Electroactive polymer actuator and method of operating the same

Abstract

An instrument suitable for surgical procedures may include: (a) a body having a distal end and a proximal end, and including a lumen between the distal and proximal ends through which a fluid moves during suction; and (b) one or more actuators attached to or embedded in the body, each actuator comprising one or more electroactive polymer layers that provide mechanical motion at the distal end in response to stimulation by a corresponding electrical control signal, the electrical control signal being supplied in a predetermined coordinated pattern. The predetermined coordinated pattern may include operating two or more groups of actuators sequentially, simultaneously, or in combination thereof.

Description

Technical Field

[0001] The present invention relates to medical devices that function by electroactive polymers ("EAPs", such as piezoelectric polymers). In particular, the present invention relates to surgical instruments that include EAP-based actuators or other mechanical components capable of axial, radial, torsional, or helical movement.

Summary of the Invention

[0002] According to one embodiment of the present invention, there is provided an instrument for use in a medical procedure, electrically connected to a controller that controls mechanical suction by supplying an electrical control signal, comprising: (a) a body having a distal end and a proximal end, provided with a conduit extending from the distal end to the proximal end, through which fluid is adapted to flow during suction; and (b) one or more actuators attached to or embedded within the body, each providing mechanical movement at the distal end in response to stimulation by an electrical control signal. The actuators may be EAP-based. The stimulation may be an electrical control signal in a predetermined coordinated pattern. The predetermined coordinated pattern may be an operation by sequential, simultaneous, or a combination thereof by two or more actuator groups. For example, in one embodiment, the predetermined coordinated pattern includes that two or more actuator groups are sequentially activated one by one, and within each group, two or more actuators are activated simultaneously. In one embodiment, each actuator extends along the longitudinal direction of the body, and two or more actuator groups are arranged substantially equidistantly from each other at a distance radially from the longitudinal axis of the conduit.

[0003] According to one embodiment of the present invention, the operation of the mechanical movement of the actuator is coordinated with the suction pressure. For example, when one of the mechanical movements causes a forward movement at the distal end of the body, the suction pressure may be reduced.

[0004] According to one embodiment of the present invention, the distal end of the suction device body is provided with an opening that exposes a conduit, and the portion of the body with the opening has a funnel shape.

[0005] According to one embodiment of the present invention, the first actuator of the suction device is helically wound around the circumferential wall of the main body. In another embodiment, another second actuator is also helically wound around the circumferential wall of the main body, but the second actuator has a different chirality than the first actuator.

[0006] According to one embodiment of the present invention, the first actuator of the device is wrapped around the longitudinal axis of the body, substantially over its entire circumference, on the peripheral wall of the body. When the actuator performs mechanical motion, both ends of the actuator may be in contact with each other. Alternatively, a gap may be provided between the ends of the actuator, and reinforcing material may be included that spans this gap.

[0007] According to one embodiment of the present invention, the suction catheter includes a mass in a part of the actuator to change the resonant frequency of the actuator's mechanical motion. The mass may include a radiopaque material that can be used to guide the steering of the catheter. The mass may also include tungsten to provide an adjustable effect on the actuator's mechanical motion, for example, its resonant frequency.

[0008] According to one embodiment of the present invention, each actuator of the device may include one or more reinforcing portions to restrict the mechanical motion of the actuator. The reinforcing portions of the body may be formed of a highly elastic or compliant material, and the modulus of elasticity or compliance of the reinforcing portion may be relative to the EAP layer or material that functions as the base material within the actuator.

[0009] According to one embodiment of the present invention, the body may include a patterned material layer or a textured material layer exposed toward the conduit. The patterned material layer or textured material layer may be formed from polyvinylidene fluoride (PVDF). The patterned or textured layer includes grooves or ridges, and adjacent grooves or ridges may be separated from each other by channels. In such embodiments, each ridge may have a smooth surface or a textured surface. Alternatively, the patterned or textured layer may include etched recesses. The etched recesses may be provided in the form of a rifle-shaped helical pattern extending longitudinally along the body. The patterned or textured layer may have a thread-shaped helical pattern extending longitudinally along the body.

[0010] According to one embodiment of the present invention, one or more sensors may be provided in conjunction with the EAP actuator. For example, a portion of the patterned or textured layer (e.g., the distal end) may be used as an electroactuated sensor. The sensor may be located at any position within the catheter body or outside the catheter body (e.g., inside a tube connected to the catheter). The sensor may be used to detect the presence of a thrombus and provide a sensory output as an electrical signal. The sensory output of the electroactuated sensor or other sensors may be fed back to a controller and used to adjust the suction pressure, the frequency or amplitude of the vibration of the EAP actuator, or any combination thereof.

[0011] According to one embodiment of the present invention, the patterned or textured layer may incorporate a movable element capable of axial movement and act to push the entrained thrombus proximally. In one embodiment, the patterned or textured layer may include a flexure beam that operates primarily to produce axial motion. In yet another embodiment, the patterned or textured layer may include a compliant region. In one embodiment relating to the compliant region, the flexure beams may include an elongated member connected to one another. In one embodiment relating to the compliant region, an EAP actuator may be provided in a material region with a lower modulus of elasticity than the actuator.

[0012] Various embodiments of the present invention may include a mechanical structure at the opening to the suction conduit, which, when open, provides a softly expanding opening relative to the suction structure and may also be designed to provide a strict closure limit to prevent the opening of the suction conduit from collapsing.

[0013] The present invention will be better understood by considering the following detailed description in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0014] [Figure 1A] This is a top view showing a cross-sectional view of the distal tip 101 and catheter shaft 104 of the instrument 100 according to one embodiment of the present invention. [Figure 1B] This is a cross-sectional view that crosses the cross-section of Figure 1A, showing the electrode layer 108 and the EAP layer 109 at the distal tip portion 101. [Figure 2A-1] The images show a side view and a cross-sectional view of a distal tip 200 including a plurality of individually controlled actuators (e.g., actuators 201a to 201c) according to one embodiment of the present invention, where the actuators are in a relaxed state in Figures 2A-1 and 2A-2. [Figure 2A-2]The images show a side view and a cross-sectional view of a distal tip 200 including a plurality of individually controlled actuators (e.g., actuators 201a to 201c) according to one embodiment of the present invention, where the actuators are in a relaxed state in Figures 2A-1 and 2A-2. [Figure 2A-3] This figure shows that when the actuator is in operation, the action of the substrate layer 202 causes the compliant layer 203 to bend in the circumferential direction (i.e., radial direction). [Figure 2A-4(i)] This figure shows an example of radial bending. [Figure 2A-4(ii)] This figure shows an example of radial bending. [Figure 2A-4(iii)] This figure shows an example of radial bending. [Figure 2A-5(i)] This figure shows the torsional response. [Figure 2A-5(ii)] This figure shows the torsional response. [Figure 2A-6(i)] This figure shows the response in the axial direction. [Figure 2A-6(ii)] This figure shows the response in the axial direction. [Figure 2A-7] This figure shows the helical response (i.e., a combination of torsional and axial responses). [Figure 2A-8(i)] This figure shows the simultaneous or unison response at the distal tip 200 in Figure 2A-1. [Figure 2A-8(ii)] This figure shows the simultaneous or unison response at the distal tip 200 in Figure 2A-1. [Figure 2A-9(i)] This figure shows the group response or coordinated response at the distal tip 200 of Figure 2A-1. [Figure 2A-9(ii)] This figure shows the group response or coordinated response at the distal tip 200 of Figure 2A-1. [Figure 2B] This diagram shows one of three operating patterns (sequential, simultaneous, or group), where in each pattern, four operating control signals (labeled 201a to 201d, respectively) correspond to the control signals transmitted to actuators 201a to 201b. [Figure 2C]It is a diagram showing one of three types of operation patterns (sequential, simultaneous, or group), and in each pattern, four operation control signals (labeled 201a to 201d respectively) correspond to the control signals transmitted to the actuators 201a to 201b. [Figure 2D] It is a diagram showing one of three types of operation patterns (sequential, simultaneous, or group), and in each pattern, four operation control signals (labeled 201a to 201d respectively) correspond to the control signals transmitted to the actuators 201a to 201b. [Figure 2E] It is a diagram showing how the operation of the EAP actuator is coordinated with the suction pattern according to an embodiment of the present invention. [Figure 3A-1] It is a diagram showing a funnel-shaped distal tip portion 300 provided with actuators (e.g., actuators 301a to 301c) around the distal end of the instrument 300 according to an embodiment of the present invention. [Figure 3A-2] It is a diagram showing the structure of another funnel-shaped distal tip portion according to an embodiment of the present invention. [Figure 3A-3] It is a diagram showing the structure of another funnel-shaped distal tip portion according to an embodiment of the present invention. [Figure 3A-4] It is a diagram showing the structure of another funnel-shaped distal tip portion according to an embodiment of the present invention. [Figure 3B] It is a diagram showing an actuator 321 wound helically around the peripheral wall of the distal tip portion 300 according to an embodiment of the present invention. [Figure 3C] It is a diagram showing a state in which a highly elastic material 322 having a different chirality is wound helically in the opposite direction around the helical actuator 321 at the distal tip portion 300 according to an embodiment of the present invention. Also, it shows a tubular instrument 350 having an EAP actuator 326 wound circumferentially around the main body of the tubular instrument 150 between the tip portion 300 and the proximal portion 305 according to a second embodiment of the present invention. [Figure 3D]This figure shows how, according to a second embodiment of the present invention, the EAP actuator 326 is wrapped around the body of the tubular instrument 350 in the circumferential direction between the distal end 300 and the proximal end 305 of the distal end 300 at the distal tip 300 of the tubular instrument 350. [Figure 3E] This figure shows a tubular instrument 370 having circumferentially wound EAP actuators 326-1, 326-2, 326-3, and 326-4 according to one embodiment of the present invention. [Figure 3F] This figure shows a mass body 345 arranged longitudinally at the distal end of the distal tip portion 300, according to one embodiment of the present invention. [Figure 3G] This figure shows a plurality of reinforcing actuators (including actuators 341-1 and 341-2) incorporated into the configuration of Figure 2A according to one embodiment of the present invention. [Figure 3H-1] This figure shows a configuration in which the motion of actuator 360 is enhanced by substrate 351, according to one embodiment of the present invention. [Figure 3H-2] This figure shows a configuration in which the motion of actuator 360 is enhanced by substrate 351, according to one embodiment of the present invention. [Figure 3H-3] This figure shows a configuration in which the motion of actuator 360 is enhanced by substrate 351, according to one embodiment of the present invention. [Figure 3I-1] This figure shows the passive operation at the distal tip 300 of the instrument 380 according to one embodiment of the present invention. [Figure 3I-2] This figure shows the passive operation at the distal tip 300 of the instrument 380 according to one embodiment of the present invention. [Figure 3I-3] This figure shows the passive operation at the distal tip 300 of the instrument 380 according to one embodiment of the present invention. [Figure 3J-1] This figure shows how a second passive mechanical action is incorporated into the tip portion 300 according to another embodiment of the present invention. [Figure 3J-2]This figure shows how a second passive mechanical action is incorporated into the tip portion 300 according to another embodiment of the present invention. [Figure 3J-3] This figure shows how a second passive mechanical action is incorporated into the tip portion 300 according to another embodiment of the present invention. [Figure 3J-4] This figure shows how a second passive mechanical action is incorporated into the tip portion 300 according to another embodiment of the present invention. [Figure 4A-1] This figure shows a textured surface 410 provided on the wall of the lumen 120 at the distal tip 300 of a catheter, according to one embodiment of the present invention. [Figure 4A-2] This is a side view of a textured surface 410 cut in a step-like pattern into the inner wall of the lumen 120. [Figure 4A-3] This is a perspective view of the textured surface 410 cut in a step-like pattern into the inner wall of the lumen 120. [Figure 4A-4] This is a cross-sectional view of the textured surface 410, which has patterned step-shaped protrusions, as seen from the inside of the opening of the lumen 120. [Figure 4A-5] This is a cross-sectional view of the textured surface 410, which has patterned step-shaped protrusions, as seen from the outside of the opening of the lumen 120. [Figure 4A-6] This is a side view of the textured surface 410, which has other patterned step-shaped protrusions. [Figure 4A-7] This is a perspective cross-sectional view of a textured surface 410 with other patterned, stepped protrusions. [Figure 4A-8] This is a perspective view of the textured surface 410, which has other patterned, stepped protrusions. [Figure 4B] This figure shows the wall of a lumen 120 having a raised portion 411 separated by a channel 412, according to one embodiment of the present invention. [Figure 4C-1] This is a cross-sectional view of a helical groove 422 formed in the wall of the lumen 120. [Figure 4C-2] This is a perspective view of the spiral groove 422 formed in the wall of the lumen 120. [Figure 4D-1] This is a cross-sectional view of a screw-shaped raised structure 423 having a helix formed on the enclosure wall of a lumen 120, according to one embodiment of the present invention. [Figure 4D-2] This is a perspective view of a screw-shaped raised structure 423 having a helical curve formed on the enclosure wall of a lumen 120, according to one embodiment of the present invention. [Figure 5A-1] This figure shows the operation of a textured structure 500 provided on the surrounding side wall of a lumen 120, according to one embodiment of the present invention. [Figure 5A-2] This figure shows the operation of a textured structure 500 provided on the surrounding side wall of a lumen 120, according to one embodiment of the present invention. [Figure 5A-3] This figure shows the operation of a textured structure 500 provided on the surrounding side wall of a lumen 120, according to one embodiment of the present invention. [Figure 5B-1] This figure shows the operation of a second textured structure 550 provided on the side wall of a lumen 120, according to one embodiment of the present invention. [Figure 5B-2] This figure shows the operation of a second textured structure 550 provided on the side wall of a lumen 120, according to one embodiment of the present invention. [Figure 6A-1] This figure shows a clamshell structure 610 that controls the opening of a lumen 120 according to one embodiment of the present invention, the clamshell structure 610 having a soft opening and a rigid closure limit. [Figure 6A-2] This figure shows a clamshell structure 610 that controls the opening of a lumen 120 according to one embodiment of the present invention, the clamshell structure 610 having a soft opening and a rigid closure limit. [Figure 6B-1] This figure shows a stent-like mechanical structure 650 that controls the opening of a lumen 120 according to one embodiment of the present invention. Similar to the clamshell structure 610 in Figures 6A-1 and 6A-2, the stent-like mechanical structure 650 may also have a soft opening, but maintains a rigid closure restriction to the opening of the lumen 120. [Figure 6B-2]This figure shows a stent-like mechanical structure 650 that controls the opening of a lumen 120 according to one embodiment of the present invention. Similar to the clamshell structure 610 in Figures 6A-1 and 6A-2, the stent-like mechanical structure 650 may also have a soft opening, but maintains a rigid closure restriction to the opening of the lumen 120. [Figure 6C-1] This figure shows the operation of a tubular compliant structure 680 that controls a lumen 120 using a foldable membrane material, according to one embodiment of the present invention. [Figure 6C-2] This figure shows the operation of a tubular compliant structure 680 that controls a lumen 120 using a foldable membrane material, according to one embodiment of the present invention. [Figure 6C-3] This figure shows the operation of a tubular compliant structure 680 that controls a lumen 120 using a foldable membrane material, according to one embodiment of the present invention. [Figure 7A] This figure shows an integrated thrombectomy device 700 according to one embodiment of the present invention. [Figure 7B] This is an enlarged view of an integrated EAP actuator 725 provided at the distal tip 724 of an integrated thrombectomy device 700 according to one embodiment of the present invention. [Figure 7C] This figure shows the formation of a Tecoflex casing in an integrated EAP actuator 725 according to one embodiment of the present invention. [Modes for carrying out the invention]

[0015] This application discloses various embodiments of a suction catheter or other surgical devices, the surgical device including a tip at its distal end, which vibrates strongly upon operation and can achieve desired mechanical effects suitable for use in various surgical applications (e.g., thrombectomy). For example, in thrombectomy, vibration can impart a desired force to the thrombus, thereby achieving agitation, disruption, fragmentation, compression, or rupture of the thrombus, facilitating its removal. For example, rupturing the thrombus is desirable to prevent "corking" and thus allows the thrombus to be directly aspirated into the catheter or surgical instrument. Unlike devices in minimally invasive surgery, where the tissue treated in such surgery is accessed through a small incision as needed, intravascular sites are typically accessed via a long, flexible catheter (often 100 cm or longer). However, while this specification provides examples of the invention being carried out in combination with a catheter, the invention can also be carried out with minimally invasive surgical devices. Therefore, the term "instrument" herein should be understood to refer to a device associated with a catheter or any suitable surgical device.

[0016] The distal end tip of the instrument ("distal tip") may be provided with one or more electroactive polymer (EAP) actuators. Each EAP actuator may be actuated (e.g., set to a motion or vibration state) by an electrical signal transmitted from the proximal end of the instrument. In this configuration, the mechanical motion of the distal tip can be limited and substantially not transmitted in the longitudinal direction of the instrument. In some embodiments, the operation of the EAP actuators does not necessarily have to be linear. Linear motion may be complemented by other mechanical motion of the distal tip. For example, in some embodiments, the range of mechanical motion at the distal tip may include any radial, axial, torsional, and helical motion, or a combination thereof. In this specification, "torsional motion" means rotational motion about the axial direction, and "helical motion" means a combination of torsional and axial motion. Suitable electroactive polymers include various combinations of vinylidene fluoride (VDF), trifluoroethylene (TrFE), 1,1-chlorofluoroethylene (CFE), and chlorotrifluoroethylene (CTFE). For example, ternary copolymers P(VDF-TrFE-CTFE) and P(VDF-TrFE-CFE) are commercially available and can be obtained from Piezotech (located in Paris, France, a subsidiary of Arkema SA). These ternary copolymers have different electroactivity properties and exhibit large electrostriction (e.g., 0.5% or more, preferably 3.0% or more) under an electric field of 20-200 V / μm (e.g., 20-100 V / μm, preferably about 50 V / μm).

[0017] Figure 1A is a plan view showing the distal tip 101 and instrument shaft 104 at the distal end of an instrument 100 according to one embodiment of the present invention. The distal tip 101 may be an actuator itself, or it may include one or more actuators capable of performing electrically controlled motion. The instrument 100 includes a proximal end 105 (not shown) having a watertight connection for receiving an electrical signal (e.g., 20 to 200 Hz, preferably 50 to 150 Hz) to an electronic drive circuit, and this electrical signal is optimized for the resonant frequency of the distal tip 101. This makes the instrument suitable for fragmenting thrombi and taking up thrombus fragments by suction. A higher frequency range is considered more preferable for thrombus take-up performance. In the envisioned operation, each electrical signal may have an amplitude of, for example, 50.0 to 300.0 volts and may or may not have a DC offset.

[0018] The instrument shaft 104 may have a conventional mechanical design, such as having an inner layer or liner of polytetrafluoroethylene (PTFE), Pebax, or thermoplastic polyurethane (TPU). The PTFE inner layer may be covered by an outer layer of a reflowable material (e.g., Pebax with a durometer that changes over the length of the instrument shaft 104). Furthermore, the instrument shaft 104 includes both an active electrode 106a and a return electrode 106b that are electrically insulated from each other, with each electrode extending over the entire length of the instrument shaft 104. These electrodes may be formed from any suitable conductive wire. The inner layer or conductive wire may have sufficient mechanical strength to impart mechanical strength and break resistance to the instrument shaft 104, or may be provided in the form of a blade or coil. The conductive wire may be embedded in an electrically nonconductive blade or coil (e.g., composed of polyetheretherketone (PEEK)) that extends over the entire length of the instrument 100. These blades and coils are available in various patterns from, for example, Steeger USA, US Biodesign, Inc., and Admedes, Inc. Alternatively, they may be all-metal blades or coils with electrically insulated wires for the active electrode 106a and return electrode 106b. However, to avoid short circuits, it is preferable to embed the electrodes in non-conductive blades or coils. Figure 1A shows only the active electrode 106a and return electrode 106b for illustrative purposes, but any appropriate number of active and return electrodes can be used.

[0019] The distal tip 101, located at the distal end of the instrument 100, is configured to engage with a thrombus. The distal tip 101 is preferably flush or inclined, allowing for maximum utilization of the opening to capture the thrombus. A layer of electroactive polymer (EAP) is embedded within the distal tip 101. Each EAP layer deforms when an electric field is applied to both sides (a greater electric field yields greater deformity, although the relationship between deformity and electric field is generally nonlinear). As shown in Figure 1A, each EAP layer is positioned between thin, flexible electrode layers, for example, between electrode 102 and electrode 103 located below it. Electrodes 102 and 103 are electrically connected to either an active electrode 106a or a return electrode 106b, respectively. In this way, motion occurs only at the distal tip 101 located at the distal end of the instrument 100, and no energy is lost due to the movement of the active electrode 106a and return electrode 106b within the instrument shaft 104. In one embodiment, each EAP layer may have a thickness of 2 to 20 μm. The distal tip portion 101 can move in both the longitudinal and transverse directions.

[0020] According to one embodiment of the present invention, each EAP layer may be formed by dip coating. For example, the distal tip 101 provided at the distal end of the instrument 100 can be immersed in an EAP solution in a polar solvent such as diethylformamide (DMF) or methyl ethyl ketone (MEK). This method allows for the formation of coaxial EAP layers having a thickness of 20 to 200 μm within the distal tip 101 in a series of immersion steps. After each EAP layer is formed, an electrode layer may be formed on its exposed surface, for example, by sputtering (e.g., gold or aluminum), clip coating (e.g., silver-containing urethane), pad printing, or spray coating using conductive electrical ink or particle-free metal complex conductive ink (e.g., conductive inks available from Electroninks or LiquidX). The process of forming the EAP layer-electrode layer combination can be repeated multiple times. The electrode layers thus formed are connected to an active electrode 106a or a return electrode 106b, and electrodes with different polarities are formed on both sides of the EAP layer, thereby substantially forming a capacitor. Figure 1B is a cross-sectional view of the distal tip portion 101 in a direction transverse to the cross-section of Figure 1A, showing the electrode layer 108 and the EAP layer 109. Depending on the desired mechanical properties, each EAP layer may have various thicknesses. Furthermore, a non-EAP layer (not shown) may be additionally included.

[0021] Fragmented or compressed thrombi generated by the movement of the distal tip of the device 100 can be removed from the blood vessel by suction. The efficiency of thrombus uptake depends on several factors (e.g., the combination of the actuator's operating parameters and the periodic or variable suction pattern). The inventors believe that the movement of the distal tip can compress the thrombus. Such compression removes serum from the thrombus, resulting in a reduction in its volume and facilitating its uptake.

[0022] The suction pattern is generated by switching the suction mechanism on and off according to a predetermined waveform pattern. In the prior art, the suction pressure pattern uses very low frequency changes (e.g., 6-12 Hz) because the pressure pattern is driven from the proximal end of the instrument 100. When an EAP actuator is incorporated into the instrument, the inventors have found that very strong suction can create a force that hinders the outward movement of the distal tip 101 in longitudinal or axial motion. According to one embodiment of the present invention, the suction pattern and the vibration pattern are electronically controlled in coordination to optimize both the movement of the instrument tip and the uptake of thrombus. For example, in the movement of the distal tip 101, suction is reduced when the longitudinal movement is outward, and conversely, suction is increased when the longitudinal movement is inward. By coordinating the movement of the distal tip with the suction pressure, faster response times can be achieved, and a wide frequency response range up to 1 kHz can be utilized.

[0023] A lumen 120 extending over substantially the entire length of the shaft of the instrument 100 provides a conduit for suction inlet and outlet. A polyvinylidene fluoride (PVDF) copolymer sensor can be placed at the distal end of the lumen 120 or at other locations to detect if the instrument 100 has become “corked” or blocked. Suitable tactile pressure sensors include, for example, any pressure-sensing guidewire disclosed in U.S. Patent Application No. 17 / 510,257, “Pressure-Sensing Guidewire,” filed October 25, 2021. When a blockage or blockage is detected, the controller activates and modifies the suction and vibration patterns to release the blockage in the instrument.

[0024] In the above embodiment, electrodes for the EAP layer or multiple layers of the actuator are provided individually. Multiple actuators can be linearly incorporated into the tip of the instrument and operated independently. For example, according to one embodiment of the present invention, Figures 2A-1 and 2A-2 are side and cross-sectional views of a distal tip 200 including multiple independently controllable actuators (e.g., actuators 201a to 201d, actuator 201d is not shown in Figure 2A-1 because it is positioned opposite to the other). In this configuration, each actuator may have a proximal end that is an axially or longitudinally aligned cantilever beam encased in a circumferentially wound substrate layer 202. As shown in Figure 2A-1, an inner layer 203 made of a compliant polymer material may be placed on the inner surface of the lumen 120. The circumferentially wound substrate layer 202 covers both the proximal end of the actuator and the inner compliant layer 203. The substrate layer 202 may be formed from a material that is more elastic than the surrounding material (e.g., the compliant layer 203). Figure 2A-1 shows the actuators in a relaxed state. During operation, each actuator extends axially or longitudinally. Because the circumferentially wrapped substrate layer 202 reinforces the proximal end of the distal tip 200, the actuators cause preferential circumferential (i.e. radial) bending of the compliant layer 203. As a result, as shown in Figure 2A-3, the opening of the lumen 120 at the distal tip of the instrument 200 widens outward (i.e., its diameter increases), forming a flared shape.

[0025] By using combinations of operating patterns, medical professionals can drive actuators 201a to 201d individually or in coordination to obtain various effects. For example, Figures 2A-4(i) to 2A-4(iii) show examples of radial bending. Figure 2A-4(i) shows radial expansion at the tip and middle of the distal tip, providing a flare-out response (Figure 2A-4(ii)) and a radial bulge response (Figure 2A-4(iii)), respectively. Similarly, Figures 2A-5(i) and 2A-5(ii) show torsional responses, Figures 2A-6(i) and 2A-6(ii) show axial responses, and Figure 2A-7 shows a helical response (i.e., a combination of torsional and axial responses).

[0026] Figures 2B to 2D show the control signals to actuators 201a to 201c in sequential operation patterns, simultaneous operation patterns or unison operation patterns, and coordinated operation patterns or group operation patterns, respectively. For example, in the sequential operation pattern shown in Figure 2B, actuators 201a to 201b operate in a predetermined order. In the simultaneous or unison operation pattern shown in Figure 2C, actuators 201a to 201b operate simultaneously. Figures 2A-8(i) and 2A-8(ii) show the simultaneous or unison response at the distal tip 200 of Figure 2A-1. In the coordinated operation pattern shown in Figure 2D, actuators 201a and 201c and actuators 201b and 201d form two groups, and each group operates sequentially. However, the actuators within each group operate simultaneously. Figures 2A-9(i) and 2A-9(ii) show the grouped or coordinated response at the distal tip 200 of Figure 2A-1. In the operating pattern shown in Figure 2D, actuators 201a and 201c and actuators 201b and 201d form two actuator groups facing opposite directions. In embodiments with more actuators, even more complex but appropriate operating patterns can be constructed. Importantly, actuators can be operated to produce a specific desired result by combining their operating patterns into a series of operating patterns.

[0027] Figure 2E illustrates the coordination of EAP actuator operation and suction patterns according to one embodiment of the present invention. As shown in Figure 2E, at the end of the period from time A to B, the suction pump signal ASP slightly reduces (deactivates) the suction before the EAP activation signal that activates one or more EAP actuators at time C. At time D, the suction pump signal ASP activates again (increases suction) and resumes suction, immediately before the EAP activation signal that deactivates the EAP actuators at time E. This operation pattern can be repeated or varied in any appropriate way, as shown in Figure 2E. In Figure 2E, the mechanical response of the distal tip is shown as the displacement waveform DIS.

[0028] On the other hand, according to one embodiment of the present invention, the EAP actuator may be integrated with other mechanical or electrical elements to constitute an actuator ("integrated EAP actuator") and used as a building block for constructing an instrument. The integrated EAP actuator has electromechanical properties and may be formed into any desired shape for placement in an instrument (e.g., the distal tip 101 at the distal end of instrument 100). Thus, one or more integrated EAP actuators can be incorporated into the distal tip 101 at the distal end of instrument 100 (for example, as a three-dimensional array of integrated actuators).

[0029] Each embodiment described herein may be driven by a drive electronic circuit. If the distal tip 101 is designed to include a plurality of independently controllable actuators, a plurality of waveforms can be supplied to each active electrode. In most embodiments described above, the drive circuit can supply a drive waveform of, for example, 50.0 to 250.0 volts (peak to peak). The drive waveform may be a sine wave, a triangular wave, a square wave, or any desired waveform (preferably a square wave as shown in Figures 2B to 2D), and is used to provide maximum acceleration or vibration. A suitable drive circuit can be provided, for example, using Microchip's HV56020 or HV56022.

[0030] The shape of the distal tip may be various appropriate shapes. For example, Figure 3A-1 shows a funnel-shaped distal tip 300 according to one embodiment of the present invention, in which actuators (e.g., actuators 301a to 301c) are provided around the distal tip 300. The actuators are provided as cantilever beams, each supported at one end by a highly elastic substrate 302, similar to the configuration described above with reference to Figures 2A-1 to 2A-3. The arrangement of actuators 301a to 301c on the funnel-shaped distal tip 300 is merely illustrative, and any number of actuators can be used in any appropriate arrangement. For example, the actuator arrangements and operating patterns shown in Figures 2A-1 to 2A-3 (e.g., the operating patterns in the 4-actuator configuration shown in Figures 2B to 2D) are also applicable. Furthermore, actuators 301a to 301c do not need to operate in the longitudinal direction. As will be detailed below, different actuator configurations are possible to obtain a desired result. The funnel-shaped structure allows for greater displacement of the tip, enabling "grooming" of the thrombus into a preferred shape to facilitate its removal.

[0031] In Figure 3A-1, the proximal ends of each actuator 301a to 301c (i.e., the side away from the funnel-shaped opening) are preferentially reinforced with a relatively rigid actuator material (i.e., a highly elastic material). This limits bending at the proximal end, while increasing the degrees of freedom at the distal end in both the anterior and lateral axial directions, allowing for greater displacement. In this specification, the "anterior" or "outward" direction refers to the direction in which the distance from the proximal end increases. Greater displacement is considered advantageous for thrombus uptake.

[0032] Figures 3A-2 to 3A-4 show other structures of a funnel-shaped distal tip according to one embodiment of the present invention. As shown in Figure 3A-2, instead of individually operable cantilever beams, the distal tip 350 includes a substrate layer formed as a circumferential portion 322 and a plurality of cantilever beam portions (e.g., cantilever beam portions 323a to 323c). In Figures 3A-2 to 3A-4, the underlying compliant layer covering the lumen 120 from the inside is omitted for clarity. The cantilever beams are positioned around an annular EAP actuator 321 that expands radially when operated. The substrate layer may be formed from a highly elastic material, for example, compared to the underlying compliant layer. On the other hand, each cantilever beam portion can be made flexible by removing local thickness at a pivot point. The pivot point is located, for example, where the cantilever beam extends from the circumferential portion 322. Local thickness removal can be performed, for example, by laser ablation. Figures 3A-2 and 3A-3 show the relaxed and activated states of the distal tip 350. In the activated state, the cantilever beam opens outward due to the expansion of the EAP actuator 321, and the diameter of the distal tip 350 increases.

[0033] Figure 3A-4 shows the mechanical action due to the expansion of the EAP actuator 321. As shown in Figure 3A-4, the expanded EAP actuator 321 has an outer radius R1, which is amplified by the cantilever beam to a flared radius R2 at the opening of the lumen 120. In this configuration, the EAP actuator 321 is located at a distance L1 from the pivot point, and the flared opening at the distal tip 350 is located at a distance L2 from the pivot point. The limited strain of the EAP actuator 321 is amplified in this configuration according to the relationship R1 / R2 = L1 / L2.

[0034] The actuator of the present invention can also be integrated as one or more long strips at the distal tip, and can be wrapped around the distal tip by a helical pattern that further extends longitudinally toward the proximal end of the instrument. Figure 3B shows an actuator 321 helically wrapped around the distal tip 300 according to one embodiment of the present invention. In practice, the desired action can be obtained even if the strip wrapped around the distal tip is passive (i.e., not actively controllable). For example, additional polymer material can be wrapped actively or passively in the same helical direction as the actuator 321 (e.g., clockwise when viewed from the distal tip 300 toward the proximal end of the instrument) or in the opposite helical direction (e.g., counterclockwise when viewed from the distal tip 300 toward the proximal end of the instrument). Figure 3C shows a highly elastic material 322 wrapped in the opposite helical direction (i.e., opposite chirality or direction) to the helical actuator 321 of the distal tip 300 according to one embodiment of the present invention.

[0035] The highly elastic material 322 itself may be the EAP actuator. In one embodiment, the highly elastic material 322 may be formed using a more elastic polymer material than the relatively compliant substrate around which it is wound. Reverse winding (i.e., arranging two strips with opposite chiralities as shown in Figure 3C) allows the extension of the actuator 321 to combine axial and rotational motion at the distal tip 300. As shown in Figure 3C, the actuator 321 may be formed using an elastomer inner layer (e.g., PTFE, Pebax, or TPU). (Pebax is a type of block copolymer composed of a rigid polyamide block and a soft polyether block, with varying hardnesses.) The elastomer inner layer is supported by the highly elastic material 322 (e.g., a harder Pebax), and the highly elastic material 322 is wound with a different chirality than the actuator 321. This directs energy away from the actuator 321, resulting in axial extension of the distal tip 300.

[0036] Alternatively, the actuator of the present invention may be in a form that is primarily wound on its own (i.e., wound circumferentially). Figure 3D shows a distal end 300 of a tubular instrument 350, according to a second embodiment of the present invention, which includes an EAP actuator 326 wound circumferentially around the body of the tubular instrument 350 between the distal end 300 and the proximal end 305 of the distal end 300. When activated, the EAP actuator 326 expands and relaxes circumferentially around the distal end 300, thereby providing radial motion that dynamically changes the inner diameter of the distal end 300 (i.e., the diameter of the lumen 120) by the EAP actuator 326. The EAP actuator 326, composed of a material with higher elasticity than the underlying compliant material, provides mechanical support and resistance to crushing during suction. In one embodiment, a single-wound EAP actuator 326 can be formed so that both ends abut each other when activated. In this embodiment, when not activated, the single-wound actuator 326 may have a gap between its ends. Reinforcement material can be provided in the gaps to reinforce the operating single-wind actuator 326. Alternatively, the single-wind actuator 326 can be formed by folding one end of the EAP strip over the other end.

[0037] Furthermore, additional EAP actuators can be provided along the proximal portion 155 to facilitate the transport of the aspirated thrombus or thrombus fragment through the lumen 120. Figure 3E shows a tubular instrument 370 equipped with EAP actuators 326-1, 326-2, 326-3, and 326-4 wound circumferentially around it, according to one embodiment of the present invention. In some embodiments, the circumferentially wound actuators 326-1 to 326-3 can act in an interdependent and cooperative manner to generate peristaltic motion that assists the passage of the thrombus in a predetermined operating pattern. The movement of the actuators can assist in advancing the instrument 370 toward an intravascular, ureter, gallbladder, or other appropriate target location. Furthermore, by integrating reinforcing material inside or around the actuators, it is also possible to guide the kinetic energy of the actuators toward optimal motion in a preferred direction.

[0038] In short, by integrating one or more actuators at the distal tip of the instrument, adjustable mechanical energy can be provided to optimize the instrument's operation. To further fine-tune performance, a mass can also be integrated into the instrument to increase the energy output at a selected resonant frequency. In some embodiments, a radiopaque material may be used as the integration material, thereby achieving the additional purpose of providing visibility under fluoroscopy when guiding the instrument within the patient's body. Alternatively, a tungsten mass can be used. Tungsten is a commonly used material in instrument construction, and its safety, manufacturability, and cost characteristics are well understood. Figure 3F shows a mass 345 positioned along the distal end of the distal tip 300 according to one embodiment of the present invention. Alternatively, one or more masses may be positioned more proximal (e.g., in the middle portion of the distal tip 300). The resonant frequency of maximum operation in the mass 345 can be optimized by adjusting the size and center of gravity of the mass 345 along the length of the mechanical operation of the distal tip 300.

[0039] Furthermore, the displacement of an actuator can be optimized by constraining its movement at one or more points, which may increase the action or effect at other points. In some embodiments, constraint can be achieved by incorporating a less rigid material at the point where greater displacement is desired, either by attaching or enclosing a more rigid material at the constrained point. Figure 3G shows an example in which multiple reinforced actuators (including actuators 341-1 and 341-2) are integrated into the configuration of Figure 2A according to one embodiment of the present invention. As shown in Figure 3G, both the proximal and distal ends of each actuator 341-1 and 341-2 function as points to be constrained or compliance points to adjust the displacement of the respective actuator. For example, if the proximal end 347-1 of actuator 341-1 is stiffened and constrained, the displacement along the entire length of actuator 341-1 is increased. The effect is further increased if the distal end 346-1 is also constrained. If actuator 341-1 is restricted only at its proximal end 347-1 and its distal end 346-1 is relatively unrestricted or has compliance, actuator 341-1 provides maximum displacement at its distal end.

[0040] In some embodiments, limitations in the actuator work in cooperation with the substrate to which the actuator is embedded or mounted to impart a desired operation (e.g., maximum displacement) at the distal end of the actuator. Figures 3H-1 to 3H-3 show a configuration in which the operation of the actuator 360 is enhanced by a substrate 351 according to one embodiment of the present invention. For example, in Figure 3H-1, the actuator 360 is embedded in a substrate 351 whose thickness changes along the longitudinal direction of the actuator 360. As a result, the desired operating position (e.g., maximum displacement position) can be controlled depending on the elastic modulus of the material of the substrate 351 and whether or not there is a limitation along the length of the actuator 360. Figure 3H-2 shows a configuration in which the actuator 360 is mounted on a substrate 351 whose thickness decreases near or at the midpoint of the actuator 360. In this configuration, the maximum displacement is obtained near or at the midpoint of the actuator 360. Figure 3H-3 shows a configuration in which the actuator 360 is mounted on a substrate 351 which has a limitation imposed at the proximal end. In this case, the maximum displacement is obtained at the free distal end of the actuator 360. Therefore, the desired operation of the actuator 360 can be achieved by adjusting the flexibility of the substrate (e.g., appropriate selection of the substrate width, thickness, and other dimensions).

[0041] In some embodiments, passive mechanical motion can be incorporated into the opening of the lumen 120 at the distal tip of the instrument. Figures 3I-1 and 3I-3 show an example in which passive action is incorporated into the distal tip 300 of the instrument 380 according to one embodiment of the present invention. As shown in Figure 3I-1, at the opening of the lumen 120, the distal tip 300 may include a diamond pattern structure 390 formed from braided wire (e.g., round braided wire or flat braided wire) or a net-like component (e.g., laser-cut tubing) (it is known to those skilled in the art that laser-cut tubing has conventionally been used in stent structures). In Figures 3I-1 to 3I-3, a polymer coating layer may be provided on the diamond pattern structure 390, but it is omitted in these figures to clearly show the diamond pattern structure 390. The diamond pattern structure 390 consists of rows of diamond-shaped elements. As shown in Figure 3I-2, the angle of each diamond element in the rows near the distal end of the diamond pattern structure 390 decreases towards the proximal end. In this configuration, when a thrombus is captured and the opening of the lumen 120 at the distal tip 300 is occluded, the suction pressure within the lumen 120 decreases. This decrease in suction pressure compresses the tubular structure of the distal tip 300 in the axial direction, causing the diamond pattern structure 390 to expand radially from the proximal to the distal portion, thereby increasing the size of the opening of the lumen 120 (see Figure 3I-3).

[0042] Figures 3J-1 to 3J-4 show an example of incorporating a second passive mechanical action into the distal tip 300 according to another embodiment of the present invention. Figure 3J-1 shows the distal tip 300 in a stationary state. The distal tip 300 includes a tubular flexible region 395 defined by rings 397-1 and 397-2 behind the opening of the lumen 120. Rings 397-1 and 397-2 may be formed of a more elastic material than the tubular flexible region 395. Multiple flexible flexure beams oriented along the axial direction are attached to both rings 397-1 and 397-2 (although only a single flexure beam 396 is shown in Figures 3J-1 to 3J-4, it should be understood that beams like flexure beam 396 are arranged at equal or unequal intervals around the flexible region 395, each attached to both rings 397-1 and 397-2). Rings 397-1 and 397-2 are relatively more elastic than flexible region 395, but also have sufficient compliance to allow the inner radius of each ring to expand to allow the thrombus to pass through when it is pressed against the ring.

[0043] First, upon reaching the thrombus at the opening of the lumen 120, the suction pressure within the lumen 120 decreases, and the tubular flexible region 395 is compressed radially and stretched axially. This action causes the tubular flexible region 395 to move toward the thrombus. The force promoting the forward movement of the flexible region 395 is transmitted via the flexure beam (e.g., flexure beam 396), causing the distal tip 300 to expand at the opening of the lumen 120. This state is shown in fluoroscopic and lateral views in Figures 3J-2 and 3J-3, respectively. The expanded opening of the lumen 120 allows the thrombus to be drawn in by the suction pressure and then pulled inward. Figure 3J-4 shows the drawn-in thrombus 399 being pressed against the ring 397-1, expanding the inner radius of the ring 397-1, which increases the likelihood that the thrombus 399 will be drawn into the tubular flexible region 395 by the suction pressure.

[0044] It is known that an inner lining may be provided on the surface of the suction conduit of a suction device. The distal tip of conventional devices has a slightly rounded or inclined (i.e., angled forward or oblique) shape. Such a distal tip does not cause trauma to surrounding tissue when the distal tip passes through a blood vessel. The inclined tip can increase the cross-sectional area of ​​the opening of the suction conduit through which the thrombus is taken up. In such a suction device, the innermost tubular layer (e.g., the wall of the suction conduit through which the taken-up thrombus passes) may be formed of, for example, an etched PTFE layer, Pebax, or other material. A coil or braided layer is arranged surrounding the inner layer, and a urethane or Pebax material is reflowed over it to form a consistent structure. Since etched PTFE is not a melt-workable material, its shape is limited to a straight tube shape. On the other hand, according to one embodiment of the present invention, the inner layer of the device may be formed of Pebax (e.g., nylon) or PVDF, which is a melt-workable fluoropolymer. Both Pebax and PVDF can be used to shape liners to the desired dimensions for thrombectomy.

[0045] In one embodiment of the present invention, a patterned or textured liner (e.g., the surface of a PVDF layer) may be provided along part or the entire length of the suction conduit of the instrument, particularly along the distal end of the instrument. Figure 4A-1 shows a textured surface 410 provided on the wall of the lumen 120 of the distal end 300 of the instrument. Such a liner can facilitate additional movement and apply additional stress to the ingested thrombus or thrombus fragment, thereby making it easier to further break down the ingested thrombus or thrombus fragment. Such a liner can also move the ingested thrombus or thrombus fragment to facilitate its removal. These effects can be further enhanced by operating the instrument with axial vibration in the anterior-posterior direction, with or without vibration by the actuator at the distal end of the instrument or with or without suction pressure.

[0046] In one embodiment of the present invention, one or more sensors or transducers may be provided in combination with the EAP actuator. For example, one or more portions of a patterned or textured layer (e.g., distal end) can function as electroactive sensors. The sensors can be located at any position within the catheter body or outside the catheter body (e.g., inside a tube connected to the catheter). The sensors are used to detect the presence of a thrombus and provide an electrical signal as a sensory output. The sensory outputs of the electroactive sensors or other sensors are fed back to the controller, which can assist in performing a thrombectomy by adjusting the suction pressure, the frequency or amplitude of vibration of the EAP actuator, or a combination thereof.

[0047] Figures 4A-2 and 4A-3 show a side view and a perspective view, respectively, of exemplary textured surfaces 410 provided as steps cut into the inner wall of the lumen 120.

[0048] Figures 4A-4 and 4A-5 show cross-sections of the textured surface 410, which is provided in the form of patterned step-like protrusions, when viewed toward the opening of the lumen 120 and when viewed from inside the distal tip toward the opening of the lumen 120, respectively.

[0049] Figures 4A-6 to 4A-8 show (a) a side view and a perspective cross-sectional view, and (b) a perspective view, of the textured surface 410 provided in the form of other patterned step-shaped protrusions.

[0050] In another embodiment of the present invention, the inner layer may be etched to form a "fluted" surface on the wall of the suction conduit. A fluted surface refers to a surface having axially extending protrusions, which are separated from each other by axially extending gaps or channels. Figure 4B shows the wall of the lumen 120, where the raised portion 411 is separated by channels 412. The raised portion 411 may have a textured or patterned surface (e.g., formed using PVDF) or a smooth surface using an appropriate material.

[0051] In other embodiments of the present invention, the wall of the suction conduit may be etched to form etched recesses. For example, the etched recesses may form a "rifle-shaped" channel (i.e., a continuous helical groove) that extends along part of the total length of the distal tip, or along a substantial portion or the entire length of the instrument. Figures 4C-1 and 4C-2 show a cross-sectional and a perspective view, respectively, of a helical groove 422 formed in the enclosure wall of the lumen 120. In other embodiments, the patterned surface may be formed into a screw-like structure with a helix, which, combined with the mechanical motion of one or more actuators, presses against the inner patterned surface as the aspirated thrombus rotates as it passes through the instrument. In this process, the size of the thrombus may be reduced by abrasion along the suction conduit. Figures 4D-1 and 4D-2 show a cross-sectional and a perspective view, respectively, of a screw-like raised structure 423 with a helix formed in the enclosure wall of the lumen 120, according to one embodiment of the present invention.

[0052] In other embodiments, the patterned surface may have a scaly appearance (for example, a configuration similar to the familiar patterns found on the soles of cross-country skis, snakeskin, or woodworking rasp).

[0053] The textured surface on the side wall of the lumen 120 can incorporate actuators or movable or extendable elements to preferentially move the aspirated thrombus proximally. Figures 5A-1 to 5A-3 show the operation of a textured structure 500 provided on the enclosing side wall of the lumen 120 according to one embodiment of the present invention. As shown in Figure 5A-1, the structure 500 includes a highly elastic movable element 501—which may itself be an EAP actuator—which can move or extend axially relative to a fixed flexure beam 502 provided to restrict lateral (i.e., radial) movement. The textured structure 500 also includes a compliant region formed from a reinforcing flexure beam 504 connected laterally by an extendable element 503. The extension element 503 acts as a compressible spring that stretches the compliant region laterally while resisting the pressure on the distal tip 300 proximal to the axial movement of the highly elastic movable element 501. The EAP actuator 506, which extends axially across the entire compliant region, has one end attached to the highly elastic movable element 501 and the other end attached to the proximal portion of the distal tip 300 beyond the compliant region. In this embodiment, the actuator 506 is mounted outside the lining of the lumen 120 and is therefore not shown in Figure 5A-1.

[0054] Figure 5A-2 is a perspective view of the distal tip 300, which has two textured structures 500 on each of the opposite side walls of the lumen 120. For clarity in the following explanation, the actuator 506 is not shown in Figure 5A-2. Figure 5A-3 shows the actuator 506 provided on the extension element 503 in the compliant region of the structure 500. When a thrombus is pushed proximal by suction pressure within the lumen 120, the lumen 120 may become corked, thereby reducing the suction pressure. At this time, the actuator 506 operates in a vibrating manner, causing the highly elastic movable element 501 to move axially back and forth. Simultaneously, the extension element 503 in the compliant region also participates in the movement. In the relaxed state of the actuator 506, it provides a restoring force to push back the highly elastic movable element 501, and in the activated state, the lateral movement of the extension element 503 increases the diameter of the lumen 120. This radial expansion of the lumen 120 facilitates the movement of the aspirated thrombus or thrombus fragment toward the proximal end of the textured structure 500. The reinforcing flexure beam 504 limits the bending of the extension element 503, maintaining the structural integrity of the distal tip 300. The combined effect of the axial and radial motion of the textured structure 500 is highly effective in preventing caulking of the lumen 120 and guiding the aspirated thrombus or thrombus fragment toward a preferred direction.

[0055] Figures 5B-1 to 5B-2 show the operation of a second textured structure 550 provided on the side wall of a lumen 120 according to one embodiment of the present invention. The textured structure 550 operates on essentially the same principle as the textured structure 500 shown in Figures 5A-1 to 5A-3. On the other hand, the extension element 503 of the compliant region is replaced with a membrane 553 having a lower modulus of elasticity than the highly elastic movable element 551. As shown in Figure 5B-1, the textured structure 550 is provided with a highly elastic movable element 551, which can move axially relative to the fixed flexure beam 552 when an actuator 556 (not shown) is activated. One end 557a of the membrane 553 of the compliant region is connected to the highly elastic movable element 551, and the other end 557b is connected to the proximal side of the distal tip 300. The actuator 556 is fixed to the textured structure 550 on the outside of the lumen 120 (see Figure 5B-2), and the membrane 553 is connected to a reinforcing flexure beam 554, which restricts the movement of the membrane 553 within the membrane plane when the actuator 556 is activated. When the actuator 556 is activated, the highly elastic movable element 551 moves towards the proximal end of the textured structure 550, increasing the diameter of the lumen 120 by laterally extending the region of the low-elastic material. The reinforcing flexure beam 554 maintains structural integrity by restricting the bending of the low-elastic material region. Thus, the operation of the highly elastic movable element 551 and the membrane 553 is substantially similar to the corresponding structures shown in Figures 5A-1 to 5A-3. In some embodiments, the actuator 553 can also be embedded in the membrane 553, in which case the membrane 553 is formed from a two-layer laminate of the low-elastic material. As shown in Figure 5B-2, two textured structures 550 can be provided on each of the opposite side walls of the lumen 120. The combined action of the highly elastic movable element 551 and the membrane 553 is effective in releasing the caulking of the lumen 120 and moving the captured thrombus or thrombus fragment toward the proximal end of the distal tip 300.

[0056] Various additional embodiments aim to improve the flexibility of the funnel-shaped opening to the lumen 120 when open, while maintaining the opening to a fixed size when closed. Figures 6A-1 and 6A-2 show a clamshell structure 610 that controls the opening of the lumen 120. According to one embodiment of the present invention, the clamshell structure 610 has a flexible opening and a rigid closure limit. As shown in Figure 6A-1, the clamshell structure 610 at the distal tip 300 of the instrument includes a first structure 600a and a second structure 600b connected by elastic elements 601a and 601b. The clamshell structure 610 is provided with a compliant polymer coating, which is not shown for clarity. The first structure 600a and the second structure 600b are hinged together by integrally formed planar hinge flexures 602a and 602b at the proximal side of the distal tip 300. The planar hinge flexure 602b is located at the distal tip 300, 180 degrees opposite to the planar hinge flexure 602a. Figure 6A-1 shows the clamshell structure 610 in the closed position, maintaining rigid closure restriction to the opening of the lumen 120. The elastic elements 601a and 601b are actuated by EAP actuators (not shown), respectively, which stretch the polymer coating, thereby unfolding the first structure 600a and the second structure 600b outward and bringing them into the open position shown in Figure 6A-2. In some embodiments, if the tension of the polymer coating is sufficient, the clamshell structure 610 can be held open via the elastic elements 601a and 601b. This configuration allows for large displacement of the opening of the lumen 120 while strictly limiting the size of the opening in the closed position.

[0057] Figures 6B-1 and 6B-2 show a stent-like mechanical structure 650 for controlling the opening of the lumen 120. According to one embodiment of the present invention, similar to the clamshell structure 610 in Figures 6A-1 and 6A-2, the stent-like mechanical structure 650 also allows a flexible open state relative to the opening while maintaining a rigid closing limit in the closed state. As shown in Figure 6B-1, the stent-like mechanical structure 650 is provided in a compliant (i.e., low-elasticity) polymer layer 651 that forms the inner wall of the lumen 120. The stent-like mechanical structure 650 may consist of a laser-cut connected mechanical framework formed from NiTi or other suitable material. Figure 6B-1 shows the stent-like mechanical structure 650 in a relaxed or closed state. Figure 6B-2 shows the compliant structure 650 in an open state. Thus, the stent-like mechanical structure 650 has the advantage of having low rigidity in the open state and high rigidity in the closed state, and can maintain strict closure limits to prevent the opening of the suction conduit from collapsing.

[0058] Alternatively, the compliant structure for controlling the opening of the lumen 120 may be formed using a foldable membrane material. Figures 6C-1 to 6C-3 show the operation of controlling the lumen 120 by a tubular compliant structure 680 using a foldable membrane material according to one embodiment of the present invention. Figure 6C-1 shows the distal tip 300 with the tubular compliant structure 680 provided at the opening of the lumen 120. The tubular compliant structure 680 may be provided with a polymer cover (not shown). The tubular compliant structure 680 is connected to a non-compliant base 681 at the proximal part 681 of the distal tip 300. The tubular compliant structure 680 includes a number of rigid sliding plates 693 and a foldable membrane sheet 692 connecting them. Figure 6C-1 shows the tubular compliant structure 680 in a closed or folded state. Figure 6C-2 shows the tubular compliant structure 680 in an open state. Figure 6C-3 shows the configuration of the tubular compliant structure 680 in the open state (A) and the closed or folded state (B). In position A, stretching the polymer cover (e.g., by an EAP actuator) causes the folded membrane sheet 692 to sag, and each sliding plate 693 expands to the opening position (i.e., minimum overlap), providing a large displacement of the tubular compliant structure 680 from the folded state. On the other hand, in position B, the folded membrane sheet 692 is under tension, and each sliding plate 693 is in the state of maximum overlap with each other, maintaining the minimum diameter at the opening of the lumen 120.

[0059] Figure 7A shows an integrated thrombectomy device or instrument 700 according to one embodiment of the present invention. As shown in Figure 7A, the integrated thrombectomy device 700 includes a distal tip 724, a flexible catheter body 726, and a digital controller 728. The distal tip 724 comprises an integrated EAP actuator 725 and an expander 721. As previously stated, “integrated EAP actuator” refers to a combination of one or more EAP actuators and other electrical and mechanical elements to form a component for constructing a functional device. The expander 721 has a tapered outer shape. The flexible catheter body 726 has a large-diameter lumen continuously along its entire length and functions as a suction and fluid conduit. In one embodiment, the lumen at the distal end 722 of the flexible catheter body 726 is designed to be larger than that of the rest of the flexible catheter body 726, thereby improving the suction pressure at the distal end. The proximal end of the flexible catheter body 726 is provided with a port 727 that can be connected to a suction device (not shown), allowing for the supply of suction pressure and fluid drainage. The integrated EAP actuator 725 receives electrical control signals from the digital controller 728 via electrical conductors or wiring embedded in the cylindrical wall of the flexible catheter body 726 (see inset 723 in the figure). In one embodiment, the electrical wiring includes at least two copper coils and at least one stainless steel coil. The copper coils are provided to transmit electrical control and data signals between the digital controller 728 and the integrated EAP actuator 725. The stainless steel coil provides structural strength to the flexible catheter body 726, preventing the large diameter lumen from collapsing under suction pressure (i.e., suction pressure of 30 in. Hg or less) and preventing kinking along the flexible catheter body 726. If necessary, an additional support ring or band (metal ring, e.g., stainless steel ring) can be provided at an appropriate location on the flexible catheter body 726 (e.g., near the EAP actuator 725) to restrict the inward or longitudinal movement of the integrated EAP actuator 725, while also providing the flexible catheter body 726 with additional structural strength and integrity.

[0060] The distal tip 724 may be provided with one or more radiopaque markers to guide the distal tip 724 within the blood vessel. As shown in Figure 7A, the radiopaque markers are located between the integrated EAP actuator 725 and the dilator 721. The dilator 721 has a shape that facilitates the passage of the distal tip 724 through the blood vessel to reach the target site. The dilator 721 may be configured to expose or open a large-diameter lumen for thrombus uptake using any of the techniques described above.

[0061] Figure 7B is an enlarged view of the integrated EAP actuator 725 at the distal tip 724 of an integrated thrombectomy device 700 according to one embodiment of the present invention. Figure 7B shows a later stage in the formation of the integrated EAP actuator 725. As shown in Figure 7B, the integrated EAP actuator 725 may be formed circumferentially on the outer surface of the mandrel 702. At the end of the formation of the integrated EAP actuator 725, the mandrel 702 is removed to provide a large-diameter lumen. The mandrel 702 may be, for example, a PTFE glass-filled cylinder or tube whose outer circumference matches the desired large-diameter lumen in the integrated EAP actuator 725. The first to be formed on the mandrel 702 is the inner polymer layer 703 of the integrated EAP actuator 725. The inner polymer layer 703 may be a Pebax layer. In some embodiments, multiple Pebax layers of different durometers may be provided as transition layers.

[0062] A polyimide flexible circuit 704 is provided on the outer surface of the inner polymer layer 702. The polyimide flexible circuit 704 may be provided with two or more electrodes 707 for attaching the EAP actuator (for example, using conductive ink). As shown in Figure 7B, the EAP actuator 705 is formed on the polyimide flexible circuit 704. The EAP actuator 705 is shown electrically in contact, for example, at position 706. The EAP actuator 705 may be formed from one or more suitable electroactive polymers as described above. In one embodiment, the EAP actuator 705 is formed from a rectangular sheet (for example, 11.0 mm × 23.5 mm) and then wound circumferentially around the inner polymer layer 720, with opposing long sides in contact with each other. The electrodes 707 may be electrically connected to copper coils embedded in a flexible catheter body 726, for example, using wire soldering techniques. In one embodiment, the flexible catheter body 726 has two copper coils and one stainless steel coil embedded in it, each coil having, for example, 26 turns per inch. In one embodiment, as shown in Figure 7B, a Pebax coating 710 (with different durometers for transitions as needed) is provided along the outer surface of the flexible catheter body 726, extending distally to the vicinity of the polyimide flexible circuit 704. The remaining portion of the integrated EAP actuator 725 (shown as the ellipse 701 in Figure 7B) is coated with Tecoflex material using techniques described later in connection with Figure 7C. The Tecoflex material can be obtained, for example, as an adhesive based on a rapidly crystallizing polyurethane resin.

[0063] Figure 7C shows the formation of the Tecoflex sheath in an integrated EAP actuator 725 according to one embodiment of the present invention. A short sheath portion of Tecoflex is provided to cover the integrated EAP actuator 726, with its ends overlapping the mandrel 702 and the coating material 710. In one embodiment, the Tecoflex sheath may be, for example, 0.003 inches thick. As shown in Figure 7C, the Tecoflex sheath 732 has its proximal end 731 overlapping the coating material 710 and its distal end 733 overlapping the mandrel 702. Subsequently, the proximal end 731 and distal end 733 are heated, and these polymer materials fuse with the inner polymer layer 703 and the coating material 710 (i.e., Tecoflex melts into the hydrophilic coating at the distal end 733 and into Pebax at the proximal end 731, and then reflows). In this way, the integrated EAP actuator 725 is hermetically sealed without the Tecoflex sheath 732 mixing with the EAP actuator 705.

[0064] The integrated thrombectomy device 700 may be coated with a hydrophilic coating to improve navigation characteristics and lubricity of the outer layer.

[0065] The detailed description above is provided to illustrate specific embodiments of the invention and is not intended to limit it. Numerous modifications and variations are possible within the scope of the invention. The invention is defined by the following appendix claims.

Claims

1. A device suitable for use in medical procedures, electrically connected to a controller that provides electrical control signals and mechanical suction force, A body having a distal end and a proximal end, and including a conduit between the distal end and the proximal end through which fluid moves during suction, The main body comprises one or more actuators attached to or embedded in the main body, Each actuator includes one or more electroactive polymer layers that provide mechanical motion at the distal end in response to a stimulus by the electrical control signal. The electrical control signal is provided according to at least one predetermined pattern in the device.

2. The apparatus according to claim 1, wherein it is possible to sequentially operate two or more groups of the actuators according to the predetermined pattern.

3. The apparatus according to claim 1, wherein it is possible to operate two or more groups of the actuators simultaneously according to the predetermined pattern.

4. The device according to claim 1, wherein it is possible to sequentially operate two or more groups of actuators according to the predetermined pattern, and to simultaneously operate two or more actuators within each group.

5. The apparatus according to claim 4, wherein each actuator extends along the longitudinal direction of the main body.

6. The apparatus according to claim 5, wherein two or more groups of the actuators are arranged at a radial distance from the longitudinal axis of the conduit.

7. The apparatus according to claim 1, wherein the mechanical suction force changes in coordination with the predetermined pattern.

8. The apparatus according to claim 7, wherein the pressure of the mechanical suction force decreases when one of the mechanical movements includes longitudinal movement at the distal end of the main body.

9. The apparatus according to claim 1, wherein the distal end of the main body is provided with an opening for exposing the conduit, and the portion of the main body provided with the opening has a funnel shape.

10. The apparatus according to claim 9, wherein the actuator is located behind the opening.

11. The actuator includes a first actuator, The apparatus according to claim 1, wherein the first actuator is spirally wound around the main body.

12. The actuator includes a second actuator, The apparatus according to claim 11, wherein the second actuator is wrapped around the main body with a chirality different from that of the first actuator.

13. The actuator includes a first actuator, The apparatus according to claim 1, wherein the first actuator is substantially wound circumferentially with respect to the longitudinal axis of the main body.

14. The apparatus according to claim 13, wherein the first actuator has a first end and a second end, and the first end and the second end come into contact with each other during the mechanical movement of the first actuator.

15. The device according to claim 13, wherein the first actuator has a first end and a second end, a gap is provided between the first end and the second end, and the first actuator is attached to a reinforcing material that straddles the gap.

16. The apparatus according to claim 1, further comprising a flexible circuit to which the actuator is attached.

17. The apparatus according to claim 1, further comprising a mass body disposed in one of the actuators for changing the resonant frequency of the mechanical motion of the actuator.

18. The apparatus according to claim 17, wherein the mass body contains a radiation-impermeable material.

19. The apparatus according to claim 17, wherein the mass body contains tungsten.

20. The device according to claim 1, wherein each actuator has a first end and a second end, and the mechanical movement of the actuator is restricted by reinforcing one or both ends of the actuator.

21. Each actuator is embedded in or attached to a part of the main body containing a highly elastic material. The apparatus according to claim 1, wherein the highly elastic material has a higher modulus of elasticity than the electroactive polymer layer of the actuator, and the part of the main body functions as a substrate.

22. The apparatus according to claim 21, wherein the portion of the high-elasticity material is arranged to cause the mechanical motion.

23. (i) A flexible circuit formed on the substrate, (ii) The apparatus according to claim 21, further comprising electrodes provided in the flexible circuit for supplying an electrical signal to the actuator.

24. The apparatus according to claim 1, wherein each actuator is embedded in or attached to a portion of the body comprising a low modulus material having a modulus lower than the modulus of elasticity of an electroactive polymer layer, and the portion of the body functions as a substrate.

25. The apparatus according to claim 1, wherein the main body includes a patterned material layer or a textured material layer exposed to the conduit.

26. The apparatus according to claim 25, wherein the pattern processing material layer or the texture processing material layer contains one or more of polyvinylidene fluoride (PVDF), trifluoroethylene (TrFE), 1,1-chlorofluoroethylene (CFE), and chlorotrifluoroethylene (CTFE).

27. The apparatus according to claim 25, wherein the patterned material layer or the textured material layer comprises a copolymer of polyvinylidene fluoride (PVDF) and one or more monomers selected from the group including trifluoroethylene (TrFE), 1,1-chlorofluoroethylene (CFE), and chlorotrifluoroethylene (CTFE).

28. The apparatus according to claim 25, wherein the patterned material layer or the textured material layer has one or more grooves or raised portions, and adjacent grooves or raised portions are separated from each other by channels.

29. The apparatus according to claim 28, wherein each raised portion further includes a smooth surface.

30. The apparatus according to claim 28, wherein each raised portion further includes a textured surface.

31. The apparatus according to claim 25, wherein the patterned material layer or the textured material layer includes etched recesses.

32. The apparatus according to claim 31, wherein one of the etched recesses is formed to have a rifled spiral pattern extending in the longitudinal direction of the main body.

33. The apparatus according to claim 25, wherein the patterned material layer or the textured material layer is formed to have a screw-shaped helical pattern extending along the longitudinal direction of the main body.

34. The apparatus according to claim 25, wherein a movable element that enables axial movement is incorporated in the patterned material layer or the textured material layer.

35. The apparatus according to claim 34, further comprising a flexure beam that restricts the movable element mainly to axial movement.

36. The apparatus according to claim 35, wherein the patterned material layer or the textured material layer further includes a compliant region having higher compliance than the region in which the movable element moves.

37. The apparatus according to claim 36, wherein the compliant regions include flexure beams connected to each other by extension elements.

38. The apparatus according to claim 37, wherein the extension element pushes the flexure beam in the compliant region, causing the conduit to expand radially.

39. The apparatus according to claim 1, further comprising a mechanical structure opening toward the conduit, wherein one of two positions in the mechanical structure is a flared opening toward the conduit, and the other is maintained so as not to widen beyond the size of the conduit.

40. The apparatus according to claim 39, wherein the exterior of the mechanical structure is covered with a polymer coating.

41. The apparatus according to claim 39, wherein the mechanical structure includes a first part and a second part connected to each other by one or more elastic elements.

42. The apparatus according to claim 39, wherein the mechanical structure includes a plurality of movable plates connected to one another by a sheet of foldable membrane material.

43. The apparatus according to claim 1, comprising one or more radiopaque elements provided at the distal end of the main body.

44. The apparatus according to claim 1, wherein the distal end of the main body is coated with a hydrophilic coating.

45. The apparatus according to claim 1, further comprising one or more support bands that provide mechanical support to the main body.

46. The apparatus according to claim 45, wherein each of the support bands is made of stainless steel.

47. The device according to claim 45, wherein the support band maintains the conduit in an open state when the suction pressure is 30 inHg or less.

48. The device according to claim 1, further comprising one or more support bands on the main body, thereby restricting the longitudinal or axial movement of one or more actuators.

49. A device suitable for use in medical procedures, configured to operate according to electrical signals received from a controller, It includes a catheter body having a proximal end and a distal end, The distal end includes a tapered tip portion, An integrated electroactive polymer (EAP) actuator is positioned between the tapered tip and the proximal end. (i) The catheter body includes a lumen that extends continuously along the entire length of the catheter body and forms a fluid conduit, thereby allowing fluid to flow in from the tapered opening at the tip and flow toward the proximal end of the catheter body under suction pressure. (ii) The catheter body further includes two or more electrical conductors inside which the electrical signal is transmitted between the controller and the integrated EAP actuator, (iii) The integrated EAP actuator operates by the electrical signal, (iv) A device in which the electrical signal and the suction pressure change in a coordinate manner according to one or more predetermined patterns.

50. The device according to claim 49, wherein the tapered tip portion includes an expander.

51. The device according to claim 49, wherein the fluid conduit of the catheter body has a larger radius at the distal end than at the proximal end.

52. The device according to claim 49, wherein the proximal end of the catheter body is provided with a port that opens toward the fluid conduit and is adapted to be connected to a suction device.

53. The device according to claim 52, wherein each electrical conductor is helically embedded inside the catheter body.

54. The device according to claim 49, wherein one or more wires are spirally embedded inside the catheter body to provide mechanical support.

55. The device according to claim 54, wherein the wire is made of stainless steel.

56. The device according to claim 49, wherein the fluid conduit is mechanically supported in the catheter body so that it remains open when the suction pressure is 30 inHg or less.

57. The device according to claim 49, further comprising one or more support rings or support bands to provide mechanical support.

58. The device according to claim 57, wherein the support ring or support band restricts the inward or longitudinal movement of the EAP actuator.

59. The device according to claim 57, wherein one or more of the support rings or support bands function as radiopaque markers for guiding the distal end of the catheter body within a blood vessel.

60. The device according to claim 49, wherein the integrated EAP actuator comprises one or more EAP actuators and an inner polymer layer.

61. The device according to claim 60, wherein the inner polymer layer comprises Pebax.

62. The device according to claim 60, wherein the inner polymer layer is composed of multiple layers having different durometer hardnesses.

63. The device according to claim 60, wherein the integrated EAP actuator further includes a flexible circuit having electrodes for mounting and electrically connecting the EAP actuator.

64. The device according to claim 63, wherein the flexible circuit further includes conductive ink provided for electrically connecting the electrical conductor inside the catheter body to the electrode.

65. The device according to claim 60, wherein each EAP actuator is formed from a rectangular sheet wound circumferentially around the inner polymer layer, with opposing sides of the rectangles in contact with each other.

66. The device according to claim 60, wherein the electrical conductors inside the catheter body are each embedded in the form of conductive coils.

67. The device according to claim 60, wherein a covering material (outer jacket) is provided along the outer surface of the portion of the catheter body excluding the integrated EAP actuator.

68. The device according to claim 67, wherein the integrated EAP actuator is encased in a thermoplastic polyurethane (TPU) material.

69. The device according to claim 68, wherein a part of the distal end of the catheter body is coated with an aqueous coating.

70. The device according to claim 69, wherein the TPU material is bonded to the inner polymer layer and the coating material.

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