Adjustable shunt system and related systems and methods

Abstract

The present technology is directed to an adjustable shunt system for draining fluid from a first body region to a second body region, which may include a shunt element, an opening in the shunt element, and an actuator for selectively controlling fluid flow through the opening. The actuator may include a gate element movable between a first position that does not substantially interfere with fluid flow through the opening and a second position that at least partially blocks fluid flow through the opening, and a shape memory actuation element configured to move the gate element from the first position to and / or toward the second position when actuated. The system may further include a friction element configured to frictionally engage the gate element to releasably hold the gate element at and / or proximate to the second position following actuation of the shape memory actuation element.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 175,147, filed April 15, 2021, and U.S. Provisional Patent Application No. 63 / 216,801, filed June 30, 2021, the disclosures of both of which are incorporated herein by reference in their entireties.

[0002] The present technology relates generally to implantable medical devices, and more particularly to shunt systems and related methods for selectively controlling fluid flow between a first body region and a second body region of a patient. [Background technology]

[0003] Implantable shunt systems are widely used to treat various patient conditions by shunting fluid from a first body region / cavity to a second body region / cavity. Fluid flow through a shunt system is primarily controlled by the pressure gradient across the shunt and the physical characteristics of the flow path defined through the shunt (e.g., the resistance of the shunt lumen). However, most shunt systems have a single, static flow path that is not adjustable. Therefore, one challenge with conventional shunt systems is selecting an appropriately sized shunt for a particular patient. A shunt that is too small may not provide sufficient therapy to the patient, while a shunt that is too large may create additional problems for the patient. Despite this, most conventional shunts cannot be adjusted after implantation and therefore cannot be adjusted or titrated to meet the individual and varying needs of patients. Summary of the Invention [Means for solving the problem]

[0004] The present technology is directed to an adjustable shunt system for draining fluid from a first body region to a second body region of a patient. The adjustable shunt system can include a shunt element configured to extend between the first and second body regions, an opening fluidly connecting an exterior of the shunt element to an interior of the shunt element, and an actuator for selectively controlling fluid flow through the opening. To do so, the actuator can include (a) a gate element movable between a first position that does not substantially interfere with fluid flow through the opening and a second position that at least partially blocks fluid flow through the opening, and (b) a shape-memory actuation element configured to, when actuated, move the gate element from the first position to and / or toward the second position. The system can further include a friction element configured to frictionally or otherwise mechanically engage the gate element to releasably hold the gate element at and / or adjacent to the second position after actuation of the shape-memory actuation element. For example, the friction element can engage the end portion of the gate element with a force low enough to allow translation of the end portion during actuation of the actuation element, but high enough to prevent or at least reduce translation of the end portion after the actuation event. For example, in some embodiments, (1) a first translational (e.g., rotational) force imparted to the gate element during actuation of the actuation element is greater than the static and dynamic friction between the gate element and the friction element, and (2) a second translational (e.g., rotational) force imparted to the gate element after actuation of the actuation element is less than the static friction between the gate element and the friction element. In some embodiments, the system can also include a sealing element on the gate element to improve sealing at the opening when the gate element is in the second position. The present invention provides, for example, the following. (Item 1) 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, a gate element movable between a first position that does not interfere with fluid flow through the opening and a second position that at least partially blocks fluid flow through the opening; and an actuator having a shape memory actuation element configured to, when actuated, move the gate element from the first position to and / or towards the second position; a friction element configured to physically engage the gate element to releasably retain the gate element at and / or adjacent to the second position after actuation of the shape memory actuation element. (Item 2) Item 10. The system of item 1, wherein the friction element is configured to frictionally engage the gate element. (Item 3) 2. The system of claim 1, wherein the shape memory actuation element is a first shape memory actuation element, and the system further comprises a second shape memory actuation element configured to, when actuated, move the gate element from the second position to and / or toward the first position. (Item 4) Item 4. The system of item 3, wherein the second shape memory actuation element is configured to overcome a force between the gate element and the friction element to move the gate element from the second position to and / or toward the first position. (Item 5) 4. The system of claim 3, wherein the friction element is a first friction element, the system further comprising a second friction element configured to engage with the gating element to hold the gating element at and / or proximate to the first position after actuation of the second shape memory element. (Item 6) Item 10. The system of item 1, wherein the actuator is positioned within a chamber between a first surface having the opening and a second surface having the friction element. (Item 7) 7. The system of claim 6, wherein the friction element includes a ledge on the second surface, the ledge aligned with an axis extending through the opening. (Item 8) Item 8. The system of item 7, wherein the gate element includes a first surface configured to engage with the opening when in the second position and a second surface configured to engage with the ledge when in the second position. (Item 9) Item 9. The system of item 8, wherein the ledge is further configured to direct the gate element toward the opening as the gate element moves from the first position toward the second position to improve contact between an upper surface of the gate element and the opening. (Item 10) Item 8. The system of item 7, wherein the ledge is wedge-shaped. (Item 11) Item 8. The system of item 7, wherein the ledge is textured. (Item 12) Item 1, wherein the system includes a plate assembly, the plate assembly having the opening, the actuator, and the friction element. (Item 13) Item 13. The system of item 12, wherein the plate assembly includes a plurality of sheets, and the friction element is integrated with one of the plurality of sheets. (Item 14) Item 10. The system of item 1, wherein the shape memory actuation element is configured to exhibit a recovery movement after actuation, and the friction element is configured to reduce any undesired movement of the gate element during the recovery movement of the shape memory actuation element. (Item 15) Item 10. The system of item 1, wherein the system is an intraocular shunt system, the first body region is the anterior chamber of the patient's eye, and the second body region is a desired outflow location. (Item 16) Item 1, wherein the gate element includes a sealing element configured to abut and / or partially occupy the opening when the gate element is in the second position to improve a fluid seal of the opening. (Item 17) Item 17. The system of item 16, wherein the sealing element is at least partially constructed from a lubricious material and / or includes a lubricious coating. (Item 18) Item 17. The system of item 16, wherein the sealing element is constructed at least in part from silicone. (Item 19) Item 17. The system of item 16, wherein the sealing element is comprised of a combination of hydrophobic and hydrophilic materials. (Item 20) Item 17. The system of item 16, wherein when in the second position, the gate element has a first surface facing the inlet and a second surface facing away from the inlet, and the sealing element includes a first portion positioned on the first surface and configured to abut and / or partially occupy the opening, and a second portion positioned on the second surface and configured to engage the friction element. (Item 21) 21. The system of claim 20, wherein the first portion of the sealing element is constructed from a lubricious material and / or includes a lubricious coating. (Item 22) Item 22. The system of item 21, wherein the second portion of the sealing element is constructed from a non-lubricating material. (Item 23) the opening is a first opening, and the system comprises: a first channel fluidly coupled to the first opening; a second opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; Item 10. The system of item 1, further comprising: a second channel fluidly coupled to the second opening, the second channel being substantially fluidly isolated from the first channel, the second opening not including any corresponding actuator and configured to remain substantially open when the system is implanted. (Item 24) 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured, when actuated, to move the gate element from the first position to and / or toward the second position; and an actuator having a second shape memory actuation element configured, when actuated, to move the gate element from the second position to and / or toward the first position; a friction element configured to physically engage the first end portion of the gate element; 1. An adjustable shunt system, wherein: (a) when the gate element is in the first position, the friction element biases the gate element toward the first position and / or releasably holds the gate element in the first position; and (b) when the gate element is in the second position, the friction element biases the gate element toward the second position and / or releasably holds the gate element in the second position. (Item 25) The friction element is upon actuation of the first shape memory actuation element, permitting movement of the gating element from the first position to and / or towards the second position; preventing movement of the gating element from the second position toward the first position after actuation of the first shape memory actuation element; upon actuation of the second shape memory actuation element, permitting movement of the gating element from the second position to and / or towards the first position; and preventing movement of the gate element from the first position toward the second position after actuation of the second shape memory actuation element. (Item 26) Item 25. The system of item 24, wherein the first shape memory actuation element and the second shape memory actuation element are configured to exhibit a recovery movement after actuation, and the friction element is configured to reduce and / or prevent any undesired movement of the gate element after actuation of the first actuation element and after actuation of the second actuation element. (Item 27) Item 25. The system of item 24, wherein the first shape memory actuation element, when actuated, is configured to impart a rotational force to the gating element toward the second position, the rotational force being greater than a static friction force between the gating element and the friction element, such that the gating element slides past the friction element toward the second position. (Item 28) Item 25. The system of item 24, wherein the second shape memory actuation element, when actuated, is configured to impart a rotational force to the gating element toward the first position, the rotational force being greater than a static friction force between the gating element and the friction element such that the gating element slides past the friction element toward the first position. (Item 29) 25. The system of claim 24, wherein the friction element is integrated with the actuator. (Item 30) 25. The system of claim 24, wherein the friction elements are tabs, lumps, protrusions, or bumps. (Item 31) 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated that moves the gating element from the first position to and / or toward the second position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; an actuator having a second shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated to move the gating element from the second position to and / or toward the first position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; a friction element configured to physically engage the first end portion of the gate element; An adjustable shunt system, wherein the friction element is configured to reduce undesired movement of the gate element during secondary movement of the first actuation element and during secondary movement of the second actuation element. (Item 32) Item 32. The system of item 31, wherein the secondary movement of the first actuating element is a restoring movement caused at least in part by the second actuating element, and the secondary movement of the second actuating element is a restoring movement caused at least in part by the first actuating element. (Item 33) 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, Gate element, a first shape memory actuation element coupled to a first portion of the gate element; and an actuator having a second shape memory actuation element coupled to a second portion of the gate element; the first shape memory actuation element is configured to move the gating element from a first low-energy position in which the gating element does not interfere with fluid flow through the opening, through an intermediate high-energy position, to a second low-energy position in which the gating element at least partially interferes with fluid flow through the opening; An adjustable shunt system, wherein the second shape memory actuation element is configured to move the gating element from the second low-energy position, through the intermediate high-energy position, and to the first low-energy position. (Item 34) Item 34. The system of item 33, wherein the actuator is configured to reduce and / or prevent undesired movement of the gate element during recovery movement of the first or second shape memory actuation element by the intermediate high energy position. (Item 35) The actuator a first force exerted by the first shape memory actuation element on the gating element during actuation of the first shape memory actuation element is sufficient to move the gating element through the intermediate high energy position; Item 35. The system of item 34, wherein a second force exerted by the first shape memory actuating element on the gating element during the recovery movement of the first shape memory actuating element is not sufficient to move the gating element through the intermediate high energy position. (Item 36) Item 34. The system of item 33, wherein the gating element has a first internal stress distribution at the first low-energy position, a second internal stress distribution at the second low-energy position, and a third internal stress distribution at the intermediate high-energy position, and the gating element is biased toward the first internal stress distribution and / or the second internal stress distribution. (Item 37) Item 37. The system of item 36, wherein the first internal stress distribution and the second internal stress distribution are approximately equal. (Item 38) 1. A method of regulating fluid flow through an opening in a shunt, comprising: actuating a shape memory actuator to move a gating element between (a) a first position that does not interfere with fluid flow through the opening, and (b) a second position that at least partially interferes with fluid flow through the opening; moving the gate element between the first position and the second position, wherein moving the gate element includes overcoming a first biasing force directing the gate element toward the first position; releasably holding the gate element in the second position during a recovery movement of the shape memory actuator. (Item 39) 39. The method of claim 38, wherein releasably retaining the gate element in the second position includes preventing movement of the gate element from the second position toward the first position during the recovery movement of the shape memory actuator. (Item 40) Item 39. The method of item 38, wherein releasably retaining the gate element in the second position includes engaging the gate element with a friction element. (Item 41) Item 41. The method of item 40, wherein the friction element generates the biasing force. (Item 42) 39. The method of claim 38, wherein the gating element has a first stored energy in the first position and the second position, and moving the gating element from the first position to the second position includes transitioning the gating element through an intermediate position having a second stored energy greater than the first stored energy. [Brief explanation of the drawings]

[0005] Many aspects of the present technology can be better understood with reference to the following drawings. Components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed on clearly illustrating the principles of the present technology. Additionally, components may be shown as transparent in certain figures for clarity of illustration only, and are not intended to imply that the illustrated components are necessarily transparent. Components may also be shown in schematic form.

[0006] [Figure 1A] 1 illustrates an adjustable shunt system constructed in accordance with selected embodiments of the present technology. [Figure 1B] FIG. 1B is an enlarged view of a plate assembly of the system shown in FIG. 1A and configured in accordance with selected embodiments of the present technology. [Figure 1C] 3 is an enlarged view of a portion of the plate assembly shown in FIG. 2 and configured in accordance with selected embodiments of the present technology. [Figure 2A] 1 illustrates an actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 2B] 1 illustrates an actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 2C] 1 illustrates an actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 2D] 1 illustrates an actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 3A]10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 3B] 10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 3C] 10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 4A] 10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 4B] 10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 4C] 10 illustrates another actuator for use with an adjustable shunt system and configured in accordance with selected embodiments of the present technology. [Figure 5] 1 illustrates an actuator used with an intraocular shunt system and configured in accordance with selected embodiments of the present technology. [Figure 6A] 1 illustrates another adjustable shunt system constructed in accordance with selected embodiments of the present technology. [Figure 6B] FIG. 5B is an enlarged view of a portion of the adjustable shunt system shown in FIG. 5A and configured in accordance with selected embodiments of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0007] Shape memory actuators for adjustable shunt systems have been previously described, such as in U.S. Patent Application No. 17 / 175,332, the disclosure of which is incorporated herein by reference in its entirety. Depending on the shape memory actuator's structure, manufacturing process, microstructure, and / or operating conditions, a shape memory actuator may undergo a recovery effect in which the actuator moves at least slightly back toward its pre-actuation geometric configuration after an actuation event that imparts a geometric change to the actuator. For example, in a shape memory actuator having two opposing but coupled actuation elements, actuation of the first actuation element moves the first actuation element toward the actuation configuration (e.g., its preferred geometric shape) but generally deforms the second actuation element relative to its preferred geometric shape. However, after actuation, the first actuation element may move at least slightly back toward its pre-actuation configuration as it seeks equilibrium with external (e.g., mechanical) stresses (e.g., stresses imparted by the second actuation element, which further deforms it relative to its preferred geometric shape) that push it away from its preferred geometric shape. This movement back toward its pre-actuation configuration after actuation is referred to herein as a “recovery movement,” “recovery movement,” “reaction movement,” “recoil,” or “equilibration movement.” When a shape-memory actuator is utilized to move a gate element that controls fluid flow through an opening, this recovery movement can cause undesired movement of the gate element (e.g., by moving the gate element away from a desired position after actuation) that reduces the level of flow control imparted by the actuator. The present technology is expected to address the effects of the recovery movement on the gate element by including features, such as friction elements, that reduce or eliminate the effect of the recovery movement on the gate element, thereby improving the control imparted by the actuator. The present technology is also expected to improve fluid control by including sealing elements that can selectively form a partial or complete fluid seal with the opening to prevent fluid from flowing through the shunt system.

[0008] The terminology used in the description provided below is intended to be interpreted in its broadest reasonable manner, even when used in conjunction with detailed descriptions of certain specific embodiments of the present technology. Certain terms may even be emphasized below; however, any terms intended to be interpreted in any limited manner are expressly and specifically defined as such in this detailed description section. Additionally, the present technology may include other embodiments within the scope of the examples that are not described in detail with respect to FIGS. 1A-6B.

[0009] Throughout this specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the technology. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features or characteristics may be combined in any suitable manner in one or more embodiments.

[0010] Throughout this specification, when reference is made to relative terms such as "generally," "approximately," and "about," this specification is used to mean the stated value plus or minus 10%. Throughout this specification, reference to the term "resistance" refers to fluid resistance unless the context clearly dictates otherwise. The terms "discharge rate," "flow rate," and "flow" are used interchangeably to describe the movement of fluid through a structure.

[0011] As used herein, the terms "friction element" and "frictional element" are used interchangeably to describe a first structure configured to physically contact / engage a second structure. These terms are not limited to configurations in which contact occurs or is configured to occur between parallel surfaces of the first and second structures. Rather, the terms "friction element" and "frictional element" include a first structure configured to physically engage / contact a portion of a second structure to at least partially resist movement of the second structure, regardless of the orientation of the engagement between the structures.

[0012] While certain embodiments herein are described with respect to shunting fluid from the anterior chamber of the eye, those skilled in the art will understand that the present technology can be readily adapted to shunt fluid from and / or between other portions of the eye, or more generally, from and / or between a first body region and a second body region. Furthermore, while certain embodiments herein are described in the context of treating glaucoma, any embodiment herein, including those referred to as "glaucoma shunts" or "glaucoma devices," may nevertheless be used and / or modified to treat other diseases or conditions, including other diseases or conditions of the eye or other body regions. For example, the systems described herein can be used to treat diseases characterized by increased pressure and / or fluid accumulation, including, but not limited to, heart failure (e.g., heart failure with preserved ejection fraction, heart failure with reduced ejection fraction, etc.), pulmonary failure, renal failure, hydrocephalus, etc. Furthermore, although generally described with respect to shunting water, the systems described herein may be equally applied to shunt other fluids, such as blood or cerebrospinal fluid, between a first body region and a second body region.

[0013] 1A illustrates a shunt system 100 ("system 100") configured in accordance with selected embodiments of the present technology. As described in more detail below, system 100 is configured to provide adjustable therapy for draining fluid from a first body region, such as draining aqueous humor from the anterior chamber of a patient's eye.

[0014] The system 100 generally includes an elongated housing 102 and a plate assembly 120. The elongated housing 102 (which may also be referred to as a casing, membrane, shunt element, etc.) extends between a first end portion 102a and a second end portion 102b. The elongated housing 102 substantially and / or completely encases the plate assembly 120 at or adjacent the first end portion 102a. In the illustrated embodiment, the elongated housing 102 includes three openings 104 (e.g., a first opening 104a, a second opening 104b, and a third opening 104c) that align with respective fluid inlets in the plate assembly 120, as described in further detail below with respect to FIG. 1B. The elongated housing 102 further includes a main fluid conduit 110 that fluidly couples the plate assembly 120 to one or more fluid outlets 106 positioned proximate the second end 102b of the elongated housing 102. In some embodiments, the elongated housing 102 is constructed from a slightly elastic or flexible biocompatible material (e.g., silicone, etc.). The elongated housing 102 can also optionally include one or more wings or appendages 112 with holes (e.g., suture holes) for securing the elongated housing 102 in a desired position.

[0015] The plate assembly 120 (which may also be referred to as a flow control plate, flow control cartridge, plate structure, etc.) is positioned within the elongated housing 102 and is configured to control the flow of fluid through the system 100. For example, as best shown in FIG. 1B , the plate assembly 120 includes one or more fluid openings or inlets 124 (e.g., a first fluid inlet 124 a, a second fluid inlet 124 b, and a third fluid inlet 124 c) that align with corresponding openings 104 a-c in the elongated housing 102. The fluid inlets 124 allow fluid to enter the interior of the plate assembly 120 (and thus the interior of the elongated housing 102) from an environment external to the system 100. In some embodiments, the top surface of the plate assembly 120 forms a substantial fluid seal with the interior surface of the elongated housing 102 at the first end portion 102 a, such that the only path for fluid to enter the system 100 is through the fluid inlets 124. Thus, for fluid to flow through the system 100 , the fluid must generally flow through the plate assembly 120 .

[0016] The fluid path through the plate assembly 120 depends on which fluid inlet 124 the fluid enters. For example, fluid entering the system 100 through the first fluid inlet 124a flows into the first chamber 121a of the plate assembly 120 and is discharged into the main fluid conduit 110 via the first channel 136a. Fluid entering the system 100 through the second fluid inlet 124b flows into the second chamber 121b of the plate assembly 120 and is discharged into the main fluid conduit 110 via the second channel 136b. Fluid entering the system 100 through the third fluid inlet 124c flows into the third chamber 121c of the plate assembly and is discharged into the main fluid conduit 110 via the third channel 136c. The chambers 121a-c may be fluidically separated such that there are three separate flow paths through the plate assembly 120. The channels 136a-c can also have different geometric configurations (e.g., lengths) relative to one another so that they have different fluid resistances and thus provide different flow rates for a given pressure. The relative level of therapy provided by each fluid pathway can differ, such that a user can adjust the level of therapy provided by the system 100 by selectively opening and / or closing various fluid pathways (e.g., by selectively impeding or allowing flow through individual fluid inlets 124), as described below. For example, under a given pressure, when fluid enters primarily through the first fluid inlet 124a, the system 100 can provide a first discharge rate; when fluid enters primarily through the second fluid inlet 124b, the system 100 can provide a second discharge rate that is less than the first discharge rate; and when fluid enters primarily through the third fluid inlet 124c, the system 100 can provide a third discharge rate that is less than the first discharge rate. In other embodiments, channels 136a-c may have the same or generally the same geometric configuration to have the same or generally the same fluid resistance and therefore provide similar flow rates for a given pressure.

[0017] Plate assembly 120 is configured to selectively control the flow of fluid entering system 100. Specifically, plate assembly 120 includes a first actuator 130a positioned within first chamber 121a and configured to control the flow of fluid through first fluid inlet 124a, a second actuator 130b positioned within second chamber 121b and configured to control the flow of fluid through second fluid inlet 124b, and a third actuator 130c positioned within third chamber 121c and configured to control the flow of fluid through third fluid inlet 124c. The first actuator 130a may include, for example, a first protrusion or gate element 134a configured to movably interface with the first fluid inlet 124a to move between a first (e.g., “open”) position in which the gate element 134a does not substantially prevent fluid from flowing through the first fluid inlet 124a (e.g., by not interfering with the first fluid inlet 124a) and a second (e.g., “closed”) position in which the gate element 134a substantially prevents fluid from flowing through the first fluid inlet 124a (e.g., by blocking the first fluid inlet 124a). In some embodiments, the first actuator 130a is designed such that in the second (e.g., “closed”) position, there is an intentional leak through the first fluid inlet 124a (e.g., the gate element 134a does not completely block fluid flow through the first fluid inlet 124a). In some embodiments, the gate element 134a can be configured to move to one or more intermediate positions between a first (e.g., open) position and a second (e.g., closed) position. The second actuator 130b can include a second gate element 134b, and the third actuator 130c can include a third gate element 134c that operates in a similar manner to the gate element 134a (e.g., movable between open and closed positions relative to the second and third fluid inlets 124b and 124c).

[0018] The first actuator 130a may further include a first actuating element 132a1 and a second actuating element 132a2 that drive movement of the gate element 134a between a first (e.g., open) position and a second (e.g., closed) position. The first actuating element 132a1 and the second actuating element 132a2 may be at least partially composed of a shape memory material or alloy (e.g., Nitinol). Thus, the first actuating element 132a1 and the second actuating element 132a2 may be transitionable between at least a first material phase or state (e.g., a martensitic state, an R-phase, a composite state between martensite and R-phase, etc.) and a second material phase or state (e.g., an austenitic state, an R-phase state, a composite state between austenite and R-phase, etc.). In the first material state, the first and second actuating elements 132a1 and 132a2 may have reduced (e.g., relatively less stiff) mechanical properties that make the actuating elements more easily deformable (e.g., compressible, expandable, etc.) relative to when the actuating elements are in the first material state. In the second material state, the first and second actuating elements 132a1 and 132a2 may have increased (e.g., relatively more stiff) mechanical properties relative to the first material state, causing an increased preference for a particular preferred geometry (e.g., original geometry, manufactured or fabricated geometry, heat-set geometry, etc.). The first and second actuating elements 132a1 and 132a2 may be energized by applying energy (e.g., laser energy, electrical energy, etc.) to the first and second actuating elements 132a1 or 132a2 to exceed a transition temperature (e.g., an austenite finish temperature (A ) generally above body temperature). f ) can selectively and independently transition between a first material state and a second material state. When heated above a transition temperature, if first actuating element 132a1 (or second actuating element 132a2) is deformed relative to its preferred geometry, first actuating element 132a1 (or second actuating element 132a2) moves to and / or toward its preferred geometry. In some embodiments, first actuating element 132 a1 and the second actuation element 132 a2is the number of actuating elements that have been actuated (e.g., the first actuating element 132 a1 ) transitions towards its preferred geometry, the non-actuated actuation element (e.g., second actuation element 132 a2 ) is operatively coupled to be further deformed relative to its preferred geometry.

[0019] When the temperature drops below the transition temperature (e.g., after cessation of energy application), the actuated actuation element (e.g., first actuation element 132a1) may exhibit some recovery or reaction movement back toward the pre-actuation geometry as it transitions to and / or toward its first material state and seeks equilibrium with external (e.g., mechanical) stresses (e.g., stresses imparted by unactuated actuation elements further deforming relative to their preferred geometry) that push the actuation element away from its preferred geometry. Depending on the degree of deformation in the actuation element before actuation and the degree of external stress acting on the actuation element, the recovery movement generally does not cause the actuation element to return completely to its pre-actuation geometry, but rather to an intermediate geometry between the preferred geometry and the pre-actuation geometry. Because the actuation element is coupled to the gate element 134a, the recovery movement in the actuation element may also cause corresponding movement in the gate element 134a even if minimal and / or no phase transformation occurs. However, as described below with respect to FIG. 1C, the plate assembly 120 may include one or more features that reduce and / or prevent the return movement of the actuating element from causing corresponding movement of the gate element 134a and / or that reduce and / or prevent the return movement of the actuating element itself.

[0020] The first actuating element 132a1 and the second actuating element 132a2 generally act in opposite directions. For example, the first actuating element 132a1 can actuate the gate element 134a to and / or toward a first (e.g., open) position, and the second actuating element 132a2 can actuate the gate element 134a to and / or toward a second (e.g., closed) position. Additionally, as described above, the first actuating element 132a1 and the second actuating element 132a2 can be coupled such that as one moves toward its preferred geometric shape during a material phase transition, the other deforms relative to its preferred geometric shape. This allows the actuating element 132a to be repeatedly actuated, cycling the gate element 134a repeatedly between the first (e.g., open) position and the second (e.g., closed) position. However, because the first actuating element 132a1 and the second actuating element 132a2 are coupled, stress in the first actuating element 132a1 can cause a restoring movement in the second actuating element 132a2 after actuation of the second actuating element 132a2, and stress in the second actuating element 132a2 can cause a restoring movement in the first actuating element 132a1 after actuation of the first actuating element 132a1.

[0021] The second actuator 130b and the third actuator 130c also each include a pair of opposing shape memory actuators and can operate in the same or similar manner as the first actuator 130a. Additional details regarding the operation of shape memory actuators and adjustable glaucoma shunts are described in U.S. Patent Application No. 17 / 175,332, U.S. Patent Application Publication No. 2020 / 0229982, and International Patent Applications Nos. PCT / US20 / 55144, PCT / US20 / 55141, PCT / US21 / 14774, PCT / US21 / 18601, PCT / US21 / 23238, and PCT / US21 / 27742, the disclosures of which are incorporated herein by reference in their entireties for all purposes.

[0022] In some embodiments, plate assembly 120 is formed in part by multiple separate sheets (e.g., glass sheets) bonded together (e.g., via chemical bonding, welding, adhesives, etc.). The multiple separate sheets can be designed to form channels 136a-c and chambers 121a-c. Additional details, including the manufacture of plate assemblies having similar aspects to plate assembly 120, are described in U.S. Provisional Patent Application No. 63 / 140,655, the disclosure of which is incorporated herein by reference in its entirety.

[0023] 1C is an enlarged view of a portion of plate assembly 120 illustrating first chamber 121a with first actuator 130a omitted for clarity. As illustrated, plate assembly 120 may include a stop element 127a (e.g., a wall) within first chamber 121a that engages gate element 134a (FIG. 1B) as gate element 134a moves from a first (e.g., open) position to and / or toward a second (e.g., closed) position. This prevents gate element 134a from moving past the second (e.g., closed) position when second actuation element 132a2 (FIG. 1B) is actuated.

[0024] Plate assembly 120 also generally includes a raised portion or ledge 125a positioned generally below first fluid inlet 124a (e.g., positioned so that an axis extending through the center of first fluid inlet 124a also extends through ledge 125a). Ledge 125a is raised relative to the portion of the plate assembly that forms the “floor” of first chamber 121a. While ledge 125a is shown in FIG. 1C with a flat, stepped cross-sectional profile, the ledge cross-sectional profile can be any shape that is raised relative to the floor, including triangular, circular, sinusoidal, parabolic, hyperbolic, spherical, conical, etc. Ledge 125a can serve several purposes that are expected to improve the operation of first actuator 130a, described below.

[0025] The ledge 125a can reduce undesired movement of the gate element 134a (e.g., by reducing the effect of restorative movement on the gate element 134a) as the gate element 134a moves from a first (e.g., open) position to and / or toward a second (e.g., closed) position. As described above with reference to FIG. 1B , when the gate element 134a is in the first (e.g., open) position, actuating the second actuating element 132a2 causes the gate element 134a to move toward the second (e.g., closed) position (e.g., such that the gate element 134a is generally positioned below the first fluid inlet 124a). However, when heat is removed from the second actuating element 132a2, it may exhibit restorative movement as it transitions back toward its first material state. Because the second actuation element 132a2 is connected to the gate element 134a, this return movement can also cause corresponding (and undesired) movement in the gate element 134a back toward the first (e.g., open) position, thereby moving the gate element 134a away from the desired stop position and partially or completely unblocking the first fluid inlet 124a. This is disadvantageous because it may allow fluid to enter the plate assembly 120 through the first fluid inlet 124a and / or increase the amount of fluid entering, even when a user desires to “close” the first fluid inlet 124a. To prevent or reduce this undesired movement of the gate element 134a, the ledge 125a is configured to form a friction interface with the first (e.g., lower) surface of the gate element 134a when the gate element 134a is in the second (e.g., closed) position. Thus, the ledge 125a may also be referred to as a “friction element.” The friction interface force can be weak enough to allow the gate element 134a to move in a selected actuation direction, yet strong enough to prevent, or at least impede, the gate element 134a from moving back toward the open position if the first actuator 130a exhibits a restoring motion. Thus, the ledge 125a helps to "hold" the gate element 134a in the closed position.The force of the friction interface is weak enough that when a user desires to "open" the first fluid inlet 124a, they can overcome it by actuating the first actuation element 132a1 and intentionally returning the gate element 134a to the open position.

[0026] The ledge 125a can also improve the seal between the gate element 134a and the first fluid inlet 124a when the gate element 134a is in the closed position. For example, the ledge 125a can orient the gate element 134a upward toward the first fluid inlet 124a so that the second (e.g., upper) surface of the gate element contacts the underside of the first fluid inlet 124a. This contact can prevent, or at least substantially prevent, fluid from entering the plate assembly 120 through the first fluid inlet 124a. Of course, some small leakage may still exist even when the gate element 134a is in the closed position. However, the incorporation of the ledge 125a is expected to advantageously reduce any leakage. The ledge 125a can also prevent the gate element 134a from deflecting downwardly away from the first fluid inlet 124a in response to increased pressure in the environment external to the first fluid inlet 124a.

[0027] Thus, ledge 125a can be configured to (1) form a frictional interface with the lower surface of gate element 134a and (2) improve contact (and therefore sealing) between the upper surface of gate element 134a and first fluid inlet 124a. In some embodiments, ledge 125a is a plateau-like structure, with the plane of the ledge being approximately parallel to the plane of the lower surface of first chamber 121a. In other embodiments, ledge 125a can be a wedge-shaped structure forming a slope with a surface that is non-parallel to the plane of the lower surface of first chamber 121a. In some embodiments, ledge 125a is textured or has other surface features to improve frictional interference with gate element 134a.

[0028] In some embodiments, the ledge 125a is formed on one of the sheets that form the plate assembly 120. For example, the ledge 125a can be integral with the sheet that forms the lower surface of the first chamber 121a. Thus, the ledge 125a can be composed of the same material (e.g., glass) as the sheet. In other embodiments, the ledge 125a can be a separate feature that is adhered (e.g., welded, glued, or otherwise secured) to the lower surface of the first chamber 121a.

[0029] In some embodiments, ledge 125a is a first ledge, and first chamber 121a further includes a second ledge (not shown). The second ledge can also be positioned on a surface of the plate assembly that forms the “floor” of first chamber 121a. However, unlike ledge 125a, the second ledge can be positioned to frictionally engage with the second ledge when gate element 134a is moved to the open position. Thus, the second ledge can prevent undesired movement of gate element 134a back toward the closed position after actuation of first actuation element 132a1 to move gate element 134a from the closed position to the open position.

[0030] Although not described for brevity, the plate assembly 120 may also include one or more ledges (not shown) in the second chamber 121b to reduce the effect of the restoring motion during actuation of the second actuator 130b, and one or more ledges (not shown) in the third chamber 121c to reduce the effect of the restoring motion during actuation of the third actuator 130c. These additional ledges may operate in a manner substantially similar to the ledge 125a described herein. Furthermore, although described as having three inlets 124 and three actuators 130, the plate assembly 120 may have more or fewer inlets 124 and actuators 130. For example, the plate assembly 120 may have one, two, four, five, six, or more inlets 124 and one, two, four, five, six, or more actuators 130.

[0031] System 100 can be used to treat a number of patient conditions. For example, system 100 can be used to drain aqueous humor from the anterior chamber of the eye to treat glaucoma. Thus, when system 100 is implanted in an eye to treat glaucoma, first end portion 102a of elongated housing 102 can be positioned within the anterior chamber of the patient's eye so that fluid inlet 124 is in fluid communication with the anterior chamber, and second end portion 102b can be positioned within a target outflow location, such as the subconjunctival bleb space, so that fluid outlet 106 is in fluid communication with the target outflow location. Aqueous humor can flow into the elongated housing via fluid inlet 124, through plate assembly 120, into main fluid conduit 110, and out via fluid outlet 106.

[0032] In addition to, or instead of, the ledge 125 described above, the systems described herein can include other features that reduce or otherwise inhibit undesired movement of the gating element caused by recovery movement of the actuation element after actuation of the actuation element. For example, FIGS. 2A-2D illustrate an actuator 230 configured in accordance with selected embodiments of the present technology for use with an adjustable shunt system (e.g., system 100 of FIGS. 1A-1C). The actuator 230 can be generally similar to the actuator 130 described above with respect to FIGS. 1A-1C. For example, with general reference to FIGS. 2A-2D, the actuator 230 can include a gating element 234 positioned between a first actuation element 232a and a second actuation element 232b. The gate element 234 may include a first (e.g., distal) end portion 234a configured to interface with a corresponding fluid inlet or opening of the shunt system (e.g., fluid inlet 124 of system 100, not shown in FIGS. 2A-2D ) and a second (e.g., proximal) end portion 234b opposite the first end portion 234a. The first actuating element 232a may be configured to move the first end portion 234a of the gate element 234 in a first direction and / or toward a first (e.g., open) position (e.g., to unblock the fluid inlet 124 shown in FIGS. 1A-1C ), and the second actuating element 232b may be configured to move the first end portion 234a of the gate element 234 in a second direction and / or toward a second (e.g., closed) position (e.g., to interfere with the fluid inlet 124 shown in FIGS. 1A-1C ). Actuator 230 can optionally include a perimeter 238 that surrounds or at least partially surrounds gate element 234, first actuation element 232a, and second actuation element 232b.

[0033] FIG. 2A illustrates the actuator 230 in an unstrained configuration (e.g., an “as-manufactured” or “as-cut” configuration). In the unstrained configuration, the first actuating element 232 a and the second actuating element 232 b both occupy their preferred geometries. FIG. 2B illustrates the actuator 230 in a strained configuration (e.g., a “loaded” or “tensioned” configuration). In the strained configuration, both the first actuating element 232 a and the second actuating element 232 b are deformed (e.g., stretched, tensioned, etc.) relative to their preferred geometries, causing stress in both the first actuating element 232 a and the second actuating element 232 b. In the illustrated embodiment, the actuator 230 can be transitioned between the unstrained and strained configurations by securing the second end portion 234 b of the gate element 234 to the periphery 238, as shown in FIG. 2B. However, in other embodiments, actuator 230 can be transitioned to the strained configuration by otherwise deforming and fixing the first and second actuating elements. In some embodiments, actuator 230 can be generally similar to the shape memory actuators described in U.S. Patent Application No. 17 / 175,332, previously incorporated by reference herein.

[0034] 2C and 2D illustrate the operation of actuator 230. In addition to actuator 230, FIGS. 2C and 2D also illustrate friction element 225 (which may also be referred to as a latching element or a retaining element). Similar to ledge 125 described with respect to FIG. 1C, friction element 225 may be formed on and / or coupled to one of the sheets forming the plate assembly (e.g., plate assembly 120 shown in FIGS. 1A-1C) that houses actuator 230. Friction element 225 may also be secured to another suitable portion of the shunt system. Friction element 225 may be a pin, tab, nub, ridge, protrusion, etc., and may have any suitable shape / geometry (e.g., cylindrical, cubic, rectangular, pyramidal, etc.). In some embodiments, friction element 225 has a height equal to or greater than the thickness of actuator 230.

[0035] 2C and 2D, the friction element 225 is configured to interfere with and / or engage (e.g., physically, mechanically, frictionally, etc.) with the first end portion 234a of the gate element 234. In this manner, as described in more detail below, the friction element 225 can bias the first end portion 234a of the gate element 234 toward a particular position and / or prevent the first end portion 234a from moving away from a particular position (e.g., via static friction). For example, as shown in FIG. 2C, when the first end portion 234a is in a first position (e.g., an open position), the friction element 225 can bias the first end portion 234a of the gate element 234 toward the first position and / or maintain / hold the first end portion 234a in the first position. 2D , when first end portion 234a is in the second position (e.g., the closed position), friction element 225 can bias and / or maintain / hold first end portion 234a of gate element 234 toward the second position. Thus, friction element 225 generally at least partially resists movement of first end portion 234a away from the position it occupies at any given time.

[0036] The biasing force (e.g., static friction) generated by the engagement of the gate element 234 and the friction element 225 can be overcome by actuating one of the actuating elements 232. For example, to move the gate element 234 from a first (e.g., open) position shown in FIG. 2C to a second (e.g., closed) position shown in FIG. 2D, the second actuating element 232b can be actuated, such as by heating the second actuating element 232b above its transition temperature. As the second actuating element 232b transitions from a first material state (e.g., martensite) to a second material state (e.g., austenite), increased mechanical properties (e.g., increased stiffness) within the second actuating element 232b cause the second actuating element 232b to transition to its preferred geometric shape, contracting the second actuating element 232b. The contraction of the second actuating element 232b imparts a first rotational force to the gate element 234 toward the second (e.g., closed) position. This first rotational force is initially resisted by static friction between the friction element 225 and the first end portion 234a of the gate element 234. However, as the first rotational force increases as the second actuation element 232b further contracts toward its preferred geometric shape, the first rotational force eventually overcomes (e.g., becomes greater than) the frictional force or other mechanical bias between the friction element 225 and the first end portion 234a of the gate element 234. For example, the first rotational force can be greater than the static and dynamic frictional forces between the gate element 234 and the friction element 225. As a result, the first end portion 234a “slips” or “slides” past the friction element 225 to occupy the second (e.g., closed) position, as shown in FIG. 2D (e.g., similar to a pawl sliding over the teeth of a ratchet). Thus, in some embodiments, the actuator 230 exhibits hysteresis as a result of the friction element 225.

[0037] After energy delivery ends and the second actuating element 232b cools, the second actuating element 232b may exhibit a recovery motion as it transitions back toward its first material state as it seeks equilibrium with external (e.g., mechanical) stresses (e.g., stresses imparted by the first actuating element 232a further deforming its preferred geometric shape) that push the second actuating element 232b away from its preferred geometric shape. Because the second actuating element 232b is connected to the gate element 234, this recovery motion may also impart a second rotational force on the gate element 234 (e.g., opposite to the first rotational force) toward the first (e.g., open) position. However, when the gate element 234 is in the second (e.g., closed) position, the friction element 225 imparts a frictional force or other mechanical biasing force against the first end portion 234a of the gate element 234 that is greater than the second rotational force caused by the recovery motion. For example, the second rotational force is less than the static friction force between the gate element 234 and the friction element 225. As such, the friction element 225 holds the first end portion 234a in the second (e.g., closed) position shown in FIG. 2D even as the second actuating element 232b transitions back to the first material state (thereby returning to a stiffness similar to that of the first actuating element 232a) and exhibits a recovery motion.

[0038] Thus, similar to the ledge 125 described with respect to FIG. 1C , the friction element 225 is expected to help reduce or mitigate the effects of recovery motion on the ability to selectively titrate fluid flow using the actuator 230. However, unlike the ledge 125, the friction element 225 helps reduce and / or mitigate the effects of recovery motion after actuation of both the first actuation element 232 a and the second actuation element 232 b. For example, the operation described above with respect to FIGS. 2C and 2D can be reversed by heating the first actuation element 232 a and providing energy to move the gate element 234 from the second (e.g., closed) position shown in FIG. 2C to the first (e.g., open) position shown in FIG. 2D . During such operation, the friction element 225 helps to hold the gate element 234 in the first (e.g., open) position after actuation of the first actuation element 232 a. Thus, friction element 225 is expected to increase the consistency of movement in gate element 234 (e.g., by reducing the effect of any restoring movement on gate element 234), and thus increase the fluid control achievable using actuator 230.

[0039] 3A-3C illustrate another actuator 330 configured in accordance with selected embodiments of the present technology for use with an adjustable shunt system (e.g., system 100 of FIGS. 1A-1C). Referring generally to FIGS. 3A-3C, actuator 330 can be actuated in a manner generally similar to actuators 130 and 230 described above. For example, actuator 330 can include a gate element 334 having a first end portion 334a and a second end portion 334b ​​configured to control fluid flow through an inlet (not shown) in the shunt system. Actuator 330 can also include a first actuating element 332a, a second actuating element 332b, and a periphery 338.

[0040] FIG. 3A illustrates the actuator 330 in an unstrained state (e.g., an "as manufactured" or "as cut" configuration) in which the first and second actuating elements 332a, 332b assume their preferred geometries. FIG. 3B illustrates the actuator 330 in a first strained configuration in which at least the second actuating element 332b is deformed (e.g., compressed) relative to its preferred geometry and the gate element 334 is in a first (e.g., open) position that does not interfere with a corresponding fluid inlet (not shown). FIG. 3C illustrates the actuator 330 in a second strained configuration in which at least the first actuating element 332a is deformed (e.g., compressed) relative to its preferred geometry and the gate element 334 is in a second (e.g., closed) position configured to interface with a corresponding fluid inlet (not shown). Thus, relative to the actuator 230, the actuating elements 332 are configured to be compressed relative to their preferred geometries when in the strained configuration.

[0041] The periphery 338 of the actuator 330 may include a first finger 337a and a second finger 337b (collectively referred to as fingers 337). The first finger 337a and the second finger 337b may form a pivot point that engages an intermediate portion of the gate element 334 between the first end portion 334a and the second end portion 334b ​​during actuation of the first actuating element 332a and the second actuating element 332b, respectively. As a result, actuating the first actuating element 332a causes the gate element 334 to pivot or otherwise flex about the first finger 337a, which moves the first end portion 334a from the second (e.g., closed) configuration shown in FIG. 3C to and / or toward the first (e.g., open) position shown in FIG. 3B. Actuating the second actuation element 332b causes the gate element 334 to pivot or otherwise flex about the second finger 337b, which moves the first end portion 334a from the first (e.g., open) position shown in Figure 3B to and / or toward the second (e.g., closed) position shown in Figure 3A. Without being bound by theory, the use of the finger 337b as a pivot point may allow the gate element 334 to have a shorter length while still achieving a sufficient range of motion to toggle the first end portion 334a between the first and second positions.

[0042] The actuator 330 also includes a friction element 325 configured to reduce and / or mitigate the effects of recovery motion in the actuator 330 after actuation of the first actuation element 332a and after actuation of the second actuation element 332b. The friction element 325 can operate in a manner similar to the friction element 225 described with respect to FIGS. 2C and 2D . For example, the friction element 225 can engage the first end portion 334a of the gate element 334 with a force low enough to allow translation of the first end portion 334a during actuation of the actuation element, but high enough to prevent, or at least reduce, translation of the first end portion 334a after the actuation event. However, unlike the friction element 225, the friction element 325 is integrated with the actuator 330 and, therefore, can be fabricated along with the other components of the actuator.

[0043] In some embodiments, the actuator may be configured to reduce or otherwise inhibit undesired movement of the gate element caused by restoring movement in the actuation element without the use of a friction element. For example, FIGS. 4A-4C illustrate an actuator 430 configured in accordance with selected embodiments of the present technology for use with an adjustable shunt system (e.g., system 100 of FIGS. 1A-1C). The actuator 430 may include certain features generally similar to the previously described actuators 130, 230, and 330. For example, the actuator 430 may include a gate element 434 having a first end portion 434a and a second end portion 434b, a first actuation element 432a, a second actuation element 432b, and a periphery 438. However, unlike the previously described actuators 230 and 330, the first end portion 434a of the gate element is not configured to control fluid flow through an inlet (not shown) in the shunt system. Rather, the first end portion 434a is coupled to the perimeter 438 at a receiving feature 436 (e.g., a groove, a notch, etc.) within the perimeter 438, and the gate element 434 further includes an intermediate portion 434c configured to control fluid flow through an inlet (not shown) within the shunt system.

[0044] 4A illustrates the actuator 430 in an unstrained (e.g., "as manufactured" or "as cut" configuration) in which the first and second actuating elements 432a, 432b assume their preferred geometric shapes. FIG. 4B illustrates the actuator 430 in a strained configuration in which at least the first actuating element 432a is deformed (e.g., compressed) relative to its preferred geometric shape and the gate element 434 is in a first (e.g., open) position that does not interfere with a corresponding fluid inlet (not shown). FIG. 4C illustrates the actuator 430 in a strained configuration in which at least the second actuating element 432b is deformed (e.g., compressed) relative to its preferred geometric shape and the gate element 434 is in a second (e.g., closed) position configured to interface with a corresponding fluid inlet (not shown). The first and second positions of the gate element 434 represent relatively low internal energy states (e.g., states having relatively low stored energy within the gate element 434) and therefore may be referred to herein as a "first equilibrium position or state" and a "second equilibrium position or state," respectively. As described in more detail below, the gate element 434 preferentially resides in (e.g., is biased toward) either the first position or the second position.

[0045] The actuator 430 can be transitioned between the unstrained configuration shown in FIG. 4A and the strained configuration shown in FIGS. 4B and 4C by disposing the second end portion 434b within a retention element 428, which serves to retain the actuator 430 in the strained (e.g., compressed) configuration. The retention element 428 can be formed on and / or coupled to one of multiple sheets forming the plate assembly (e.g., the plate assembly 120 shown in FIGS. 1A-1C) that houses the actuator 430. The retention element 428 can also be secured to another suitable portion of the shunt system. As shown in FIG. 4B, moving the actuator 430 from the unstrained configuration to the strained configuration causes the gate element 434 to bend outward relative to its longitudinal axis. In some embodiments, the gate element 434 bends outward because the distance between the retention element 428 (engaging with the second end portion 434b) and the receiving feature 436 (engaging with the first end portion 434a) is less than the length of the gate element 434. Thus, the bent configuration shown in FIGS. 4B and 4C depicts the low energy state of the gate element 434.

[0046] 4B and a second (e.g., closed) position shown in FIG. 4C by actuating the first or second actuating element 432. For example, to transition the gate element 434 from the open position to the closed position, the first actuating element 432a can be actuated, such as by heating the first actuating element 432a above its transition temperature. As the first actuating element 432a transitions from a first material state (e.g., martensite) to a second material state (e.g., austenite), increased mechanical properties (e.g., increased stiffness) within the first actuating element 432a cause the first actuating element 432a to transition to its preferred geometric shape, causing the first actuating element 432a to elongate. Extending the first actuation element 432a imparts a first rotational force to the gate element 434 toward the second (eg, closed) position, as previously described with respect to actuators 230 and 330.

[0047] This first rotational force is initially resisted by the gate element 434. As previously described, when the gate element 434 is in the first position shown in FIG. 4B , it exists in a first equilibrium or low-energy state. Thus, in some embodiments, the gate element 434 generally has a relatively low internal stress when in the first position compared to other potential configurations of the gate element 434. However, moving the gate element 434 from the open position (e.g., a first low-energy state) toward the closed position (e.g., a second low-energy state) requires the gate element 434 to transition through an intermediate position (not shown) in which it at least temporarily exists in a higher-energy transition state that generally has a relatively high internal stress compared to the low internal stress present in the low-energy states shown in FIGS. 4B and 4C . For example, in some embodiments, the gate element 434 temporarily assumes / passes through an s-shape or other high-energy configuration in the intermediate position / higher-energy transition state, although other configurations are possible. 4C, the gate element 434 must at least temporarily pass through a relatively high energy (and high stress) state (referred to herein as moving through an "energy gradient" or "stress gradient"). Accordingly, this energy gradient, at least initially, resists movement of the gate element 434 from the open position toward the closed position, and thus, at least initially, resists movement of the gate element 434 in response to the first rotational force imparted by actuation of the first actuation element 432a. However, as the first actuation element 434a further lengthens toward its preferred geometry, the first rotational force overcomes the biasing force of the energy gradient, and thus the gate element 434 moves from a first position in which it exists in a first, low-energy state having relatively low internal stress, through an intermediate position in which it exists at least temporarily in a relatively high-energy state having relatively high internal stress, to a second position in which it exists again in a second, low-energy state having relatively low internal stress.Notably, because the first and second positions represent low-energy states to which the gate element 434 is biased, the gate element 434 consistently and rapidly moves between the first and second positions upon actuation. Accordingly, the gate element 434 rapidly passes through any intermediate high-energy states between the first and second positions. For this reason, the gate element 434 may be described herein as "snapping" between the first and second positions upon actuation of the actuator, because both the open and closed positions represent the lowest energy states of the gate element 434.

[0048] After energy delivery ends and the first actuating element 432a cools, it may exhibit a restoring motion as it transitions back toward its first material state, as previously described. For example, the first actuating element 432a may seek equilibrium with an external (e.g., mechanical) stress (e.g., a stress imparted by the second actuating element 432b, which is further deformed relative to its preferred geometric shape) that pushes the first actuating element 432a away from its preferred geometric shape. Because the first actuating element 432a is connected to the gate element 434, this restoring motion may also impose a second rotational force on the gate element 434 (e.g., opposite the first rotational force) back toward the first (e.g., open) position. However, the energy gradient biasing the gate element 434 toward the second position prevents or reduces any undesired movement of the gate element 434 away from the second position during the recovery movement of the first actuating element 434a (e.g., because the biasing force generated by the energy gradient is greater than the second rotational force).

[0049] Accordingly, the actuator 430 is designed to help reduce or mitigate the effects of restorative motion on the ability to selectively titrate fluid flow using the actuator 430. More specifically, this is achieved by designing the actuator 430 so that the gating element 434 moves through a relatively high-energy, high-stress intermediate configuration as it moves between a first, relatively low-energy, low-stress configuration (e.g., a first position) and a second, relatively low-energy, low-stress configuration (e.g., a second position). Notably, this can be achieved without the need for external friction elements acting on the gating element 434. Such a configuration is also expected to improve the consistency and repeatability of moving the gating element 434 between the first and second positions (e.g., by minimizing the amount of time the gating element 434 occupies the other position), as the first and second positions represent two “stable” (e.g., low-energy) positions that the gating element 434 can occupy.

[0050] Although described in terms of a transition from a first, low energy state, through a relatively higher energy intermediate state, to a second, low energy state, operation of actuator 430 may be described in other terms. For example, the gating element may have a first internal stress and / or strain distribution or field when in the first, low energy state, a second internal stress and / or strain distribution when in the second, low energy state, and a third internal stress and / or strain distribution when in the intermediate, higher energy state. In such embodiments, actuator 430 may be biased toward the first and second stress distributions (e.g., by these distributions representing the lowest energy states).

[0051] The actuators described herein may include additional features that improve the function of the shunt system. For example, Figure 5 illustrates an actuator 530 configured in accordance with selected embodiments of the present technology for use with an adjustable shunt system (e.g., system 100 of Figures 1A-1C). Actuator 530 may be substantially similar to actuators 130, 230, 330, and 430 described with reference to Figures 1A-4C. For example, the actuator 530 may include a gate element 534 configured to interface with a corresponding fluid inlet or opening of the shunt system (e.g., the fluid inlet 124 of the system 100), a first actuating element 532a for moving the gate element 534 in a first direction to and / or toward a first (e.g., open) position (e.g., to unblock the fluid inlet 124), and a second actuating element 532b for moving the gate element 534 in a second direction generally opposite the first direction to and / or toward a second (e.g., closed) position (e.g., to block the fluid inlet 124).

[0052] 1A-4C, the actuator 530 further includes a sealing element 540 coupled to a first end region 534a of the gating element 534. The sealing element 540 includes a first portion 542 positioned on a first (e.g., upper) surface of the first end region 534a and, in at least some embodiments, optionally includes a second portion 544 positioned on a second (e.g., lower) surface of the first end region 534a. In some embodiments, the first portion 542 and the second portion 544 are connected by an intermediate portion (not shown) that extends through an opening in the first end region 534a, thereby securing the sealing element 540 to the first end region 534a. The sealing element 540 may also be secured to the gating element 534 via other suitable techniques, such as a mechanical tether, band, barb, staple, suture, or the like. In some embodiments, the sealing element 540 is a coating or other material on the surface of the gate element 534 (e.g., that completely or at least partially surrounds the first end region 534a) and therefore does not necessarily extend through an opening in the first end region 534a.

[0053] In some embodiments, the sealing element 540 is expected to improve the flow blocking effect of the gate element 534 by increasing the fluid resistance through the fluid inlet 124 ( FIG. 1B ) when the gate element 534 is in the second (e.g., closed) position. For example, the sealing element 540 can improve the seal between the first end portion 534 a of the gate element 534 and the fluid inlet 124 when the gate element 534 is in the second position, helping to prevent, reduce, or otherwise control leakage through the fluid inlet 124. In particular, when the gate element 534 is in the second position, the first portion 542 of the sealing element 540 may abut, conform to, and / or partially insert into the fluid inlet 124 to reduce and / or eliminate fluid flow through the fluid inlet 124. In some embodiments, the sealing element 540 does not eliminate leakage through the fluid inlet 124, but rather provides a consistent fluid resistance through the fluid inlet 124 when the gate element 534 is in the second (e.g., closed) position, providing a known leakage. In embodiments in which the sealing element 540 includes a second portion 544 positioned below the first end region 534a, the second portion 544 can further direct the gate element 534 toward the fluid inlet 124 by contacting a surface below the gate element 534 (e.g., the ledge 125a shown in FIG. 1C).

[0054] To further improve its sealant effect, the sealing element 540 may be at least partially constructed from an impermeable, partially compressible, or flexible material (e.g., an elastomeric material, a material with a low durometer, etc.) that can at least partially conform to the fluid inlet 124 when the gate element 534 is in the second position. For example, the sealing element 540 may be constructed from a hydrophobic material such as silicone. In another example, the sealing element 540 may be constructed from a hydrophilic material or a combination of hydrophobic and hydrophilic materials. In some embodiments, the sealing element 540, or at least a portion thereof, is constructed from a lubricious material, coating, or gel. For example, in some embodiments, the first portion 542 of the sealing element 540 is constructed from a lubricious material or includes a lubricious coating, and the second portion 544 is constructed from a non-lubricious material or coating. As another example, the entire sealing element 540 (including the first portion 542 and the second portion 544) may be constructed from a lubricious material and / or include a lubricious coating.

[0055] In addition to improving the seal between the gate element 534 and the fluid inlet 124, in some embodiments, the sealing element 540 can also increase the frictional interference that holds the gate element 534 in or near the second (e.g., closed) position. For example, contact between the first portion 542 of the sealing element 540 and the surface defining the fluid inlet 124, in conjunction with the ledge 125a (shown in FIG. 1C ) or the frictional features 225, 325 (shown in FIGS. 2C-3C ), can create a frictional force that can help prevent or reduce undesired movement of the gate element 534 after actuation of the actuator 530. Similarly, contact between the second portion 544 of the sealing element 540 and the surface below the actuator 530 can create a frictional force that further helps prevent or reduce undesired movement of the gate element 534 after actuation of the actuator 530. In other embodiments, the sealing element 540 does not substantially contribute to the frictional force holding the gate element 534 at or near the second position (e.g., embodiments in which the sealing element is a hydrophilic and lubricious coating or gel). Although described as being coupled to the gate element 534, in other embodiments, the systems described herein may include a sealing element coupled to a surface defining the fluid inlet instead of, or in addition to, a sealing element coupled to the gate element. For example, some systems configured in accordance with the present technology may include an impermeable and flexible membrane positioned adjacent to the fluid inlet such that when the gate element is in the first (e.g., open) position, the gate element is at least partially spaced from the fluid inlet, thus allowing fluid to enter the system. When the gate element is in the second (e.g., closed) position, the gate element may contact the membrane and press it against and / or against the fluid inlet to form a fluid seal at the fluid inlet. Thus, the present technology is not limited to the explicit embodiments depicted and described herein, but instead encompasses embodiments related to those described herein.

[0056] 6A and 6B illustrate another shunt system 600 ("system 600") configured in accordance with selected embodiments of the present technology. System 600 may be generally similar to system 100. For example, system 600 may include a generally elongated housing 602 and a plate assembly 620 configured to provide adjustable therapy for draining fluid from a first body region, such as for draining aqueous humor from the anterior chamber of a patient's eye.

[0057] 6B , similar to system 100, system 600 includes three flow paths for discharging fluid through plate assembly 620 to main fluid conduit 310 of elongated housing 602. For example, plate assembly 620 includes a first fluid inlet 624a, a second fluid inlet 624b, and a third fluid inlet 624c. First fluid inlet 624a is fluidly coupled to first channel 636a, second fluid inlet 624b is fluidly coupled to second channel 636b, and third fluid inlet 624c is fluidly coupled to third channel 636c. Similar to system 100, plate assembly 620 includes a first actuator 630a configured to selectively control the flow of fluid through first fluid inlet 624a and a second actuator 630b configured to selectively control the flow of fluid through second fluid inlet 624b.

[0058] Unlike system 100, plate assembly 620 does not include an actuator for selectively controlling fluid flow through third fluid inlet 624c (and thus fluid flow through third channel 636c). Instead, third fluid inlet 624c is configured to remain open / accessible when system 600 is implanted. Thus, fluid can continuously drain through plate assembly 620 via third fluid inlet 624c and third channel 636c when system 600 is implanted. Without being bound by theory, ensuring a base level of continuous therapy (e.g., flow) may be advantageous in certain situations, such as to ensure that at least a minimum level of therapy is provided. The level of therapy can then be increased or otherwise varied relative to the base level by selectively activating first actuator 630a and / or second actuator 630b, as described in detail above with respect to FIGS. 1A-5.

[0059] In some embodiments, such as the illustrated embodiment, the channel that does not have a corresponding actuator and is therefore configured to remain continuously open has the highest fluidic resistance of any of the channels. For example, the third channel 636c has a longer length and therefore a greater resistance than the first channel 636a and the second channel 636b. In other embodiments, the channel that does not have a corresponding actuator can have a fluidic resistance that is equal to or lower than the channels that have a corresponding actuator.

[0060] As will be appreciated by those skilled in the art, system 600 can include any of the features described with respect to system 100, such as one or more friction elements or ledges to reduce the effect of the restoring motion of first actuator 630 a and / or second actuator 630 b and / or one or more sealing elements to improve sealing between first actuator 630 a and first fluid inlet 624 a and / or second actuator 630 b and second fluid inlet 624 b. System 100 can also include more or fewer channels through plate assembly 620, such as two, four, five, six, or more.

[0061] While the present disclosure describes recovery motion in shape-memory actuation elements, those skilled in the art will understand that this phenomenon can be described in alternative ways. For example, movement of an actuation element during an actuation event (e.g., movement toward a preferred geometric configuration of the actuation element) can be described as a primary movement of the actuation element. The “recovery motion” of the same actuation element after an actuation event can be described as a secondary movement of the actuation element because it generally occurs subsequent to (e.g., after) the primary movement. Similarly, movement of a gate element during an actuation event (e.g., movement of a gate element during its primary movement) can be described as a “desired movement” or primary movement of the gate element. Movement of a gate element after an actuation event (e.g., movement of a gate element caused by a secondary movement of the actuation element) can be referred to as an “undesired movement,” “indirect movement,” and / or a secondary or tertiary movement of the gate element because it occurs subsequent to (e.g., after) the primary movement of the gate element. Accordingly, those skilled in the art will understand that the actuators described herein can demonstrate a series of movements over time during and after an actuation event. The friction features described herein are expected to allow some of these movements while mitigating (and / or mitigating the effects of) others. For example, the friction features generally allow primary movement of both the actuation element and the gate element, while preventing secondary movement of the gate element that may typically be caused by secondary movement of the actuation element.

[0062] Example Several aspects of this technology are described in the following examples. 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through an opening, a gate element movable between a first position that does not interfere with fluid flow through the opening and a second position that at least partially blocks fluid flow through the opening; and an actuator having a shape memory actuation element configured to, when actuated, move the gate element from a first position to and / or toward a second position; and a friction element configured to physically engage with the gate element to releasably hold the gate element in and / or adjacent to the second position after actuation of the shape memory actuation element. 2. The system of example 1, wherein the friction element is configured to frictionally engage the gate element. 3. The system of Example 1 or 2, wherein the shape memory actuation element is a first shape memory actuation element, and the system further comprises a second shape memory actuation element configured to, when actuated, move the gate element from the second position to and / or toward the first position. 4. The system of example 3, wherein the second shape memory actuation element is configured to overcome a force between the gate element and the friction element to move the gate element from the second position to and / or toward the first position. 5. The system of example 3 or example 4, wherein the friction element is a first friction element, and the system further comprises a second friction element configured to engage with the gate element to hold the gate element at and / or proximate to the first position after activation of the second shape memory element. 6. The system of any one of Examples 1-5, wherein the actuator is positioned within a chamber between a first surface having an opening and a second surface having a friction element. 7. The system of example 6, wherein the friction element includes a ledge on the second surface, the ledge aligned with an axis extending through the opening. 8. The system of example 7, wherein the gate element comprises a first surface configured to engage with the opening when in the second position and a second surface configured to engage with the ledge when in the second position. 9. The system of example 8, wherein the ledge is further configured to direct the gate element toward the opening as the gate element moves from the first position toward the second position to improve contact between the top surface of the gate element and the opening. 10. The system of any one of Examples 7-9, wherein the ledge is wedge-shaped. 11. The system of any one of Examples 7-10, wherein the ledge is textured. 12. The system of any one of Examples 1-11, wherein the system includes a plate assembly, the plate assembly having an opening, an actuator, and a friction element. 13. The system of example 12, wherein the plate assembly includes a plurality of sheets, and the friction element is integrated with one of the plurality of sheets. 14. A system described in any one of Examples 1 to 13, wherein the shape memory actuation element is configured to exhibit a recovery movement after actuation, and the friction element is configured to reduce any undesired movement of the gate element during the recovery movement of the shape memory actuation element. 15. The system of any one of Examples 1-14, wherein the system is an intraocular shunt system, the first body region is the anterior chamber of the patient's eye, and the second body region is a desired outflow location. 16. The system of any one of Examples 1-15, wherein the gate element includes a sealing element configured to abut against and / or partially occupy the opening when the gate element is in the second position to improve fluid sealing of the opening. 17. The system of example 16, wherein the sealing element is at least partially constructed from a lubricious material and / or includes a lubricious coating. 18. The system of example 16 or example 17, wherein the sealing element is at least partially composed of silicone. 19. The system of any one of Examples 16-18, wherein the sealing element is comprised of a combination of hydrophobic and hydrophilic materials. 20. The system of any one of Examples 16-19, wherein when in the second position, the gate element has a first surface facing the inlet and a second surface facing away from the inlet, and the sealing element includes a first portion positioned on the first surface and configured to abut the opening and / or partially occupy the opening, and a second portion positioned on the second surface and configured to engage with the friction element. 21. The system of example 20, wherein the first portion of the sealing element is constructed from a lubricious material and / or includes a lubricious coating. 22. The system of example 21, wherein the second portion of the sealing element is composed of a non-lubricating material. 23. The opening is a first opening, and the system a second opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; a first channel fluidly coupled to the first opening; The system of any one of Examples 1 to 22, further comprising: a second channel fluidly coupled to the second opening, the second channel being substantially fluidly isolated from the first channel, the second opening not including any corresponding actuator, and configured to remain substantially open when the system is implanted. 24. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through an opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured, when actuated, to move the gate element from a first position to and / or toward a second position; and an actuator having a second shape memory actuation element configured, when actuated, to move the gating element from the second position to and / or toward the first position; a friction element configured to physically engage the first end portion of the gate element; 1. An adjustable shunt system, wherein: (a) when the gate element is in a first position, a friction element biases the gate element toward the first position and / or releasably holds the gate element in the first position; and (b) when the gate element is in a second position, the friction element biases the gate element toward the second position and / or releasably holds the gate element in the second position. 25. The friction element is enabling movement of the gating element from a first position to and / or toward a second position upon actuation of the first shape memory actuation element; preventing movement of the gate element from the second position toward the first position after actuation of the first shape memory actuation element; enabling movement of the gating element from the second position to and / or toward the first position upon actuation of the second shape memory actuation element; 25. The system of example 24, configured to prevent movement of the gate element from the first position toward the second position after activation of the second shape memory activation element. 26. A system described in Example 24 or 25, wherein the first shape memory actuation element and the second shape memory actuation element are configured to exhibit a recovery movement after actuation, and the friction element is configured to reduce and / or prevent any undesired movement of the gate element after actuation of the first actuation element and after actuation of the second actuation element. 27. A system described in any one of Examples 24-26, wherein the first shape memory actuation element, when actuated, is configured to impart a rotational force to the gate element toward the second position, the rotational force being greater than the static friction force between the gate element and the friction element, such that the gate element slides past the friction element toward the second position. 28. The system of any one of Examples 24-27, wherein the second shape memory actuation element, when actuated, is configured to impart a rotational force to the gate element toward the first position, the rotational force being greater than the static friction force between the gate element and the friction element, such that the gate element slides past the friction element toward the first position. 29. The system of any one of Examples 24-28, wherein the friction element is integrated with the actuator. 30. The system of any one of Examples 24-28, wherein the friction element is a tab, lump, protrusion, or bump. 31. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through an opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated that moves the gating element from a first position to and / or toward a second position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; an actuator having a second shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated to move the gating element from the second position to and / or toward the first position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; a friction element configured to physically engage the first end portion of the gate element; An adjustable shunt system, wherein the friction element is configured to reduce undesired movement of the gate element during secondary movement of the first actuation element and during secondary movement of the second actuation element. 32. The system described in Example 31, wherein the secondary movement of the first actuating element is a recovery movement caused at least in part by the second actuating element, and the secondary movement of the second actuating element is a recovery movement caused at least in part by the first actuating element. 33. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through an opening, Gate element, a first shape memory actuation element coupled to a first portion of the gate element; and an actuator having a second shape memory actuation element coupled to a second portion of the gate element; a first shape memory actuation element configured to move the gating element from a first low-energy position in which the gating element does not interfere with fluid flow through the opening, through an intermediate high-energy position, to a second low-energy position in which the gating element at least partially interferes with fluid flow through the opening; An adjustable shunt system, wherein a second shape memory actuation element is configured to move the gating element from a second low-energy position, through an intermediate high-energy position, to the first low-energy position. 34. The system described in Example 33, wherein the actuator is configured to reduce and / or prevent undesired movement of the gate element during recovery movement of the first or second shape memory actuation element by an intermediate high energy position. 35. The actuator a first force exerted by the first shape memory actuation element on the gating element during actuation of the first shape memory actuation element is sufficient to move the gating element through the intermediate high energy position; The system of Example 34, configured such that during the recovery movement of the first shape memory actuating element, the second force exerted by the first shape memory actuating element on the gate element is not sufficient to move the gate element through the intermediate high energy position. 36. A system described in Example 33 or Example 34, wherein the gate element has a first internal stress distribution at a first low-energy position, a second internal stress distribution at a second low-energy position, and a third internal stress distribution at an intermediate high-energy position, and the gate element is biased toward the first internal stress distribution and / or the second internal stress distribution. 37. The system of example 36, wherein the first internal stress distribution and the second internal stress distribution are approximately equal. 38. A method of regulating fluid flow through an opening in a shunt, comprising: actuating the shape memory actuator to move the gating element between (a) a first position that does not interfere with fluid flow through the opening and (b) a second position that at least partially interferes with fluid flow through the opening; moving the gate element between the first position and the second position, wherein moving the gate element includes overcoming a first biasing force directing the gate element toward the first position; releasably holding the gate element in the second position during a recovery movement of the shape memory actuator. 39. The method of example 38, wherein releasably holding the gate element in the second position includes preventing movement of the gate element from the second position toward the first position during a recovery movement of the shape memory actuator. 40. The method of example 38, wherein releasably holding the gate element in the second position includes engaging the gate element with a friction element. 41. The method of example 40, wherein a friction element generates the biasing force. 42. The method of any one of Examples 38-41, wherein the gating element has a first stored energy in the first position and the second position, and moving the gating element from the first position to the second position comprises transitioning the gating element through an intermediate position having a second stored energy greater than the first stored energy.

[0063] conclusion The above detailed description of embodiments of the present technology is not intended to be exhaustive or to limit the present technology to the precise forms disclosed above. While specific embodiments and examples of the present technology have been described above for illustrative purposes, those skilled in the art will recognize that various equivalent modifications are possible within the scope of the present technology. For example, any of the features of the intraocular shunts described herein can be combined with any of the features of the other intraocular shunts described herein, and vice versa. Furthermore, while steps are presented in a given order, steps may be performed in a different order in alternative embodiments. The various embodiments described herein may also be combined to provide further embodiments.

[0064] From the foregoing, it will be understood that, while specific embodiments of the present technology have been described herein for purposes of illustration, well-known structures and functions associated with intraocular shunts have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Where the context permits, singular or plural terms may also include the plural or singular terms, respectively.

[0065] Unless the context clearly dictates otherwise, throughout the description and examples, words like "comprise," "comprising," and the like should be construed in an inclusive sense, i.e., meaning "including, but not limited to," rather than an exclusive or exhaustive sense. As used herein, the terms "connected," "coupled," or any variation thereof, mean any direct or indirect connection or coupling between two or more elements. The coupling between elements may be physical, logical, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above detailed description using the singular or plural may each be in the plural or singular. As used herein, the phrase "and / or" appearing in "A and / or B" may refer to A only, B only, or both A and B. Additionally, the term "comprising" is used throughout to mean the inclusion of at least the recited features, without excluding any more of the same features and / or other features of additional types. While specific embodiments have been described herein for illustrative purposes, it will also be understood that various modifications may be made without departing from the present technology. Furthermore, while advantages associated with some embodiments of the present technology have been described in the context of these embodiments, other embodiments may also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the present technology. Thus, the present disclosure and related technology may encompass other embodiments not explicitly shown or described herein.

Claims

1. 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured, when actuated, to move the gate element from the first position to and / or toward the second position; and an actuator having a second shape memory actuation element configured, when actuated, to move the gate element from the second position to and / or toward the first position; a friction element configured to physically engage the first end portion of the gate element; 1. An adjustable shunt system, wherein: (a) when the gate element is in the first position, the friction element releasably holds the gate element in the first position; and (b) when the gate element is in the second position, the friction element releasably holds the gate element in the second position.

2. The friction element is upon actuation of the first shape memory actuation element, permitting movement of the gate element from the first position to and / or towards the second position; preventing movement of the gate element from the second position toward the first position after actuation of the first shape memory actuation element; upon actuation of the second shape memory actuation element, permitting movement of the gate element from the second position to and / or towards the first position; and preventing movement of the gate element from the first position toward the second position after actuation of the second shape memory actuation element.

3. 2. The system of claim 1, wherein the first shape memory actuating element and the second shape memory actuating element are configured to exhibit a recovery movement after actuation, and the friction element is configured to reduce and / or prevent any movement of the gate element during the recovery movement of the first shape memory actuating element and the recovery movement of the second shape memory actuating element.

4. 2. The system of claim 1, wherein the first shape memory actuation element, when actuated, is configured to impart a rotational force to the gating element toward the second position, the rotational force being greater than a static friction force between the gating element and the friction element, such that the gating element slides past the friction element toward the second position.

5. 2. The system of claim 1, wherein the second shape memory actuation element, when actuated, is configured to impart a rotational force to the gating element toward the first position, the rotational force being greater than a static friction force between the gating element and the friction element such that the gating element slides past the friction element toward the first position.

6. The system of claim 1 , wherein the friction element is integral with the actuator.

7. The system of claim 1 , wherein the friction elements are tabs, lumps, protrusions, or bumps.

8. 1. An adjustable shunt system for draining fluid from a first body region to a second body region, comprising: a shunt element configured to extend at least partially between the first body region and the second body region; an opening fluidly connecting the exterior of the shunt element to the interior of the shunt element; an actuator configured to selectively control fluid flow through the opening, a gate element movable between a first position in which a first end portion of the gate element does not interfere with fluid flow through the opening and a second position in which the first end portion of the gate element at least partially interferes with fluid flow through the opening; a first shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated that moves the gating element from the first position to and / or toward the second position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; an actuator having a second shape memory actuation element configured to (1) exhibit a primary movement toward a preferred geometry when actuated to move the gating element from the second position to and / or toward the first position, and (2) exhibit a secondary movement away from the preferred geometry after actuation; a friction element configured to physically engage the first end portion of the gate element; An adjustable shunt system, wherein the friction element is configured to reduce movement of the gate element during secondary movement of the first shape memory actuation element and secondary movement of the second shape memory actuation element.

9. 9. The system of claim 8, wherein the secondary movement of the first shape memory actuating element is a recovery movement caused at least in part by the second shape memory actuating element, and the secondary movement of the second shape memory actuating element is a recovery movement caused at least in part by the first shape memory actuating element.

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