Conduit pump and impeller thereof

Abstract

Disclosed is an impeller and a conduit pump, the impeller comprising: a hub, and a vane formed on the hub and switchable between a folded state and an unfolded state. The cross-sectional shape of the vane at any position perpendicular to the axial direction of the hub is curved, and the bending direction is consistent with the rotation direction of the impeller during operation. The vane comprises first and second material layers arranged in layers, and the first material layer is located on the outer side of the second material layer along the bending direction. The first and second material layers have different expansion coefficients for a specific stimulus, and the first material layer has a different expansion deformation amount than the second material layer under the specific stimulus.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a catheter pump and its impeller. Background Technology

[0002] Catheter pumps are designed to be inserted into the desired location within the patient's body to assist in blood pumping. To reduce patient discomfort and complications at the puncture site, it is desirable for the pump head to be inserted into the body in a small size, and foldable catheter pumps meet this requirement. The pump head of a foldable catheter pump is folded in place when delivered into the body and unfolds after reaching the target location, balancing a small interventional size with a large unfolded diameter. To achieve this, the impeller of the pump head is typically made of a flexible material to enable folding.

[0003] The folding of a folding impeller is generally achieved through relative movement with the folding sheath, using the compressive force of the sheath to fold. However, because the impeller needs to move relative to the folding sheath, relative friction will occur between the sheath and the blades, resulting in damage to the blades.

[0004] Furthermore, the flexibility of foldable impellers is detrimental to maintaining optimal rigidity during blood pumping. Blood back pressure can cause the blades to bend, leading to blade shape instability and affecting the impeller's hydraulic performance. In existing technologies, such as CN102791303B or CN104984424B, a support structure is incorporated within the blades, filled with a hardenable material. During transport, this material is not stimulated, and the blades remain relaxed. Once the impeller reaches its deployment position, stimulation is applied, causing the material to harden and increase blade strength.

[0005] The impellers provided by the aforementioned prior art do not break through the conventional concept of designing foldable impellers in this field. That is, the main structure of the impeller—the blades—is made of other materials, and then a support structure that can be manipulated and hardened is set within the blades. The purpose of this arrangement is to allow the blades to be in a relatively soft and relaxed state when no stimulation is applied, thereby providing better transport properties. After the impeller is inserted into the human body, stimulation is applied to harden the filling material, thus strengthening the blades. However, since the hardening of the material requires the corresponding stimulation to be continuously present to be maintained, the blades only expand radially for the same duration as the corresponding field action. This means that stimulation is continuously applied during the impeller's pumping process, which can lead to a series of adverse consequences. For example, stimulation that needs to be applied to the blades through human tissue (such as light, ultraviolet light, laser radiation, X-rays or alpha radiation, beta radiation or gamma radiation, electromagnetic fields, etc.) may have adverse effects on the human body. The stimulation may be affected by external conditions such as vibration, patient movement, etc., causing the blades to detach from the stimulation source, thus preventing the stable maintenance of the blade expansion and hardening, and so on. Summary of the Invention

[0006] In view of this, the present invention provides a duct pump and its impeller, which can at least partially solve the above problems, including: avoiding blade damage caused by external extrusion pressure in the prior art, and ensuring that the blade deployment can be stably maintained.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A folding impeller with controllable folding or unfolding for use in a catheter pump, which can be inserted into a subject's body to rotate and pump blood, includes a hub and blades formed on the hub. The blades have a folded state and an unfolded state, and their cross-sectional shape is curved at any position perpendicular to the hub axis, comprising two stacked material layers. Along the curvature direction, the first material layer is located outside the second material layer. The first and second material layers have different coefficients of expansion for a specific stimulus, so that under a specific stimulus, the expansion deformation of the first material layer differs from that of the second material layer, causing the blades to switch between the folded and unfolded states.

[0009] In one embodiment, the specific stimulus is temperature or humidity, and one of the application and removal of the specific stimulus is provided by the external environment when the impeller is outside the subject, and the other is provided by the environment inside the subject's body when the impeller is delivered into the subject's body.

[0010] When the specific stimulus is temperature, the coefficients of thermal expansion of the first material layer and the second material layer are different. When the impeller is at the first temperature outside the subject's body, the blades are in a folded state. When the impeller is at the second temperature inside the subject's body, the blades switch to an unfolded state. The second temperature is different from the first temperature.

[0011] When the specific stimulus is humidity, the water absorption and expansion coefficient of the first material layer is less than that of the second material layer. When the impeller is in the first humidity level outside the subject's body, the blades are in a folded state. When the impeller is in the second humidity level inside the subject's body, the blades switch to an unfolded state. The second humidity level is greater than the first humidity level.

[0012] In another embodiment, the specific stimulus is an electric field, an alternating magnetic field, or a magnetic field. The specific stimulus is applied when the impeller is outside the subject's body to cause the blades to be in a folded state, and is removed when the impeller is delivered into the subject's body to cause the blades to return to an unfolded state.

[0013] When the specific stimulus is an electric field or an alternating magnetic field, both the first and second material layers are made of [material name missing], or both are made of electrostrictive material. The electrostriction coefficient of the first material layer is different from that of the second material layer.

[0014] When the specific stimulus is a magnetic field, both the first and second material layers are made of magnetostrictive material, and the magnetostriction coefficient of the first material layer is different from that of the second material layer.

[0015] The duct pump includes an impeller as described in any of the above embodiments.

[0016] By configuring the blades as two stacked material layers with different expansion coefficients for specific stimuli, the folding or unfolding of the blades can be achieved by applying or removing the specific stimulus. Therefore, the folding and unfolding of the blades does not require external compressive force, avoiding the damage to the impeller blades caused by external compressive force in existing technologies. Furthermore, the impeller blades automatically unfold or fold under specific stimuli using their own expansion properties, eliminating the need for additional complex mechanical drives, making the folding or unfolding operation more convenient. Moreover, the unfolding or folding of the blades is achieved with the application or removal of the stimulus, making the unfolding or folding more controllable.

[0017] Furthermore, in some embodiments, the working environment after the impeller is intervened, including the subject's body temperature and the humidity provided by blood, can be used to provide continuous stimulation for the blades to switch from a folded to an unfolded state, and for the blades to maintain a stable unfolded state. This stimulation is obviously much more advantageous than existing solutions. This is because the aforementioned temperature or humidity stimulation is inherent or naturally present within the subject's body, which is precisely the impeller's working environment. Stimulating the impeller using its working environment to switch it to an unfolded state makes the blade unfolding process simple and easy to achieve. Moreover, these stimuli are always present during the impeller's operation, allowing the blades to maintain their unfolded state better during the working process where they are required to function. Compared to applying external stimuli such as radiation or field effects to the impeller during operation, this stimulation provided by the impeller's working environment is obviously more stable and less susceptible to external conditions such as vibration or subject movement. Therefore, the blades will not detach from the stimulation source, and the unfolded state of the blades can be maintained stably and sustainably.

[0018] Similarly, in other embodiments, when the specific stimulus is a magnetic field, alternating magnetic field, or electric field, these stimuli can be applied externally, causing the impeller to be in a folded state when outside the body. Upon insertion into the subject's body, the stimulus is removed, and the impeller returns to its unfolded state. Thus, applying the aforementioned stimulus to keep the impeller in a folded state outside the subject and removing the stimulus upon insertion into the subject's body avoids harm to the subject while simultaneously achieving a controllable switching of the impeller from a folded to an unfolded state. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the duct pump according to an embodiment of the present invention;

[0020] Figure 2 for Figure 1 A cross-sectional view of the working component in the process;

[0021] Figures 3A to 3E A schematic diagram illustrating the changes in the state of a leaf under temperature stimulation;

[0022] Figures 4A to 4B A schematic diagram illustrating the changes in the state of leaves under humidity stimulation;

[0023] Figures 5A to 5E This is a schematic diagram showing the state changes of a blade under the stimulation of an electric field, an alternating magnetic field, or a magnetic field. Detailed Implementation

[0024] The catheter pump of this invention can at least partially assist the heart's pumping function, thereby at least partially reducing the burden on the heart. In one illustrative scenario, the catheter pump can be used as a left ventricular assist device, with its pump head inserted into the left ventricle. When the pump head is in operation, it can pump blood from the left ventricle into the ascending aorta.

[0025] It is worth noting that the above example of using it for left ventricular assist is only one feasible application scenario for this catheter pump. In other feasible and not explicitly excluded scenarios, the catheter pump can also be used for right ventricular assist, with the pump head inserted into the right ventricle to pump venous blood into the right ventricle when the pump head is operating. Of course, the catheter pump can also be used for kidney assist, acting as a renal pump. The following description primarily focuses on the application of this catheter pump for left ventricular assist. However, as can be seen from the above description, the scope of protection of the embodiments of the present invention is not limited thereto.

[0026] like Figure 1 and Figure 2 As shown, the tubing pump 1000 includes a drive assembly 100 and a working assembly 200. The drive assembly 100 includes a motor housing 101, a motor (not shown) housed within the motor housing 101, and a drive member (not shown) driven by the motor. The working assembly 200 includes a tubing 201, a drive shaft 202 passing through the tubing 201, a driven member connected to the proximal end of the drive shaft 202, a drive tubing handle 204 connected to the proximal and distal ends of the tubing 201, and a pump head 205. The pump head 205 includes a pump housing 2051 having an inlet 2051a and an outlet 2051b, and an impeller 2052 housed within the pump housing 2051, the impeller 2052 being connected to the distal end of the drive shaft 202. When the impeller 2052 rotates, blood can be drawn into the pump housing 2051 from the inlet 2051a and then pumped out of the pump housing 2051 from the outlet 2051b.

[0027] The pump housing 2051 includes a support 20511 and an elastic membrane 20512 covering the support 20511. The metal lattice of the support 20511 has a mesh design. The membrane 20512 covers the middle and rear portions of the support 20511. The mesh of the front portion of the support 20511 not covered by the membrane 20512 forms an inlet 2051a. The rear end of the membrane 20512 covers the distal end of the conduit, and the outlet 2051b is an opening formed at the rear end of the membrane 20512.

[0028] The impeller 2052 has a folded state and an unfolded state, and includes a hub 20521 and blades 20522 formed on the outer wall of the hub 20521. In the unfolded state, the blades 20522 have a curved cross-sectional shape at any position perpendicular to the axial direction of the hub 20521, and this curvature is consistent with the rotation direction of the impeller 2052 during operation. The blades 20522 can be folded radially, thereby forming a foldable pump head 205 with the support 20511 and the diaphragm 20512.

[0029] The drive shaft 202 includes a flexible shaft 2021 and a rigid shaft 2022 connected to the distal end of the flexible shaft 2021. The flexible shaft 2021 passes through the guide tube 201, and the rigid shaft 2022 passes through and is fixed in the hollow channel of the hub 20521. The proximal and distal ends of the bracket 20511 are respectively connected to the proximal bearing chamber 206 and the distal bearing chamber 207, and the proximal bearing chamber 206 and the distal bearing chamber 207 are respectively provided with a proximal bearing 208 and a distal bearing 209. The proximal and distal ends of the rigid shaft 2022 pass through the proximal bearing 208 and the distal bearing 209, respectively. In this way, the two ends of the rigid shaft 2022 are supported by two bearings, and coupled with the high rigidity of the rigid shaft 2022, the impeller 2052 can be better retained within the pump casing 2051.

[0030] The rigid shaft 2022 is provided with a stop 211 located near the proximal bearing 208 to limit the distal movement of the rigid shaft 2022 and the impeller 2052, preventing the impeller 2052 from moving distally due to the reverse action of blood during its rotation and pumping of blood. The rigid shaft 2022 is also provided with a limiter 212 located near the stop 211 to limit the proximal movement of the rigid shaft 2022 and the stop 211, preventing the stop 211 from abrading the distal end of the conduit 201 and causing the release of particulate matter.

[0031] The distal end of the distal bearing chamber 207 is provided with a protective head 210 made of flexible material. The protective head 210 can be supported on the ventricular wall in a non-invasive or non-damaging manner, separating the suction port 2051a of the pump head 205 from the ventricular wall, preventing the suction port 2051a from sticking to the ventricular wall due to the reaction force of blood during the operation of the pump head 205, and ensuring the pump suction area.

[0032] The drive catheter handle 204 and the drive assembly 100 are detachably connected, and the connection method can be a lock nut or a snap-fit ​​connection provided by US9421311B2. The driven member and the driving member are non-contactly coupled to transmit the rotational power of the motor to the drive shaft 202, thereby driving the impeller 2052 to rotate and pump blood. Both the driven member and the driving member can be magnets, or one can be a magnet and the other a conductor; this embodiment does not limit this.

[0033] The aforementioned duct pump uses an external motor. However, duct pumps can also employ an internal motor structure. In this case, the motor is connected to the distal end of the duct, and a thin, flexible drive shaft no longer runs through the duct. The motor drives the impeller via a rigid short shaft, magnetic coupling, or other methods.

[0034] Combination Figures 3A to 5E As shown, the blade 20522 includes a first material layer 351a and a second material layer 351b stacked together. Along the bending direction of the blade 20522, the first material layer 351a is located outside the second material layer 351b, and the two material layers have different coefficients of expansion for a specific stimulus. Under a specific stimulus, the amount of expansion deformation of the first material layer 351a is different from that of the second material layer 351b, causing the blade 20522 to switch between a folded state and an unfolded state.

[0035] In this embodiment, the amount of expansion and deformation after being subjected to a specific stimulus is defined as a vector value. When the amount of expansion and deformation of the first material layer 351a is less than the amount of expansion and deformation of the second material layer 351b, the blade 20522 bends outward and switches to the deployed state. Conversely, when the amount of expansion and deformation of the first material layer 351a is greater than the amount of expansion and deformation of the second material layer 351b, the blade 20522 bends inward and switches to the folded state.

[0036] In one embodiment, the specific stimulus is temperature or humidity, the application and removal of which are provided by the external environment when the impeller 2052 is outside the subject, and by the environment inside the subject's body when the impeller 2052 is delivered into the subject's body.

[0037] Please see Figures 3A to 3E When the specific stimulus is temperature, the coefficient of thermal expansion of the first material layer 351a is different from that of the second material layer 351b. When the impeller 2052 is at a first temperature outside the subject's body, the blades 20522 are in a folded state. When the impeller 2052 is at a second temperature inside the subject's body, which is different from the first temperature, the blades 20522 switch to an unfolded state.

[0038] The second temperature is approximately equal to human body temperature, such as internal body temperature (e.g., 34-40°C). The first temperature is the external temperature, which can be set depending on the situation. In one scenario, the second temperature is higher than the first temperature, meaning the subject's internal body temperature is higher than the external ambient temperature, or the external environment is relatively cold while the internal environment is relatively hot. In this case, the first temperature can be provided by normal room temperature, such as 15-25°C. In another scenario, the second temperature is lower than the first temperature, meaning the subject's internal body temperature is lower than the external ambient temperature, or the external environment is relatively hot while the internal environment is relatively cold. In this case, the first temperature can be provided by a thermal insulation device, for example, the impeller 2052 is kept in a thermal insulation device when it is outside the body.

[0039] In this embodiment, positive expansion manifests as an elongation of the length of the first material layer 351a or the second material layer 351b, and is further characterized by an increase in the thickness of the first material layer 351a or the second material layer 351b. Similarly, negative expansion mainly manifests as a shortening of the length of the first material layer 351a or the second material layer 351b, and can also be further characterized by a thinning of the thickness of the first material layer 351a or the second material layer 351b.

[0040] Please see Figure 3A In the first embodiment of temperature stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, the first material layer 351a does not expand, while the second material layer 351b expands positively. The length and thickness of the first material layer 351a remain essentially unchanged, while the length and / or thickness of the second material layer 351b increase, and the blade 20522 bends outward to switch to an unfolded state. To achieve the above objective, the first material layer 351a can be made of a solid material unaffected by temperature; that is, during the switching between the first and second temperatures, the first material layer 351a maintains a fixed configuration, and its length and thickness remain essentially unchanged. When the first temperature is greater than the second temperature, that is, when the ambient temperature outside the subject is greater than the temperature inside the subject's body, the temperature decreases from outside to inside the body. The second material layer 351b is made of a material with negative thermal expansion, and its length and / or thickness increase as the temperature decreases, achieving positive expansion. Alternatively, when the first temperature is lower than the second temperature, that is, when the ambient temperature outside the subject is lower than the temperature inside the subject's body, the temperature rises from outside to inside the body. The second material layer 351b is made of a positive thermal expansion material, and its length and / or thickness increases with the increase of temperature, thus achieving positive expansion.

[0041] Please see Figure 3BIn the second embodiment of temperature stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, the first material layer 351a expands in the opposite direction, while the second material layer 351b does not expand. At this time, the length and thickness of the second material layer 351b remain essentially unchanged, while the length and / or thickness of the first material layer 351a shortens, and the blade 20522 bends outwards as a whole, switching to the deployed state. To achieve the above objective, the second material layer 351b can be made of a solid material. When the first temperature is higher than the second temperature, the first material layer 351a is made of a material with positive thermal expansion, and its length and / or thickness shorten as the temperature decreases, achieving negative expansion. When the first temperature is lower than the second temperature, the first material layer 351a is made of a material with negative thermal expansion, and its length and / or thickness decrease as the temperature increases, achieving negative expansion.

[0042] Please see Figure 3C In the third embodiment of temperature stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, the first material layer 351a expands in the reverse direction, and the second material layer 351b expands in the positive direction. At this time, the length of the first material layer 351a shortens and / or its thickness decreases, while the length and / or thickness of the second material layer 351b increases, and the blade 20522 bends outwards as a whole, switching to an unfolded state. To achieve the above objective, when the first temperature is higher than the second temperature, the first material layer 351a can be made of a positively thermally expanding material, which shortens in length as the temperature decreases, achieving negative expansion. The second material layer 351b can be made of a negatively thermally expanding material, which increases in length as the temperature decreases, achieving positive expansion. When the first temperature is lower than the second temperature, as the temperature rises, the first material layer 351a can be made of a negatively thermally expanding material, which shortens in length as the temperature rises, achieving negative expansion. The second material layer 351b can be made of a positively thermally expanding material, which increases in length as the temperature rises, achieving positive expansion.

[0043] Please see Figure 3DIn the fourth embodiment of temperature stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, both the first material layer 351a and the second material layer 351b undergo positive expansion. The coefficient of thermal expansion of the first material layer 351a is less than that of the second material layer 351b. At this time, the length and / or thickness of both the first material layer 351a and the second material layer 351b increase. However, since the coefficient of thermal expansion of the first material layer 351a is less than that of the second material layer 351b, the amount of thermal expansion deformation of the first material layer 351a is less than that of the second material layer 351b. During the same positive expansion process, the length of the first material layer 351a is relatively shortened and / or the thickness is relatively thinned relative to the second material layer 351b, which allows the blade 20522 to bend outward as a whole, switching to the unfolded state. To achieve the above objectives, when the first temperature is higher than the second temperature, both the first material layer 351a and the second material layer 351b can be made of negative thermal expansion materials, and both can increase in length and / or thickness as the temperature decreases, achieving positive expansion. When the first temperature is lower than the second temperature, both the first material layer 351a and the second material layer 351b are made of positive thermal expansion materials, and both can increase in length and / or thickness as the temperature increases, achieving positive expansion.

[0044] Please see Figure 3E In the fifth embodiment of temperature stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, both the first material layer 351a and the second material layer 351b undergo negative expansion, with the thermal expansion coefficient of the first material layer 351a being greater than that of the second material layer 351b. At this time, the length and / or thickness of both the first material layer 351a and the second material layer 351b decrease. However, since the thermal expansion coefficient of the first material layer 351a is greater than that of the second material layer 351b, the thermal expansion deformation of the first material layer 351a is greater than that of the second material layer 351b. During the same negative expansion process, the length of the first material layer 351a is relatively extended and / or the thickness is relatively increased relative to the second material layer 351b, which allows the blade 20522 to bend outward as a whole, switching to the unfolded state. To achieve the above objectives, when the first temperature is higher than the second temperature, both the first material layer 351a and the second material layer 351b are made of positively thermally expanding materials, and both can shrink in length and / or thickness as the temperature decreases, achieving negative expansion. When the first temperature is lower than the second temperature, both the first material layer 351a and the second material layer 351b are made of negatively thermally expanding materials, and both can shrink in length and / or thickness as the temperature increases, achieving negative expansion.

[0045] Materials that expand positively with increasing temperature (positive thermal expansion) can be bimetallic strips or polymers such as polyvinyl chloride (PVC), polystyrene (PS), polyvinylidene fluoride (PVDF), parylene, polyimide (PI), polyethylene (PE), polypropylene (PP), silicone resin, nylon (PA-66), SU-8, polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET). For materials that expand negatively with increasing temperature (negative thermal expansion), the known embodiments provided in WO2019042033A1 can be used, and will not be elaborated upon here.

[0046] In this embodiment, when the external environment is relatively hot and the internal environment is relatively cold, the stimulus (temperature) is applied externally and not applied (withdrawn) internally. Conversely, when the external environment is relatively cold and the internal environment is relatively hot, the stimulus (temperature) is applied internally and not applied (withdrawn) externally.

[0047] Please see Figures 4A to 4B When the specific stimulus is humidity, the water absorption and expansion coefficient of the first material layer 351a is less than that of the second material layer 351b, and the water absorption and expansion deformation of the first material layer 351a is less than that of the second material layer 351b. When the impeller 2052 is in the first humidity level outside the subject's body, the blades 20522 are in a folded state. When the impeller 2052 is in the second humidity level inside the subject's body, the blades 20522 switch to an unfolded state. The second humidity level is greater than the first humidity level, meaning the humidity inside the subject's body is greater than the ambient humidity outside the subject's body.

[0048] Please see Figure 4A In the first embodiment of humidity stimulation, when the impeller 2052 is switched from outside the subject to inside the subject, the first material layer 351a does not expand, while the second material layer 351b expands positively. To achieve this, the first material layer 351a is made of a solid material unaffected by humidity; that is, at least during the switching between the first and second humidity levels, the first material layer 351a maintains a fixed configuration, with its length and thickness remaining substantially unchanged. The second material layer 351b is made of a water-absorbing and swelling material. Since the second humidity inside the subject's body is greater than the first humidity outside the subject's body, the second material layer 351b absorbs moisture and expands positively. Similarly, water absorption and swelling can be an increase in the length and / or thickness of the blade 20522.

[0049] Please see Figure 4BIn the second embodiment of humidity stimulation, when the impeller 2052 is switched from being outside the subject to being inside the subject, both the first material layer 351a and the second material layer 351b undergo positive expansion. Both the first material layer 351a and the second material layer 351b are made of water-absorbing and swelling material, and the water absorption and swelling coefficient of the second material layer 351b is greater than that of the first material layer 351a. This results in a greater amount of water absorption and swelling deformation in the second material layer 351b than in the first material layer 351a, and a greater increase in the length and / or thickness of the second material layer 351b compared to the first material layer 351a. This allows the blade 20522 to bend outwards as a whole, switching to the unfolded state.

[0050] In this embodiment, under conditions of relatively low external humidity and relatively high internal humidity, the stimulus (humidity) is applied internally and not applied externally (removed). Since the leaf is immersed in blood during operation, the high internal humidity can be naturally provided by the blood, while the relatively low external humidity is provided by the room temperature environment.

[0051] In another embodiment, the specific stimulus is an electric field, an alternating magnetic field, or a magnetic field. These stimuli are controllable field effects, and to avoid harm to the human body, they are applied when the impeller 2052 is outside the subject's body to keep the blades 20522 in a folded state, and removed when the impeller 2052 is delivered into the subject's body to allow the blades 20522 to return to an unfolded state.

[0052] Please see Figures 5A to 5E When the specific stimulus is an electric field or an alternating magnetic field, at least one of the first material layer 351a and the second material layer 351b is made of an electrostrictive material, and the electrostriction coefficient of the first material layer 351a is different from that of the second material layer 351b. The alternating magnetic field can induce an electric field within the first material layer 351a and the second material layer 351b, thereby causing changes in the length and / or thickness of the materials. Alternatively, when the specific stimulus is a magnetic field, at least one of the first material layer 351a and the second material layer 351b is made of a magnetostrictive material, and the magnetostriction coefficient of the first material layer 351a is different from that of the second material layer 351b. When the impeller 2052 is outside the subject's body, the blades 20522 are folded in place due to the applied field stimulus. When the impeller 2052 is inside the subject's body, the field stimulus is removed, and the blades 20522 return to their unfolded state.

[0053] Please see Figure 5AIn the first embodiment of electric / alternating magnetic field or magnetic field stimulation, when the impeller 2052 is outside the subject's body, the first material layer 351a does not expand, while the second material layer 351b expands in the opposite direction. The first material layer 351a is made of a solid material unaffected by the electric field, alternating magnetic field, or magnetic field, and the second material layer 351b is made of an electrostrictive or magnetostrictive material. When the electric / alternating magnetic field or magnetic field is removed, the second material layer 351b returns to its naturally elongated state from a state of length and / or thickness contraction, and the blade 20522 bends outward as a whole, switching to the unfolded state.

[0054] Please see Figure 5B In the second embodiment, when the impeller 2052 is outside the subject's body, the first material layer 351a expands positively, while the second material layer 351b does not expand. The second material layer 351b is made of a solid material, and the first material layer 351a is made of an electrostrictive or magnetostrictive material. When the electric / alternating magnetic field or magnetic field is removed, the second material layer 351b returns to its naturally shortened state from an elongated state in length and / or thickness, and the blade 20522 bends outward as a whole, switching to the deployed state.

[0055] Please see Figure 5C In the third embodiment of electric / alternating magnetic field or magnetic field stimulation, when the impeller 2052 is outside the subject's body, the first material layer 351a expands forward, and the second material layer 351b expands in the opposite direction. The first material layer 351a is made of an electro-elongating or magneto-elongating material, and the second material layer 351b is made of an electro-contracting or magneto-contracting material. When the electric / alternating magnetic field or magnetic field is removed, the first material layer 351a returns to its naturally shortened state from a state of elongation in length and / or thickness, and the second material layer 351b returns to its naturally elongated state from a state of contraction in length and / or thickness. The blade 20522 bends outward as a whole, switching to the unfolded state.

[0056] Please see Figure 5DIn the fourth embodiment of electric / alternating magnetic field or magnetic field stimulation, when the impeller 2052 is outside the subject's body, both the first material layer 351a and the second material layer 351b undergo negative expansion. Both the first material layer 351a and the second material layer 351b are made of electro-constrictive or magneto-constrictive materials, and the amount of electro-constrictive or magneto-constrictive deformation of the first material layer 351a is less than that of the second material layer 351b. When the electric / alternating magnetic field or magnetic field is removed, both the first material layer 351a and the second material layer 351b return to their naturally elongated state from a state of length and / or thickness contraction. Since the elongation of the first material layer 351a is less than that of the second material layer 351b, the reduction in length and / or thickness of the first material layer 351a is smaller than that of the second material layer 351b, causing the blade 20522 to bend outwards as a whole, switching to an unfolded state.

[0057] Please see Figure 5E In the fifth embodiment of electric / alternating magnetic field or magnetic field stimulation, when the impeller 2052 is outside the subject's body, both the first material layer 351a and the second material layer 351b undergo positive expansion. Both the first material layer 351a and the second material layer 351b are made of electro-elongating or magneto-elongating materials, and the electro-elongating or magneto-elongating deformation of the first material layer 351a is greater than that of the second material layer 351b. When the electric / alternating magnetic field or magnetic field is removed, both the first material layer 351a and the second material layer 351b return to their naturally shortened state from an elongated state. Since the elongation of the first material layer 351a is greater than that of the second material layer 351b, the reduction in length and / or thickness of the first material layer 351a is greater than that of the second material layer 351b, causing the blade 20522 to bend outwards as a whole, switching to an unfolded state.

[0058] When the impeller 2052 is inside the subject's body, the above-mentioned field stimulation is removed, the first material layer 351a and the second material layer 351b are restored, and the length of the restored first material layer 351a is greater than the length of the second material layer 351b. The blade 20522 is brought together inward and reset to the folded state.

[0059] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents.

Claims

1. An impeller, which can be inserted into a subject's body to rotate and pump blood, comprising: A hub, blades formed on the hub, the blades having a folded state and an unfolded state; In the deployed state, the blade has a curved cross-sectional shape at any position perpendicular to the hub axis. The blade includes a first material layer and a second material layer stacked together. Along the bending direction, the first material layer is located outside the second material layer. The first and second material layers have different expansion coefficients for a specific stimulus, so that under the specific stimulus, the expansion deformation of the first material layer is different from that of the second material layer, causing the blade to switch between the folded and deployed states. Specifically, when the expansion deformation of the first material layer is less than that of the second material layer, the blade bends outward, switching to the deployed state; when the expansion deformation of the first material layer is greater than that of the second material layer, the blade bends inward, switching to the folded state.

2. The impeller of claim 1, wherein the specific stimulus is temperature or humidity, and one of the application and removal of the specific stimulus is provided by the external environment when the impeller is outside the subject, and the other is provided by the environment inside the subject's body where the impeller is located when the impeller is delivered into the subject's body.

3. The impeller as described in claim 1 or 2, wherein when the specific stimulus is temperature, the coefficient of thermal expansion of the first material layer is different from that of the second material layer; when the impeller is at a first temperature outside the subject's body, the blades are in a folded state; when the impeller is at a second temperature inside the subject's body, the blades switch to an unfolded state; the second temperature is different from the first temperature.

4. The impeller as described in claim 3, When the impeller is switched from outside the subject's body to inside the subject's body, the first material layer does not expand, while the second material layer expands positively; wherein... The first material layer is made of a solid material unaffected by temperature; when the first temperature is higher than the second temperature, the second material layer is made of a material with negative thermal expansion; when the first temperature is lower than the second temperature, the second material layer is made of a material with positive thermal expansion; or... When the impeller is switched from outside the subject's body to inside the subject's body, the first material layer expands in the opposite direction, while the second material layer does not expand; wherein, the second material layer is made of a solid material unaffected by temperature; when the first temperature is greater than the second temperature, the first material layer is made of a material with positive thermal expansion; when the first temperature is less than the second temperature, the first material layer is made of a material with negative thermal expansion; or... When the impeller is switched from outside the subject's body to inside the subject's body, the first material layer expands in the reverse direction, and the second material layer expands in the forward direction; wherein, when the first temperature is greater than the second temperature, the first material layer is made of a material with positive thermal expansion, and the second material layer is made of a material with negative thermal expansion; when the first temperature is less than the second temperature, the first material layer is made of a material with negative thermal expansion, and the second material layer is made of a material with positive thermal expansion; or... When the impeller is switched from outside the subject's body to inside the subject's body, both the first and second material layers undergo positive expansion; wherein, the coefficient of thermal expansion of the first material layer is less than that of the second material layer; when the first temperature is greater than the second temperature, both the first and second material layers are made of negative thermal expansion materials; when the first temperature is less than the second temperature, both the first and second material layers are made of positive thermal expansion materials; or... When the impeller is switched from outside the subject to inside the subject, both the first material layer and the second material layer undergo negative expansion; wherein, the coefficient of thermal expansion of the first material layer is greater than that of the second material layer; when the first temperature is greater than the second temperature, both the first material layer and the second material layer are made of positive thermal expansion material; when the first temperature is less than the second temperature, both the first material layer and the second material layer are made of negative thermal expansion material.

5. The impeller as described in claim 1 or 2, wherein when the specific stimulus is humidity, the water absorption expansion coefficient of the first material layer is less than that of the second material layer; when the impeller is in a first humidity level outside the subject's body, the blades are in a folded state; when the impeller is in a second humidity level inside the subject's body, the blades switch to an unfolded state; the second humidity level is greater than the first humidity level.

6. The impeller as described in claim 5, When the impeller is switched from outside the subject's body to inside the subject's body, the first material layer does not expand, while the second material layer expands positively; wherein... The first material layer is made of a solid material unaffected by humidity, and the second material layer is made of a water-absorbing and swelling material; or, When the impeller is switched from outside the subject to inside the subject, both the first material layer and the second material layer undergo positive expansion; wherein, both the first material layer and the second material layer are made of water-absorbing and expanding material, and the water absorption and expansion coefficient of the second material layer is greater than that of the first material layer.

7. The impeller as claimed in claim 1, wherein the specific stimulus is an electric field, an alternating magnetic field, or a magnetic field; the specific stimulus is applied when the impeller is outside the subject's body to cause the blades to be in a folded state, and is removed when the impeller is delivered into the subject's body to cause the blades to return to an unfolded state.

8. The impeller as claimed in claim 1 or 7, wherein when the specific stimulus is an electric field or an alternating magnetic field, at least one of the first material layer and the second material layer is made of an electrostrictive material; the electrostriction coefficient of the first material layer is different from that of the second material layer.

9. The impeller as described in claim 8, When the impeller is outside the subject's body, the first material layer does not expand, while the second material layer expands in the opposite direction; wherein... The first material layer is made of a solid material unaffected by an electric field or alternating magnetic field, and the second material layer is made of an electro-shrinkable material; or, When the impeller is outside the subject's body, the first material layer expands positively, while the second material layer does not expand; wherein the second material layer is made of a solid material unaffected by an electric field or alternating magnetic field, and the first material layer is made of an electroextensible material; or... When the impeller is outside the subject's body, the first material layer expands in the forward direction, and the second material layer expands in the reverse direction; wherein the first material layer is made of an electrostrictive elongating material, and the second material layer is made of an electrostrictive contractile material; or... When the impeller is outside the subject's body, both the first and second material layers undergo negative expansion; wherein, both the first and second material layers are made of electro-shrinkable materials, and the electro-expansion deformation of the first material layer is less than that of the second material layer; or... When the impeller is outside the subject's body, both the first material layer and the second material layer undergo positive expansion; wherein, both the first material layer and the second material layer are made of electro-elongating material, and the electro-elongation deformation of the first material layer is greater than that of the second material layer.

10. The impeller as claimed in claim 1 or 7, wherein when the specific stimulus is a magnetic field, at least one of the first material layer and the second material layer is made of a magnetostrictive material, and the magnetostriction coefficient of the first material layer is different from that of the second material layer.

11. The impeller as claimed in claim 10, When the impeller is outside the subject's body, the first material layer does not expand, while the second material layer expands in the opposite direction; wherein... The first material layer is made of a solid material unaffected by a magnetic field, and the second material layer is made of a magnetostrictive material; or, When the impeller is outside the subject's body, the first material layer expands positively, while the second material layer does not expand; wherein the second material layer is made of a solid material unaffected by a magnetic field, and the first material layer is made of a magnetostrictive material; or... When the impeller is outside the subject's body, the first material layer expands in the forward direction, and the second material layer expands in the reverse direction; wherein the first material layer is made of a magnetostrictive elongation material, and the second material layer is made of a magnetostrictive contraction material; or... When the impeller is outside the subject's body, both the first and second material layers undergo negative expansion; wherein, both the first and second material layers are made of magnetostrictive material, and the magnetostrictive expansion deformation of the first material layer is less than that of the second material layer; or... When the impeller is outside the subject's body, both the first material layer and the second material layer undergo positive expansion; wherein, both the first material layer and the second material layer are made of magnetostrictive elongation material, and the magnetostrictive expansion deformation of the first material layer is greater than that of the second material layer.

12. A duct pump, comprising: catheter; A pump head, comprising: a pump casing connected to the distal end of the conduit and having an inlet end and an outlet end, and an impeller as described in any one of claims 1-11; The impeller is housed within the pump casing and driven to rotate, drawing blood from the inlet end into the pump casing and discharging it from the outlet end.

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