atmospheric pressure. The encapsulated backfill passage is then sealed.

[0146] 26A and 26B, the inlet block 1400 may be similar to the inlet block 601 in FIG. 18. As shown in FIG. 26A, the inlet block 1400 may include at least a portion of a stator assembly and an inlet cannula 1402. For example, the inlet block 1400 may include a stator engagement portion 1406 for engaging with the stator assembly. The stator engagement portion 1406 may be a threaded portion. The inlet block 1400 may further include a number of partitions 1404 located near the bottom of the inlet cannula 1402 that create a mechanical connection between the actuator and the housing. As shown in FIG. 26B, which is a top view of the inlet block 1400, blood may enter the pump through the inlet cannula 1402. The shape of the partitions 1404 may be designed to prevent flow stagnation and reduce the risk of clot formation. As blood traverses the inlet block 1400, it may be divided into various blood flow passages by partitions 1404. The inlet block 1400 may comprise channels for electrically connecting an actuator assembly to the outside of the pump and / or channels filling the cavity 1122 as shown in FIG.

[0147] 27A-27B, a pump 1500 is illustrated. Pump 1500 may be similar to pump 500 in FIG. 17. For example, pump 1500 may include inlet cannula 1502, stator assembly 1507, top encapsulator 1510, magnetic assembly 1511, bottom encapsulator 1514, electromagnetic assembly 1512, upper housing portion 1503, lower housing portion 1505, membrane assembly 1509, and outlet cannula 1515, each of which may be similar to inlet cannula 501, stator assembly 511, top encapsulator 532, magnetic assembly 513, bottom encapsulator 531, electromagnetic assembly 503, upper housing portion 515, lower housing portion 517, membrane assembly 538, and outlet cannula 502, as described above with respect to FIG. As shown in Figure 27A, the elastic properties of the top encapsulator 1510 and bottom encapsulator 1514 may provide a spring function to return the actuator to a centered position. As shown in Figure 27B, the pump housing 1500 may include one or more bearing portions 1517. The bearing portions 1517 may resist radial movement of the magnetic assembly 1511 within the pump 1500.

[0148] 28, a pump 1600 is illustrated that may include a top encapsulator 1603 and a bottom encapsulator 1610, each of which may include a bellows. The pump 1600 may be similar to the pump 500 in FIG. 17. For example, the pump 1600 may include an inlet cannula 1610, a stator assembly 1604, a magnetic assembly 1602, a bottom encapsulator 1610, an electromagnetic assembly 1605, an upper housing portion 1611, a lower housing portion 1612, and a membrane assembly 1613, each of which may be similar to the inlet cannula 501, the stator assembly 511, the magnetic assembly 513, the electromagnetic assembly 503, the upper housing portion 515, the lower housing portion 517, and the membrane assembly 538 of FIG. 17. Top encapsulator 1603 and bottom encapsulator 1610 may be similar to top encapsulator 532 and bottom encapsulator 531 of FIG. 17, however, top encapsulator 1603 may include bellows 1614 and bottom encapsulator 1610 may include bellows 1615. For example, top encapsulator 1603 and bottom encapsulator 1610 may be formed from one or more known metals or metal alloys, and bellows 1614 and 1615 may be pleated bellows. In this manner, top encapsulator 1614 and bottom encapsulator 1614 may be metallic but still flexible to facilitate movement of magnetic assembly 1602.

[0149] 29A-29B, a pump 1700 is illustrated that includes a flexure spring 1710 attached to an actuator compartment 1716. The pump 1700 may be similar to the pump 500 in FIG. 17. For example, the pump 1700 may include an inlet cannula 1701, a stator assembly 1702, an upper encapsulator 1704, a magnetic assembly 1705, a bottom encapsulator 1706, an electromagnetic assembly 1708, and a membrane assembly 1738 that may be similar to the inlet cannula 501, the stator assembly 511, the upper encapsulator 532, the magnetic assembly 513, the bottom encapsulator 531, the electromagnetic assembly 503, and the membrane assembly 538 of FIG.

[0150] The membrane assembly 1738 may be coupled to the magnetic assembly 1705. The electromagnetic assembly 1708 may be located within an actuator compartment 1716, which may be a cylindrical or similarly shaped structure that serves as a physical connection between the magnet ring and the flexure bearing, which may be porous. For example, the actuator compartment may be a thin-walled cylinder. The electromagnetic assembly 1708 may be isolated from the rest of the pump 1700 by a top encapsulator 1704 and a bottom encapsulator 1706. The actuator compartment 1716 may be connected to the stator assembly 1702 via one or more flexure (spiral) springs 1701. The flexure springs 1710 are shown in more detail in FIG. 29B. The flexure springs 1710 may include several curved through cuts 1720 that provide a spiral shape on the flexure springs 1710. The flexure spring 1710 may optionally include a number of actuator compartment engagement portions along the permit of the flexure spring 1710. The flexure spring 1710 may connect to the stator assembly 1702 at the stator receiving portion 1723 and to the actuator compartment 1716 via the actuator compartment engagement portion 1722. The flexure spring 1710 may incorporate dimensions and material properties that enable it to provide a spring force. The actuator compartment 1716 may be coupled to the magnetic assembly 1705; in an embodiment, the actuator compartment 1716 and the magnetic assembly 1705 are flexibly connected by a flexure bearing. The flexure bearing may provide a restoring force and may resist radial motion.

[0151] 29B, a perspective view of the flexure springs and actuator compartment is illustrated. As shown in FIG. 29B, the stator assembly 1702 may include a central component 1734 that may be cylindrical in shape and may engage with upper and lower flexure springs 1730 and 1732, each of which may be similar to the flexure spring 1710. The upper and lower flexure springs 1730 and 1732 may also each be coupled to an actuator compartment 1716 that may be rigidly coupled to a magnetic assembly 1705. The top encapsulator 1704 and bottom encapsulator 1706 may be coupled to the stator assembly 1702 and magnetic assembly 1705, respectively. An electromagnetic assembly (not shown) may be disposed within the actuator compartment 1716, which may be rigidly connected to the central component 1734 such that it is free to move axially relative to the stator assembly 1702. A membrane assembly 1738 may be coupled to the magnetic assembly 1705.

[0152] When the magnetic assembly 1705 interacts with the electromagnetic assembly, the magnetic assembly 1705 may be caused to reciprocate up and down relative to the stator assembly 1702. Because the actuator compartment 1716 may be rigidly coupled to the magnetic assembly 1705, the actuator compartment 1716 may reciprocate as well. The upper and lower flexure springs 1730 and 1732 may allow the actuator compartment 1716 to move axially, and the upper and lower flexure springs 1730 and 1732 may return the actuator compartment 1716 and, therefore, the magnetic assembly 1738 to a neutral position due to the spring forces in the upper and lower flexure springs 1730 and 1732. Additionally, upper flexure spring 1730 and lower flexure spring 1732 may resist twisting or tilting of actuator component 1716 and magnetic assembly 1705 .

[0153] While various illustrative embodiments of the present invention are described above, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the invention. For example, the pump assembly 70 shown in FIG. 9 may be ordered differently and may include additional or fewer components of various sizes and compositions. It is intended that the appended claims cover all such changes and modifications that are within the true spirit and scope of the invention.

Claims

1. A housing having an inlet and outlet configured to communicate fluidly with the patient's circulatory system; A membrane disposed within the housing; An actuator disposed within the housing, configured to pump blood by causing the membrane to reciprocate; and An encapsulation assembly configured to encapsulate an actuator so that blood does not come into contact with the actuator, the encapsulation assembly being located within a housing and configured to define a flow path between the housing and the encapsulation assembly. A blood pump system comprising, A blood pump system in which, during operation, blood enters the inlet, flows between the housing and the encapsulation assembly within the flow path, is pushed across the membrane to the outlet, and pumps the blood.

2. The blood pump system according to claim 1, wherein the actuator further comprises a magnetic assembly.

3. The blood pump system according to claim 2, wherein the magnetic assembly is annular.

4. The blood pump system according to claim 2, further comprising at least one spring coupled to the magnetic assembly, The encapsulated assembly is coupled to the magnetic assembly, and The blood pump system wherein at least one spring and the encapsulation assembly apply a spring force to the magnetic assembly.

5. The blood pump system according to claim 1, wherein the encapsulation assembly reduces the risk of damage to the blood due to shear conditions.

6. The blood pump system according to claim 1, wherein the flow path is configured to minimize damage to von Willebrand factor polymers in the blood.

7. The blood pump system according to claim 1, wherein the flow path is fixed in size and configured to promote blood flow toward the outlet and resist blood flow toward the inlet.

8. The blood pump system according to claim 1, wherein the flow path is precisely sized and configured to reduce the risk of shear conditions for the blood within the flow path and to reduce the recirculation of the blood.

9. The blood pump system according to claim 1, further comprising an encapsulated fluid disposed between the encapsulation assembly and the actuator.

10. The blood pump system according to claim 9, wherein the encapsulated fluid is a perfluorocarbon.

11. The blood pump system according to claim 9, wherein the encapsulated fluid is selected from one of silicone oil, physiological saline, deionized water, or perfluorodecalin.

12. A housing having an inlet and an outlet, wherein the outlet is designed to be in fluid communication with the patient's circulatory system; An actuator comprising an electromagnetic assembly configured to generate a magnetic field; the actuator assembly is located within the housing, Stator assembly coupled to the actuator; A magnetic assembly configured to reciprocate in response to the magnetic field; and An encapsulation assembly coupled to the magnetic assembly and the stator assembly, the encapsulation assembly being designed to encapsulate the actuator together with the magnetic assembly and the stator assembly; and A flexible film coupled to the magnetic assembly and configured to reciprocate in response to the magnetic assembly; A blood pump system comprising, The blood pump system, during operation, wherein blood enters the inlet, flows between the inner wall of the housing and the magnetic assembly, the stator assembly, and the encapsulation assembly, and is pushed across the flexible membrane to the outlet.

13. The blood pump system according to claim 12, wherein the stator assembly comprises an upper stator assembly and a lower stator assembly.

14. The blood pump system according to claim 13, wherein the upper stator assembly and the lower stator assembly are each coupled to the magnetic assembly.

15. The blood pump system according to claim 13, wherein the magnetic assembly is annular.

16. The blood pump system according to claim 13, further comprising at least one spring coupled to the magnetic assembly.

17. The blood pump system according to claim 12, wherein the encapsulation assembly reduces the risk of damage to the blood due to shear conditions.

18. The blood pump system according to claim 17, wherein the encapsulation assembly and the housing define a flow path.

19. The blood pump system according to claim 18, wherein the flow path is fixed in size and configured to promote blood flow toward the outlet and resist blood flow toward the inlet.

20. The blood pump system according to claim 18, wherein the flow path is configured to reduce the recirculation of the blood.

21. A device for use in a method of pumping blood using a blood pump, wherein the method is A blood pump designed to communicate fluidly with the patient's circulatory system: A housing having an entrance and an exit; An actuator comprising an electromagnetic assembly designed to generate a magnetic field, wherein the actuator assembly is located within the housing, and: Stator assembly, and The actuator comprises a magnetic assembly configured to reciprocate in response to the magnetic field; An encapsulation assembly coupled to the magnetic assembly and the stator assembly, the encapsulation assembly being designed to encapsulate the actuator; and A flexible film is coupled to the magnetic assembly and configured to reciprocate in response to the magnetic assembly. To prepare the pump equipped with; and Sending an electrical signal to the actuator to excite the electromagnetic assembly and generate the magnetic field; Includes, The apparatus wherein the magnetic field causes the flexible membrane to reciprocate, thereby propagating waves along the flexible membrane, moving blood from the inlet, across the flexible member between the inner wall of the housing, the magnetic assembly, the stator assembly, and the encapsulation assembly, and out through the outlet.

22. A housing having an inlet and an outlet, and configured to communicate fluidly with the circulatory system; An actuator disposed within the housing, An electromagnetic assembly configured to generate a magnetic field; Upper stator coupled to the electromagnetic assembly; Lower stator coupled to the electromagnetic assembly; and A magnetic assembly comprising at least one magnet, configured to reciprocate in response to a magnetic field; The actuator comprises: The upper stator and the first encapsulation portion coupled to the magnetic assembly; The lower stator and the second encapsulation portion coupled to the magnetic assembly; and A flexible film coupled to the magnetic assembly and configured to reciprocate in response to the magnetic assembly, A blood pump comprising: A blood pump in which, during operation, blood enters the inlet and flows between the inner wall of the housing and the first encapsulation portion, the magnetic assembly, and the second encapsulation portion, and is pushed across the flexible membrane to the outlet, the first encapsulation portion, the magnetic assembly, and the second encapsulation portion encapsulate the actuator.

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