ELECTROCHEMICAL ACTUATORS AND ACTUATOR ARRAYS

Abstract

Electrochemical actuators including a sealed electrolytic chamber with two or more electrodes disposed therein and associated reservoirs are described. In some embodiments, the electrochemical actuators include one or more rigid structures that are overmolded onto one or more electrodes to form the electrolytic chambers. In some embodiments, multiple rigid structures that are overmolded onto two or separate electrodes may be connected to form one or more electrolytic chambers with a desired configuration of electrodes contained therein. Manufacturing methods and structures related to the formation of an array of electrochemical actuators are also described.

Claims

1. An actuator comprising: a sealed electrolytic chamber, wherein the sealed electrolytic chamber includes a first rigid portion and a compliant portion at least partially enclosing an interior of the sealed electrolytic chamber; and a first electrode extending from an exterior of the sealed chamber to an interior of the sealed chamber through the first rigid portion.

2. The actuator of claim 1, further comprising a second rigid portion of the sealed electrolytic chamber and a second electrode extending from the exterior of the sealed electrolytic chamber to the interior of the sealed electrolytic chamber through the second rigid portion, and wherein the first rigid portion is bonded to the second rigid portion of the sealed electrolytic chamber.

3. The actuator of claim 1, further comprising a second electrode extending from the exterior of the sealed electrolytic chamber to the interior of the sealed electrolytic chamber through the first rigid portion.

4. The actuator of claim 3, wherein the first and second electrodes are interdigitated.

5. The actuator of claim 1, further comprising a reservoir configured to contain a liquid attached to the sealed electrolytic chamber, wherein the compliant portion of the sealed electrolytic chamber forms at least a portion of the reservoir such that deformation of the compliant portion into an interior of the reservoir displaces the liquid out of the reservoir.

6. The actuator of claim 1, wherein the compliant portion comprises a first membrane.

7. The actuator of claim 6, further comprising a second layer attached to the sealed electrolytic chamber such that a volume disposed between the first membrane and the second layer forms a reservoir configured to contain a liquid.

8. The actuator of claim 7, wherein the second layer is a second membrane.

9. The actuator of claim 1, further comprising a fluid tight seal between the first electrode and the first rigid portion of the sealed electrolytic chamber.

10. The actuator of claim 1, further comprising a through hole extending from an exterior surface of the first rigid portion to an interior surface of the first rigid portion.

11. The actuator of claim 9, further comprising a seal disposed on, or in, the through hole.

12. The actuator of claim 1, further comprising an electrolyte disposed in the sealed electrolytic chamber that decomposes to generate a gas when exposed to a predetermined voltage potential and/or current.

13. The actuator of claim 1, wherein the compliant portion is configured to extend at least partially into an interior of the chamber in an initial configuration.

14. The actuator of claim 1, wherein the sealed electrolytic chamber is overmolded onto at least a portion of the first electrode.

15-19. (canceled)

20. The actuator 2 of claim 1, wherein the first electrode forms at least a portion of an interior surface of the sealed electrolytic chamber.

21. The actuator 2 of claim 1, wherein an elastomeric material is disposed between the first electrode and the first rigid portion.

22. An actuator array comprising: a plurality of sealed electrolytic chambers formed in a rigid structure, wherein each sealed electrolytic chamber of the plurality of sealed electrolytic chambers comprises: an opening; and at least two electrodes extending from an exterior of the sealed electrolytic chamber to an interior of the sealed electrolytic chamber; and a first membrane disposed on the plurality of sealed electrolytic chambers, wherein the first membrane seals the opening of each sealed electrolytic chamber.

23. The actuator array of claim 22, wherein the first membrane is configured to extend at least partially into an interior of each sealed electrolytic chamber in an initial configuration.

24-26. (canceled)

27. An actuator array comprising: a first sealed electrolytic chamber including a first compliant portion; a second sealed electrolytic chamber including a second compliant portion; a first electrode extending into an interior of the first sealed electrolytic chamber; a second electrode extending into the interior of the first sealed electrolytic chamber and an interior of the second sealed electrolytic chamber; and a third electrode extending into the interior of the second sealed electrolytic chamber.

28. The actuator array of claim 27, wherein the first electrode and the second electrode are configured to have opposite electrical polarities and the first electrode and the third electrode are configured to have the same electrical polarities.

29-47. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0042] FIG. 1 is a schematic cross-sectional view of one embodiment of an electrochemical actuator during operation;

[0043] FIG. 2 is a schematic cross-sectional view of one embodiment of an electrochemical actuator;

[0044] FIG. 3 is a schematic exploded cross-sectional view of one embodiment of an electrolytic chamber;

[0045] FIG. 4 is a top view of one embodiment of an array of sealed electrolytic chambers;

[0046] FIG. 5 is an exploded perspective view of one embodiment of an array of electrochemical actuators;

[0047] FIG. 6 is a cross-sectional view of one embodiment of an array of electrochemical actuators;

[0048] FIG. 7 is a perspective view of one embodiment of an electrode formation process;

[0049] FIG. 8 is a perspective view of one embodiment of an overmolding process;

[0050] FIG. 9 is a perspective view of one embodiment of applying a flexible membrane to an array of electrolytic chambers;

[0051] FIG. 10 is a perspective view of one embodiment of inverting a strip including multiple arrays of electrolytic chambers for a filling process;

[0052] FIG. 11 is a perspective view of one embodiment of an electrolyte filling process;

[0053] FIG. 12 is a perspective view of one embodiment of a sealing process for through holes formed in the arrays of electrolytic chambers;

[0054] FIG. 13 is a perspective view of one embodiment of a process for separating the individual arrays of sealed electrolytic chambers;

[0055] FIG. 14 is a perspective view of reels including the various intermediate components of arrays of electrolytic chambers disposed along the length of strips wound onto the individual reels;

[0056] FIG. 15 is an exploded perspective view of one embodiment of a sealed electrolytic chamber;

[0057] FIG. 16 is a perspective view of the embodiment of a sealed electrolytic chamber of FIG. 15;

[0058] FIG. 17 is a top cross-sectional view of one embodiment of a sealed electrolytic chamber; and

[0059] FIG. 18 is a top cross-sectional view of one embodiment of a sealed electrolytic chamber.

DETAILED DESCRIPTION

[0060] To provide a desired delivery rate of a substance by an infusion pump, infusion pumps oftentimes include expensive and/or bulky pumps. These pumps may both increase the size and/or limit the amount of a therapeutic compound that may be provided to a subject within a desired form factor. Accordingly, the Inventors have recognized a need for pumps that are smaller in form factor, easier to manufacture, offer modular volume capabilities, and/or that provide improved accuracy relative to current infusion pumps.

[0061] In view of the above, the Inventors have recognized the benefits associated with electrochemical actuators including a sealed chamber, such as a sealed electrolytic chamber, that is formed in one or more rigid structures. A compliant portion of the sealed chamber may correspond to a flexible membrane sealed around a periphery of an opening of the chamber formed in the one or more rigid structures. For example, the chamber, or multiple chambers, may be formed in a single unitary rigid structure or multiple rigid portions are connected to one another to form a rigid combined structure that the one or more chambers are formed in. In either case, the electrochemical actuator may also include at least two electrodes that extend from an exterior of the rigid structure to an interior of the sealed chamber through the rigid structure for each sealed chamber. At least a portion of each electrode may be exposed to the interior of the sealed chamber to permit electrolysis of an electrolyte contained within the sealed chamber. In some embodiments, the rigid structure may be formed by overmolding one or more rigid structures onto the electrodes. In some embodiments, a reservoir is placed into contact with a compliant portion of an electrolytic chamber to form the overall electrochemical actuator. In some instances, the reservoir may correspond to a rigid layer, such as a rigid membrane, bonded to a second flexible membrane to form the reservoir there between. The second flexible membrane, or other appropriate compliant portion of the reservoir may be disposed on the first flexible membrane, or other compliant portion, of the sealed electrolytic chamber such that gas evolved in the sealed electrolytic chamber may apply a pressure to the reservoir to deform the flexible membrane of the reservoir to dispense a material contained within the reservoir out of an outlet of the reservoir.

[0062] In some embodiments, it may be desirable to modify an interface between an electrode and a structure overmolded onto the electrode for various reasons. For example, different configurations and/or types of materials may be used to supplement the bonding of the inherently different materials of the electrodes and overmolded structure. In one such embodiment, an elastomeric material may be overmolded onto, or otherwise applied to, a portion of an electrode prior to an overmolding process. Accordingly, the elastomeric material may be disposed between the electrode and the final rigid overmolded structure such that the overmolded structure applies a compressive force to the elastomeric material which may improve a seal between the overmolded structure and the electrode. In other embodiments, an overmolded structure may be formed using multiple polymers where at least one of the polymers included in the structure exhibits better adhesion to a metal of the electrodes while the other polymers may provide other desired functionalities. In some instances, a surface of an electrode may be modified prior to overmolding to improve the resulting adhesion. For instance, a surface roughness of the one or more overmolded electrodes may be modified prior to overmolding to improve the final bond and interface between the structures. A portion of an electrode to be overmolded may also be coated with an adhesion assisting material and/or a tie layer. In still other embodiments, mechanical features such as mechanical protuberances and/or other features may be formed into a portion of the one or more electrodes to be overmolded. This may create a mechanical interference between the electrodes and overmolded structure that improves the retention of the one or more electrodes in the final overmolded structure. It should be understood that the various modifications to an overmolded structure noted above may either be used individually and/or in combination with each other. Additionally, other modifications to an overmolded interface between an electrode and a structure are also contemplated as the disclosure is not limited to any particular overmolding process.

[0063] In some embodiments, it may be desirable to form an array of electrochemical actuators. In such an embodiment, a first compliant membrane may be disposed on a rigid structure including a plurality of chambers, such as a plurality of electrolytic chambers, formed in the rigid structure. Thus, the first complaint membrane may cover a plurality of openings formed in the structure to seal the plurality of chambers. For instance, the first compliant membrane may be bonded around a periphery of an opening of each separate chamber to form a plurality of sealed chambers. Depending on the particular embodiment, electrolyte may either be present in the chambers prior to sealing the first complaint membrane to the structure, or the sealed chambers may be filled after bonding the first complaint membrane to the structure as the disclosure is not so limited. After forming the sealed chambers, in some embodiments, a corresponding plurality of reservoirs may be formed and placed in contact with the flexible portion of the first complaint membrane covering the openings of the separate sealed chambers. For example, a second complaint membrane may be bonded to a rigid membrane to form a plurality of reservoirs there between. The plurality of reservoirs may then be placed into the openings of the separate chambers with the second flexible membrane of the reservoir disposed on the first compliant membrane to form an array of electrochemical actuators.

[0064] Turning to the figures, specific non-limiting embodiments are described in further detail. It should be understood that the various systems, components, features, and methods described relative to these embodiments may be used either individually and/or in any desired combination as the disclosure is not limited to only the specific embodiments described herein.

[0065] FIG. 1 presents a schematic of one embodiment of how gas electrolysis may be used to operate an electrochemical actuator 10 as described herein. Specifically, electrodes 20 disposed within an electrolytic chamber apply a voltage differential and/or current to an electrolyte disposed within the electrolytic chamber 30 to disassociate the electrolyte into a gas. The evolved gas produces a pressure for driving the flow of therapeutic compound, or other appropriate composition, from the actuator 10. The reservoir containing the therapeutic compounds, or other composition, and the electrolytic chamber are separated by a flexible membrane 60, so that the electrolyte is not mixed with the medication. The flexible membrane 60 may exhibit the desired mechanical flexibility and barrier properties for the particular application for which it is used. The amount of the therapeutic compound displaced out of the reservoir may be determined by the amount of gas generated within the actuator 10. The amount of generated gas is determined by the total charge passed through the two electrodes which can be measured using an appropriate current sensor, Coulomb counting sensor, or other appropriate type of sensor.

[0066] FIG. 2 depicts another embodiment of an electrochemical actuator. In the depicted embodiment, the electrochemical actuator includes a sealed chamber formed in a rigid structure 50 in the form of an electrolytic chamber 30 including a bottom portion and one or more side portions extending from the bottom portion. In some embodiments, the rigid structure 50 is a unitary structure that is formed as a single integral component, though embodiments in which multiple rigid portions of a structure are separately formed and connected to one another to form one or more chambers are also contemplated. In either case, a compliant membrane 60 is sealed around an opening formed by the one or more side portions to form the sealed electrolytic chamber 30 containing an electrolyte. Two or more electrodes 20 may extend into the interior of the sealed chamber 30 through either a side, top, and/or bottom portion of the rigid structure forming the chamber. The electrodes 20 may be sealed to the rigid structure in any appropriate fashion to ensure that the chamber 30 is sealed. A second compliant membrane is sealed to a separate rigid structure such as a rigid membrane or other structure to form a reservoir 70 containing a desired therapeutic compound or other substance there between. The resulting reservoir 70 is then placed into the opening of the rigid structure with the second compliant membrane of the reservoir disposed on the first compliant membrane of the electrolytic chamber 30. The reservoir may be held against the electrolytic chamber in any appropriate fashion including, for example, bonding, welding, and/or clamping the reservoir within the opening against the first flexible membrane of the electrolytic chamber. Thus, the first membrane of the electrolytic chamber 30 may be deformed against the second membrane of the reservoir by gas generated within the electrolytic chamber 30 to displace a liquid from within the reservoir 70 through an outlet of the reservoir.

[0067] In the above embodiment, the first compliant membrane is used to contain an electrolyte to be used to electrolysis within the electrolytic chamber 30 and the second compliant membrane is in contact with a liquid therapeutic compound, or other substance, contained within the reservoir 70 after filling. Advantageously, the reservoir 70 may go through an independent fabrication process to that of the electrolytic chamber 30. This approach may offer several advantages in isolating the therapeutic compounds, or other substance, from potential interaction with the electrolyte used for electrolysis. It may also facilitate quality control steps of the two items. Considering the technical requirements for therapeutic compounds packaging and electrolyte containment, this manufacturing approach may also increase the number of options available for materials to be used in the construction of these components.

[0068] FIG. 3 presents one embodiment of a rigid structure 50 with an electrolytic chamber formed in the structure. In the depicted embodiment, the rigid structure is bonded to a corresponding flexible membrane to seal the electrolytic chamber. For example, as shown in the figure, the rigid structure 50 including the chamber may be bonded to the flexible membrane using an ultrasonic welding process with appropriate energy directors formed between the portions of the unitary structure in the membrane to be bonded. Additionally, in some embodiments, a sealing cap 99, or other appropriate seal, may be bonded to a side of the rigid unitary structure opposite the flexible membrane, or on another appropriate portion of the rigid structure forming the electrolytic chamber, to seal a filling hole 95 for placing electrolyte into the resulting electrolytic chamber.

[0069] In some embodiments, an electrochemical actuator is produced using an over-molding process to form one or more rigid structures directly on the electrodes. Depending on the embodiment, the overmolding process may be done where multiple separate rigid portions of a structure in which the chambers are formed are overmolded onto separate electrodes and/or a single unitary rigid structure may be overmolded onto the electrodes. For example, a molded rigid structure may include a cavity with a size and shape of the desired electrolytic chamber formed therein. This structure may be overmolded onto the electrodes such that at least a portion of each electrode passes through a portion of the rigid structure such that each electrode is exposed to an interior of the resulting electrolytic chamber to permit the desired voltage differentials and/or current to be applied to the electrolyte contained therein during operation. The alternative or more common method of making an electrochemical actuator is to use photochemical etching. Compared with photochemical etching, there are two benefits of using an over-molding process to produce an electrochemical actuator. Specifically, overmolding of a structure onto the electrodes allows for integration of different metals into the process because the overmolding process is not limited to particular chemistries since it is a mechanical process. Additionally, the interfaces between the electrodes and the portion of the overmolded structure that the electrodes extend through into the resulting electrolytic chamber may be automatically sealed during the molding process. In contrast, when using a photochemical process, these interfaces need to be sealed after formation which may increase the risk of leaking electrolyte through the interfaces. That said, embodiments in which a photochemical process, or other formation process, is used to form the described electrochemical actuators are also contemplated. While an individual actuator has been described in the above embodiments, it should be understood that the described electrochemical actuators may be incorporated into an array. For example, as shown in FIG. 4 in some embodiments, a plurality of electrochemical actuators 10 may be incorporated into an array 100 of electrochemical actuators.

[0070] FIGS. 5 and 6 show one embodiment of a system including one or more arrays including multiple reservoirs 70 and corresponding electrolytic chambers 30 to form an array of electrochemical actuators. In the depicted arrays, the overall approach is the same: a set of reservoirs and a corresponding set of electrolytic chambers 30 may include corresponding rigid 50 and compliant 60 structures similar to the embodiments described above. However, in some embodiments, it may be advantageous to form multiple reservoirs between a single rigid structure, such as a rigid membrane and a corresponding compliant membrane bonded to the rigid membrane. Additionally, multiple electrolytic chambers 30 may be formed in a rigid structure, which may include one unitary structure or multiple connected rigid portions, with a single flexible membrane bonded around the openings of the multiple electrolytic chambers to form the desired sealed electrolytic chambers. These structures may be assembled and held proximate to one another to form the overall electrochemical actuators for pumping a substance out of the reservoirs.

[0071] In the depicted embodiment, the overall device may include eight separate reservoirs, or any other appropriate number of separate reservoirs, which may either be fluidly connected to a common outlet from the device and/or separate outlets as the disclosure is not so limited. In either case, the depicted construction may simplify the manufacturing of multiple electrochemical actuators using multiple structures formed in the various described rigid and compliant components.

[0072] FIGS. 7-14 depict one possible manufacturing method for forming an array of electrochemical actuators. As shown in the figures, a metal strip 82 may be fed into a stamping 84, or other formation process, to form a desired pattern of a plurality of electrodes along a length of the metal strip 82. In the depicted embodiment, the electrodes 20 extend across a width of the metal strip 82 in a direction that is angled, and in some instances perpendicular, to a length of the strip extending in the machine direction of the process. After forming the desired pattern of electrodes on the metal strip, the metal strip may be deburred as well as subjected to cleaning, rinsing, and/or drying depending on the condition of the electrodes after the formation process.

[0073] After forming the electrodes, the metal strip 82 may be fed into a mold 86 where one or more rigid unitary structures may be overmolded onto the as formed electrodes. For example, as shown in the figures, sets of electrodes 20 may have multiple electrolytic chambers 30 overmolded onto the electrodes 20 such that at least two electrodes extend into and are exposed to an interior of each electrolytic chamber 30. After overmolding of the rigid structures onto the sets of electrodes 20, a compliant membrane 60 may be bonded to each electrolytic chamber 30 to form a sealed electrolytic chamber. In some embodiments, a separate compliant membrane may be bonded to each structure with the electrolytic chambers 30 formed therein. Alternatively, a continuous membrane may be applied to the various structures as the disclosure is not limited in this fashion. As also shown in the figures, the membranes 60 may be formed such that a portion of the membrane may extend into each electrolytic chamber. In either case, after the depicted bonding and sealing process, the combined structure of the sealed electrolytic chamber may then be subjected to an electrolyte filling process.

[0074] In some embodiments, the overmolded structures 90, as shown in FIGS. 9 and 10, may include a plurality of through holes 95 that extend from an exterior surface of the overmolded structure to an interior surface of each corresponding electrolytic chamber. In the depicted embodiment, the through holes 95 are formed on a bottom surface of the overmolded structure 90. Accordingly, the strip including the sealed electrolytic chambers may be inverted, as shown in FIG. 10, such that the through holes 95 are oriented vertically upwards relative to a local direction of gravity. One or more filling nozzles 98 may then be placed in fluid communication with the through holes 95 to fill the sealed electrolytic chambers with a desired electrolyte, as shown in FIG. 11. After the electrolyte filling process, one or more sealing structures, such as the sealing strip 99, may be applied to the through holes to seal the through holes with the electrolyte contained within the electrolytic chambers, as shown in FIG. 12.

[0075] After filling, the strips including the individual arrays of sealed electrolytic chambers may be separated using any appropriate cutting and/or machining process. Additionally, in some instances, one or more sides of the electrodes may be trimmed such that the electrode connections are present on either one or both sides of the chambers depending on the desired electrical layout. In either case, individual arrays of sealed electrolytic chambers 100 may be provided, as shown in FIG. 13. Depending on the particular embodiment, either individually formed reservoirs, and/or a corresponding array of reservoirs, may be placed into the openings of the sealed electrolytic chambers against the flexible membrane to form an array of electrochemical actuators.

[0076] It should be understood that the above-described manufacturing processes may either be done on an individual set of electrodes and/or using continuous strips of material. Accordingly, the disclosed arrays of electrochemical actuators may either be manufactured using a continuous manufacturing process using reel to reel processing techniques, see reels 200 including strips of components in various states of manufacture in FIG. 14, and/or individual batch manufacturing may be used as the disclosure is not limited in this fashion.

[0077] The above embodiments have been directed to electrolytic chambers that are formed in a single unitary rigid structure. However, as previously noted, embodiments in which one or more electrolytic chambers are formed in multiple connected rigid portions of an overall rigid structure are also contemplated. One such embodiment is depicted in FIGS. 15 and 16 which depict an electrochemical actuator 10 that may be manufactured using two or more electrodes 20 overmolded into two separate portions of an electrolytic chamber 30 that are subsequently bonded to each other to form the overall electrolytic chamber with an opening sealed by a flexible membrane 60 disposed on and bonded around a periphery of the opening. Depending on the particular materials used, the rigid portions of the overall rigid structure forming the one or more chambers may be bonded to one another using thermal welding, ultrasonic welding, adhesives, brazing, and/or any other appropriate method capable of providing a combined structure with a desired number of sealed chambers formed therein. In either case, the electrodes overmolded into the two or more rigid portions of the structure may have portions that extend through the associated rigid portion of the structure such that the electrodes are exposed to an interior of the resulting one or more chambers once the rigid portions are connected to one another as previously discussed. In embodiments in which the rigid portions of the combined structure are made from one or more polymers, the resulting polymer-to-polymer interface may provide increased bonding strength and increased sealing of the resulting electrolytic chamber. However, embodiments in which different materials are used for the rigid portions of the structure are also contemplated.

[0078] FIGS. 17 and 18 depict different embodiments of how an electrode 20 may extend from an exterior of a rigid structure to an interior of an electrolytic chamber 30 formed in the structure. In some instances, it may be desirable to increase a length of the electrode extending through a wall of the electrolytic chamber without increasing a thickness of the electrolytic chamber. For example, as shown in FIG. 17, the electrode 20 extends directly through a wall of the electrolytic chamber in a relatively straight linear arrangement such that a relatively smaller length of the electrode is embedded in the rigid structure. In contrast, FIG. 18 depicts an embodiment in which a length of the electrode 20 embedded in the overmolded structure 90 is greater than a thickness of the wall of the electrolytic chamber the electrode extends through. Such a configuration may be provided using a number of different electrode configurations. For example, the electrode may include one or more electrode leads that follow one or more non-linear paths from an exterior surface of a rigid structure to an interior surface of a corresponding electrolytic chamber formed in the rigid structure. Of course, it should be understood that embodiments in which a thickness of a wall of the chamber is simply increased to provide a desired length of an electrode overmolded within a rigid structure are also contemplated.

[0079] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Accordingly, the foregoing description and drawings are by way of example only.