Patent Description:
Percutaneous circulatory support devices such as blood pumps typically provide circulatory support for up to approximately three weeks of continuous use. Wear at bearing surfaces can limit the lifetime of the devices. <CIT> discloses a blood pump rotor bearing utilizing blood as a lubricant. Furthermore, <CIT> relates to a centrifugal blood pump comprising bearings disposed in a bearing chamber and rotatably supporting a shaft of the pump. However, heat generation and mechanical interactions with the blood at the bearing surface can lead to hemolysis, which can further lead to health complications such as anemia, requiring blood transfusions.

The present disclosure relates to a blood pump as defined in claim <NUM>. The dependent claims depict preferred embodiments of the blood pump. According to an aspect of the present disclosure, a blood pump comprises an impeller, a drive shaft coupled to the impeller and configured to rotate with the impeller, a motor configured to drive the impeller, and a bearing assembly configured to retain an end of the drive shaft. The bearing assembly comprises a bearing, wherein the end of the drive shaft is at least partially rounded, and the bearing comprises a concave depression defined in a first side of the bearing. The depression is configured to receive the end of the drive shaft. The bearing assembly comprises a lubricant chamber holding a hydrophobic lubricant. The bearing assembly further comprises a cup washer having a base and a peripheral wall extending from the base, forming a cavity bounded by an inner surface of the peripheral wall and an inner surface of the base. The bearing is configured to be at least partially disposed within the cavity. The cup washer further comprises a shaft aperture defined in the base, extending from the outer surface of the base to the inner surface of the base. The shaft aperture is configured to receive a portion of the drive shaft. At least a portion of the lubricant chamber is defined between the inner surface of the peripheral wall of the cup washer, the inner surface of the base of the cup washer, and a first side of the bearing.

While multiple embodiments are disclosed, still other embodiments of the presently disclosed subject matter will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the disclosed subject matter.

While the disclosed subject matter is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the subject matter disclosed herein to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the subject matter disclosed herein, and as defined by the appended claims.

As used herein in association with values (e.g., terms of magnitude, measurement, and/or other degrees of qualitative and/or quantitative observations that are used herein with respect to characteristics (e.g., dimensions, measurements, attributes, components, etc.) and/or ranges thereof, of tangible things (e.g., products, inventory, etc.) and/or intangible things (e.g., data, electronic representations of currency, accounts, information, portions of things (e.g., percentages, fractions), calculations, data models, dynamic system models, algorithms, parameters, etc.), "about" and "approximately" may be used, interchangeably, to refer to a value, configuration, orientation, and/or other characteristic that is equal to (or the same as) the stated value, configuration, orientation, and/or other characteristic or equal to (or the same as) a value, configuration, orientation, and/or other characteristic that is reasonably close to the stated value, configuration, orientation, and/or other characteristic, but that may differ by a reasonably small amount such as will be understood, and readily ascertained, by individuals having ordinary skill in the relevant arts to be attributable to measurement error; differences in measurement and/or manufacturing equipment calibration; human error in reading and/or setting measurements; adjustments made to optimize performance and/or structural parameters in view of other measurements (e.g., measurements associated with other things); particular implementation scenarios; imprecise adjustment and/or manipulation of things, settings, and/or measurements by a person, a computing device, and/or a machine; system tolerances; control loops; machine-learning; foreseeable variations (e.g., statistically insignificant variations, chaotic variations, system and/or model instabilities, etc.); preferences; and/or the like.

The terms "up," "upper," and "upward," and variations thereof, are used throughout this disclosure for the sole purpose of clarity of description and are only intended to refer to a relative direction (i.e., a certain direction that is to be distinguished from another direction), and are not meant to be interpreted to mean an absolute direction. Similarly, the terms "down," "lower," and "downward," and variations thereof, are used throughout this disclosure for the sole purpose of clarity of description and are only intended to refer to a relative direction that is at least approximately opposite a direction referred to by one or more of the terms "up," "upper," and "upward," and variations thereof.

Although the term "block" may be used herein to connote different elements illustratively employed, the term should not be interpreted as implying any requirement of, or particular order among or between, various blocks disclosed herein. Similarly, although illustrative methods may be represented by one or more drawings (e.g., flow diagrams, communication flows, etc.), the drawings should not be interpreted as implying any requirement of, or particular order among or between, various steps disclosed herein. However, certain embodiments may require certain steps and/or certain orders between certain steps, as may be explicitly described herein and/or as may be understood from the nature of the steps themselves (e.g., the performance of some steps may depend on the outcome of a previous step). Additionally, a "set," "subset," or "group" of items (e.g., inputs, algorithms, data values, etc.) may include one or more items, and, similarly, a subset or subgroup of items may include one or more items. A "plurality" means more than one.

Embodiments of the subject matter disclosed herein include bearing designs that may facilitate reducing heat formation by using lubrication, and reducing mechanical blood damage by preventing ingress of blood onto bearing surfaces. Bearing designs that include concave depressions and closed cavities facilitate preventing blood ingress onto bearing surfaces. Lubrication may be used to provide a fluid film at bearing surfaces to minimize wear. In accordance with the invention, any hydrophobic, water- insoluble lubricants (e.g., perfluoropolyether or poly-alpha-olefins classes of synthetic lubricants) may be used.

<FIG> depicts a cross-sectional side view of a portion of an illustrative percutaneous mechanical circulatory support device <NUM> (also referred to herein, interchangeably, as a "blood pump"), in accordance with embodiments of the subject matter disclosed herein. As shown in <FIG>, the circulatory support device <NUM> includes a motor <NUM> disposed within a motor housing <NUM>. The motor <NUM> is configured to drive an impeller assembly <NUM> to provide a flow of blood through the device <NUM>. The impeller assembly <NUM> is disposed within an impeller assembly housing <NUM>, which includes a number of outlet apertures <NUM> defined therein. According to embodiments, the motor housing <NUM> and the impeller assembly housing <NUM> may be integrated with one another. In other embodiments, the motor housing <NUM> and the impeller assembly housing <NUM> may be separate components configured to be coupled together, either removeably or permanently.

A controller (not shown) is operably coupled to the motor <NUM> and is configured to control the motor <NUM>. The controller may be disposed within the motor housing <NUM> in embodiments, or, in other embodiments, may be disposed outside the housing <NUM> (e.g., in a catheter handle, independent housing, etc.). In embodiments, the controller may include multiple components, one or more of which may be disposed within the housing <NUM>. According to embodiments, the controller may be, include, or be included in one or more Field Programmable Gate Arrays (FPGAs), one or more Programmable Logic Devices (PLDs), one or more Complex PLDs (CPLDs), one or more custom Application Specific Integrated Circuits (ASICs), one or more dedicated processors (e.g., microprocessors), one or more central processing units (CPUs), software, hardware, firmware, or any combination of these and/or other components. Although the controller is referred to herein in the singular, the controller may be implemented in multiple instances, distributed across multiple computing devices, instantiated within multiple virtual machines, and/or the like.

As shown in <FIG>, the impeller assembly <NUM> includes a drive shaft <NUM><NUM> and an impeller <NUM> coupled thereto, where the drive shaft <NUM> is configured to rotate with the impeller <NUM>. As shown, the drive shaft <NUM> is at least partially disposed within the impeller <NUM>. In embodiments, the drive shaft <NUM> may be made of any number of different rigid materials such as, for example, steel, titanium alloys, cobalt chromium alloys, nitinol, high-strength ceramics, and/or the like. The impeller assembly <NUM> further includes an impeller rotor <NUM> coupled to, and at least partially surrounding, the drive shaft <NUM>. The impeller rotor <NUM> may be any type of magnetic rotor capable of being driven by a stator <NUM> that is part of the motor <NUM>. In this manner, as a magnetic field is applied to the impeller rotor <NUM> by the stator <NUM> in the motor <NUM>, the rotor <NUM><NUM> rotates, causing the drive shaft <NUM><NUM> and impeller <NUM> to rotate.

As shown, the impeller assembly is maintained in its orientation by the drive shaft <NUM><NUM>, which is retained, at a first end <NUM>, by a first bearing assembly <NUM> and, at a second end <NUM>, by a second bearing assembly <NUM>. According to embodiments, the first bearing assembly <NUM> and the second bearing assembly <NUM> may include different types of bearings. In accordance with the invention, the first bearing assembly <NUM> and/or the second bearing assembly <NUM> include lubrication. Various embodiments of bearing technology are described herein with respect to the first and second bearing assemblies <NUM> and <NUM>.

For reference, <FIG> is a close-up view of the first bearing assembly <NUM> of <FIG>. The second bearing assembly <NUM> may include, for example, a journal bearing, or any other type of suitable bearing. As shown in <FIG>, the first bearing assembly <NUM> includes a bearing <NUM> having a first side <NUM>, facing toward the impeller assembly <NUM>, and an opposite, second side <NUM>, facing toward the motor <NUM>. A concave depression <NUM> is defined in the first side <NUM> of the bearing <NUM>. The concave depression <NUM> is configured to receive the first end <NUM> of the drive shaft <NUM>. As shown, the first end <NUM> of the drive shaft <NUM> is at least partially rounded and, in embodiments, may include a curvature corresponding to the curvature of the concave depression <NUM>. In this manner, the surface area of contact between the drive shaft <NUM> and the bearing <NUM> may be as small as possible, reducing the chance that any blood cells will be able to get between the drive shaft <NUM> and the bearing <NUM> at their interface.

According to embodiments, the first bearing assembly <NUM> may also include a biasing feature <NUM> disposed between the second side <NUM> of the bearing <NUM> and the motor <NUM>. The biasing feature <NUM> may have a compliance configured such that the biasing feature <NUM> biases the bearing <NUM> in the direction of the drive shaft <NUM>, resisting the load generated by the attraction between the impeller rotor <NUM> and the stator <NUM>, while allowing enough flexibility to prevent the bearing <NUM> from being cracked or otherwise broken by the load. The bearing <NUM> may also, as shown, be retained in place by a bearing support feature <NUM>, which may be integrated into the motor housing <NUM>, the impeller assembly housing <NUM>, or which may be a separate feature coupled to the motor housing <NUM> and/or the impeller assembly housing <NUM>. According to embodiments, the bearing support feature <NUM> may include any number of different types of features configured to maintain the bearing <NUM> in its position. For example, the bearing support feature <NUM> may include multiple edges, a notch configured to receive a tab or edge, edges configured to form an interference fit with the periphery of the bearing, and/or the like.

The illustrative circulatory support device <NUM> shown in <FIG> and <FIG> is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the present disclosure. The illustrative circulatory support device <NUM> also should not be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, various components depicted in <FIG> and <FIG> B may be, in embodiments, integrated with various ones of the other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the present disclosure.

<FIG> depicts a perspective view of an illustrative percutaneous mechanical circulatory support device <NUM>, in accordance with embodiments of the subject matter disclosed herein; and <FIG> depicts a cross-sectional side view of the circulatory support device <NUM> depicted in <FIG>, in accordance with embodiments of the subject matter disclosed herein. According to embodiments, the circulatory support device <NUM>, and/or any number of various components thereof, may be the same as, or similar to, corresponding components of the circulatory support device <NUM> depicted in <FIG> and <FIG>.

As shown in <FIG> and <FIG>, the circulatory support device <NUM> includes a motor <NUM> disposed within a motor housing <NUM>. The motor <NUM> is configured to drive an impeller assembly <NUM> to provide a flow of blood through the device <NUM>. The impeller assembly <NUM> is disposed within an impeller assembly housing <NUM>, which includes a number of inlet apertures <NUM> and a number of outlet apertures <NUM><NUM> defined therein. According to embodiments, the motor housing <NUM> and the impeller assembly housing <NUM> may be integrated with one another. In other embodiments, the motor housing <NUM> and the impeller assembly housing <NUM> may be separate components configured to be coupled together, either removeably or permanently. A controller (not shown) is operably coupled to the motor <NUM> and is configured to control the motor <NUM>. The controller may be disposed within the motor housing <NUM> in embodiments, or, in other embodiments, may be disposed outside the housing <NUM> (e.g., in a catheter handle, independent housing, etc.). In embodiments, the controller may include multiple components, one or more of which may be disposed within the housing <NUM>. According to embodiments, the motor <NUM> may be, be similar to, include, or be included in the motor <NUM> depicted in <FIG>.

As shown in <FIG>, the impeller assembly <NUM> includes a drive shaft <NUM> and an impeller <NUM> coupled thereto, where the drive shaft <NUM> is configured to rotate with the impeller <NUM>. As shown, the drive shaft <NUM> is at least partially disposed within the impeller <NUM>. In embodiments, the drive shaft <NUM> may be made of any number of different rigid materials such as, for example, steel, titanium alloys, cobalt chromium alloys, nitinol, high-strength ceramics, and/or the like. The impeller assembly <NUM> further includes an impeller rotor <NUM> coupled to, and at least partially surrounding, the drive shaft <NUM>. The impeller rotor <NUM> may be any type of magnetic rotor capable of being driven by a stator (not shown, but which may be the same as, or similar to, the stator <NUM> depicted in <FIG> and <FIG>) that is part of the motor <NUM>. In this manner, as a magnetic field is applied to the impeller rotor <NUM> by the stator in the motor <NUM>, the rotor <NUM> rotates, causing the drive shaft <NUM> and impeller <NUM> to rotate.

As shown, the impeller assembly is maintained in its orientation by the drive shaft <NUM>, which is retained, at a first end <NUM>, by a first bearing assembly <NUM> and, at a second end <NUM>, by a second bearing assembly <NUM>. According to embodiments, the first bearing assembly <NUM> and the second bearing assembly <NUM> may include different types of bearings. In accordance with the invention, the first bearing assembly <NUM> and/or the second bearing assembly <NUM> include a lubricant chamber configured to hold a lubricant. Various embodiments of bearing technology are described herein with respect to the first and second bearing assemblies <NUM> and <NUM>.

<FIG> is a close-up view of the first bearing assembly <NUM> of <FIG>, in accordance with embodiments of the subject matter disclosed herein. The second bearing assembly <NUM> may include, for example, a journal bearing, or any other type of suitable bearing. As shown in <FIG>, the first bearing assembly <NUM> includes a bearing <NUM> having a first side <NUM>, facing toward the impeller assembly <NUM>, and an opposite, second side <NUM>, facing toward the motor <NUM>. A concave depression <NUM> is defined in the first side <NUM> of the bearing <NUM>. The concave depression <NUM> is configured to receive the first end <NUM> of the drive shaft <NUM>. As shown, the first end <NUM> of the drive shaft <NUM> is at least partially rounded and, in embodiments, the concave depression <NUM> may be sized to just fit the first end <NUM> of the drive shaft <NUM>.

As shown in <FIG>, the concave depression <NUM> may include a first portion <NUM> and a second portion <NUM> , where the first portion <NUM> has an at least approximately cylindrical shape and extends into the bearing <NUM> from the first side <NUM> of the bearing <NUM>. The second portion <NUM> has an at least approximately concave shape. In embodiments, the first portion <NUM> may be sized to fit a corresponding first portion <NUM> of the first end <NUM> of the drive shaft <NUM>, while the second portion <NUM> may be sized to fit a corresponding second portion <NUM> of the first end <NUM> of the drive shaft <NUM>. In embodiments, the first portion <NUM> of the first end <NUM> of the drive shaft <NUM> may have an approximately cylindrical shape, and the second portion <NUM> of the first end <NUM> of the drive shaft <NUM> may have an approximately convex shape. In this manner, the first portion <NUM> of the depression <NUM> may facilitate maintaining the drive shaft <NUM> in its orientation.

Additionally, the concave geometry of the depression, in conjunction with the rounded end of the drive shaft, creates a relatively large bearing surface, thereby distributing axial load over more area. The diameter of the end of the drive shaft (and, thus, of the concave depression) may be configured to facilitate desired performance characteristics. For example, increasing these diameters may lead to higher velocity of rotation, while reducing axial stresses, thereby reducing friction. According to embodiments, the dimensions of the various aspects of the bearing assembly may be selected based on implementation, performance, materials, and/or the like.

According to embodiments, the first bearing assembly <NUM> may also include a biasing feature (not shown) disposed between the second side <NUM> of the bearing <NUM> and the motor <NUM>. The biasing feature may have a compliance configured such that the biasing feature biases the bearing <NUM> in the direction of the drive shaft <NUM>, resisting the load generated by the attraction between the impeller rotor <NUM> and the stator, while allowing enough flexibility to prevent the bearing <NUM> from being cracked or otherwise broken by the load. The bearing <NUM> may also, as shown, be retained in place by a bearing support feature <NUM>, which may be integrated into the motor housing <NUM>, the impeller assembly housing <NUM>, or which may be a separate feature coupled to the motor housing <NUM> and/or the impeller assembly housing <NUM>. According to embodiments, the bearing support feature <NUM> may include any number of different types of features configured to maintain the bearing <NUM> in its position. For example, the bearing support feature <NUM> may include multiple edges, a notch configured to receive a tab or edge, edges configured to form an interference fit with the periphery of the bearing, and/or the like.

As shown, the bearing assembly <NUM> also includes a cup washer <NUM> having a base <NUM> and a peripheral wall <NUM> extending away from the base <NUM> towards the motor <NUM>, forming a cavity <NUM> bounded by an inner surface <NUM> of the base <NUM> and an inner surface <NUM> of the peripheral wall <NUM>. The peripheral wall <NUM> may be oriented approximately orthogonal to the base <NUM>. A shaft aperture <NUM> is defined through the base <NUM>, extending from an outer surface <NUM> of the base <NUM> to the inner surface <NUM> of the base <NUM>, and is configured to receive a portion of the drive shaft <NUM>. As shown, the bearing <NUM> is configured to be at least partially disposed within the cavity <NUM>.

Additionally, a lubricant may be disposed within the cavity to facilitate preservation of the bearing <NUM> and its interface with the drive shaft <NUM>. That is, at least a portion of a lubricant chamber is defined between the inner surface <NUM> of the base <NUM> of the cup washer <NUM>, the inner surface <NUM> of the peripheral wall <NUM> of the cup washer <NUM>, and the first side <NUM> of the bearing <NUM>. Additionally or alternatively, a portion of a lubricant chamber may be defined within the bearing (e.g., within the bearing <NUM>). In accordance with the invention, the lubricant is any type of hydrophobic lubricant suitable for use in a blood pump. For example, in embodiments, but without intending to limit the disclosure, the lubricant may be a modified silicone lubricant such as, for example, a modified Polydimethylsiloxane (PDMS). In other embodiments, the lubricant may be an oil-based lubricant, a synthetic oil, a carbon-based lubricant, and/or the like.

The illustrative circulatory support device <NUM> shown in <FIG> is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the present disclosure. The illustrative circulatory support device <NUM> also should not be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, various components depicted in <FIG> may be, in embodiments, integrated with various ones of the other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the present disclosure.

For reference, <FIG> depicts a cross-sectional side view of an illustrative circulatory support device <NUM> having an impeller assembly <NUM>. According to embodiments, the circulatory support device <NUM>, and/or any number of various components thereof, may be the same as, or similar to, corresponding components of the circulatory support device <NUM> depicted in <FIG> and <FIG>, and/or the circulatory support device <NUM> depicted in <FIG>.

As shown in <FIG>, the impeller assembly <NUM> is disposed within an impeller assembly housing <NUM>, which includes a number of outlet apertures <NUM> defined therein. The impeller assembly <NUM> includes a drive shaft <NUM> and an impeller <NUM> coupled thereto, where the drive shaft <NUM> is configured to rotate with the impeller <NUM>. As shown, the drive shaft <NUM> is at least partially disposed within the impeller <NUM>. In embodiments, the drive shaft <NUM> may be made of any number of different rigid materials such as, for example, steel, titanium alloys, cobalt chromium alloys, nitinol, high-strength ceramics, and/or the like. The impeller assembly <NUM> further includes an impeller rotor <NUM> coupled to, and at least partially surrounding, the drive shaft <NUM>. The impeller rotor <NUM> may be any type of magnetic rotor capable of being driven by a stator (not shown, but which may be the same as, or similar to, the stator <NUM> depicted in <FIG> and <FIG>) that is part of the motor. In this manner, as a magnetic field is applied to the impeller rotor <NUM> by the stator in the motor, the rotor <NUM> rotates, causing the drive shaft <NUM> and impeller <NUM> to rotate.

As shown, the impeller assembly <NUM> is maintained in its orientation by the drive shaft <NUM>, which is retained, at a first end <NUM>, by a first bearing assembly <NUM> and, at a second end (not shown), by a second bearing assembly (not shown). According to embodiments, the first bearing assembly <NUM> and the second bearing assembly may include different types of bearings. According to embodiments, the first bearing assembly <NUM> and/or the second bearing assembly may include a lubricant chamber configured to hold a lubricant. The first bearing assembly <NUM> includes a bearing <NUM> having a first side <NUM>, facing toward the impeller assembly <NUM> , and an opposite, second side <NUM>, facing toward the motor. A concave depression <NUM> is defined in the first side <NUM> of the bearing <NUM>. The concave depression <NUM> is configured to receive the first end <NUM> of the drive shaft <NUM> and may, in embodiments, be configured in a manner similar to the concave depression <NUM> depicted in <FIG> and/or the concave depression <NUM> depicted in <FIG>. As shown, the first end <NUM> of the drive shaft <NUM> may configured similar to the first end <NUM> of the drive shaft <NUM><NUM> depicted in <FIG> and <FIG> and/or the first end <NUM> of the drive shaft <NUM> depicted in <FIG>. According to embodiments, the first bearing assembly <NUM> may also include a biasing feature (not shown) disposed between the second side <NUM> of the bearing <NUM> and the motor.

As shown, the bearing assembly <NUM> also includes a cup washer <NUM> or other similar basin-like structure, having a base <NUM> and a peripheral wall <NUM> extending away from the base <NUM> toward the impeller assembly <NUM>, forming a cavity <NUM> bounded by an inner surface <NUM> of the base <NUM> and an inner surface <NUM> of the peripheral wall <NUM>. As shown, the bearing <NUM> is configured to be at least partially disposed within the cavity <NUM>. A cover <NUM> may be disposed adjacent to the first side <NUM> of the bearing <NUM>, and include a shaft aperture <NUM> configured to receive a portion of the drive shaft <NUM>. In embodiments, for example, the cover <NUM> may be a layer of graphite, a polymer, and/or the like.

As is further shown in <FIG>, the bearing assembly <NUM> includes a lubricant chamber configured to retain a lubricant. The lubricant chamber may include at least one channel <NUM> defined in the second side <NUM> of the bearing <NUM>. In embodiments, the channel or channels pass through the depression <NUM>. According to embodiments, the bearing <NUM> may include two or more channels <NUM> defined therein. As can be seen from <FIG>, at least a portion of the inner surface <NUM> of the base <NUM> may form a boundary of the lubricant chamber.

<FIG> depicts a cross-sectional side view of an illustrative circulatory support device <NUM> having an impeller assembly <NUM>, in accordance with embodiments of the subject matter disclosed herein. According to embodiments, the circulatory support device <NUM>, and/or any number of various components thereof, may be the same as, or similar to, corresponding components of the circulatory support device <NUM> depicted in <FIG> and <FIG>, the circulatory support device <NUM> depicted in <FIG>, and/or the circulatory support device <NUM> depicted in <FIG>. In embodiments, the portion of the circulatory support device <NUM> depicted in <FIG> is the portion of an impeller assembly associated with an end opposite the end adjacent the motor. That is, for example, the bearing assembly <NUM> depicted in <FIG> may be, be similar to, and/or otherwise correspond to the bearing assembly <NUM> depicted in <FIG> and/or the bearing assembly <NUM> depicted in <FIG>. In embodiments, implementations of the bearing assembly <NUM> may be used, alternatively or additionally, as the bearing assembly <NUM> depicted in <FIG> and <FIG>, the bearing assembly <NUM> depicted in <FIG> and <FIG>, the bearing assembly <NUM> depicted in <FIG>, and/or the like.

As shown in <FIG>, the impeller assembly <NUM> is disposed within an impeller assembly housing <NUM>, which includes a number of apertures (not shown) defined therein. The impeller assembly <NUM> includes a drive shaft <NUM> and an impeller <NUM> coupled thereto, where the drive shaft <NUM> is configured to rotate with the impeller <NUM>. As shown, the drive shaft <NUM> is at least partially disposed within the impeller <NUM>. In embodiments, the drive shaft <NUM> may be made of any number of different rigid materials such as, for example, steel, titanium alloys, cobalt chromium alloys, nitinol, high-strength ceramics, and/or the like.

The impeller assembly <NUM> is maintained in its orientation by the drive shaft <NUM>, which is retained, at a first end (not shown), by a first bearing assembly (not shown) and, at a second end <NUM>, by the bearing assembly. According to embodiments, the first bearing assembly and the second bearing assembly <NUM> may include different types of bearings. According to embodiments, the first bearing assembly and/or the second bearing assembly <NUM> may include a lubricant chamber configured to hold a lubricant. The bearing assembly <NUM> includes a cylindrical-shaped bearing <NUM> disposed in the end <NUM> of the drive shaft <NUM>. The bearing <NUM> includes a first inside surface <NUM> facing away from the impeller and a second inside surface <NUM> extending away from the first inside surface. According to embodiments, the second inside surface <NUM> may be oriented approximately orthogonal to the first inside surface <NUM>.

As shown in <FIG>, cylindrical-shaped bearing is disposed at an intersection of the drive shaft <NUM> and a stationary shaft mounting pin <NUM>. The shaft mounting pin may be made of any number of different materials. For example, in some embodiments, the shaft mounting pin <NUM> may be made of the same material as the drive shaft <NUM>. The shaft mounting pin <NUM> may be coupled to a pin support <NUM>. The drive shaft <NUM> is configured to rotate with respect to the stationary shaft mounting pin <NUM>. To facilitate reduction of friction and preservation of the bearing assembly <NUM>, the bearing assembly <NUM> includes a lubricant chamber <NUM>. The lubricant chamber <NUM> may be defined between the first inner surface <NUM> of the bearing <NUM> and an outer surface <NUM> of the stationary shaft mounting pin <NUM>. The lubricant chamber <NUM> may be further bounded by at least a portion of the second inner surface <NUM> of the bearing <NUM>.

As indicated above, a portion of a lubricant chamber may be defined within a bearing. For reference, <FIG> are perspective views of an illustrative bearing <NUM>. According to embodiments, the bearing <NUM> may be, or be similar to, the bearing <NUM> depicted in <FIG> and <FIG>, the bearing <NUM> depicted in <FIG>, the bearing <NUM> depicted in <FIG>, and/or the like. In embodiments, the bearing <NUM> includes a first side <NUM>, configured to face toward an impeller assembly, and an opposite, second side <NUM>, configured to face toward a motor. A concave depression <NUM> is defined in the first side <NUM> of the bearing <NUM>. The concave depression <NUM> is configured to receive an end of a drive shaft. As discussed herein, the end of the drive shaft may be at least partially rounded and, in embodiments, the concave depression <NUM> may be sized to just fit the end of the drive shaft.

As shown, the concave depression <NUM> may include a first portion <NUM> and a second portion <NUM>, where the first portion <NUM> has an at least approximately cylindrical shape and extends into the bearing <NUM> from the first side <NUM> of the bearing <NUM>. The second portion <NUM> has an at least approximately concave shape. In embodiments, the first portion <NUM> may be sized to fit a corresponding first portion of the end of the drive shaft, while the second portion <NUM> may be sized to fit a corresponding second portion of the end of the drive shaft. In embodiments, the first portion of the end of the drive shaft may have an approximately cylindrical shape, and the second portion of the end of the drive shaft may have an approximately convex shape. In this manner, the first portion <NUM> of the depression <NUM> may facilitate maintaining the drive shaft in its orientation.

As is further shown, two channels <NUM> are defined in the second side <NUM> of the bearing <NUM>. According to embodiments, the bearing <NUM> may include any number of channels (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc.) having any number of different depths, widths, and/or the like. In embodiments, for example, the channels do not extend through the outside surface <NUM> of the periphery wall <NUM>. In embodiments, the bearing <NUM> may include multiple channels of varying size. For example, the bearing <NUM> may include microchannels (e.g., channels that are substantially narrower and shallower than the channels <NUM> such as, for example, by at least a factor of <NUM>) defined in an upper surface <NUM> of the concave depression. According to embodiments, using bearings with channels defined therein for lubricant chambers may facilitate using thinner bearings, thereby enabling the rotor of the impeller assembly to be closer to the stator of the motor, which may enable increased torque and efficiency.

Claim 1:
A blood pump (<NUM>; <NUM>), comprising:
an impeller (<NUM>; <NUM>):
a drive shaft (<NUM>; <NUM>) coupled to the impeller (<NUM>; <NUM>) and configured to rotate with the impeller (<NUM>; <NUM>);
a motor (<NUM>) configured to drive the impeller (<NUM>; <NUM>); and
a bearing assembly (<NUM>; <NUM>) configured to retain an end (<NUM>) of the drive shaft (<NUM>; <NUM>), the bearing assembly (<NUM>; <NUM>) comprising:
a bearing (<NUM>), wherein the end (<NUM>) of the drive shaft (<NUM>) is at least partially rounded, and the bearing comprising a concave depression (<NUM>) defined in a first side (<NUM>) of the bearing, wherein the depression (<NUM>) is configured to receive the end (<NUM>) of the drive shaft (<NUM>); and
a lubricant chamber holding a hydrophobic lubricant,
characterized in that the bearing assembly (<NUM>) further comprises a cup washer (<NUM>) having a base (<NUM>) and a peripheral wall (<NUM>) extending away from the base (<NUM>), forming a cavity (<NUM>) bounded by an inner surface (<NUM>) of the peripheral wall (<NUM>) and an inner surface (<NUM>) of the base (<NUM>), wherein the bearing is configured to be at least partially disposed within the cavity (<NUM>), and
in that the cup washer (<NUM>) further comprises a shaft aperture (<NUM>) defined in the base (<NUM>), extending from the outer surface (<NUM>) of the base (<NUM>) to the inner surface (<NUM>) of the base (<NUM>), wherein the shaft aperture (<NUM>) is configured to receive a portion of the drive shaft (<NUM>; <NUM>), and
in that at least a portion of the lubricant chamber is defined between the inner surface (<NUM>) of the peripheral wall (<NUM>) of the cup washer (<NUM>), the inner surface (<NUM>) of the base (<NUM>) of the cup washer (<NUM>), and the first side (<NUM>) of the bearing.