Shape memory alloy (SMA) bimorph actuators with reduced wire exit angle

Abstract

A Shape Memory Alloy (SMA) actuator comprises a beam 612 with fixed 620 and free 608 ends, and an SMA wire 610 connected between the ends so that it bends the beam 612 when the SMA 610 contracts due t

Description

CROSS-REFERENCE TO RELATED APPLICATION [00011 Tins application claims the benefit of, and priority to, U.S. Patent Application No. 18 / 142,471, filed on May 2, 2023, which is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the invention relate to the field of shape memoiy alloy systems. More particularly, embodiments of the invention relate to the field of shape memory alloy actuators and methods related thereto. BACKGROUND [00031 Shape memory' alloy (‘‘SMA'’) systems can include an actuator or structure that can be used in conjunction with various components, such as a camera, lens element as an autofocusing drive or an optical image stabilization (OIS) drive. The SMA actuator can be configured to actuate responsive to providing an electrical current to the SMA wire. [0004[ For example, a first end of an SMA wire can be engaged at a fixed end fixed to an actuator. Further, a second end of the SM A wire can be engaged to a free end configured to move in response to the actuation of the SMA wire. For instance, the free end can move in a z-direction in response to the actuation of the SMA wire. SUMMARY

[0005] The present embodiments relate to a shape memory alloy (SMA) actuator with SMA wires affixed to a bottom surface of the SMA actuator for increased resiliency of the SMA actuator.

[0006] In a first example embodiment, a shape memory alloy (SMA) actuator is provided. The SMA actuator can include at least one fixed end configured to be fixed to a carriage and at least one free end. Hie SMA actuator can also include at least one beam connecting the fixed end and the free end. [00071 The SMA actuator can also include at least one SMA wires. The at least one SMA wire can be electrically connected to the at least one fixed end and the at least one free end via electrical contact portions. The at least one SMA wire can be disposed to corresponding electrical contact portions at a bottom surface comprising a surface directed at the carriage.

[0008] In some instances, the electrical contact portions comprise a first set of electrical contact portions at the at least one fixed end. A first end of each of the at least one SMA wire can be disposed at each of the first set of electrical contact portions. The electrical contact portions can also include a second set of electrical contact portions at the at least one free end. A second end of each of the at least one SMA wire can be disposed at each of the second set of electrical contact portions.

[0009] In some embodiments, the SMA actuator can include a first fixed end with a first electrical contact portion connected to a first end of a first SMA wire, a first free end with a second electrical contact portion connected to a second end of the first SMA wire, and a first beam disposed between the first fixed end and first free end.

[0010] The SMA actuator can include a second fixed end with a third electrical contact portion connected to a second end of a second SMA wire, a second free end with a fourth electrical contact portion connected to a second end of the second SMA ware, and a second beam disposed between the second fixed end and second free end. The first free end can be directed in a direction opposing a direction of the second free end,

[0011] In some instances, responsive to obtaining an electrical current at the at least one SMA wire, the at least one free end is configured to move in a positive z-direction. Further, the actuator can include a wire exit angle comprising an angle between the at least one fixed end and the at least one SMA wire being less than 10 degrees upon actuation of each of the at least one SMA wire.

[0012] In some instances, the SMA actuator can be part of an autofocus system or an optical image stabilization system for a camera.

[0013] In another example embodiment, a device is provided. The device can include a carriage and an actuator engaged to the carriage. The actuator can include a fixed end fixed to the carnage, a free end, a beam connecting the fixed end and the free end, and at least one shape memory alloy (SMA) wire. Tire at least one SMA wire can be electrically connected to the fixed end and the free end via electrical contact portions, lire at least one SMA wire can be disposed to the electrical contact portions at a bottom surface of the electrical contact portions directed at the carriage.

[0014] In some instances, the electrical contact portions comprise a first set of electrical contact portions at the at least one fixed end. A first end of the at least one SMA wire can be disposed at the first set of electrical contact portions. The electrical contact portions can also include a second set of electrical contact portions at the at least one free end. A second end of the at least one SMA wire can be disposed at the second set of electrical contact portions.

[0015] In some instances, the actuator can include a first fixed end with a first electrical contact portion connected to a first end of a first SMA wire, a first free end with a second electrical contact portion connected to a second end of the first SMA wire, and a first beam disposed between the first fixed end and first free end. In some instances, the actuator can include a second fixed end with a third electrical contact portion connected to a second end of a second SMA wire, a second free end with a fourth electrical contact portion connected to a second end of the second SMA wire, and a second beam disposed between the second fixed end and second free end. In some instances, the first free end is directed in a direction opposing a direction of the second free end.

[0016] In some instances, a wire exit angle comprising an angle between the fixed end and the at least one SMA wire or an angle between the free end and the at least one SMA wire is less than 5 degrees upon actuation of the at least one SMA wire.

[0017] In another example embodiment, a system is provided. The system can include a first actuator portion. The first actuator portion can include a first fixed end, a first free end, and a first SMA wire. The first SMA ware can include a first end wielded to a bottom surface at the first fixed end and a second end welded to the bottom surface at the first free end. The system can also include a second actuator portion. The second actuator portion can include a second fixed end, a second free end, and a second SMA wire. The second SMA wire can comprise a first end welded to the bottom surface at the second fixed end and a second end welded to the bottom surface at the second free end.

[0018] In some instances, the system can include a carriage. The first fixed end and the second fixed end can be fixed to the carnage. Further, the bottom surface can comprise a surface directed toward the carriage.

[0019] In some instances, a direction of the first actuator portion opposes a direction of the second actuator portion. In some instances, any of the first free end and the second free end are configured to move in a positive z-direction. In some instances, the system is part of an autofocus system or an optical image stabilization system. In some instances, a wire exit angle comprising an angle between the first fixed end and the first SMA wire or an angle between the first free end and the first SMA wire is less than 10 degrees upon actuation of each of the first SMA wire.

[0020] Other features and advantages of embodiments of the present invention will be apparent from the accompanying drawings and from the detailed description that follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the present invention are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

[0022] FIG. 1 illustrates an example prior art SMA bimorph actuator according to an embodiment.

[0023] FIG. 2 illustrates an example actuator with an adhesive applied according to an embodiment.

[0024] FIG. 3 illustrates a first example SMA actuator according to an embodiment.

[0025] FIG. 4 illustrates a second example SMA actuator according to an embodiment.

[0026] FIG. 5 illustrates an example of the force coupling between the wire and the weld tongue according to an embodiment,

[0027] FIG, 6A illustrates a side view of an SMA actuator in a non-actuated position according to an embodiment.

[0028] FIG. 6B illustrates a side view of the SMA actuator in an actuated position according to an embodiment.

[0029] FIG. 7 is an illustration of an example actuator with multiple SMA wires according to an embodiment.

[0030] FIG. 8 illustrates a set of SMA wires affixed at an electrical circuit according to an embodiment. DETAILED DESCRIPTION [00311 The present embodiments relate to shape memory alloy (SMA) actuators. SMA actuators as described herein can include a compact footprint and provide a high actuation height, for example movement in the positive z~axis direction (z-direction), referred to herein as z-stroke movement. The SMA actuator as described herein can include an SMA bimorph actuator. 'The SMA actuator may be used in many applications including, but not limited to, a lens assembly as an autofocus actuator, a micro-fluidic pump, a sensor shift, optical image stabilization, optical zoom assembly, to mechanically strike two surfaces to create vibration sensations typically found in haptic feedback sensors and devices, and other systems where an actuator is used. For example, embodiments of an actuator described herein could be used as a haptic feedback actuator for use in cellphones or wearable devices configured to provide the user an alarm, notification, alert, touched area or pressed button response. Further, more than one SMA actuator could be used in a system to achieve a larger stroke.

[0032] In some embodiments, the SMA actuator can include a z-stroke that is greater than 0.4 millimeters. Further, the SMA actuator for various embodiments can have a height in the z-direction of 2.2 millimeters or less, when the SMA actuator is in its initial, a de-actuated position. Various embodiments of the SMA actuator can be configured as an autofocus actuator in a lens assembly may have a footprint as small as 3 millimeters greater than the lens inner diameter. According to various embodiments, the SMA actuator may have a footprint that is wider in one direction to accommodate components including, but not limited to, sensors, wires, traces, and connectors. According to some embodiments, the footprint of an SMA actuator is 0.5 millimeters greater in one direction, for example the length of the SMA actuator is 0.5 millimeters greater than the width.

[0033] FIG. 1 illustrates an example prior art SMA bimorph actuator 100 according to some embodiments. As shown in FIG. 1, in many cases, the actuator 100 can include a carriage 104. In many instances, the actuator can be affixed to the carriage 104 as described herein. The carriage 104 can increase resiliency of the actuator 100 by providing support for the actuator.

[0034] Ilie actuator 100 can include a fixed end 106 and a free end 108. The fixed end 106 can be fixed to the carnage 104, while the free end 108 can include a load point 120 and can be detached from the carnage 104. As described in greater detail below, the free end 108 can move in a z-stroke direction (e.g., direction DI) responsive to providing an electrical current to SMA wires 110a, 110b.

[0035] As shown in FIG. 1, SMA wires 110a, 110b can extend from the fixed end 106 to the free end 108 of the actuator 100. Further, a beam 112 can be disposed below the SMA wires 110a, 110b and can connect the fixed end 106 and free end 108. The SMA wires 110a, 110b can connect to the actuator lOOat each end via. electrical contacts. For example, at a first end of each SMA wires 110a, 110b, the SMA wires 110a, 110b can connect to the fixed end 106 at. electrical contacts 114a, 114b. Further, at a second end (e.g., at. the free end 108), the SMA wires 110a, 110b can connect to the free end 108 at electrical contacts 118a, 118b (e.g., via a welding or soldering process).

[0036] The actuator lOOcan consist of a material such as steel or stainless steel, for example. Further, electrical contacts 114a~b, 118a-b can include a material allowing for receiving a welding or soldering joint, such as a gold-plated stainless steel, for example. Further, at free end 106, a dielectric 116 can isolate the electrical contacts 114a-b to prevent electrical current between the contacts. Dielectric 116 can include insulative materials, such as a Polyimide, for example. In some embodiments, a dielectric can be disposed between SMA wires 110a-110b and beam 112 at the free end 108 to electrically isolate the SMA wires HOa-b from the beam 112.

[0037] In some instances, the actuator can include a three-layer design, with a first layer comprising stainless steel (e.g., forming actuator 100), a second layer comprising a polyimide (e.g., isolating electrical contacts, and a third layer comprising gold-plated stainless steel.

[0038] For instance, in the actuator 100 as shown in FIG. 1, the SMA 110a-b can be engaged (e.g., at 114a-b, 118a-b) at atop or upper surface of the actuator (e.g., a surface facing away from the carnage 104). The SMA can be welded (or soldered) to atop stainless-steel surface (or, in some cases, a gold-plated metal). However, as described in greater detail below, such a configuration can result in lower resiliency of the weld joint due at least to the wire angle and maximum stress occurring at the weld joint as the SMA actuates.

[0039] In some instances, to increase resiliency of the weld joint disposed at a top surface of the actuator, an adhesive application process can be performed. An adhesive application process can include applying an adhesive to the weld joint. Further, the process can include an oven heating process to cure the adhesive. FIG. 2 illustrates an example actuator 200 with an adhesive applied. For example, an adhesive can be applied at weld joints 202a-b, 204a-b. However, an adhesive application process as described herein can include multiple steps, which can be resource and time intensive.

[0040] Ilie present embodiments relate to SMA actuators (e.g., a bimorph actuator) with weld joints between the SMA and a actuator being at a lower or bottom surface of the actuator. Affixing the SMA wire at a bottom surface of the actuatorcan allow' for a reduced wire exit angle and lower stress at the weld joints between SMA wire and the actuator.

[0041] FIG. 3 illustrates a first example SMA actuator 300. As shown in FIG. 3, the SMA wires 310a-b can be connected to the actuator at both a fixed end 306 and a free end 308. The actuator can include weld tongues to facilitate engaging the SMA wire to the actuator. For example, at the fixed end 306, a first set of weld tongues 314a-b can include the weld joint to a first end of the SMA wires 310a-b. Similarly, at the free end 308, a second set of weld tongues 318a-b can include the weld joint to a second end of the SMA wires 31 Oa-b, The weld joints can be at a bottom surface (e.g., a surface facing a carriage) of the actuator.

[0042] FIG. 4 illustrates a second example SMA actuator 400. As shown in FIG. 4, the SMA actuator can include multiple actuators, each with independent fixed ends and free ends. For example, a first actuator can include a first fixed end 402a and a first free end 404a. Further, a second actuator can include a second fixed end 402b and a second free end 404b. The actuators can be directed opposing one another,

[0043] Further, each actuator can include weld tongue comprising a portion of the actuatorin which the SMA wires are affixed. For example, a first weld joint 406a can be disposed at the first fixed end 402a, and a second weld joint 408a can be disposed at a first free end 404a. Similarly, a third weld joint 406b can be disposed at the second fixed end 402b, and a fourth weld joint 408b can be disposed at a second free end 404b. [00441 Favorable force coupling between the ware and compliant weld tongue is generated when the wire is welded on the opposite (bottom) surface of the SSt. This can result in a reduction in a wire exit angle at a large stroke. FIG. 5 illustrates an example of the force coupling between the wire and the weld tongue. For example, as shown in FIG. 5, a SMA wire can include a first end 502 and a second end 504. The first end 502 can be affixed (e.g., welded, soldered) to the fixed end 506. Further, the second end 504 can be affixed to the free end 508.

[0045] As shown in FIG. 5, force directions of the SMA wire and the actuator can cause force coupling between the SMA wire and the actuator. For example, the first end of the wire can have a direction 510 facing the second end of the wire 504. Further, the second end of the wire 504 can include a direction 512 facing the first end 502. Similarly, the fixed end 506 can have a direction 514 rotating away from the SMA wire. Further, free end 508 can have a direction 516 rotating away from the SMA wire. The differing directions of force between the SMA wire can cause force coupling between the SMA wire and the actuator.

[0046] FIGS. 6A-6B illustrate a side view7 of an example SMA actuator in both a nonactuated position (e.g., in FIG. 6A) and an actuated position (e.g., in FIG. 6B). As shown in FIG. 6A, the SMA actuator 600a can include a fixed end 606 and a free end 608, with a beam 612 disposed between the ends 606, 608. Further, an SMA wire 610 can be disposed between the fixed end 606 and the free end 608.

[0047] The SMA wire 610 can include a first end connected to the fixed end 606 at a first weld joint 614. Further, the second end of the SMA wire 610 can connect to free end 608 at a second weld joint 616. The ends of the SMA ware 610 can be affixed to the actuator (e.g., at weld joints 614, 616) at a bottom surface 618 of the actuator. The bottom surface 618 can include a surface of the actuator directed toward carriage 604. While only one SMA wire 610 is shown in FIG. 6A, two or more SMA wires can be disposed in the SMA actuator.

[0048] FIG. 6B illustrates a side view- of the SMA actuator 600b in an actuated position. As shown in FIG. 6B, the SMA wire 610 can actuate in response to receiving an electrical current. The actuation of the SMA wire 610 can allow' for the free end 608 to move in a positive z-direction. Further, the free end 608 can move in the z-direction responsive to an amount of electrical current provided to the SMA wire.

[8049] As shown in FIG. 6B, the beam 612 can be modified due to the actuation of the SMA wire 610. Further, an angle 620 between the fixed end 606 and the first weld joint 614 can be modified. Similarly, an angle specifying a difference between the free end 608 and the SMA wire 610 can be modified due to the actuation of the SMA wire 610.

[0050] As an example, a max stroke wire exit angle (e.g., angle 620) at the fixed end can be around 0 degrees with the weld joint 614 being disposed at the bottom surface of the actuator. In other actuators with the weld joint on a top surface of the actuator (e.g., as shown in FIG. 2), the angle between fixed end and the SMA wire can be upwards of 8 degrees. Similarly. A max stroke wire exit angle (e.g., angle 622) at the free end 608 can be around 2.2 degrees. In other actuators with the weid joint on a top surface of the actuator (e.g., as shown in FIG. 2), the angle between fixed end and the SMA wire can be upw-ards of 6.5 degrees. The reduction in ware exit angle can result in reduced bending of the SMA wire, which can reduce overall stress on the weld joints between the SMA wires and the actuator. This can also improve reliability of the near-weld wire. In some instances, the increased reliability of the SMA actuators as described herein can remove a requirement for additional process steps to increase resiliency, such as an adhesive addition process (e.g., as described with respect to FIG. 2).

[0051] In a first example embodiment, a shape memory alloy (SMA) actuator is provided. The SMA actuator (e.g., 300 in FIG. 3) can include at least one fixed end (e.g., 306) configured to be fixed to a carriage (e.g., 104 in FIG. 1) and at least one free end (e.g., 308). The SMA actuator can also include at least one beam (e.g., 320) connecting the fixed end (e.g,, 306) and the free end (e.g., 308).

[0052] The SMA actuator can also include at least one SMA wire (e.g., SMA wires 310a-b). Each of the at least one SMA wire can be electrically connected to the at least one fixed end and the at least one free end via electrical contact portions (e.g., 314a-b, 318a-b). The at least one SMA wire can be disposed to corresponding electrical contact portions at a bottom surface of the actuator (e.g., 618) comprising a surface directed at the carnage. [00531 In some instances, the electrical contact portions comprise a first set of electrical contact portions (e.g., 314a-b) at the at least one fixed end (e.g,, 306). A first end of each of the at least one SMA wire can be disposed at each of the first set of electrical contact portions. The electrical contact portions can also include a second set of electrical contact portions (e.g., 318a-b) at the at least one free end. A second end of each of the at least one SMA wire can be disposed at each of the second set of electrical contact portions. In some embodiments, the SMA actuator can include a first fixed end (e.g., 402a) with a first electrical contact portion (e.g., 406a) connected to a first end of a first SMA wire (e.g., 408a), a first free end (e.g., 404a) with a second electrical contact portion (e.g., 408a) connected to a second end of the first SMA wire, and a first beam disposed betw een the first fixed end and first free end.

[0054] In some instances, the SMA actuator can include a balanced SMA actuator, such as the actuator 400 as described with respect to FIG. 4. Tire SMA actuator can include a second fixed end (e.g., 402b) with a third electrical contact portion (e.g., 406b) connected to a second end of a second SMA wire, a second free end (e.g., 404b) with a fourth electrical contact portion (e.g,, 408b) connected to a second end of the second SMA wire, and a second beam disposed between the second fixed end and second free end. The first free end (e.g., 404a) can be directed in a direction opposing a direction of the second free end (e.g., 404b).

[0055] In some instances, responsive to obtaining an electrical current at the at least one SMA wire, the at least one free end is configured to move in a positive z-direction. Further, the actuator can include a wire exit angle (e.g., 620) comprising an angle between the at least one fixed end (e.g., 606) and the at least one SMA wire (e.g., 610) being less than 10 degrees (e.g., or between 0 and 2 degrees) upon actuation of the at least one SMA wire.

[0056] In some instances, the SMA actuator can be part of an autofocus system for a camera.

[0057] In another example embodiment, a device is provided. The device can include a carriage and an actuator engaged to the carriage. The actuator can include a fixed end fixed to the camage, a free end, a beam connecting the fixed end and the free end, and at least one shape memory ahoy (SMA) wire. The at least one SMA wire can be electrically connected to the fixed end and the free end via electrical contact portions. Ilie at least one SMA wire can be disposed to the electrical contact portions at a bottom surface of the electrical contact portions directed at the carriage.

[0058] In some instances, the electrical contact portions comprise a first set of electrical contact portions at the at least one fixed end. A first end of the at least one SMA wire can be disposed at the first set of electrical contact portions. The electrical contact portions can also include a second set of electrical contact portions at the at least one free end. A second end of the at least one SMA wire can be disposed at the second set of electrical contact portions.

[0059] In some instances, the actuator can include a first fixed end with a first electrical contact portion connected to a first end of a first SMA wire, a first free end with a second electrical contact portion connected to a second end of the first SMA wire, and a first beam disposed between the first fixed end and first free end. In some instances, the actuator can include a second fixed end with a third electrical contact portion connected to a second end of a second SMA wire, a second free end with a fourth electrical contact portion connected to a second end of the second SMA wire, and a second beam disposed between the second fixed end and second free end. In some instances, the first free end is directed in a direction opposing a direction of the second free end.

[0060] In some instances, a wire exit angle comprising an angle between the fixed end and each of the at least one SMA wire or an angle between the free end and the at least one SMA wire is less than 5 degrees upon actuation of each of the at least one SMA wire.

[0061] In another example embodiment, a system is provided. The system can include a first actuator portion. The first actuator portion can include a first fixed end, a first free end, and a first SMA wire. The first SMA wire can include a first end welded to a bottom surface of the actuator at the first fixed end and a second end welded to the bottom surface of the actuator at the first free end. The system can also include a second actuator portion. The second actuator portion can include a second fixed end, a second free end, and a second SMA wire. The second SMA wire can comprise a first end welded to the bottom surface of the actuator at the second fixed end and a second end welded to the bottom surface of the actuator at the second free end.

[0062] In some instances, the system can include a carnage. The first, fixed end and the second fixed end can be fixed to the carriage. Further, the bottom surface of the actuator comprises a surface of the actuator directed toward tire carriage.

[0063] In some instances, a direction of the first actuator portion opposes a direction of the second actuator portion. In some instances, any of the first free end and the second free end are configured to move in a positive z-direction. In some instances, the system is part of an autofocus system or an optical image stabilization system. In some instances, a wire exit angle comprising an angle between the first fixed end and the first. SMA ware or an angle between the first free end and the first SMA wire is between 0 and 2 degrees upon actuation of each of the first SMA wire.

[0064] In some embodiments, an actuator can include multiple SMA elements (e.g., wires) connected from a base to a load point of the actuator. FIG. 7 is an illustration of an example actuator 700 with multiple SMA wires 702A-B. As shown in FIG. 7, the actuator 700 can include multiple SMA wires 702A-B. The wires 702A-B can be connected at a first end to an electrical circuit 704 at the base (or fixed end) of the actuator 700. A second end of the wires 702A-B can be affixed to an electrical circuit at a load point 706 (or unfixed end). The SMA wires 702A-B can be configured to receive a current and move the load point end 706 as described herein. The SMA wires 702A-B can each be connected to the electrical circuit 704 such that a current is delivered to each SMA wire 702A-B. In some instances, each SMA wire can be electrically isolated from one another.

[0065] FIG. 8 illustrates a set of SMA wires 802A-C affixed at an electrical circuit. As shown in FIG. 8, the ends of the SMA wires 802A-C can be affixed to an electrical circuit such that each wire is part of the same circuit. The wires 802A-C can be affixed using any of a variety of techniques, such as using an adhesive, soldering, resistance welding, etc. While three wires 802A-C are shown in FIG. 8, any suitable number of wires can be added to an actuator as described herein.

[0066] In an example embodiment, a SMA actuator is provided. The SMA wire can include a fixed end configured to be fixed to a carriage, a free end, and a beam connecting the fixed end and the free end. The SMA actuator can also include at least two SMA wires. The at least two SMA wires can be electrically connected to the at least one fixed end and the at least one free end via electrical contact portions. In some instances, each of the at least two SMA wires are connected to a same electrical circuit at any of the fixed and the free end.

[0067] It will be understood that terms such as “top,” “bottom,” “above,” “below,” and x-direction, y-direction, and z-direction as used herein as terms of convenience that denote the spatial relationships of parts relative to each other rather than to any specific spatial or gravitational orientation. Thus, the terms are intended to encompass an assembly of component parts regardless of whether the assembly is oriented in the particular orientation shown in the drawings and described in the specification, upside down from that orientation, or any other rotational variation.

[0068] It will be appreciated that the term “present invention” as used herein should not be construed to mean that only a single invention having a single essential element or group of elements is presented. Similarly, it will also be appreciated that the term "present invention" encompasses a number of separate innovations, which can each be considered separate inventions. Although the present invention has been described in detail with regards to the preferred embodiments and drawings thereof, it should be apparent to those skilled in the art that various adaptations and modifications of embodiments of the present invention may be accomplished without departing from the spirit and the scope of the invention. Accordingly, it is to be understood that the detailed description and the accompanying drawings as set forth hereinabove are not intended to limit the breadth of the present invention, which should be inferred only from the following claims and their appropriately construed legal equivalents.

Claims

What is claimed is:

1. A shape memory alloy (SMA) actuator comprising:at least one fixed end configured to be fixed to a carriage;at least one free end;at least one beam connecting the fixed end and the free end; andat least one SMA wire wherein the at least one SMA wire is electrically connected to the at least one fixed end and the at least one free end via electrical contact portions, wherein the at least one SMA wire has a first end connected to a first electrical contact portion at the at least one fixed end and a second end connected to a second electrical contact portion at the at least one free end, wherein the at least one SMA wire is disposed to the first and second electrical contact portions at a bottom surface of the SMA actuator comprising a surface directed at the carriage.

2. The SMA actuator of claim 1, wherein the electrical contact portions comprise:a first set of electrical contact portions at the at least one fixed end, wherein a first end of each of the at least one SMA wire is disposed at each of the first set of electrical contact portions; anda second set of electrical contact portions at the at least one free end, wherein a second end of each of the at least one SMA wire is disposed at each of the second set of electrical contact portions.

3. The SMA actuator of claim 1, further comprising:a first fixed end with the first electrical contact portion connected to the first end of the at least one SMA wire;a first free end with the second electrical contact portion connected to the second end of the at least one SMA wire; anda first beam disposed between the first fixed end and first free end.

4. The SMA actuator of claim 3, further comprising:a second fixed end with a third electrical contact portion connected to a first end of a second SMA wire;a second free end with a fourth electrical contact portion connected to a second end of the second SMA wire; anda second beam disposed between the second fixed end and second free end.

5. The SMA actuator of claim 4, wherein the first free end is directed in a direction opposing a direction of the second free end.

6. The SMA actuator of any preceding claim, wherein, responsive to obtaining an electrical current at the at least one SMA wire, the at least one free end is configured to move in a positive z-direction.

7. The SMA actuator of any preceding claim, wherein a wire exit angle comprising an angle between the at least one fixed end and the at least one SMA wire is less than 10 degrees upon actuation of each of the at least one SMA wire.

8. The SMA actuator of any preceding claim, wherein the SMA actuator is part of an autofocus system or an optical image stabilization system for a camera.

9. A device comprising:a carriage;an actuator engaged to the carriage, the actuator comprising:a fixed end fixed to the carriage;a free end;a beam connecting the fixed end and the free end; andat least one shape memory alloy (SMA) wire, wherein the at least one SMA wire comprises a first end electrically connected to the fixed end at a first electrical contact portion and a second end of the SMA wire electrically connected to the free end at a second electrical contact portion, wherein the at least one SMA wire is disposed to the first and second electrical contact portions at a bottom surface of the electrical contact portions directed at the carriage.

10. The device of claim 9, wherein the electrical contact portions comprise:a first set of electrical contact portions at the at least one fixed end, wherein a first end of each of the at least one SMA wire is disposed at the first set of electrical contact portions; and a second set of electrical contact portions at the at least one free end, wherein a second end of each of the at least one SMA wire is disposed at the second set of electrical contact portions.

11. The device of claim 9, further comprising:a first fixed end with the first electrical contact portion connected to the first end of the at least one SMA wire;a first free end with the second electrical contact portion connected to the second end of the at least one SMA wire; anda first beam disposed between the first fixed end and first free end.

12. The device of claim 11, further comprising:a second fixed end with a third electrical contact portion connected to a first end of a second SMA wire;a second free end with a fourth electrical contact portion connected to a second end of the second SMA wire; anda second beam disposed between the second fixed end and second free end.

13. The device of claim 12, wherein the first free end is directed in a direction opposing a direction of the second free end.

14. The device of any of claims 9 to 13, wherein a wire exit angle comprising an angle between the fixed end and each of the at least one SMA wire or an angle between the free end and the at least one SMA wire is less than 10 degrees upon actuation of each of the at least one SMA wire.

15. A system comprising:a first actuator portion including:a first fixed end configured to be fixed to a carriage;a first free end; anda first SMA wire, wherein the first SMA wire comprises a first end welded to a bottom surface at the first fixed end and a second end welded to the bottom surface at the first free end, the bottom surface comprising a surface directed at the carriage; and a second actuator portion including:a second fixed end configured to be fixed to the carriage;a second free end; anda second SMA wire, wherein the second SMA wire comprises a first end welded to the bottom surface at the second fixed end and a second end welded to the bottom surface at the second free end, the bottom surface comprising a surface directed at the carriage.

16. The system of claim 15, further comprising:the carriage, wherein the first fixed end and the second fixed end are fixed to the carriage.

17. The system of claim 15 or claim 16, wherein a direction of the first actuator portion opposes a direction of the second actuator portion.

18. The system of any of claims 15 to 17, wherein any of the first free end and the second free end are configured to move in a positive z-direction.

19. The system of any of claims 15 to 18, wherein the system is part of an autofocus system or an optical image stabilization system.

20. The system of any of claims 15 to 19, wherein a wire exit angle comprising an angle between the first fixed end and the first SMA wire or an angle between the first free end and the first SMA wire is less than 5 degrees upon actuation of each of the first SMA wire.

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