Biomedical finger assembly with ratchet lock

Abstract

The present disclosure provides systems, devices, and apparatuses for prosthetic fingers that can be used in a person who has had a metacarpophalangeal joint or proximal amputation. The apparatus provides opposition to force in the extension direction via a spring-loaded pawl and locking rack and pinion mechanism, restoring grip force in a person missing a finger or thumb, allowing the individual to manipulate or stabilize objects. The finger can be spring loaded in the extension direction by a torsion spring or other biasing member. The pawl can automatically disengage the rack when the finger reaches full flexion, and the full flexion disengagement stop can be adjustable. The pawl can automatically engage the rack when the finger is fully extended, and the extension stop is adjustable. The pawl can include a transverse feature that creates an obstruction with the anchoring linkage and limits deflection of the structure under loading.

Description

[0001] This application is a divisional application of the Chinese national phase application of application number 202080066884.4, filed on September 22, 2020, with the title “Biomedical finger assembly with ratchet lock”.

[0002] Related Applications Cross Reference To

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 904,506, filed on September 23, 2019, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0004] The present technology relates generally to an adjustable prosthesis to replace a finger or thumb at the metacarpophalangeal joint or proximal. BACKGROUND

[0005] Partial hand loss is the most common upper extremity amputation, and traditional treatments have historically failed to provide adequate service. The origin of most hand amputations is traumatic, and many amputations occur in the workplace where physical labor is performed. Partial hand loss changes the ability to sort mail, play a musical instrument, return to a profession, and even dress, cut food, or take food. This injury is so devastating that physical laborers often cannot return to the same job.

[0006] The primary goal of functional partial hand prosthesis interventions is to restore oppositional grasp: a sufficiently forceful grasp between the thumb and other fingers so that objects can be stabilized and manipulated. However, due to the wide range of anatomical and functional presentations following amputation, and the complexity of replacing a powerful, dexterous, and small human hand, traditional technology has struggled to provide restorative interventions. Partial hand loss includes any amputation distal to the carpal bones or through the carpal bones, including finger loss. Within this definition, four distinct regions can be considered: (1) distal to the metacarpophalangeal joint (MCP, or “finger joint”); (2) at or proximal to the MCP joint, but distal to the carpal bones (transmetacarpal); (3) at the carpal bones; and (4) the thenar (all or part of the thumb).

[0007] Prosthetic interventions available to transmetacarpal partial hand amputees can be broadly divided into three categories: (1) cosmetic restoration; (2) passive prostheses; and (3) powered (active) prostheses. Cosmetic restoration describes a realistic silicone restoration that aims to resemble the original anatomy, which provides almost complete psychosocial support for the individual, with very limited functional ability. While invaluable during the rehabilitation process, cosmetic restoration is often abandoned within a few years.

[0008] Passive prostheses are non-actively driven devices. These prostheses can be end effectors for specific tasks, such as a handle suitable for mounting on a bicycle handlebar, can be put on and taken off for specific activities. Passive prostheses refer also to fixed posts for restoring the oppositional grasp of the hand, either between the fixed post and the intact thumb and fingers, or between the intact thumb and the fixed fingers. In recent years, this passive category has expanded to include adjustable oppositional systems. These devices typically replace the finger and have one, two, or three joints that mimic the MCP, PIP, and DIP joints. The device can also be applied to the socket of any upper limb amputation, such as for end effectors for mechanisms (e.g., for radial artery amputations). They are spring loaded and adjustable to several postures representing different angles of the finger orientation. Passive prostheses are typically the most commonly used choice for returning to work in physically demanding environments due to their robust nature and simplicity.

[0009] Active prostheses can be powered by the body or by electricity. Body powered devices are typically operated by more proximal intact joints via linkages, cables, or straps. Some systems use cables that pass through the wrist joint to drive artificial fingers in response to wrist flexion. An exemplary partial hand system uses a shoulder strap to drive the fingers or thumb in an on / off fashion. Electric partial hand solutions typically have individual electrically powered fingers and rely on a battery pack mounted on the forearm and myoelectric signals to generate multiple hand grips with the fingers. One disadvantage of these systems is that they inhibit wrist motion and can be sensitive to moisture. Body powered and electrically powered partial hand systems have historically been limited in their use environments due to weak power and sensitive components. BRIEF DESCRIPTION OF DRAWINGS

[0010] Many aspects of the technology can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on clearly illustrating the principles of the technology. Additionally, components can be shown in certain views as transparent for clarity reasons only, and not to indicate that the components must be transparent. Components can also be shown schematically.

[0011] Figure 1A and 1B show a front view and a perspective view, respectively, of a three-segment prosthetic finger configured in accordance with an embodiment of the technology.

[0012] Figures 2A-2C show a front view, a cross-sectional view, and a perspective view, respectively, of a three-segment prosthetic finger configured in accordance with an embodiment of the technology. Figure 1A and 1B show a front view, a cross-sectional view, and a perspective view, respectively, of a three-segment prosthetic finger configured in accordance with an embodiment of the technology.

[0013] Figure 2D and 2E show a front view, a cross-sectional view, and a perspective view, respectively, of a three-segment prosthetic finger configured in accordance with an embodiment of the technology. Figure 1A and 1BA front view of a three segment prosthetic finger showing the proximal and distal four bar linkage rotational connections.

[0014] Figures 3A-3C A perspective view, a front view, and a cross-sectional view of a prosthetic finger showing full flexion are shown for Figure 1A and 1B

[0015] Figure 4A A front view of a two segment prosthetic finger configured in accordance with another embodiment of the present technology is shown. 4B DETAILED DESCRIPTION

[0016] A. SUMMARY

[0017] The present technology relates to a prosthetic finger configured to replace a finger or thumb. Among other uses, the prosthetic is generally designed to provide adjustability, strength, and rigidity opposition to a driving (either complete or prosthetic) thumb or finger. As explained in greater detail below, the prosthetic can be adjusted to a plurality of positions, representing increasing flexion of the finger, and controlled by the interaction between a spring-loaded pawl and a rack having a plurality of teeth. In the illustrated embodiment, the prosthetic is shown having the rack located in a first segment and having ten positions corresponding to teeth of the rack; however, the rack can be located in other segments (e.g., second segment, third segment, etc.) of the prosthetic and can have any number of adjustment positions. As the finger is moved in flexion, the pawl is free to move over the rack teeth in the flexion direction, but is stopped in the extension direction due to the engagement of the pawl nose with the rack teeth. This ratcheting lock configuration correspondingly provides the opposition required to hold an object in a flexed position, against an opposable finger, and / or in the palm of a user.

[0018] It is generally desirable for the prosthetic finger to be lightweight, compact, robust, and include a natural motion pattern. The finger configured in accordance with the present technology can restore the prehension of a person missing a finger or thumb by providing opposition to a complete finger, such that manipulation and stabilization of an object can be performed. The finger can exhibit a kinematic motion profile that facilitates a natural prehension pattern and provide opposition to forces in the extension direction via a spring-loaded pawl and locking rack ratcheting mechanism, thereby allowing the individual to manipulate or stabilize an object. The finger can be spring-loaded in the extension direction by a torsion spring or other biasing member. When the finger reaches full flexion, the pawl can automatically disengage the rack, and the full flexion disengagement stop can be adjustable. When the finger is fully extended, the pawl can automatically engage the rack, and the extension stop can be adjustable. The pawl can incorporate a transverse feature that under load creates an obstruction to the deflection of the anchoring linkage and limits the deflection of that structure. Practical considerations must also be made to the clinical fitting process, which dictates the application of the finger to the user's hand via a close-fitting mounting socket.

[0019] ​​The finger can be moved to a new position using the user's other hand, other objects, or via a routing tendon controlled by a more proximal joint or external power source, or other movement options. The pawl mechanism and surrounding linkages can be combined with a switching device configured to selectively disable the ratchet function and place the finger in a "free movement" mode, so that the ratchet mechanism does not stop the finger's extension. In this respect, the finger can function as an adjustable counter-system or an actuated finger to provide gripping patterns such as a power hook, key, and cylindrical grip, as well as other modes and positions. The ability to perform these and other possible grips is part of Activities of Daily Living (ADL).

[0020] The terminology used in the description presented below is intended to be interpreted in its broadest and most reasonable manner, even as it is used in connection with a detailed description of certain specific embodiments of the present technology. Certain terms may even be emphasized below; however, any term intended to be interpreted in any limited manner will be disclosed and specifically defined in this detailed description section. Furthermore, the present technology may be included within the scope of the claims, but no other embodiments are described in detail with respect to Figures 1-4B.

[0021] Throughout this specification, references to "an 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 present technology. Therefore, the phrases "in an embodiment" or "in one embodiment" appearing in multiple places throughout the specification do not necessarily refer to the same embodiment. Furthermore, specific features or characteristics may be combined in any suitable manner in one or more embodiments.

[0022] B. The prosthesis refers to the selected embodiment.

[0023] Figure 1A and 1B The images show a front view and a perspective view of a three-segment prosthetic finger 100 (“prosthetic finger 100”) configured according to embodiments of the present technology. The prosthetic finger 100 can be mounted to a rigid or flexible substrate (not shown) for user use, which may include an insertion port (e.g., a partial hand insertion port, a transradial insertion port, etc.) or a frame. The substrate secures the prosthetic finger 100 to the user's hand at approximately the location of the user's anatomical finger. In some embodiments, the prosthetic finger 100 can be mounted non-anatomically, for example in cases of unique clinical presentation. The prosthetic finger 100 typically includes an anchor 1 configured to be attached to or embedded in the user's insertion port, and a base 2 of the prosthetic finger 100 attached via a fastener or any other suitable attachment method. The prosthetic finger 100 can be detached from the hand by removing the base 2 from the anchor 1. The prosthetic finger 100 includes a first segment P1, a second segment P2, and a third segment P3, typically representing the bones of the finger, and the connections between them represent the MCP, PIP, and DIP joints.

[0024] exist Figure 1A and 1B In the illustrated embodiment, the prosthetic finger 100 includes mounted decorative and gripping fairings 4a and 5a. Fairings 4a and 5a may include portions with increased gripping material configured to increase the friction of fairings 4a and 5a. Fairing 4a can be mounted to the prosthetic finger 100 via fasteners at a first mounting point 4b, and fairing 5a can be mounted to the prosthetic finger 100 via fasteners at a second mounting point 5c (see [link to documentation]). Figure 2B (Fasteners not shown). One or more of the fairings 4a and 5a may include a release slit 5b to allow for the extension range of the coupling of the second segment P2 and the third segment P3 of the prosthetic finger 100. These fairings may provide silicone interfaces for enhanced gripping of objects and allow users to choose the design and color, or replace these trim pieces when wear occurs.

[0025] Anchor 1 can be configured to attach to or embed in a user's residual interface (not shown) and may include features designed to allow successful integration with the manufactured socket. These materials can withstand high temperatures to withstand the exothermic epoxy reaction anticipated during socket manufacturing. Anchor 1 may also include various slots, holes, and other attachment features designed to allow successful integration with carbon fiber, epoxy, silicone, and other anchoring methods commonly used in the prosthesis field.

[0026] Figures 2A-2C They were displayed respectively Figure 1A and 1B The prosthetic finger 100 is shown in a front view, cross-sectional view, and perspective view, still in its fully extended state, but with fairings 4a and 5a removed for illustration. The prosthetic finger 100 may include a first pair of intersecting linkages 6 and 7a with offset rotary connections A1 and B1. For example, linkage 7a may include multiple rack teeth 7b designed to engage with the pawl nose 3b of pawl 3a, thereby allowing free movement in the buckling direction (e.g., toward...). Figures 3A-3C (as shown in the position movement), and creates a structural position lock in the extension direction. The rack tooth 7b is configured to engage with the pawl nose 3b and can be made of hardened steel or other sufficiently strong and wear-resistant materials. The pawl 3a is connected to the linkage mechanism 6 by a pin 11 in a rotary pin connection and can engage / disengage with the rack tooth 7b via a spring-loaded stop 12a, which has a stop member 12b mounted on the proximal lower side of the pawl 3a and in the linkage mechanism 6 (see...). Figure 2B). In other embodiments, the rack teeth are located on or coupled to any suitable linkage of the prosthetic finger 100 (e.g., linkages 6, 8, 9, 10, etc.), and in these configurations the pawl can be configured to engage with the rack teeth, allowing free motion in the flexion direction and locking the position of the prosthetic finger 100 in the extension direction.

[0027] The pawl 3a can be moved between at least two positions via the proximally spring-loaded detent 12a and the detent member 12b: (a) engaged, such that the detent member 12b engages with the engagement surface 17b of the pawl 3a; (b) disengaged, such that the detent member 12b engages with the disengagement surface 17c of the pawl 3a. The engagement surface 17b and the disengagement surface 17c are separated by a transition peak 17a, which is disposed to prevent settling of the detent member 12b between the engagement surface 17b and the disengagement surface 17c. In some embodiments, one or both of the engagement surface 17b and the disengagement surface 17c have a profile shape of an Euler curve (e.g., as shown in FIG. 6), which is configured to minimize the variation in force of the detent member 12b on the pawl 3a as the pawl 3a rotates through the range of motion. In these configurations, the pressure variation is minimized by maintaining a substantially constant contact angle between the detent member 12b and the engagement surface 17b and / or the disengagement surface 17c. Figure 2B

[0028] To move the prosthetic finger 100 in the extension direction, the pawl 3a is disengaged by moving the spring-loaded detent 12a to the disengaged position, in which the detent member 12b engages with the disengagement surface 17c, thereby allowing the prosthetic finger 100 to freely move toward extension by disengaging the pawl nose 3b from the rack teeth 7b. In this disengaged position, the pawl 3a is forced back to the engaged position via a hard stop when the prosthetic finger 100 is fully extended (as best shown in FIG. 5). Figure 2A

[0029] The spring-loaded detent 12a can be threaded and adjustable to account for tolerance stack-ups. For example, in the illustrated embodiment, the spring-loaded detent 12a comprises a spring-loaded circular plunger that deflects when pressed. The plunger surface slides over a proximal curved portion of the pawl 3a (e.g., 17b) and acts as a detent, holding the pawl 3a in the engaged or disengaged position. Upon assembly, the linear position of the spring detent can be adjusted to the appropriate spring loading corresponding to a comfortable switch between the engaged and disengaged positions, and can be further adjusted to account for user preferences, to correspond to a particular installation, etc.

[0030] ​​In some embodiments, the anchor 1 and the base 2 can be configured such that only one attachment direction between the components is possible. However, in other embodiments, the components have multiple possible attachment directions. The base 2 can include a torsion spring 16 (see Figure 3A ), which exerts a constant extension direction force on the system for maintaining the pawl nose 3b in an engaged position with the rack tooth 7b and returning the system to extension when the pawl 3a disengages from the rack tooth 7b. For example, the torsion spring 16 can bias the prosthetic finger 100 toward the extension position shown. The torsion spring 16 has at least two purposes: (1) to force the pawl nose 3b to cooperate with the rack tooth 7b, thereby maintaining the posture after a user’s selection; (2) to automatically return the prosthetic finger 100 to extension when the pawl nose 3b disengages from the rack tooth 7b. Figures 1A-2C

[0031] Referring to Figure 2A , the prosthetic finger 100 can also include linkages 8, 9, and 10, which form part of a coupled distal four-bar linkage ( Figure 2E ) to interact with a proximal four-bar linkage ( Figure 2D ) to create a relatively smooth, satisfying motion, and kinematic space for the prosthetic finger 100 that resembles an anatomical finger. The linkages 6, 7a, 8, 9, and 10 form two serial four-bar linkages via revolute connections. Figure 2D and 2E show front views of the revolute connections of the proximal and distal four-bar linkages, respectively, of the prosthetic finger 100. For example, Figure 2D shows the revolute connections of the proximal four-bar linkage of the first segment P1. The proximal four-bar linkage of the first segment P1 is rotatably coupled to the base 2 at revolute connection Al and revolute connection Bl. As the prosthetic finger 100 transitions from full extension ( Figures 2A-2C ) to full flexion ( Figures 3A-3C ), the linkages 6 and 7a rotate clockwise ( Figure 2D and 2E CW direction; counterclockwise CCW direction) about the revolute connections Al and Bl. During this clockwise rotation, the linkages 6 and 7a rotate relative to each other about the pin 11. The relative rotation of the linkages 6 and 7a about the pin 11 causes the revolute connection B2 to move along a clockwise orbital path relative to the revolute connection A2 and apart from each other.

[0032] Figure 2E ​The rotational connections of the distal four-bar linkage of the second segment P2 are shown. The distal four-bar linkage of the second segment P2 is rotatably coupled to the proximal four-bar linkage of the first segment PI at rotational connections A2 and B2. During the rotation described above from full extension to full flexion, rotational connection B2 orbits clockwise about rotational connection A2 and separates from rotational connection A2 and causes linkage 8 to rotate in a clockwise direction about rotational connection B3 relative to at least linkages 6 and 7a. This rotation causes linkage 9 to rotate clockwise about rotational connection B2 relative to linkage 6. As linkage 8 rotates clockwise, linkage 10 also rotates clockwise relative to rotational connection B3, and further, the relative motion of linkages 9 and 10 causes linkages 9 and 10 to counter-rotate about rotational connection D, which in turn causes linkage 10 to rotate clockwise about rotational connection T. The rotational positions of the linkages of the first segment PI and the second segment P2 described above can be further understood by comparing Figure 2B the position of the middle component and Figure 3C the position of the middle component.

[0033] The prosthetic fingers 100 oppose extension motion, allowing for grasping and manipulating objects to hold the objects in a flexed position, against which the prosthetic fingers 100 can oppose, and / or in the palm. One powerful direction for the prosthesis is "power hook grasp". This grasp position is used in ADLs, such as by picking up a bucket of water, or carrying plastic grocery bags, among other ADLs. The pose required to achieve power hook grasp occurs when the pawl is mated in the middle of the rack teeth (e.g., in the middle of the positions of Figures 2A-2C (adjustable full extension) and Figures 3A-3C (adjustable full flexion). When the prosthetic fingers 100 are loaded in the power hook grasp position, linkages 6 and 7a have a force that tends to bring them closer together as the device is deflected toward the extension position. This configuration exerts a compressive load on the nose of the pawl 3a, which results in a double-shear load on pin 11, tending to secure the pawl 3a to linkage 6.

[0034] The aforementioned power hook gripping loading configuration can also cause deployment deformation between linkages 6 and 7a and force the nose of pawl 3a to move proximally away from rack tooth 7b. Under certain deformation, pawl 3a may over-switch and flip, causing the pawl nose 3b to move proximally and lose its grip on rack tooth 7b, leading to mechanism failure and potential damage to components. To prevent such over-switching, pawl 3a may include one or more pawl stops 15 to reduce deflection between linkages 6 and 7a and increase the load-bearing capacity of prosthetic finger 100. In one example testing the power hook grip of prosthetic finger 100, the loading capacity of prosthetic finger 100 increased by approximately 300% when pawl stops 15 were added. The pawl stop 15 engages with the linkage 6 such that when deflection occurs due to loading, the pawl stop 15 contacts the side of the linkage 6, which redirects the load to a lower deflection state between the linkages 6 and 7 and prevents the pawl from switching excessively, thus increasing the loading capacity of the prosthetic finger 100.

[0035] Figures 3A-3C They were displayed respectively Figure 1A and 1B The prosthetic finger 100 is shown in perspective, front view, and cross-sectional view in full flexion, with fairings 4 and 5 removed for illustration. In the fully flexed position, an adjustable hard stop forces pawl 3a into the disengaged position, where stop member 12b engages with disengaged surface 17c. The hard stop allows the user to fully flex the prosthetic finger 100 via a tabletop, another hand, or other object, and return it to the extended position via torsion spring 16 (as shown). Figures 1A-2C (As shown). The fully flexed hard stop can be adjustable, allowing for variations in the socket configuration and finger placement. For example, if a clinician over-rotates the prosthetic finger 100 toward the user's palm while inserting the anchor 1 into the socket, the prosthetic finger 100 may fail to achieve an unadjustable fully flexed hard stop disengagement point due to premature impact of the mechanism's tip against the user's palm. Adjustability of the fully flexed hard stop allows this functionality to be available even in cases of poor placement by the clinician. In one embodiment, the fully flexed hard stop is a positioning screw embedded in the linkage mechanism 7a. The position of the positioning screw 13 within the linkage mechanism 7a can be adjusted to change the disengagement point of the pawl 3a. Other embodiments with adjustable fully flexed hard stops are possible and within the scope of this technology.

[0036] Similar adjustability can be provided for the extension ratchet feature 14. In this regard, if the technician inadvertently over-rotates the anchor position toward the back of the hand, the prosthetic finger 100 will have an over-extended intermediate position that impedes prosthetic device function. The extension ratchet feature can be adjusted so that the ratchet 3a is forced to engage before full extension to prevent the prosthetic finger 100 from returning to the functionally impaired, over-extended intermediate position. As noted above, in other embodiments the rack teeth are located on different linkages of the prosthetic finger 100, such as linkages 8, 9, 10, etc., and the ratchet, hard stop, and extension ratchet features can be positioned to engage with the rack teeth on the different linkages.

[0037] It is expected that embodiments of the present technology provide a number of advantages over conventional devices, including: (1) lighter weight; (2) integration of the rack and ratchet into a proximal four-bar configuration with relatively low force; (3) full flexion ratchet disengagement is adjustable, allowing adjustment if misplacement occurs during installation socket fabrication; (4) extension ratchet engagement is adjustable, allowing adjustment if misplacement occurs during installation socket fabrication; (5) ratchet block features engage during high loading and deflection, acting to reduce deflection and increase the load carrying capacity of the device; and (6) the attachment points for the consumable cosmetic cover include aesthetic features and functional grip features to improve object manipulation. These embodiments are also applicable to dynamic tendon driven fingers. The present technology is expected to provide enhanced application robustness, aesthetics, and maintainability compared to conventional prosthetic finger technology.

[0038] Figure 4A and 4B A front view of two segments of a prosthetic finger 200 ("prosthetic finger 200") is shown, which has a similar configuration to the proximal four-bar linkage of the prosthetic finger 100, including the anchor 1' and linkages 2', 6', 7a', and 8', but eliminates linkages 9 and 10 of the prosthetic finger 100. The prosthetic finger 200 provides a fixed distal joint and only one four-bar linkage, and can include fairings 20' and 21' configured to function similarly to the fairings 4a and 5a of the prosthetic finger 100. Some components of the prosthetic finger 200 are similar to those of the prosthetic finger 100, but are denoted with an apostrophe for the prosthetic finger 200 (e.g., 2', 3', etc.). Like the prosthetic finger 100, the prosthetic finger 200 can include a ratchet 3' and a hard stop 7b' to prevent over-rotation of the anchor 1' toward the back of the hand. The prosthetic finger 200 can also include an extension ratchet feature 14' to prevent over-rotation of the anchor 1' toward the front of the hand. Figure 4A and 4B The reference numbers for the prosthetic finger 200 in FIGS. 1-3C are not necessarily to be interpreted as the exact same components as the prosthetic finger 100 in FIGS. 1-3C, and Figure 4A and 4B The components in FIGS. 1-3C can differ in shape, size, function, etc. from those in FIGS. 1-3C.

[0039] Reference is made to Figure 4BIn another embodiment, as described above, the extension ratchet engagement feature is a mechanical stop 18' that is positioned distal to the ratchet 3a' and configured to engage the ratchet nose 3b' or the back surface of the ratchet block 15' to force the stop member 12b' into engagement with the surface 17b'. In some embodiments, the mechanical stop 18' is adjustable, for example by using an adjustable stop 19'. In other embodiments, the extension ratchet engagement feature can have different arrangements and / or include different features. Both the adjustable full flex hard stop and the adjustable extension ratchet engagement feature can reduce the available range of the rack teeth 7b', customizing the prosthetic finger 100 for the individual user.

[0040] In some embodiments, the ratchet 3a' can have a paddle portion on the dorsal side to allow the user to manually disengage the ratchet mechanism (ratchet nose 3b' and rack teeth 7b'). The paddle portion can be placed in a variety of locations and still allow for manual disengagement of the ratchet lock. The bottom surface of the ratchet 3a' is configured to engage with the mechanical stop 18' such that at full flex the ratchet 3a' will be forced into a disengaged position and will return the structure to full extension via the spring force generated by the torsion spring 16'. The back surface of the ratchet nose is designed with features that engage with the adjustable extension engagement feature (e.g. ratchet block 15') to return the ratchet 3a' to the engaged position at full extension.

[0041] The present technology can utilize two or three pairs of offset rotary joints connected via rigid linkages to generate coupled four-bar motion and mimic the sliding condyle motion seen in natural anatomy, providing a compact and realistic motion envelope. In the embodiments of the prosthetic finger 100 described above with reference to Figures 1A-3C In the embodiments of the prosthetic finger 200 described above with reference to Figure 4A and 4B In the embodiments of the prosthetic finger 200 described above with reference to

[0042] C. Other Examples

[0043] The following examples illustrate several embodiments of the present technology:

[0044] 1. A prosthetic finger, comprising:

[0045] an anchor configured to engage with a mounting socket;

[0046] a base, couplable with the anchor;

[0047] a first elongate linkage pivotable relative to the base, wherein the first elongate linkage includes a rack tooth;

[0048] a second elongate linkage pivotable relative to the base in an overlapping configuration with the first elongate linkage; and

[0049] a pawl pinned to the second elongate linkage, the pawl having a distal nose configured to abut the rack tooth at a mating position of the pawl.

[0050] 2. The prosthetic digit of example 1, further comprising a pawl stop extending from the distal nose to a side of the first linkage at the mating position, wherein the pawl stop contacts the first linkage during a loading deflection of the prosthetic digit.

[0051] 3. The prosthetic digit of example 1 or 2, wherein:

[0052] the first and second elongate linkages are pivotably coupled to the base;

[0053] the prosthetic digit further comprises a third linkage pivotably coupled to a distal end of the first linkage;

[0054] the third linkage includes a surface; and

[0055] the pawl is configured to abut the surface to return the pawl to the mating position.

[0056] 4. The prosthetic digit of any of examples 1-3, further comprising:

[0057] a third linkage pivotably coupled to the base and a proximal end of the first linkage; and

[0058] a fourth linkage pivotably coupled to the base and a proximal end of the second linkage.

[0059] 5. The prosthetic digit of any of examples 1-4, further comprising a biasing member configured to rotationally urge a distal end of one of the first and second elongate linkages toward a distal end of the other of the first and second elongate linkages.

[0060] 6. The prosthetic digit of any of examples 1-5, wherein the biasing member is positioned to urge the prosthetic digit toward an extended position with the distal nose resting against the rack tooth at the mating position of the pawl.

[0061] 7. The prosthetic finger of any of examples 1-6, wherein, in the disengaged position of the pawl, the distal nose is spaced apart from the rack teeth such that the distal nose does not contact the rack teeth during coupling of the prosthetic finger.

[0062] 8. The prosthetic finger of any of examples 1-7, further comprising a stop member configured to contact a concave disengagement surface on the pawl to hold the pawl in the disengaged position.

[0063] 9. The prosthetic finger of any of examples 1-8, wherein the pawl comprises a convex mating surface and the stop member is configured to contact the mating surface to hold the pawl in the engaged position.

[0064] 10. The prosthetic finger of any of examples 1-9, wherein the disengagement and mating surfaces are separated by a transition peak configured to urge the stop member toward one of the disengagement and mating surfaces, and / or wherein one or more surfaces of the disengagement and mating surfaces have a curvature that substantially follows an Euler curve.

[0065] 11. The prosthetic finger of any of examples 1-10, further comprising an adjustable flex member disposed in the first elongate linkage, the adjustable flex member configured to rotate the pawl to the disengaged position when the prosthetic finger reaches a set maximum flex position.

[0066] 12. The prosthetic finger of any of examples 1-11, further comprising an adjustable extension member configured to abut a surface to limit the rotation of the prosthetic finger at a maximum extension position.

[0067] 13. The prosthetic finger of any of examples 1-12, wherein the adjustable extension member is configured to rotate the pawl to the engaged position at the maximum extension position.

[0068] 14. The prosthetic finger of any of examples 1-13, further comprising an attachment point for a consumable fairing.

[0069] 15. A prosthetic finger having a ratchet lock, the prosthetic finger comprising:

[0070] a base configured to releasably couple with an anchor;

[0071] a first elongate linkage comprising a plurality of rack teeth, wherein the first elongate linkage is rotatably coupled to the base;

[0072] a second elongate linkage rotatably coupled to the base in an overlapping configuration with the first elongate linkage;

[0073] a third elongated linkage mechanism rotatably pinned to a distal end of the first elongated linkage mechanism and a distal end of the second elongated linkage mechanism; and

[0074] a pawl pinned to the second elongated linkage mechanism, the pawl having a distal nose configured to abut each of the plurality of rack teeth in a engaged position of the pawl,

[0075] wherein rotation of the first elongated linkage mechanism relative to the base in a first direction causes the third elongated linkage mechanism to counter-rotate in a second, opposite direction, defined as flexion of the prosthetic digit.

[0076] 16. The prosthetic digit of example 15, further comprising a pawl stop extending from the distal nose to a side of the first linkage mechanism in the engaged position, wherein the pawl stop contacts the first linkage mechanism during deflection of the prosthetic digit.

[0077] 17. The prosthetic digit of example 15 or 16, further comprising a stop surface on the third linkage mechanism configured to abut the pawl to return the pawl to the engaged position.

[0078] 18. The prosthetic digit of any of examples 15-17, further comprising a biasing member configured to rotationally urge a distal end of one of the first and second elongated linkage mechanisms toward a distal end of the other of the first and second elongated linkage mechanisms.

[0079] 19. The prosthetic digit of any of examples 15-18, wherein the biasing member is positioned to urge the prosthetic digit toward an extended position with the distal nose abutting against one of the plurality of rack teeth in the engaged position of the pawl.

[0080] 20. The prosthetic digit of any of examples 15-19, wherein in a disengaged position of the pawl, the distal nose is spaced apart from the plurality of rack teeth such that the distal nose does not contact the plurality of rack teeth during coupling of the prosthetic digit.

[0081] 21. The prosthetic digit of any of examples 15-20, further comprising a detent member configured to contact a concave disengagement surface on the pawl to hold the pawl in the disengaged position.

[0082] 22. The prosthetic digit of any of examples 15-21, wherein the pawl comprises a convex engagement surface and the detent member is configured to contact the engagement surface to hold the pawl in the engaged position.

[0083] 23. The prosthetic digit of any of examples 15-22, wherein the disengagement and engagement surfaces are separated by a transition peak configured to urge the detent member toward one of the disengagement and engagement surfaces, and / or wherein one or more of the disengagement and engagement surfaces has a curvature that substantially follows an Euler curve.

[0084] 24. The prosthetic digit of any of examples 15-23, further comprising an adjustable flexion member disposed in the first elongate linkage, the adjustable flexion member configured to rotate the detent to the disengagement position when the prosthetic digit reaches a set maximum flexion position.

[0085] 25. The prosthetic digit of any of examples 15-24, further comprising an adjustable extension member configured to abut a surface to limit the rotation of the prosthetic digit at a maximum extension position.

[0086] 26. The prosthetic digit of any of examples 15-25, wherein the adjustable extension member is configured to rotate the detent to the engagement position at the maximum extension position.

[0087] 27. The prosthetic digit of any of examples 15-26, further comprising an attachment point for a consumable fairing.

[0088] D. CONCLUSION

[0089] The above detailed description of embodiments of the technology is not intended to be exhaustive or to limit the technology to the precise form disclosed above. While specific embodiments of, and examples for, the technology are described above, it will be understood that various equivalents substitutions and modifications can be made to the technology within the scope of the technology. For example, although steps are presented in a given order, alternative embodiments can perform steps in a different order. Further, various embodiments described herein can also be combined to provide further embodiments. References to “one embodiment”, “an embodiment”, or the like, mean that a particular feature, structure, operation, or characteristic being referred to can be included in at least one embodiment of the technology. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment.

[0090] For ease of reference, like or similar components or features are identified using the same reference numbers throughout the disclosure, but the use of the same reference numbers does not mean that the features should be interpreted as the same. In fact, in many of the examples described herein, the same numbered features have multiple embodiments that differ from each other in structure and / or function. Also, the same shading can be used to represent like materials in cross-sections, but the use of the same shading does not mean that the materials should be interpreted as the same unless specifically noted herein.

[0091] Also, the use of “or” in such a list is to be interpreted as including (a) any single one of the items in the list, (b) all of the items in the list, or (c) any combination or permutation of the items in the list. Singular or plural terminology can also be used to include the plural or singular, respectively, unless otherwise clear from the context. Also, the term “comprising” is used throughout to mean “including” but also “consisting of” so that when the term “comprising” is used, it is also meant that the listed features are “consisting of” the listed features and not just “including” the listed features. Directional terms, such as “upper”, “lower”, “front”, “back”, “vertical”, and “horizontal”, can be used herein to express and clarify relationships between various elements. It should be understood that these terms do not indicate absolute directions. Also, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments can also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

1. A prosthetic digit comprising: an anchor configured to engage with a mounting socket; a base couplable with the anchor; a first elongate linkage pivotable relative to the base, wherein the first elongate linkage comprises a rack tooth; a second elongate linkage pivotable relative to the base in an overlapping configuration with the first elongate linkage; and a pawl pinned to the second elongate linkage, the pawl having a distal nose configured to abut the rack tooth in a mating position of the pawl, a biasing member configured to rotationally urge a distal end of one of the first and second elongate linkages toward a distal end of the other of the first and second elongate linkages, wherein the biasing member is positioned to urge the prosthetic digit toward an extended position with the distal nose abutting the rack tooth in the mating position of the pawl.

2. The prosthetic digit of claim 1, further comprising a pawl stop extending from the distal nose to a side of the first elongate linkage in the mating position, wherein the pawl stop contacts the first elongate linkage during loading deflection of the prosthetic digit.

3. The prosthetic digit of claim 1, wherein: the first and second elongate linkages are pivotably coupled to the base; the prosthetic digit further comprises a third elongate linkage pivotably coupled to a distal end of the first elongate linkage; the third elongate linkage comprises a surface; and the pawl is configured to abut the surface to return the pawl to the mating position.

4. The prosthetic digit of any of claims 1-3, further comprising: a third elongate linkage pivotably coupled to a distal end of the first elongate linkage; and a fourth linkage pivotably coupled to a distal end of the second elongate linkage. in a disengaged position of the pawl, the distal nose is spaced apart from the rack tooth such that the distal nose does not contact the rack tooth during coupling of the prosthetic digit.

5. The prosthetic digit of any of claims 1-3, wherein, 6. The prosthetic digit of claim 5, further comprising a detent member configured to contact a concave disengagement surface on the pawl to hold the pawl in the disengaged position. the pawl comprises a convex mating surface, and the detent member is configured to contact the mating surface to hold the pawl in the mating position.

7. The prosthetic digit of claim 6, wherein, the disengagement surface and the mating surface are separated by a transition peak configured to urge the detent member toward one of the disengagement surface and mating surface, and / or wherein one or more surfaces of the disengagement surface and the mating surface have a curvature following an Euler curve.

8. The prosthetic digit of claim 7, wherein, 9. The prosthetic digit of claim 5, further comprising an adjustable flex member positioned in the first elongate linkage, the adjustable flex member configured to rotate the pawl to the disengaged position when the prosthetic digit reaches a set maximum flex position. ​ 10. The prosthetic digit of any of claims 1-3, further comprising an adjustable extension member configured to abut a surface to limit rotation of the prosthetic digit at a maximum extension position.

11. The prosthetic digit of claim 10, wherein, The adjustable extension member is configured to rotate the pawl to the engaged position at the maximum extension position.

12. The prosthetic digit of any of claims 1-3, further comprising an attachment point for a consumable fairing.

13. A prosthetic digit having a ratchet lock, the prosthetic digit comprising: a base configured to releasably couple with an anchor; a first elongate linkage mechanism comprising a plurality of rack teeth, wherein the first elongate linkage mechanism is rotatably coupled to the base; a second elongate linkage mechanism rotatably coupled to the base in an overlapping configuration with the first elongate linkage mechanism; a third elongate linkage mechanism rotatably pinned to a distal end of the first elongate linkage mechanism and a distal end of the second elongate linkage mechanism; and a pawl pinned to the second elongate linkage mechanism, the pawl having a distal nose configured to abut each of the plurality of rack teeth in an engaged position of the pawl, wherein rotation of the first elongate linkage mechanism relative to the base in a first direction causes the third elongate linkage mechanism to counter-rotate in an opposite second direction, defined as flexion of the prosthetic digit.

14. The prosthetic digit of claim 13, further comprising a pawl stop extending from the distal nose to a side of the first elongate linkage mechanism in the engaged position, wherein the pawl stop contacts the first elongate linkage mechanism during deflection of the prosthetic digit.

15. The prosthetic digit of claim 13, further comprising a stop surface on the third elongate linkage mechanism configured to abut the pawl to return the pawl to the engaged position.

16. The prosthetic digit of any of claims 13-15, further comprising a biasing member configured to rotationally urge a distal end of one of the first and second elongate linkage mechanisms toward a distal end of the other of the first and second elongate linkage mechanisms. The biasing member is positioned to urge the prosthetic digit toward an extension position with the distal nose abutting against one of the plurality of rack teeth in the engaged position of the pawl.

17. The prosthetic digit of claim 16, wherein, In a disengaged position of the pawl, the distal nose is spaced apart from the plurality of rack teeth such that the distal nose does not contact the plurality of rack teeth during coupling of the prosthetic digit.

18. The prosthetic digit of any of claims 13-15, wherein, 19. The prosthetic digit of claim 18, further comprising a detent member configured to contact a concave disengagement surface on the pawl to hold the pawl in the disengaged position. The pawl comprises a convex engagement surface and the detent member is configured to contact the engagement surface to hold the pawl in the engaged position.

20. The prosthetic digit of claim 19, wherein, ​ 21. The prosthetic digit of claim 20, wherein, The disengagement surface and the mating surface are separated by a transition peak configured to urge the detent member toward one of the disengagement surface and mating surface, and / or wherein one or more of the disengagement surface and the mating surface has a curvature following an Euler curve.

22. The prosthetic finger of claim 18, further comprising an adjustable flex member disposed in the first elongate linkage, the adjustable flex member configured to rotate the pawl to the disengagement position when the prosthetic finger reaches a set maximum flex position.

23. The prosthetic finger of any one of claims 13-15, further comprising an adjustable extension member configured to abut a surface to limit rotation of the prosthetic finger at a maximum extension position.

24. The prosthetic digit of claim 23, wherein, The adjustable extension member is configured to rotate the pawl to the mating position at the maximum extension position.

25. The prosthetic finger of any one of claims 13-15, further comprising an attachment point for a consumable fairing.

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