Patent Grant
11918766
Not applicable
The invention relates to a steerable intraluminal medical device and, more particularly, to a flexible, narrow medical device (such as a micro-catheter or a guidewire) introduced into and controllably moved through lumens of a body. The medical device may include an electrically-actuatable bendable portion at a distal, leading end that can be selectively manipulated for steering the medical device to a targeted anatomical location within a body.
Intraluminal medical devices have various structures depending on the location within the body and the methods of treatment using the devices. Intraluminal devices generally include of a very slender and flexible tube that can be inserted into and guided through a lumen such as an artery or a vein, or a bodily passageway such as a throat, a urethra, a bodily orifice or some other anatomical passage. Examples of such medical devices include syringes, endoscopes, catheters and micro-catheters, guide wires and other surgical instruments.
Some medical devices have a portion for being introduced into a body that generally comprises a flexible material that is easily bent by application of external force. In some medical devices, a distal, leading end (usually inserted first) may be selectively bent in a desired direction through manipulation of a steering mechanism by the user. The medical device can be inserted into a targeted lumen or bodily passage and moved to dispose a distal end of the medical device at a desired location in the body.
Surgical techniques for inserting and/or guiding a medical device into and/or through a lumen or passage in a body have been proposed in response to the rise in demand for minimally invasive surgical techniques. Many surgical techniques offer poor directional control or cumbersome manipulative components.
Embodiments of the steerable intraluminal medical device provide improved steering control and intra-body positioning of an actuation part (e.g., a micro-catheter or a guidewire) of a medical device wherein the actuation part is adapted to be introduced into a lumen or a bodily passage of a body and manipulated while being extended for movement into and through the lumen and/or bodily passage to dispose a distal end of the actuation part of the medical device at a desired anatomical location within the body. Embodiments of the medical device provide more precise control of movement and positioning of one or more manipulatable microsurgical components disposed at a distal, leading end of the actuation part of the medical device for performing a surgical procedure or other medical operation at the desired location within the body.
One embodiment of a medical device having an actuation part (e.g., a micro-catheter or a guidewire) for being moved into and/or through a lumen or a bodily passage comprises a slender, elongate and flexible portion having a distal end and a proximal end, an ionic electroactive polymer actuator comprising a polymer electrolyte layer disposed adjacent to the distal end of the elongate and flexible portion. The ionic electroactive polymer actuator, as will be discussed in greater detail below, is an actuator comprising a polymer electrolyte layer in which cations are free to migrate in response to an imposed electrical field. The electrical field is provided through energization of a plurality of angularly distributed electrodes disposed on the polymer electrolyte layer. The plurality of angularly distributed electrodes are one of embedded in, deposited on and secured against at least a portion of an exterior wall of the polymer electrolyte layer. Each of the plurality of electrodes may be connected to a source of electrical current through one or more electrically-conductive conduit such as, for example, a metal wire, being surrounded with the outer member and having a proximal end coupled to the source of electrical current and a distal end coupled to the electrode. Selective electrical energization of one or more of the plurality of electrodes causes the polymer electrolyte layer to deform as a result of contraction along a side or portion of the polymer electrolyte layer and/or swelling along a side or portion of the polymer electrolyte layer. It will be understood that cations within the polymer electrolyte layer will migrate towards an energized and anodic electrode, and away from an energized and cathodic electrode, while remaining within the matrix of the polymer electrolyte layer. This causes a portion adjacent to an energized anodic electrode to swell and a portion adjacent to an energized and cathodic electrode to contract, thereby causing the polymer electrolyte layer to bend. It will be understood that coordinated control of electrical signals delivered to the electrodes through electrically-conductive conduits can produce bending in an intended direction. In some embodiments, the plurality of electrodes may be further electrically connected to a sensing member to sense changes in the electrical signal at each of the plurality of electrodes. Accordingly, the sensing member may detect whether the ionic electroactive polymer actuator deformed or not.
In one embodiment of the medical device, the ionic electroactive polymer actuator may comprise a plurality of angularly distributed electrodes equi-angularly distributed about the exterior wall of the polymer electrolyte layer. In one embodiment of the medical device, the ionic electroactive polymer actuator may be included in a bendable portion at the distal end of an actuation part (e.g., a micro-catheter or a guidewire) of the medical device. For example, but not by way of limitation, the bendable portion of the medical device may, in one embodiment, comprise three angularly-distributed electrodes that are separated, at their centerlines, one from the others by about 120 degrees (2.094 radians). As another example, but not by way of limitation, the bendable portion of the medical device may comprise eight angularly-distributed electrodes that are separated, at their centerlines, by about 45 degrees (0.785 radians). It will be understood that each of the plurality of electrodes occupies a circumferential span about the exterior wall of the polymer electrolyte layer, and that the “angular separation” may therefore be stated in terms of the centerlines of the electrodes instead of in terms of the adjacent edges of the electrodes, which will be much closer to the adjacent edge of the adjacent electrode. In some embodiments of the medical device, the electrodes are spaced in a manner to provide a substantial gap intermediate adjacent electrodes.
In a bendable portion at the distal end of an actuation part of another embodiment of the medical device, the ionic electroactive polymer actuator is provided in which the plurality of electrodes circumferentially distributed about the exterior wall of a polymer electrolyte layer are, along with at least a portion of an adjacent inner member of the elongate and flexible portion, surrounded by an outer member, coating, sheath or other barrier having a bore in which at least a portion of the plurality of electrodes and at least a portion of the polymer electrolyte layer surrounded by the electrodes are together disposed. The outer member, or an exterior wall of the outer member, may comprise a low-friction, hydrophilic and/or lubricious material that promotes smooth sliding engagement between the elongate and flexible portion of the medical device and an interior wall of a lumen or a bodily passage into which the actuation part of the medical device is introduced and through which the elongate and flexible portion of the medical device is extended to position a distal end of the actuation part of the medical device at a targeted location within a body. The outer member may comprise one or more materials including, but not limited to, nylon, polyurethane and/or a thermoplastic elastomer such as, for example, PEBAX®, a polyether block amide material available from Arkema France Corporation of Colombes, France.
In one embodiment of the medical device, the plurality of electrically-conductive conduits that conduct electrical signals from a source of electricity to one or more of the plurality of electrodes to affect bending of the polymer electrolyte layer comprise a noble metal for superior chemical stability and corrosion resistance. For example, but not by way of limitation, the electrically-conductive conduits that deliver current to selected electrodes to actuate the polymer electrolyte layer may comprise highly conductive platinum, a platinum alloy, silver or a silver alloy, or they may comprise gold or a gold alloy which, in addition to being chemically stable and corrosion resistant, is malleable and can be advantageously formed into very slender electrically-conductive conduits with very low resistance to bending.
In a relaxed or un-energized state, the polymer electrolyte layer of the ionic electroactive polymer actuator remains in its original form.
One embodiment of the elongate and flexible portion of the medical device includes an elongate, flexible inner member having a distal end, a proximal end, a radially interior bore with an axis, and a radially exterior wall, at least one ionic electroactive polymer actuator comprising polymer electrolyte layer having a bore, the polymer electrolyte layer secured adjacent to the distal end of the inner member with the bore of the polymer electrolyte layer aligned with the bore of the inner member, a plurality of electrodes circumferentially distributed about the at least one polymer electrolyte layer, and a plurality of electrically-conductive conduits, each having a proximal end and a distal end coupled to at least one of the plurality of electrodes, and an elongate and flexible center wire having a proximal end, a distal end and a diameter therebetween that is smaller than the diameter of the bore of the inner member to enable the distal end of the center wire to be introduced into the bore of the inner member and to then be pushed through the bore of the inner member to position the distal end of the center wire adjacent to the distal end of the inner member, a radially compressed and resilient spring member coupled to the distal end of the center wire, the compressed spring member sized, in an uncompressed or expanded configuration, for exceeding the diameter of the bore of the inner member in an expanded configuration and for fitting within and being positioned in the bore of the inner member by the center wire in a compressed configuration, wherein the polymer electrolyte layer of the ionic electroactive polymer actuator deforms asymmetrically in response to the application of one or more electrical signals conducted from a source of electrical current (which may be further coupled to the proximal end of each electrically-conductive conduit) through at least one of the plurality of electrically-conductive conduits to at least one of the plurality of electrodes coupled to a distal end of the at least one of the plurality of electrically-conducting electrodes, and wherein the center wire can be used to position the spring member immediately adjacent to the distal end of the inner member with the inner member disposed within or immediately adjacent to an obstruction in a lumen into which the inner member is introduced, and wherein the spring member can be expanded from the compressed configuration to the expanded configuration to engage and grip the obstruction in the lumen by retracting the inner member while maintaining the center wire stationary relative to the inner member to cause the compressed spring member to be removed from the bore of the inner member and released from the radially compressed configuration to the expanded configuration within the obstruction to be gripped by the expanded spring member, thereby allowing the obstruction to be retrieved from the lumen by retrieving the center wire and the inner member together from the lumen. In one embodiment, the spring member is a coil spring having a plurality of coils aligned in a series. In another embodiment, the spring member includes a plurality of corrugated or sinusoidally shaped wires, each wire coupled at the apexes of the waves or peaks to the apexes of the waves or peaks of an adjacent wire to form a generally tubular or cylindrically shaped spring assembly. It will be understood that expandable spring elements of this type generally elongate as they radially expand from a radially compressed configuration to a radially expanded configuration.
One embodiment of the medical device includes an electrically insulating layer disposed within the bendable portion of the medical device. This insulating layer provides a flexible insulating boundary layer that contains but conforms to the polymer electrolyte layer as it deforms in response to an electrical field imposed by electrical signals conducted to the surrounding electrodes to provide advantageous steering of the medical device as it is positioned within a lumen or bodily passage.
The polymer electrolyte layer comprises an electrolyte (e.g., ionic liquid, but not limited to this) and a polymer selected from the group consisting of fluoropolymers and intrinsically conducting polymers. One embodiment of a method of preparing a tubular polymer electrolyte layer for use in providing an ionic electroactive polymer actuator in a bendable portion of a medical device comprises: providing a liquid dispersion of a base material selected from the group consisting of fluoropolymers and intrinsically conducting polymers, disposing the liquid dispersion on a substrate, curing the liquid dispersion of the selected base material to form a polymer film on the substrate, providing a mandrel, wrapping the polymer film onto the mandrel, and providing a heat-shrink tube, covering a portion of the mandrel wrapped in the polymer film with the heat shrink tube, and heating the heat-shrink tube to cause reflow the polymer film to form a tubular polymer electrolyte layer.
The polymer electrolyte layer may comprise, for example, but not by way of limitation, a polymer membrane containing a electrolyte (e.g., solvent such as, water or an ionic liquid). Alternately, the polymer electrolyte may comprise a porous polyvinylidene fluoride or polyvinylidene difluoride, a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride, and containing ionic liquid or salt water. Alternately, the polymer electrolyte may comprise a gel formed by polyvinylidene fluoride or polyvinylidene difluoride, propylene carbonate and an ionic liquid.
In one embodiment of the method of preparing a tubular polymer electrolyte layer for use in providing an ionic electroactive polymer actuator in a bendable portion of a medical device, the material selected to use in forming the base material comprising fluoropolymers and/or intrinsically conducting polymers. For example, the material may be, one of Nafion® and Flemion®, which are perfluorinated ionomers. In another embodiment of the method, the material selected to use in forming the base material comprising one of polyvinylidene difluoride (PVDF) and/or one of a co-polymer thereof, for example, one of polyvinylidene difluoride-co-chlorotrifluoroethylene (P(VDF-CTFE)) and polyvinylidene fluoride-co-hexafluoropropylene (P(VDF-HFP)), which are fluoropolymers. In yet another embodiment of the method, the material selected to use in forming the base material comprising an intrinsically conductive polymer (ICP), for example, one of polyaniline (PAN I), polypyrrole (Ppy), poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(p-phenylene sulfide)(PPS). In yet another embodiment of the method of preparing a tubular polymer electrolyte layer, the material selected to use in forming the base material comprises a combination of two or more of the above listed and described base materials.
One embodiment of the method of preparing a tubular polymer electrolyte layer includes the step of dissolving the base material in a volatile solvent to form the liquid dispersion. The volatile solvents that may be used for this step include, but are not limited to, acetates, alcohol, chloroform, ether, aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons and ketones.
One embodiment of the method of preparing a tubular polymer electrolyte layer includes the step of disposing the liquid dispersion of the selected base material onto a solid substrate comprising one of polytetrafluoroethylene (PTFE) or glass. However, other solid substrates having non-stick surfaces may be substituted.
A first example of an embodiment of the method of preparing a tubular polymer electrolyte layer includes preparing a liquid dispersion of Nafion® in 10 to 20 wt. % alcohol, disposing the liquid dispersion on a flat PTFE substrate using a doctors' blade method to form a thickness of 15-25 pm, curing the liquid dispersion on the substrate at 68° F. (20° C.), removing volatile solvents by thermal treatment at 176 to 248° F. (80 to 120° C.), rolling the resulting Nafion® film around a stainless steel mandrel rod having an outside diameter of 0.025″ (0.635 mm) by manually rotating the mandrel while translating the mandrel across the substrate to roll-up the Nafion® film into a tubular shape having an interior diameter and a wall thickness.
The resulting interior diameter and wall thickness of the resulting polymer tubing depend on the mandrel size, the thickness of the Nafion® film and the number of times the mandrel can be wrapped with the Nafion® film during the rolling step. The mandrel with the rolled Nafion® film is fitted into a fluorinated ethylene-propylene (FEP) heat-shrink sleeve and then heated at the recovery temperature of the heat-shrink material 392 to 446° F. (200 to 230° C.). During heating, the layers of the rolled Nafion® film are reflowed into a single homogenous polymer layer. After cooling and removing the heat-shrink tube and mandrel, a Nafion® tube having a homogenous morphology without traces of rolled layers. The tolerance of the wall thickness of the prepared Nafion tube is similar to commercially extruded Nafion tubing (+1-10%) but is prepared without the need for commercial extrusion equipment that can require a large amount of space and equipment.
A second example of an embodiment of the method is to prepare a PVDF tube, including the steps of providing a plurality of Poly[(vinylidene difluoride)-co-(chlorotrifluoroethylene)] (P(VDF-CTFE)) pellets, dissolving the pellets in acetone by heating and stirring the pellets in the acetone at about 122° F. (50° C.) for 4 hours. The prepared dispersion is disposed on a flat PTFE substrate using the doctors' blade. The substrate and dispersion disposed thereon are cured at 68° F. (20° C.) for 30 minutes and the resulting film is then peeled from the PTFE substrate. The prepared P(VDF-CTFE) film is vacuum dried at 172° F. (80° C.) to remove the residual solvent. The formed PVDF film of 15-25 pm in thickness is rolled around a stainless steel mandrel rod having an outer diameter of 0.025 inches (0.635 mm) by manually rotating the mandrel and translating the mandrel across the film. The mandrel with the rolled PVDF film thereon is fitted into a heat-shrink polymer tube (e.g., fluorinated ethylene-propylene (FEP)) and heated at a recovery temperature of the heat-shrink material 392 to 446° F. (200 to 230° C.). The heating causes the layers of the rolled PVDF film to reflow into a single homogenous polymer tube wall. The heat-shrink tube is removed after cooling from the mandrel to remove the PVDF tube.
To further prepare an ionic electroactive polymer actuator, the prepared Nafion tube or PVDF tube may be further processed to deposit metal electrodes thereon (e.g., platinum or gold electrodes) using conventional methods such as an electrochemical process. Then, wires (e.g., gold wires) can be further integrated and embedded into the prepared metal electrodes using conducting paste or laser welding to serve as electrically-conductive conduits. Alternatively, in one embodiment, the prepared Nafion tube or PVDF tube may be further processed to deposit carbon-based electrodes using a new reflow method provided and explained in further detail below for use in providing a tubular ionic electroactive polymer actuator. Then, wires (such as gold wires) can be further integrated and embedded into the prepared carbon-based electrodes during the reflow method to serve as electrically-conductive conduits.
In one embodiment, a method of preparing a tubular ionic electroactive polymer actuator of a medical device by disposing carbon-based electrodes on a polymer electrolyte layer with a heat-shrink tube using reflow process is provided. The method may comprise: providing a polymer electrolyte layer having a radially exterior wall, providing a mixture of a carbon-based conductive powder in a volatile solvent, providing a plurality of electrically-conductive conduits, each having a proximal end and a distal end, disposing the mixture on the exterior wall of the polymer electrolyte layer to form a carbon electrode layer thereon, contacting the distal end of each electrically-conductive conduit to the carbon electrode layer, providing a heat-shrink tube, covering the polymer electrolyte layer and the carbon electrode layer thereon with the heat-shrink tube, and heating the heat-shrink tube to cause reflow of the polymer electrolyte layer to form the ionic electroactive polymer actuator. In another embodiment of the method of preparing a tubular ionic electroactive polymer actuator of a medical device, the polymer electrolyte layer may be further impregnated with an electrolyte. For example, the electrolyte may be an ionic liquid including, but not limited to, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or the combination thereof. In yet another embodiment of the method of preparing a tubular ionic electroactive polymer actuator of a medical device, a portion of the carbon electrode layer is further covered with one or more metal layer to increase the electrical conductivity of the obtained carbon-based electrodes. The metal layer herein may be, for example, but are not limited to a gold layer, a platinum layer or the combination thereof.
In other embodiment of the method of preparing a tubular ionic electroactive polymer actuator of a medical device, the carbon-based conductive powder may be carbide-derived carbon, carbon nanotube, carbon aerogel, graphene, or the combination thereof. In some embodiments, the carbon-based conductive powder may optionally comprise fillers such as transition metal oxide powder, metal powder or the combination thereof. In some embodiments, the mixture of a carbon-based conductive powder is disposed on the exterior surface of the polymer electrolyte layer using brush coating or spray coating. In other embodiments, the carbon electrode layer is further micro-machined to form a plurality of electrodes after heating the heat-shrink tube.
In one embodiment of the medical device, an electrical controller is provided for controlling bending of the bendable portion by applying electrical signals to an ionic electroactive polymer actuator in the bendable portion. The electrical controller may be provided at the proximal end of the elongate, flexible portion and electrically connected to the electrically-conductive conduits for selectively controlling the electrical charges carried by the electrically-conducting conduits and imparted to the plurality of electrodes to manipulate the at least one ionic electroactive polymer actuator of the medical device. In another embodiment, the electrical controller may be further instructed by a master controller. The master controller may comprise a manipulatable control member for inputting the bending control signals to the at least one ionic electroactive polymer actuator for providing two degrees of freedom of bending through the electrical controller.
To steerably control the medical device, in some embodiments, the medical device further comprises a driving assembly for moving the medical device (e.g., the flexible, elongated member portion) lengthwise. The drive assembly includes: a first rotary drive member with a gripping surface, an adjacent second rotary drive member with a gripping surface disposed proximal to the gripping surface of the first rotary drive member, and at least one electrically powered motor coupled to controllably rotate at least one of the first rotary drive member and the second rotary drive member and wherein, the medical device is disposed intermediate and engaged by the gripping surface of the first rotary drive member and the gripping surface of the adjacent second rotary drive member so that rotation of one of the first rotary drive member and the second rotary drive member axially moves the medical device. In one embodiment of steerably controlling the medical device, clockwise rotation of the first rotary drive member and counterclockwise rotation of the adjacent second rotary drive member moves the medical device in a first direction; and counterclockwise rotation of the first rotary drive member and clockwise rotation of the adjacent second rotary drive member moves the medical device in a second direction opposite to the first direction. In another embodiment, the driving assembly may be also further instructed by the master controller that comprise a manipulatable control member for inputting advance and retract control signals to the drive assembly for providing one degree of freedom of translation. In some embodiments, the master controller may provide the bending control signals as well as the advance and retract signals.
In one embodiment of steerably controlling the medical device, the medical device may further comprise a case that includes: a first portion having a sealed interior portion containing the first rotary drive member, the second rotary drive member, a proximal port through which the medical device passes, a distal port through which the medical device passes, and an interior cavity for storing windings of the medical device; and wherein the case further includes a second portion supporting the motor. In another embodiment, the second portion of the case and the first portion of the case are adapted for being coupled one to the other to operatively engage the motor with at least one of the first rotary member and the second rotary member. In other embodiments, the first portion may be disposable, for example, after use and contamination by bodily fluids contacted by the medical device.
In one embodiment, for remotely controlling/positioning the medical device when being introduced into and moving through a lumen of a human body, the medical device may further comprise: a transmitter coupled to the master controller for transmitting a signal corresponding to the manipulation of the master controller; and a receiver electrically connected to the drive assembly and the electrical controller for receiving the signal transmitted by the transmitter to the drive assembly and/or the electrical controller to correspond to the manipulation of the controller.
The appended illustrative drawings provide a further understanding of embodiments and are incorporated into and constitute a part of this application and, together with the written description, serve to explain the present invention. The appended drawings are briefly described as follows.
Medical devices such as catheters or guidewires may be sufficiently slender for being inserted into a lumen such as an artery, a vein, a throat, an ear canal, a nasal passage, a urethra or any of a number of other lumens or bodily passages. These slender catheters (also referred to as micro-catheters) and guidewires, enable physicians to perform non-invasive surgery requiring a substantially shortened recovery period by preventing the need for cutting a subject or a patient to provide local access for performing a surgical procedure or medical operation. As used herein, the terms “subject” or “patient” refer to the recipient of a medical intervention with the device. In certain aspects, the patient is a human patient. In other aspects, the patient is a companion, sporting, domestic or livestock animal.
The following paragraphs describe certain embodiments of medical devices that can be used to perform or to enable the performance of surgical operations using the same, and methods that can be used to enable the preparation of such medical devices for same. It will be understood that other embodiments of medical devices and methods are within the scope of the claims appended herein below, and the illustration of such embodiments is not limiting of the present invention.
Optionally, the proximal end 109 of the actuation part 100 may include a fastener such as, for example, threads 113, for use in securing a mating socket or other structure to the proximal end 109 of the actuation part 100. Optionally, the upper case portion imparting a forward directional aspect to a distal portion 102 of the actuation part 100 that extends beyond the case 200.
In one embodiment of the medical device 10, the ionic electroactive polymer actuator of the bendable portion 110 of
In one embodiment of the medical device 10, the electrically-conductive conduits 130 may comprise one of platinum, gold, carbon, alloys thereof or a combination thereof. In other embodiments, the material for electrodes 112 may comprise carbon, such as carbide-derived carbon, carbon nanotubes, a composite of carbide-derived carbon or ionomer, and a composite of carbon nanotube and ionomer. A method according to one embodiment of disposing the carbon-based electrodes 112 onto the polymer electrolyte layer 139 will be discussed herein below.
Each of the plurality of electrodes 112 is connected to a distal end 131 of an electrically-conductive conduit 130 through which an electrical signal may be applied to the electrode 112 to which the conduit 130 is connected, thereby causing metal cations within the polymer electrolyte layer 139 to move in a direction determined by the applied electrical signal. This cation migration produced by the applied electrical signal causes the polymer electrolyte layer 139 to swell in the portion of the polymer electrolyte layer 139 disposed proximal to the anode and to bend or warp in the direction of the remaining unswelled portion. As a result, the magnitude and the direction of bending deformations of the polymer electrolyte layer 139 of the ionic electroactive polymer actuator can be controlled by strategically selecting the electrodes 112 to energize and by adjusting the electrical signal applied through the electrically-conductive conduits 130 to the electrodes 112.
As shown in
Alternately, in the event that the actuation part 100 is observed to be in a deformed mode in the absence of the application of one or more electrical signals to one or more of the plurality of the electrodes 112, the magnitude of the observed deflection can be used to determine the magnitude and direction of an external force applied to the actuation part 100 or, alternately, in the event that the application of a known current to the electrodes 112 fails to produce an anticipated deformation of the bendable portion 110 of the actuation part 100, the difference between the anticipated deformation and the actual deformation (if any) can be used as an indicator of the magnitude of an external force applied to the bendable portion 110 at the distal end 102 of the actuation part 100 of the medical device 10.
It will be understood from
Components of the medical device 10 that are disposed in or on the lower case portion 220 are positioned to engage related components of the medical device 10 disposed in or on the upper case portion 210 to enable the coupling of these related components upon assembly of the upper case portion 210 of
In the embodiment of the medical device of
Conventional techniques and methods known in the medical sciences may be used in conjunction with the methods and with the medical device 10. For example, but not by way of limitation, the step 640 in
For example, but not by way of limitation, as the bendable portion 110 and the elongate, flexible portion 120 of the actuation part 100 is advanced forward using the drive assembly 300 of the case 200, the sensing member 117 detects whether the lumen or bodily passage through which the bendable portion 100 of the actuation part 100 is advanced is obstructed or whether there is a bend or obstruction in the lumen or bodily passage that is sufficient to prevent or impair forward movement of the actuation part 100. Also, because an electrical signal is applied to each of the plurality of electrodes 112 by the electrical controller 400, the sensing member 117 may determine whether the intended bending deformation corresponding to the plurality of electrical signals generated by the electrical controller 400 has occurred by receiving feedback about the electrical signal at each of the plurality of electrodes 112 and by comparing that feedback to the electrical signals assigned to each of the plurality of electrodes 112.
The sensing member 117 is electrically connected to each of the electrically-conductive conduits 130 that supply electrical signals to each of the electrodes 112. It will be understood that, just as the character and nature of an electrical signal delivered to an energized electrode 112 determines the unimpaired deformation imparted to the polymer electrolyte layer 139 disposed adjacent to an energized electrode 112, the actual deformation of the polymer electrolyte layer 139 can be compared to the electrical signal delivered to the adjacent electrodes to determine the direction and magnitude of an external force acting on the polymer electrolyte layer 139.
Changes in the electrode potential sensed by the sensing member 117 are caused by both an electrical signal applied to the plurality of electrodes 112 by the electrical controller 400 for bending control, and by external forces. Accordingly, the sensing member 117 may be used to determine the presence, direction and magnitude of an external force applied to the bendable portion 110 by taking into account how the electrical controller 400 performs bending control. As illustrated in
The sensing member 117 may be configured to determine the direction and/or the magnitude of an applied external force depending on whether the difference between the sensed value and the value applied by the master controller 500 exceeds a preset threshold value, AVth. For example, the actuation part 100 may be subjected to a small amount of external force as the distal end 102 is brought into contact with a lumen wall or as it encounters sliding friction while being pushed forward along a lumen or bodily passage. Accordingly, it is possible to permit an expected small amount of external force during intraluminal movement of the actuation part 100 and to detect the application of a larger magnitude external force by determining whether an external force is applied or not based on a threshold value.
While
In this exemplary embodiment, an external force is sensed by using a plurality of four electrodes 112 used for bending control, without the addition of external force sensing electrodes to the bendable portion 110. However, this is merely an example, and an external force may be sensed using various structures.
The sensing member 117 may monitor changes in electrical signal induced by the user's bending. That is, the sensing member 117 receives information about the user's bending from the electrical controller 400 or the master controller 500 and the sensing member 117 then monitors changes in electrical signals induced by bending of the bendable portion 110. Then, the sensing member 117 monitors changes in electrical signal induced by actual bending due to both internal and external forces and compares that change in the electrical signal to the isolated electrical signal indicating the intended bending.
When a change in signal (except for a change induced by bending) is sensed during monitoring, the sensing member 117 determines whether the change exceeds a preset threshold value or not, and if so, determines that an external force is applied. Furthermore, in this step, the direction of the external force or the amount of the external force may be calculated by combining information about changes at the electrodes 112.
Once the application of an external force is detected, the step of informing the user of this is performed. In this exemplary embodiment, the sensing member 117 may send an external force generation signal to the master controller 500, and issue an alarm message, an alarm sound, or haptic feedback to the user through the master controller 500. In this case, the sensing member 117 may, through the master controller 500, advise the user of both the direction and magnitude of an external force being applied to the bendable portion 110 and thereby enable the user to determine how to manipulate the bendable portion 110 for advancing beyond the obstacle engaging the actuation part 100, as well as the generation of the external force. It will be understood that if the actuation part 100 is advanced through a lumen or bodily passage with excessive force damage to contacted body tissues may occur. The capacity to detect the application of external force to the bendable portion 110 of the actuation part 100 of the medical device 10 enables the user to deactivate or slow the drive assembly 300 through the master controller 500.
The embodiments of the medical device 10 illustrated in
In an alternative embodiment of the medical device 10, the electrically-conductive conduits 130 are embedded in a radially exterior surface 122 of the inner member 120, as discussed in connection with
While
The alternate embodiment of the bendable portion 110 illustrated in
After an additional cleaning with a reducing agent such as, for example, sulfuric acid, and deionized water, the exterior wall 137 of the now platinum-coated tubular polymer electrolyte layer 139A may be further plated with a thin layer of gold (Au) using a conventional electrochemical deposition process to increase the thickness and electrical conductivity of the presently undivided metal electrodes 112 that will be ultimately formed onto the exterior wall 137 of the tubular polymer electrolyte layer 139A. Following the gold deposition processes, the circumferentially continuous sleeve-shaped platinum and gold-coated exterior wall 137 of the tubular polymer electrolyte layer 139A can be sectored into four circumferentially-distributed and isolated metal electrodes 112 using a micro-machining process. More specifically, a computer-controlled milling machine with a micro end-mill tool may be used to mechanically remove a thin layer of platinum-gold material and, optionally, a small portion of the underlying exterior wall 137 of the tubular polymer electrolyte layer 139A at a depth of, for example, twenty to forty (20 to 40) microns. In
A embodiment of a method of disposing the carbon-based electrodes 112 on the tubular polymer electrolyte layer 139A is also provided. In one example, the bendable portion 110 illustrated, e.g., in
In this exemplary example, the tubular polymer electrolyte layer 139A is preconditioned by roughening its exterior wall 137 using an abrasive (e.g., sandpaper) or by an abrasive process (e.g., sandblasting), followed by being cleaned using a reducing agent, for example, a hydrogen peroxide (H2O2) solution and/or a sulfuric acid (H2SO4) solution, and de-ionized water, but not limited to this. The roughened and cleaned tubular polymer electrolyte layer 139A is further deposition-plated with a carbon-based conductive powder, such as carbide-derived carbon, carbon nanotube, carbon aerogel, graphene, or the combination thereof.
In this exemplary example, one or more electrolytes are then incorporated in the cleaned tubular polymer electrolyte layer 139A which is first dried under vacuum (30 in Hg) at about 100 to about 140° C. for several hours to remove humidity. Thereafter, the dried tubular polymer electrolyte layer 139A is impregnated with an ionic liquid (such as EMI-BF4 or EMI-TFSI, but not limited to this) by soaking in respective ionic liquid at elevated temperature for several hours.
In this exemplary example, after being ionic liquid-impregnated, a layer of carbon-based electrodes 112 are fabricated directly onto the tubular polymer electrolyte layer 139A as follows. The conductive powder material of carbide-derived carbon (or other carbon allotrope (e.g., carbon nanotube, carbon aerogel, graphene) or the mixture thereof, but not limited to this) is dispersed in a volatile solvent of isopropanol (or the like). In an alternative embodiment, the conductive powder may further comprise fillers such as transition metal oxide powder (such as MnO2 or RUO2) or metal powder (such as Pt or Au). Ionic polymer (Nafion) dispersion in alcohol (or PVDF) is further added in the above-mentioned conductive powder dispersion for a binder. The mixture is homogenized by a treatment in an ultrasonic bath. The prepared conductive powder dispersion is then directly applied onto the tubular polymer electrolyte layer 139A using a conventional brush or spray coating technique to form a layer of carbon-based electrode 112. Volatile solvents are evaporated by a mild heating process after the desired thickness of the layer of carbon-based electrode 112 is achieved.
The electrical conductivity of the obtained layer of carbon-based electrode 112 is often inadequate to ensure proper electromechanical functionality for the ionic electroactive polymer actuator. In this exemplary example, the electrical conductivity of the obtained layer of carbon-based electrode 112 may be increased by further attaching Au microwire onto the surface of the obtained layer or by embedding Au wire in the obtained layer. Additionally, Au foil with a thickness of 50-150 nm may be rolled around the tubular polymer electrolyte layer 139A to serve as a highly conductive current collector.
Then, in this exemplary example, the layer of carbon-based electrode 112 is integrated with the tubular polymer electrolyte layer 139A by a reflow process. In this process, the heat-shrink polymer tube such as fluorinated ethylene-propylene (FEP) is fitted over the tubular polymer electrolyte layer 139A and heated up to a recovery temperature of the heat-shrink material. The supplied heat and applied compressive load by the heat-shrink tube may cause reflow of the ionic polymer from the tubular polymer electrolyte layer 139A, so that the layer of carbon-based electrode 112 and Au foil are thermally bonded with the tubular polymer electrolyte layer 139A. After this reflow process, the heat shrink tube is removed and the layer of carbon-based electrode 112 is sectored into four isolated carbon-based electrode sectors 112 using a micromachining process, where the computer-controlled milling machine with micro end-mill tool is used to mechanically remove a thin layer of carbon-Au composite and the tubular polymer electrolyte layer 139A at a depth of 30-50 microns. This process creates four equally sized carbon-based electrode sectors 112 at every 90° on the tubular polymer electrolyte layer 139A which can be independently controlled by electrical power to achieve two degrees-of-freedom actuation.
In another example, the bendable portion 110 illustrated, e.g., in
In this exemplary example, ionic polymer (Nafion) dispersion in alcohol (or PVDF) is further added in the conductive material dispersion for a binder. The mixture is homogenized by a treatment in an ultrasonic bath. Next, the prepared conductive powder dispersion is directly applied onto the tubular polymer electrolyte layer 139A using a brush or spray coating technique after being ionic liquid-impregnated. Volatile solvents are evaporated by a mild heating process until the desired thickness of the layer of carbon-based electrodes 112 is achieved.
The electrical conductivity of the obtained layer is often inadequate to ensure proper electromechanical functionality for the ionic electroactive polymer actuator. In terms of this, in this exemplary example, the electrical conductivity of the obtained layer of carbon-based electrodes 112 may be increased by attaching Au microwire onto the surface of the layer of carbon-based electrodes 112 or by embedding Au wire in the layer of carbon-based electrodes 112. Then, the layer of carbon-based electrodes 112 is integrated with the tubular polymer electrolyte layer 139A by a reflow process. In this process, the heat-shrink polymer tube such as fluorinated ethylene-propylene (FEP) is fitted over the tubular polymer electrolyte layer 139A and heated up to a recovery temperature of the heat-shrink material. The supplied heat and applied compressive load by the heat-shrink tube cause reflow of the ionic polymer, so that the layer of carbon-based electrodes 112 and Au foil are thermally bond with the tubular polymer electrolyte layer 139A. After reflow process, the heat shrink tube is removed. Additionally, the electrical conductivity of the layer of carbon-based electrodes 112 may be further increased by applying a thin layer of Pt thereon using the electroless chemical deposition and subsequent electrochemical deposition of Au.
Then, in this exemplary example, the obtained layer of carbon-based electrodes 112 is sectored into four isolated electrode sectors 112 using a micromachining process, where the computer-controlled milling machine with micro end-mill tool is used to mechanically remove a thin layer of carbon-based electrodes 112 and the tubular polymer electrolyte layer 139A at a depth of 30-50 microns. This process thus creates four equally sized electrode sectors 112 at every 90° on the surface of the tubular polymer electrolyte layer 139A which can be independently controlled by electrical power to achieve two degrees-of-freedom actuation.
Finally, in this exemplary example, the electrolyte is incorporated in the cleaned tubular polymer electrolyte membrane layer 139A. First, the tubular polymer electrolyte layer 139A is dried under vacuum (30 in Hg) at 100-140° C. for several hours to remove humidity. Thereafter, the dried tubular polymer electrolyte layer 139A is impregnated with an ionic liquid (such as EMI-BF4 or EMI-TFSI) by soaking in respective ionic liquid at elevated temperature for several hours.
In another embodiment, the flexible and elongate portion 101 of the medical device 10 (see
The polymer electrolyte layer 139 may have an outer diameter of, for example, one millimeter (1 mm), a length of, for example, twenty millimeters (20 mm). It will be understood that the size may vary with the intended application. The polymer electrolyte layer 139 may be clamped in a vertical cantilever configuration using a custom-made connector clamp with four spring-loaded prong contacts that attach to each electrode 112 formed on the polymer electrolyte layer 139 (see
In one embodiment of the medical device 10 (e.g., a micro-catheter), the bore 140 of the inner member 120 can be used to guide an inserted center wire 270 having an effector attached thereto to a predetermined position within a lumen of the body. For example, but not by way of limitation,
The spring member 271 can be expanded to engage and grip the obstruction 293 in the blood vessel 290 by retracting the actuation part 100 in the direction of arrow 292 while maintaining the center wire 270 stationary to cause the actuation part 100 to be withdrawn from a surrounding position about the spring member 271, thereby causing the spring member 271 to be released from the radially compressed configuration to the expanded configuration shown in
In one embodiment, the spring member 271 is a coil spring having a plurality of coils 296 in a series as shown in
In some embodiments a medical device 10 comprises an elongate flexible portion 101 that comprises an outer tubular layer; an inner tubular layer, wherein a space is formed between the outer tubular layer and the inner tubular layer; a support layer positioned within the space, wherein the support layer comprises: a braided wire, a coil or the combination thereof being covered on an outer surface of the inner tubular layer; a bendable portion 110 provided at a distal end 102 of the elongate flexible portion 101, comprising an ionic electroactive polymer layer, that is bendable in a desired direction in response to an applied electrical signal, wherein the ionic electroactive polymer layer comprises: an ionomer tubular layer comprising an electrolyte and a plurality of electrodes placed in contact with the ionomer tubular layer; and a transmitting member which comprises a plurality of wires respectively arranged along the space of the flexible elongate member and electrically connecting the electrodes. In some embodiments the wires further comprise an insulating layer.
In some embodiments a medical device comprises a flexible elongated member; and a bending member provided at a distal end of the flexible elongated member, made from an electroactive polymer, and bendable in a desired direction in response to an applied electrical signal, wherein the bending member comprises a main body made of an ionic electroactive polymer and a plurality of electrodes placed in contact with the main body. In some embodiments the outer surfaces of the flexible elongated member and the bending member are coated with a hydrophilic material.
In some embodiments the bendable portion 110 further comprises an encapsulation layer covering the bendable portion 110. In some embodiments the flexible inner member 120 and the bendable portion 110 are coated with a hydrophilic material and/or the bendable portion 110 further comprises a tubular insulation member 127 between the reinforcing mesh and electrically-conducting conduit 130. In some embodiments the outer tubular member further comprises a plurality of insulation layers. In some embodiments each wire passes through each insulation layer respectively. In some embodiments, the electrodes are selected from the group consisting of Pt electrodes, Au electrodes, carbon electrodes, or the combination thereof. In some embodiments the carbon electrodes are selected from the group consisting of carbide-derived carbon, carbon nanotube, graphene, a composite of carbide-derived carbon and ionomer, and a composite of carbon nanotube and ionomer. In some embodiments, the electrodes are symmetrically arranged along the circumference of the ionic electroactive polymer layer and in some embodiments there are four electrodes.
In some embodiments the device further comprises an electrical controller that transmits electrical signals through the electrically-conducting conduit 130 to the electrodes and inducing bending of the bendable portion 110. In some embodiments the electrical controller is configured to generate electrical signals in response to user manipulation such that the bendable portion 110 responds to user manipulation. In some embodiments the medical device is a catheter or a guide wire.
In some embodiments, the device further comprises a drive assembly configured to move the flexible inner member 120 lengthwise. In some embodiments the drive assembly is configured to come into partial contact with the surface of the flexible inner member 120 using a friction-based mechanism that acts between the drive assembly and the surface.
In some embodiments, the drive assembly comprises at least a pair of rotary drive members 330a, 330b and a motor 310 that operates the rotary drive members 330a, 330b. The flexible inner member 120 is arranged to pass between the pair of rotary drive members 330a, 330b and is moved along lengthwise with the operation of the rotary drive members 330a, 330b.
In some embodiments the pair of rotary drive members 330a, 330b comprise spools rotatably placed, and the flexible inner member 120 is placed to be movable between the pair of spools by the rotation of the spools. In some embodiments the drive system comprises a pair of belts that are arranged on either side of the flexible inner member 120, and the flexible inner member 120 is placed to be movable between the pair of belts by the operation of the belts.
In some embodiments the medical device further comprises: a upper case portion 210 that accommodates the flexible inner member 120; and a lower case portion 210 that is detachable from the upper case portion 210, wherein some or all parts of the drive assembly and the electrical control member are placed in the lower case portion 210. In some embodiments, the moving parts are arranged in the upper case portion 210. In some embodiments the drive assembly further comprises: a current distributor 410 electrically connecting the wires and being inside the upper case portion 210; an interlocking part for transmitting driving force from the motor 310 to the moving parts, being provided in the lower case portion 210; and an interface device 420 being connected to the electrical controller and provided in the lower case portion 210. In some embodiments the upper case portion 210 and the lower case portion 210 are fastened together, the worm gear 320 of the lower case portion 210 is connected to the moving parts of the upper case portion 210 to transmit the driving force, and the interface device 420 of the lower case portion 210 is connected to the current distributor 410 of the upper case portion 210 to transmit electrical signals from the electrical controller to the wires. Some embodiments further comprise a sensing member that senses an electrical signal at the bendable portion 110 when a deformation occurs to the bending member. In some embodiments the bendable sensing member 117 is configured to determine whether an external force is applied to the bendable portion 110 or not, considering an electrical signal generated by bending control from the electrical control member, out of electrical signals sensed at the bending member. Some embodiments further comprise a master controller that remotely instructs the electrical controller and the drive assembly. In some embodiments the medical device is a catheter in which the flexible inner member 120 and the bendable portion 110 have a conduit inside and in some embodiments the medical device is a guide wire. In some embodiments the bendable portion 110 further comprises an encapsulation layer being covered the bending member. In some embodiments the outer surfaces of the flexible inner member 120 and the bendable portion 110 are coated with a hydrophilic material. In some embodiments the medical device the wires further comprise an insulation layer. In some embodiments the bendable portion 110 further comprises a tubular insulation member 127 between the reinforcing mesh and electrically-conducting conduit 130. In some embodiments the outer tubular member further comprises a plurality of insulation layers. In some embodiments each wire passes through each insulation layer respectively. In some embodiments the electrodes are Pt electrodes, Au electrodes, carbon electrodes or the combination thereof. In some embodiments the ionic electroactive polymer layer further comprises carbon-based electrodes consisting of carbide-derived carbon, carbon nanotube, graphene, a composite of carbide-derived carbon and ionomer, and a composite of carbon nanotube and ionomer. In some embodiments the electrodes are symmetrically arranged along the circumference of the ionic electroactive polymer layer. In some embodiments there are four electrodes.
In some embodiments the electrical controller is configured to generate electrical signals, and the drive assembly is configured to move the flexible inner member 120 in response to user manipulation.
In some embodiments a system for remotely controlling the positioning of a medical device within the body of a patient comprises: a remote control member that comprises a master controller that remotely instructs the medical device to be positioned within the body of the patient; and a local communication member configured to communicate a control signal between the remote control member and the medical device. In some embodiments the communication member wirelessly transmits information using Bluetooth or wireless 802.1 1 communication over the internet. In some embodiments the system drive assembly is configured to come into partial contact with the surface of the flexible inner member 120 and move the flexible inner member 120 based on a friction-based mechanism acting between the drive assembly and the surface. In some embodiments the system drive assembly comprises at least a pair of rotary drive members 330a, 330b and a motor 310 that operates the rotary drive members 330a, 330b, and the flexible inner member 120 is arranged to pass through between the pair of rotary drive members 330a, 330b and moves lengthwise along with the operation of the rotary drive members 330a, 330b.
In some embodiments of the system the pair of rotary drive members 330a, 330b comprises a pair of spools that are rotatably placed, and the flexible inner member 120 is placed to be movable between the pair of spools by the rotation of the spools. In some embodiments the system the pair of rotary drive members 330a, 330b comprises a pair of belts that are arranged on either side of the flexible inner member 120, and the flexible inner member 120 is placed to be movable between the pair of belts by the operation of the belts. In some embodiments the system further comprises an upper case portion 210 that accommodates a tubular flexible inner member 120; and a lower case portion 210 that is placed to be detachable from the upper case portion 210, wherein some or all parts of the drive assembly and the electrical controller are placed in the lower case portion 210. In some embodiments the system the rotary drive members 330a, 330b are arranged in the upper case portion 210. In some embodiments the system the drive assembly further comprises: a current distributor 410 electrically connecting the wires and being inside the upper case portion 210; a worm gear 320 for transmitting driving force from the motor 310 to the moving parts, being provided in the lower case portion 210; and a interface device 420 being connected to the electrical controller and provided in the seconding module. In some embodiments of the system the upper case portion 210 and the lower case portion 210 are fastened together, the worm gear 320 of the lower case portion 210 is connected to the rotary drive members 330a, 330b of the upper case portion 210 to transmit the driving force, and the interface device 420 of the lower case portion 210 is connected to the current distributor 410 of the upper case portion 210 to transmit electrical signals from the electrical controller/processor to the wires.
In some embodiments the system further comprises a sensing member 117 that senses an electrical signal at the bendable portion 110 when a deformation occurs to the bending member. In some embodiments the sensing member 117 is configured to determine whether an external force is applied to the bendable portion 110 or not, considering an electrical signal generated by bending control from the electrical control member, out of electrical signals sensed at the bending member. In some embodiments the system further comprises a master controller that remotely instructs the electrical controller and the drive assembly. In some embodiments of the system the medical device is a catheter in which the flexible inner member 120 and the bendable portion 110 have a conduit inside. In some embodiments the medical device is a guide wire. In some embodiments of the system the bendable portion 110 further comprises an encapsulation layer being covered the bending member. In some embodiments of the system the outer surfaces of the flexible inner member 120 and the bendable portion 110 are coated with a hydrophilic material. In some embodiments the system the wires further comprise an insulation layer. In some embodiments of the system the bendable portion 110 further comprises a tubular insulation member 127 between the reinforcing mesh and electrically-conducting conduit 130. In some embodiments of the system the outer tubular member further comprises a plurality of insulation layers. In some embodiments of the system each wire passes through each insulation layer respectively. In some embodiments of the system the electrodes are Pt electrodes, Au electrodes, carbon electrodes or the combination thereof. In some embodiments of the system the ionic electroactive polymer layer further comprises carbon-based electrodes consisting of carbide-derived carbon, carbon nanotube, graphene, a composite of carbide-derived carbon and ionomer, and a composite of carbon nanotube and ionomer. In some embodiments of the system the electrodes are symmetrically arranged along the circumference of the ionic electroactive polymer layer. In some embodiments of the system there are four electrodes. In some embodiments of the system the electrical controller is configured to generate electrical signals, and the drive assembly is configured to move the flexible inner member 120 in response to user manipulation. In some embodiments, the inner member 120 is tubular. In some embodiments the ionomer tubular layer comprising an electrolyte is a polymer electrolyte layer 139. In some embodiments the ionic electroactive polymer layer comprises a polymer electrolyte layer 139 and a plurality of electrodes 112.
Certain embodiments include methods for preparing the bendable portion 110 of a device comprising the steps of: providing a polymer electrolyte layer 139 and a mandrel against an inner surface of the ionomer tube; forming a carbon electrode layer on an outer surface of the polymer electrolyte layer 139, wherein a mixture of a carbon-based conductive power is applied onto the outer surface of the polymer electrolyte layer 139; attaching an electrically-conducting conduit 130 on the carbon electrode layer, wherein the electrically-conducting conduit 130 comprises a plurality of wires respectively being electrically connected to the carbon electrode layer; providing a heat-shrink tubular layer covered around the carbon electrode layer and the polymer electrolyte layer 139; heating the heat-shrink polymer to cause reflow of the ionic electroactive polymer from the polymer electrolyte layer 139, so that the carbon electrode layer and the polymer electrolyte layer 139 are thermally bonded; and removing the heat-shrink tubular layer and the mandrel to form the bending member.
In some embodiments the method further comprises the steps of: forming a platinum layer on the carbon electrode layer; forming a gold layer on the platinum layer; micromachining the carbon electrode layer to be sectored into a plurality of carbon electrodes; and incorporating electrolytes into the bending member, wherein the bendable portion 110 is dried to remove humidity and impregnated with an ionic liquid. In some embodiments the platinum layer is disposed on the carbon electrode layer using electroless chemical deposition. In some embodiments the gold layer is disposed on the platinum layer using electrochemical deposition. In some embodiments a computer-controlled milling machine with a micro end-mill tool is used to mechanically remove a thin layer from the carbon electrode layer and the polymer electrolyte layer 139 at a predetermined depth. In some embodiments the predetermined depth is about 30 to about 50 microns.
In some embodiments the method for preparing a bendable portion 110 of a medical device, comprises steps of: providing a mandrel against an outer surface of a polymer electrolyte layer 139 comprising at least a ionic electroactive polymer; incorporating electrolytes into the bending member, wherein the bendable portion 110 is dried to remove humidity and impregnated with an ionic liquid; forming a carbon electrode layer on the polymer electrolyte layer 139, wherein at least a carbon-based conductive power is dispersed in a volatile solvent to form an a mixture of the carbon electrode and the mixture is applied onto the polymer electrolyte layer 139 to form a carbon electrode layer; attaching an electrically-conducting conduit 130 on the carbon electrode layer, wherein the electrically-conducting conduit 130 comprises a plurality of wires respectively being electrically connected to the carbon electrode layer; disposing a heat-shrink polymer around the carbon electrode layer and the polymer electrolyte layer 139; heating the heat-shrink polymer, the carbon electrode layer and the polymer electrolyte layer 139 to cause reflow of the ionic electroactive polymer from the polymer electrolyte layer 139, whereby the carbon electrode and the polymer electrolyte layer 139 are thermally bonded; and removing the first heat shrink material and the mandrel to form the bending member. Some embodiments further comprise the steps of: micromachining the carbon electrode layer to be sectored into a plurality of carbon electrodes. While in other embodiments a computer-controlled milling machine with micro end-mill tool is used to mechanically remove a thin layer from the carbon electrode layer and the polymer electrolyte layer 139 at a predetermined depth, for example a predetermined depth is about 30 to about 50 microns.
In some embodiments the bendable portion 110 is dried to remove humidity, and then is impregnated with an ionic liquid. In some embodiments the drying occurs under vacuum at about 100 to about 140° C. In some embodiments the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or a combination thereof. In some embodiments the ionic electroactive polymer is an ionic polymer-metal composite (IPMC). In some embodiments the ionic polymer-metal composite (IPMC) is Nafion. In some embodiments of the method the carbon-based conductive powder is selected from carbide-derived carbon, carbon nanotube, carbon aerogel, graphene, or the combination thereof. In some embodiments the carbon-based conductive powder further comprises: transition metal oxide powder or metal powder or the combination thereof. In some embodiments the transition metal oxide powder comprises: MnO2, RuO2 or the combination thereof. In some embodiments the metal powder comprises: Pt, Au or the combination thereof. In some embodiments attaching a electrically-conducting conduit 130 on the carbon electrode layer further comprises a step of attaching a gold foil layer covered the polymer electrolyte layer 139.
In some embodiments of the method at least one carbon-based conductive powder is dispersed in a volatile solvent to form a mixture that is applied onto outer surface of the polymer electrolyte layer 139 to form a carbon electrode layer. In some embodiments the mixture is applied onto the polymer electrolyte layer 139 using brush coating or spray coating to form a carbon electrode layer. In some embodiments the volatile solvent is isopropanol. In some embodiments the polymer electrolyte layer 139 is pretreated to roughen and clean the outer surface thereof. In some embodiments the outer surface of the polymer electrolyte layer 139 is roughened by a mechanical treatment, such as, but not limited to sandpapering or sandblasting. In some embodiments wherein the outer surface of the polymer electrolyte layer 139 is cleaned with hydrogen peroxide (H2O2), sulfuric acid (H2SO4) solutions, and de-ionized (DI) water.
Some embodiments provide a method for preparing a polymer electrolyte layer 139 in tubular shape for a bendable portion 110 of a device, comprising steps of: providing a liquid dispersion of a base material that is selected from the group consisting of ionic polymer, fluoropolymer and intrinsically conductive polymer; casting the liquid dispersion on a substrate; forming a polymer film on the substrate by curing the liquid dispersion; providing a mandrel, wherein the mandrel is further rolled around with the polymer film being removed from the substrate; and providing a heat-shrink tube to cover the rolled polymer film around the mandrel, and heating the heat-shrink tube to cause reflow of the rolled polymer film to form a polymer electrolyte layer 139. In some embodiments the ionic polymer comprises Nafion or Flemion. In some embodiments the fluoropolymer comprises Poly[(vinylidene difluoride)-co-(chlorotrifluoroethylene) (PVDF) or the co-polymer thereof. In some embodiments the co-polymer comprises Poly(vinylidene difluoride-co-chlorotrifluoroethylene) (P(VDF-CTFE)) or Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)).
In some embodiments the intrinsically conductive polymer comprises: polyaniline (PANI), polypyrrole (Ppy), poly(3,4-ethylenedioxythiophene) (PEDOT), or poly(p-phenylene sulfide) (PPS). In some embodiments the bendable portion 110 is an electroactive polymer actuator. In some embodiments the medical device is a catheter. In some embodiments the substrate is a PTFE plate or a glass plate. In some embodiments the heat-shrink tube is a fluorinated ethylene-propylene (FEP) tube. In some embodiments the heat-shrink tube is heated at a temperature of 200 to 230° C.
It is to be noted that various modifications or alterations can be made to the above-described exemplary embodiments of the invention without departing from the technical features of the invention as defined in the appended claims.
This application is a divisional of U.S. application Ser. No. 15/562,690 filed on Sep. 28, 2017, which is a 371 of International No. PCT/US2017/016513, filed Feb. 3, 2017, and claims the benefit of U.S. Provisional Patent Application No. 62/292,064, filed Feb. 5, 2016, which are incorporated by reference in their entirety.
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| Number | Date | Country | |
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| Number | Date | Country | |
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 15562690 | US | |
| Child | 16792765 | US |
