Patent Publication Number: US-2022233764-A1

Title: Component positioning of a linear shuttle pump

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/674,722, filed Nov. 5, 2019, the contents of which are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     Embodiments herein generally relate to medication delivery. More particularly, embodiments herein relate to wearable drug delivery devices and methods for component positioning of a linear shuttle pump. 
     BACKGROUND 
     Many wearable drug delivery devices include a reservoir for storing a liquid drug. A drive mechanism, such as a pump including a pump chamber and piston, is operated to expel the stored liquid drug from the reservoir for delivery to a user. A problem with known devices is that the delivery rate accuracy suffers when the volume of drug is small. Such inaccuracies arise in many cases from the drive mechanism(s) employed, which gives rise to variations in delivery rates. Accordingly, there is a need to provide a wearable drug delivery device capable of regulating drug delivery dosages while simultaneously verifying drive mechanism positioning and sequencing. 
     SUMMARY 
     In one approach of the disclosure, a pump may include a pump chamber operably coupled with a piston, and a detent apparatus coupled to the pump chamber or the piston. The detent apparatus may include a detent body, a detent arm, and a detent engagement member, wherein in a first position the detent engagement member is retained in contact with a first arrest location of either the detent body or the detent arm, and wherein in a second position the detent engagement member is retained in contact with a second arrest location of either the detent body or the detent arm. The pump may further include a piston grip coupled to the piston, the piston grip including a grip component engaged with an exterior of the piston, wherein movement of the piston grip causes the piston to move axially relative to the pump chamber to control receipt and delivery of a liquid drug. 
     In another approach of the disclosure, a linear volume shuttle pump may include a pump chamber operably coupled with a piston, and a detent apparatus coupled to the pump chamber or the piston. The detent apparatus may include a detent body, a detent arm, and a detent engagement member, wherein the detent engagement member is operable to move between first and second arrest locations disposed along the detent body or the detent arm. The linear volume shuttle pump may further include a piston grip coupled to the piston, the piston grip including a grip component engaged with an exterior of the piston, wherein movement of the piston grip causes the piston to move axially relative to the pump chamber to control receipt of a liquid drug from a reservoir and delivery of the liquid drug from the pump chamber. 
     In yet another approach of the disclosure, a linear volume shuttle pump may include a pump chamber operably coupled with a piston, and a detent apparatus coupled to the pump chamber or the piston. The detent apparatus may include a detent body, a detent arm, and a detent engagement member, wherein the detent engagement member is operable to move between first and second arrest locations disposed along the detent body or the detent arm. The linear volume shuttle pump may further include a piston grip coupled to the piston, the piston grip including a grip component engaged with an exterior of the piston, wherein movement of the piston grip causes the piston to move axially relative to the pump chamber to control receipt of a liquid drug from a reservoir and delivery of the liquid drug from the pump chamber. The linear volume shuttle pump may further include a contact extending from the detent apparatus or the piston grip, the contact operable to make or break contact with one or more contact members coupled to a pump housing. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings illustrate example approaches of the disclosure, including the practical application of the principles thereof, as follows: 
         FIG. 1  illustrates a perspective view of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 2  illustrates a top view of the linear volume shuttle fluid pump depicted in  FIG. 1  according to embodiments of the present disclosure; 
         FIG. 3  illustrates a perspective view of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 4  illustrates another view of the linear volume shuttle fluid pump depicted in  FIG. 3  according to embodiments of the present disclosure; 
         FIG. 5  illustrates a top view of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 6  illustrates a perspective view of the linear volume shuttle fluid pump depicted in  FIG. 5  according to embodiments of the present disclosure; 
         FIG. 7  illustrates a perspective view of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 8  illustrates a top view of the linear volume shuttle fluid pump depicted in  FIG. 7  according to embodiments of the present disclosure; 
         FIG. 9  illustrates a perspective view of an example pump housing according to embodiments of the present disclosure; 
         FIG. 10  illustrates a top view of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 11-12  illustrate close-up views of a detent apparatus of the linear volume shuttle fluid pump depicted in  FIG. 10  according to embodiments of the present disclosure; 
         FIGS. 13-14  illustrate top views of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 15-16  illustrate perspective views of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 17-18  illustrate perspective views of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 19-20  illustrate perspective views of a contact of the linear volume shuttle fluid pump depicted in  FIGS. 17-18  according to embodiments of the present disclosure; 
         FIGS. 21-22  illustrate perspective views of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 23  illustrates a top view of the linear volume shuttle fluid pump depicted in  FIGS. 21-22  according to embodiments of the present disclosure; 
         FIG. 24  illustrates a sequence for operating an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 25-26  illustrate perspective views of an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIG. 27  illustrates a top view of the linear volume shuttle fluid pump depicted in  FIGS. 25-26  according to embodiments of the present disclosure; 
         FIG. 28  illustrates a sequence for operating an example linear volume shuttle fluid pump according to embodiments of the present disclosure; 
         FIGS. 29-30  illustrate perspective views of an example linear volume shuttle fluid pump including an optical sensor according to embodiments of the present disclosure; 
         FIG. 31  illustrates a perspective view of an example linear volume shuttle fluid pump including an optical sensor according to embodiments of the present disclosure; 
         FIG. 32  illustrates a cross-sectional view of the linear volume shuttle fluid pump depicted in  FIG. 31  according to embodiments of the present disclosure; 
         FIG. 33  illustrates a perspective view of the linear volume shuttle fluid pump depicted in  FIG. 31  according to embodiments of the present disclosure; and 
         FIGS. 34-35  illustrate perspective views of an example linear volume shuttle fluid pump including a capacitive sensor according to embodiments of the present disclosure. 
     
    
    
     The drawings are not necessarily to scale. The drawings are merely representations, not intended to portray specific parameters of the disclosure. The drawings are intended to depict example embodiments of the disclosure, and therefore are not be considered as limiting in scope. In the drawings, like numbering represents like elements. 
     Furthermore, certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines otherwise visible in a “true” cross-sectional view, for illustrative clarity. Furthermore, some reference numbers may be omitted in certain drawings. 
     DETAILED DESCRIPTION 
     Various approaches in accordance with the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, where embodiments of the methods are shown. The approaches may be embodied in many different forms and are not to be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so this disclosure will be thorough and complete, and will fully convey the scope of the approaches to those skilled in the art. 
     Various examples disclosed herein provide a drive mechanism and/or pump system with the ability to control and verify pump sequencing. As a result, a drug delivery device that contains a reservoir and a pump may be made more reliable and thus safer for users. 
     Various examples described herein enable a pump, such as a linear volume shuttle pump (LVSP), to execute a pumping cycle in a proper sequence. At any given time during pump actuation, it is beneficial to know the location of different pump components, namely a pump chamber and a piston, as the pump chamber and the piston are responsible for drawing in and expelling fluid. Knowing the location of both the pump chamber and the piston also indicates whether the pump operates in a designed sequence. In some examples of the present disclosure, one or more mechanical detents and sensing/sequencing mechanisms may be implemented with the pump to both control the position of the pump chamber and the piston, thus maintaining the pump cycling in the proper sequence, and to provide feedback as to the position of the pump chamber and/or the piston. As will be described in greater detail herein, multiple methods and devices may be implemented for tracking the location of the chamber and the piston, such as electromechanical contacts, optical sensing, and/or capacitance sensing. 
       FIGS. 1-2  illustrate a linear volume shuttle fluid pump  100  (hereinafter “pump”) according to embodiments of the present disclosure. As shown, the pump  100  may include a pump housing  102  coupling together a fluid reservoir  104 , a pump chamber  106 , and a piston  108 . In some embodiments, the fluid reservoir  104  may contain a fluid or liquid drug. The pump housing  102  may include a base  110 , a chassis  111  extending from the base  110  for retaining the pump chamber  106 , and a reservoir wall  112  operable to interface with the pump chamber  106 , as will be described in greater detail herein. Although non-limiting, the pump housing  102  may be formed from an injection molded plastic or other similar material. 
     Although not shown, the pump chamber  106  may include an inlet pathway or component and an outlet pathway or component. A liquid or fluid can enter the pump chamber  106  through the inlet pathway and can exit the pump chamber  106  through the outlet pathway. One or more plunger components may operate with the inlet and outlet pathways to draw a fluid into the pump chamber  106  and to expel the fluid from the pump chamber  106 . In various examples, the pump chamber  106  may be coupled to the fluid reservoir  104  that stores a fluid or liquid drug. For example, the inlet may be coupled to the fluid reservoir  104  and the outlet pathway may be coupled to a fluid path component (not shown) that is coupled to a patient or user that is to receive the liquid drug stored in the fluid reservoir  104 . 
     As further shown, the pump  100  may include a detent apparatus  115  coupled to the pump chamber  106 . In some embodiments, the detent apparatus  115  may include a detent cap or body  116 , one or more detent arms  117  extending from the detent body  116 , and one or more detent engagement members  118 . The detent body  116  may extend over and/or abut one end of the pump chamber  106 . In some embodiments, the detent body  116  may further abut the piston  108 , wherein an opening (not shown) of the detent body  116  may allow a rod of the piston  108  to pass therethrough. 
     The detent arms  117  may include a first arrest location  120  and a second arrest location  121 . As shown, the first and second arrest locations  120 ,  121  may correspond to recesses or valleys disposed between one or more peaks  122 . The first and second arrest locations  120 ,  121  may be curved to generally compliment the dimensions of the detent engagement member  118 , which in this case, is a helical spring extending from the base  110  of the pump housing  102 . The first and second arrest locations  120 ,  121  allow discrete positioning of the pump chamber  106  and/or the piston  108  by adding additional frictional forces to restrict movement of the detent body  116  prior to a desired time. 
     In the non-limiting embodiment depicted, the detent engagement member  118  is in contact with the first arrest location  120  of the detent arm  117  when in a first position. In a second position, the detent engagement member  118  may be in contact with the second arrest location  121  of the detent arm  117 . The detent engagement member  118  may change between the first position and second position as the pump chamber  106  moves relative to the fluid reservoir  104 . 
     As further shown, the pump  100  may include a piston grip  125  coupled to the piston  108 . The piston grip  125  may include one or more grip components  126  engaged with an exterior of the piston  108 . During operation, movement of the piston grip  125  causes the piston  108  to move axially relative to the pump chamber  106  to control receipt and delivery of a liquid drug within the pump chamber  106 . The piston grip  125  may be actuated by a variety of mechanisms and/or actuators. In various examples, the piston grip  125  may be actuated by an actuator capable of producing reciprocating motion, for example, a piezoelectric-based actuator, a solenoid-based actuator, a Nitinol-based actuator, a spring-based actuator, a rotary motor with a gear drain, a direct current (DC) motor, or any combination thereof. As a result, a desired effect of shuttling fluid (e.g., a liquid drug) may be achieved. 
     In some embodiments, the piston grip  125  includes a grip body  127  extending on opposite sides of the piston  108 . The grip body  127  may be a generally planar component including one or more spring footers  128  extending therefrom. As shown, each spring footer  128  may include one or more tabs  171  to engage and retain therein a side spring  129 . In this embodiment, the side springs  129  may be disposed on opposite sides of the piston  108 , parallel to a central axis (not shown) extending through the piston  108 , the pump chamber  106 , and the detent body  116 . The side springs  129  may provide a spring force to bias the piston grip  125 , and thus the piston  108 , towards the pump chamber  106 . 
     As shown in  FIGS. 3-4 , in some embodiments, the pump  100  may include a detent cap  130  positioned atop the detent engagement members  118  to provide support/rigidity thereto, as the detent engagement members  118  may be prone to unpredictable bistable behavior. In some embodiments, the detent cap  130  may include an elongate body  131  extending between free ends of each of the detent engagement members  118 . As shown, a vertical shaft  132 , which may extend from an underside of the elongate body  131 , extends into a center cavity defined by the helical structure of each of the detent engagement members  118 . 
     Turning now to  FIGS. 5-6 , a pump  200  according to embodiments of the present disclosure will be described in greater detail. The pump  200  may be similar in many aspects to the pump  100  described above. As such, only certain aspects of the pump  200  may be described hereinafter for the sake of brevity. In this embodiment, the pump  200  may include a detent apparatus  215  coupled to a piston rod  234  of a piston  208 . The detent apparatus  215  may include a detent body  216 , which may be coupled to or integrally formed with a housing  202 . The detent apparatus  215  may further include one or more detent arms  217  extending from the piston rod  234 , wherein each detent arm  217  includes one or more detent engagement members  218  engaged with the detent body  216 . In some embodiments, the detent arms  217  may be rigid or semi-rigid elements extending towards a reservoir wall  212  of a fluid reservoir  204 . Each of the detent arms  217  may be permit a degree of radial flexing relative to a pump chamber  206  as the pump chamber  206  moves axially with respect to the fluid reservoir  204 . 
     The detent body  216  may include a first arrest location  220  and a second arrest location  221 . As shown, the first and second arrest locations  220 ,  221  may correspond to recesses or valleys disposed between protrusions or peaks  222  along a sidewall  233  of the detent body  216 . In some embodiments, the first and second arrest locations  220 ,  221  may be curved or notched to generally compliment the dimensions of the detent engagement members  218 . The first and second arrest locations  220 ,  221  allow discrete positioning of the pump chamber  206  and/or the piston  208  during use. For example, as the piston  208  moves relative to the fluid reservoir  204 , each detent engagement member  218  may move from the first arrest location  220  to the second arrest location  221 . 
     Turning now to  FIGS. 7-8 , a pump  300  according to embodiments of the present disclosure will be described in greater detail. The pump  300  may be similar in many aspects to the pumps  100  and  200  described above. As such, only certain aspects of the pump  300  may be described hereinafter for the sake of brevity. In this embodiment, the pump  300  may include a detent apparatus  315  coupled to a pump chamber  306 . The detent apparatus  315  may include a detent body  316 , which may be coupled to or integrally formed with a pump housing  302 . For example, the detent body  316  may correspond to an outer surface  337  of a chassis  311  extending from a base  310  of the pump housing  302 . 
     The detent apparatus  315  may further include one or more detent arms  317  extending from an exterior surface  345  of the pump chamber  306 . As shown, the detent arms  317  may generally extend radially away from the pump chamber  306 . Each detent arm  317  may include an opening  335  receiving a detent engagement member  318  therein. In this embodiment, the detent engagement members  318  may be helical springs extending from the base  310  of the pump housing  302 . As shown, the detent engagement members  318  may be joined together by a connector  338  to provide rigidity and support thereto. Furthermore, the connector  338  may provide an electrical connection between each of the detent engagement members  318 . 
     The detent body  316  may include a first arrest location  320  and a second arrest location  321 . As shown, the first and second arrest locations  320 ,  321  may correspond to recesses or valleys disposed between protrusions or peaks  322  along the outer surface  337  of the detent body  316 . In some embodiments, the first and second arrest locations  320 ,  321  may be curved or notched to generally compliment the dimensions of the detent engagement members  318 . The first and second arrest locations  320 ,  321  allow discrete positioning of the pump chamber  306  and/or the piston  308  during use. 
     In this embodiment, the detent body  316  may include one or more embedded contact signal pins  344  therein. As shown, the contact signal pins  344  may be positioned within the second arrest location  321 . In other embodiments, the contact signal pins  344  may be positioned within the first arrest location  320 , or within both the first and second arrest locations  320 ,  321 . In the case contact signal pins  344  are located in both the first and second arrest locations  320  and  321 , two distinct on/off states could be registered in place of a single ‘on’ or ‘off’ state. For example, this may be accomplished using a live contact signal pin  344  in each of the first and second arrest locations  320 ,  321  on one side of the pump chamber  306 , and a distinct contact signal pin in corresponding arrest locations on an opposite side of the pump chamber  306 . 
     During use of the pump  300 , the contact signal pins  344  may not be in contact with the detent engagement members  318  when the pump chamber  306  is in a first position. When the pump chamber  306  moves away from a reservoir wall  312  of a fluid reservoir  304  and into a second position within the second arrest location  321 , the contact signal pins  344  come into contact with the detent engagement members  318 . A closed circuit is then formed between the contact signal pins  344  and the detent engagement members  318 , causing a signal to be delivered to a processor or control logic/circuitry (not shown). For example, the signal obtained by actuating the closed-circuit switch may be an indicator of the status or position of the pump chamber  306 . The information obtained by the switch about the position of the pump chamber  306  can be used, for example, to ensure that the pump  300  is drawing in or expelling fluid appropriately. 
     Turning now to  FIG. 9 , the pump housing  302  of the pump  300  according to embodiments of the present disclosure will be described in greater detail. As shown, the pump housing  302  may include the base  310  and the chassis  311  extending from the base  310  for retaining the pump chamber  306  ( FIGS. 7-8 ). The pump housing  302  may further include a reservoir housing  350  defining or containing the fluid reservoir  304 , wherein the fluid reservoir contains a fluid drug therein. The reservoir wall  312  may extend along an exterior of the reservoir housing  350 , the reservoir wall  312  including a fluid opening  351  formed therethrough. In some embodiments, a needle (not shown) may extend through the fluid opening  351  to draw the fluid drug into the pump chamber  306 . 
     In other embodiments, a piston rod of the piston  308  may extend into the fluid opening  351 , initially blocking the fluid drug from being released from the fluid reservoir  304 . When the piston rod is withdrawn from the reservoir housing  350 , e.g., axially away from the reservoir wall  312 , the fluid drug may be released from the fluid reservoir  304  and into the pump chamber  306 . In some embodiments, movement of the piston rod can create a vacuum within a portion of the pump chamber  306 , such as within a fluid line. The vacuum can pull a portion of the fluid drug out of the fluid reservoir  304  and into the created space/volume within the pump chamber  306 . 
     As further shown, the chassis  311  may include a first (proximal) end  353  and a second (distal) end  354 . A trough  355  may be provided in the chassis  311  to support the pump chamber  306 . During use, the pump chamber  306  may slide within the trough  355 , between the first and second ends  353 ,  354 . The base  310  of the pump housing  302  may further include one or more openings  356  for receiving one or more contact members (not shown). 
     Referring to  FIGS. 10-12 , a pump  400  according to embodiments of the present disclosure will be described in greater detail. The pump  400  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  400  may be described hereinafter for the sake of brevity. In this embodiment, the pump  400  may include a detent apparatus  415  coupled to a pump chamber  406 . In some embodiments, the detent apparatus  415  may include a detent cap or body  416 , one or more detent arms  417  extending from the detent body  416 , and one or more detent engagement members  418 . The detent body  416  may extend over and/or abut one end of the pump chamber  406 . In some embodiments, the detent body  416  may further abut a piston  408 , wherein an opening (not shown) of the detent body  416  may allow a rod of the piston  408  to pass therethrough. 
     The detent arms  417  may include a first arrest location  420  and a second arrest location  421 . As shown, the first and second arrest locations  420 ,  421  may be defined by recesses or valleys disposed between one or more peaks  422 . The first and second arrest locations  420 ,  421  may be curved to generally compliment the dimensions of the detent engagement members  418 , which in this case, are torsion springs extending from a base  410  of the pump housing  402 . More specifically, the detent engagement members  418  may include a contact section  458  connected to a helical section  459 . In some embodiments, the helical section  459  may be housed or embedded within a spring housing  460  ( FIG. 12 ), which may extend from, or be integrally formed with, the base  410 . The first and second arrest locations  420 ,  421  allow discrete positioning of the pump chamber  406  and/or the piston  408  by adding additional frictional forces to restrict movement of the detent apparatus  415  prior to a desired time. 
     In the non-limiting embodiment depicted, the contact section  458  of the detent engagement member  418  may be retained in physical and/or electrical contact with the first arrest location  420  of the detent arm  417  when in a first position. In a second position, the contact section  458  of the detent engagement member  418  may be retained in physical and/or electrical contact with the second arrest location  421  of the detent arm  417 . The detent engagement member  418  may change between the first position and second position as the pump chamber  406  moves away from a reservoir wall  412 . 
     Referring to  FIGS. 13-14 , a pump  500  according to embodiments of the present disclosure will be described in greater detail. The pump  500  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  500  may be described hereinafter for the sake of brevity. In this embodiment, the pump  500  may include a detent apparatus  515  coupled to a pump chamber  506 . In some embodiments, the detent apparatus  515  may include a detent cap or body  516 , one or more detent arms  517  extending from the detent body  516 , and one or more detent engagement members  518 . The detent body  516  may extend over and/or abut one end of the pump chamber  506 . In some embodiments, the detent body  516  may further abut a piston  508 , wherein an opening (not shown) of the detent body  516  may allow a rod  534  ( FIG. 14 ) of the piston  508  to pass therethrough. 
     The detent arms  517  may include a first arrest location  520  and a second arrest location  521 . As shown, the first and second arrest locations  520 ,  521  may be defined by recesses or valleys disposed between one or more peaks  522 . The first and second arrest locations  520 ,  521  may be curved to generally compliment the dimensions of the detent engagement member  518 , which in this case, may be a helical spring extending from a base  510  of the pump housing  502 . The first and second arrest locations  520 ,  521  allow discrete positioning of the pump chamber  506  and/or the piston  508  by adding additional frictional forces to restrict movement of the detent apparatus  515  prior to a desired time. 
     In this embodiment, one or more of the detent engagement members  518  may include an insulative coating  562  formed thereon. As shown, the insulative coating  562  may be formed along just a portion of the detent arms such that the first arrest location  520  remains uncovered by the insulative coating  562 . During use, as the pump chamber  506  and the detent apparatus  515  move away from a fluid reservoir  504 , the detent arms  517  are repositioned relative to the detent engagement members  518  from the first arrest location  520  to the second arrest location  521 , thus terminating electrical contact between the detent engagement members  518  and detent arms  517  due to the presence of the insulative coating  562 . In other embodiments, the first arrest location  520  may be covered by the insulative coating  562 , while the second arrest location  521  is uncovered by the insulative coating  562 . As such, movement from the first arrest location  520  to the second arrest location  521  by the detent engagement members  518  may cause a closed circuit to be formed between the detent engagement members  518  and detent arms  517 . A signal representing the closed/open circuit connection between the detent engagement members  518  and detent arms  517  may be used to determine a position of the pump chamber  506  and/or the piston  508 . 
     Referring to  FIGS. 15-16 , a pump  600  according to embodiments of the present disclosure will be described in greater detail. The pump  600  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  600  may be described hereinafter for the sake of brevity. 
     As shown, the pump  600  may include one or more contact members  664 , such as helical springs, extending from a base  610  of a pump housing  602 . The contact member(s)  664  may form a closed circuit when contact is made with a perimeter  665  of a detent body  616  of a detent apparatus  615 . For example, when a pump chamber  606  is in a first position adjacent a reservoir housing  650 , as shown in  FIG. 15 , an open circuit is present. As the pump chamber  606  and the detent apparatus  615  are moved towards a distal end  654  of a chassis  611 , the perimeter  665  of the detent body  616  makes electrical and mechanical contact with the contact member(s)  664  to form a closed circuit  670 , as shown by a series of connected arrows in  FIG. 16 . A signal representing the closed/open circuit connection between the detent body  616  and the contact member(s)  664  may be used to determine a position of the pump chamber  606  and/or a piston  608 . 
     In  FIGS. 17-20 , a pump  700  according to embodiments of the present disclosure will be described in greater detail. The pump  700  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  700  may be described hereinafter for the sake of brevity. 
     As shown, the pump  700  may include one or more contact members  764 , such as helical springs, extending from a base  710  of a pump housing  702 . The contact members  764  may form a closed circuit when contact is made with a contact  767  of a detent body  716  of a detent apparatus  715 . In this embodiment, the contact  767  may be an L-shaped contact extending from the detent body  716 . As best demonstrated in  FIGS. 19-20 , the contact  767  may include a set of curled sides  768  operable to electrically and mechanically engage the contact members  764 . For example, the contact  767  may extend between each of the contact members  764 , deflecting the contact members  764  outwardly from a central axis (not shown) extending through an opening  769  ( FIG. 19 ) of the detent body  716 . It will be appreciated that the specific geometry and configuration of the contact  767  are non-limiting. 
     During use, when a pump chamber  706  is in a first position adjacent a reservoir housing  750 , as shown in  FIG. 17 , an open circuit exists. As the pump chamber  706  and the detent apparatus  715  move towards a distal end  754  of a chassis  711 , the contact  767  makes electrical and mechanical contact with the contact members  764  to form a closed circuit  770 , as shown by a series of connected arrows in  FIG. 18 . A signal representing the closed/open circuit connection between the contact  767  and the contact members  764  may be used to determine a position of the pump chamber  706  and/or a piston  708 . 
     Referring to  FIGS. 21-23 , a pump  800  according to embodiments of the present disclosure will be described in greater detail. The pump  800  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  800  may be described hereinafter for the sake of brevity. In this embodiment, the pump  800  may include a piston grip  825  coupled to a piston  808 . The piston grip  825  may include one or more grip components  826  engaged with an exterior of the piston  808 . During operation, movement of the piston grip  825  causes the piston  808  to move axially relative to a pump chamber  806  to control receipt and delivery of a liquid drug within the pump chamber  806 . 
     In some embodiments, the piston grip  825  includes a grip body  827  extending on opposite sides of the piston  808 . The grip body  827  may include one or more spring footers  828  extending therefrom. As shown, each spring footer  828  may include one or more tabs  871  to engage and retain therein a side spring  830 . In this embodiment, the side springs  830  may be disposed on opposite sides of the piston  808 , parallel to a central axis (not shown) extending through the piston  808 , the pump chamber  806 , and a detent body  816 . The side springs  830  provide a spring force to bias the piston grip  825 , and thus the piston  808 , towards the pump chamber  806 . 
     In this embodiment, the piston grip  825  may further include a contact  867  coupled thereto. Although non-limiting, the contact  867  may be an insulated dowel pin disposed along an underside of the grip body  827 . For example, the contact  867  may be an electrically conductive cylinder generally extending parallel to the central axis. In some embodiments, the contact  867  may include a first end  872  retained within a clamp  873  of the piston grip  825 , and a second, free end  874  opposite the first end  872 . The free end  874  is operable to engage one or more piston position contact members  875 , as will be described below. 
     Turning now to  FIG. 24 , operation of the pump  800  according to embodiments of the present disclosure will be described in greater detail. As shown, for each state of the pump  800 , both a side view of the pump  800  and a close-up, top view of the contact  867  and the piston position contact members  875  are depicted. In an initial stage (1), the pump chamber  806  may be directly adjacent and/or in abutment with a reservoir wall  812  of a reservoir housing  850 . Additionally, an engagement member  818  may be retained in direct physical contact with a first arrest location  820  of a detent arm  817  when the pump chamber  806  is in the initial stage (1). As shown, no contact is made, for example, between the detent body  816  and the contact members  864 , or between the contact  867  and the piston position contact members  875 . 
     Next, at a second stage (2), the piston  808  may move axially away from the pump chamber  806  to draw a liquid drug into the pump chamber  806 . More specifically, a piston rod  834  of the piston  808  may be withdrawn axially through the pump chamber  806  to release a fluid drug from the reservoir housing  850 . As shown, the piston grip  825  and the contact  867  may also move axially away from the pump chamber  806 , causing the contact  867  to engage a first pair  875 A of the piston position contact members  875 . A signal may be delivered from the piston position contact members  875  to indicate a position of the contact  867  and thus the piston  808 . An open circuit between the detent body  816  and the contact members  864  may provide an indication of a position of the pump chamber  806 . 
     Next, at a third stage (3), the pump chamber  806  and the piston  808  may move axially away from the reservoir housing  850  to bring a needle (not shown) of the pump chamber  806  into a fluid output position. As shown, the piston grip  825  and the contact  867  may engage the first pair  875 A and a second pair  875 B of the piston position contact members  875 . A signal may be delivered from the piston position contact members  875  to indicate a position of the contact  867  and thus the piston  808 . Furthermore, a closed circuit between the detent body  816  and the contact members  864  may also provide an indication of a position of the pump chamber  806 . As shown, the detent engagement member  818  may be retained in direct physical contact with a second arrest location  821  of the detent arm  817 . 
     Next, at a fourth stage (4), the piston  808  may move axially towards the pump chamber  806  to expel the fluid drug from the pump chamber  806 . As shown, the piston grip  825  and the contact  867  may engage only the first pair  875 A of the piston position contact members  875 . A signal may be delivered from the piston position contact members  875  to indicate a position of the contact  867  and thus the piston  808 . Furthermore, the closed circuit between the detent body  816  and the contact members  864  may also provide an indication of a position of the pump chamber  806 . As shown, the detent engagement member  818  may remain in direct physical contact with a second arrest location  821  of the detent arm  817  at the fourth stage. 
     Referring now to  FIGS. 25-27 , a pump  900  according to embodiments of the present disclosure will be described in greater detail. The pump  900  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  900  may be described hereinafter for the sake of brevity. In this embodiment, the pump  900  may include a piston grip  925  coupled to a piston  908 . The piston grip  925  may include one or more grip components  926  engaged with an exterior of the piston  908 . During operation, movement of the piston grip  925  causes the piston  908  to move axially relative to the pump chamber  906  and to a reservoir housing  950  containing a fluid drug. 
     In some embodiments, the piston grip  925  includes a grip body  927  extending on opposite sides of the piston  908 , and a contact  967  coupled thereto. Although non-limiting, the contact  967  may be a dowel pin disposed along an underside of the grip body  927 . For example, the contact  967  may be an electrically conductive cylinder generally extending parallel to the central axis. The contact  967  may include a first end  972  proximate contact members  964  and a second end  974  proximate one or more piston position contact members  975 . As shown, the contact  967  may be joined to the grip body  927  by one or more clamps  973 . 
     Turning now to  FIG. 28 , operation of the pump  900  according to embodiments of the present disclosure will be described in greater detail. As shown, for each state of the pump  900 , both a side view of the pump  900  and a close-up, top view of the contact  967 , the contact members  964 , and the piston position contact members  975  are depicted. In an initial stage (1), the pump chamber  906  may be directly adjacent and/or in abutment with a reservoir wall  912  of a reservoir housing  950 . Additionally, an engagement member  918  may be retained in direct physical contact with a first arrest location  920  of a detent arm  917  when the pump chamber  906  is in the initial stage (1). As shown, the contact  967  may be in direct physical and electrical contact with the contact members  964 , but not the piston position contact members  975 . 
     Next, at a second stage (2), the piston  908  may move axially away from the pump chamber  906  to draw a liquid drug into the pump chamber  906 . More specifically, a piston rod  934  of the piston  908  may be withdrawn axially through the pump chamber  906  to release a fluid drug from the reservoir housing  950 . As shown, the piston grip  925  and the contact  967  may also move axially away from the pump chamber  906 , causing the contact  967  to engage the piston position contact members  975 . A signal may be delivered from the piston position contact members  975  and the contact members  964  to indicate a position of the contact  967  and thus the piston  908 . 
     Next, at a third stage (3), the pump chamber  906  and the piston  908  may move axially away from the reservoir housing  950  to bring a needle (not shown) of the pump chamber  906  into a fluid output position. As shown, the piston grip  925  and the contact  967  may continue to move axially away from the reservoir housing  950 , causing the first end  972  of the contact  967  to break contact with the contact members  964 . One or more signals may be delivered from the piston position contact members  975  and the contact members  964  to indicate a position of the contact  967  and thus the piston  908 . In some embodiments, a closed circuit between the detent body  916  and the contact members  964  may also provide an indication of a position of the pump chamber  906 . As shown, the detent engagement member  918  may be retained in direct physical contact with a second arrest location  921  of the detent arm  917 . 
     Next, at a fourth stage (4), the piston  908  may move axially towards the pump chamber  906  to expel the fluid drug from the pump chamber  906 . As shown, the contact  967  may again engage both the piston position contact members  975  and the contact members  964 . A signal may be delivered from the piston position contact members  975  and the contact members  964  to indicate a position of the contact  967  and thus the piston  908 . Furthermore, the closed circuit between the detent body  916  and the contact members  964  may also provide an indication of a position of the pump chamber  906 . As shown, the detent engagement member  918  may remain in direct physical contact with a second arrest location  921  of the detent arm  917  at the fourth stage. 
     Turning now to  FIGS. 29-30 , a pump  1000  according to embodiments of the present disclosure will be described in greater detail. The pump  1000  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  1000  may be described hereinafter for the sake of brevity. In this embodiment, the pump  1000  may include a piston grip  1025  coupled to a piston  1008 . The piston grip  1025  may include one or more grip components  1026  engaged with an exterior of the piston  1008 . During operation, the piston grip  1025  and the piston  1008  may move together, axially relative to a pump chamber  1006 . 
     In some embodiments, the piston grip  1025  includes a grip body  1027  extending on opposite sides of the piston  1008 . The grip body  1027  may further include a sensor plate  1080  extending between a pair of side springs  1030 . A sensor arm  1082  may extend perpendicularly from the sensor plate  1080 , wherein the sensor arm  1082  operates with an optical sensor  1085  to detect a position of the piston grip  1025  and thus the piston  1008 . More specifically, as better shown in  FIG. 30 , the sensor arm  1082  may travel between a light source  1083  (e.g., LED) and a photodiode  1084 . The light source  1083  and the photodiode  1084  may extend from a base  1010  of a housing  1002 . 
     The photodiode  1084  is operable to detect light from the light source  1083 . When the sensor arm  1082  is positioned between the light source  1083  and the photodiode  1084 , the photodiode will not detect any light. When the sensor arm  1082  is not positioned between the light source  1083  and the photodiode  1084 , the photodiode will detect the light output from the light source  1083 . Based on the detection or non-detection of light, the position of the piston grip  1025  and thus the piston  1008  can be determined. 
     Turning now to  FIGS. 31-33 , a pump  1100  according to embodiments of the present disclosure will be described in greater detail. The pump  1100  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  1100  may be described hereinafter for the sake of brevity. In this embodiment, the pump  1100  may include a piston grip  1125  coupled to a piston  1108 . During operation, movement of the piston grip  1125  causes the piston  1108  to move axially relative to a pump chamber  1106  and/or a piston rod  1134 . 
     In some embodiments, the piston grip  1125  includes a grip body  1127  extending on opposite sides of the piston  1108 . The grip body  1127  may further include a sensor plate  1180  extending between a pair of side springs  1130 . As further shown, the sensor plate  1180  may positioned distal of the piston  1108 . In this embodiment, the sensor plate  1180  may include an optical opening  1186  positioned above an optical sensor  1185 . Light from a light source (not shown), may reach a photodiode  1184  of the optical sensor  1185  depending on a position of the sensor plate  1180 . For example, when a solid portion  1187  of the sensor arm  1182  is positioned between the light source and the photodiode  1184 , the photodiode will not detect any light. However, when the optical opening  1186  is positioned over the photodiode  1184 , light from the light source is permitted to reach the photodiode  1184 . Based on the detection or non-detection of light by the photodiode  1184 , the position of the piston grip  1125  and thus the piston  1108  can be determined. In some embodiments, the optical sensor  1185  can be elevated to a position proximate the grip body  1127  by a sensor block  1190  extending from a base  1110  of a housing  1102  of the pump  1100 . Embodiments herein are not limited in this context, however. 
     Turning now to  FIGS. 34-35 , a pump  1200  according to embodiments of the present disclosure will be described in greater detail. The pump  1200  may be similar in many aspects to the pumps described above. As such, only certain aspects of the pump  1200  may be described hereinafter for the sake of brevity. In this embodiment, the pump  1200  may include a piston grip  1225  coupled to a piston  1208 . During operation, movement of the piston grip  1225  causes the piston  1208  to move axially relative to a pump chamber  1206 . 
     In some embodiments, the piston grip  1225  includes a grip body  1227  extending on opposite sides of the piston  1208 . The grip body  1227  may operate with a capacitive sensor  1285 . For example, the capacitive sensor  1285  may include a capacitive plate  1294  mounted atop a capacitor block  1295  extending from a base  1210  of a housing  1202 . During use, a temporary capacitor may be formed when grip body  1227 , which is grounded, moves above the capacitive plate  1294 . The capacitance can be measured, for example, by a component on a logic board (not shown) and can directly indicate the location of the piston grip  1215  and thus the piston  1208 . This approach can offer multiple degrees of resolution between pump states since the capacitance measured by the capacitive sensor  1285  increases and decreases linearly with the motion of the grip body  1227  of the capacitive plate  1294 . 
     In sum, the systems, apparatuses, and methods disclosed herein may be used to extract a portion of a liquid drug or other fluid from a reservoir. The pumps disclosed herein may be the linear shuttle pumps and/or and linear volume shuttle fluid pumps for providing a stored liquid drug to a user by, for example, extracting a liquid drug from a reservoir, temporarily storing the extracted liquid drug within the pump, and then expelling the liquid drug from the pump for delivery to the patient. Each of the disclosed pumps may be part of a wearable medical device such as, for example, a wearable insulin delivery device. 
     The foregoing discussion has been presented for purposes of illustration and description and is not intended to limit the disclosure to the form or forms disclosed herein. For example, various features of the disclosure may be grouped together in one or more aspects, embodiments, or configurations for the purpose of streamlining the disclosure. However, it should be understood that various features of the certain aspects, embodiments, or configurations of the disclosure may be combined in alternate aspects, embodiments, or configurations. 
     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Accordingly, the terms “including,” “comprising,” or “having” and variations thereof are open-ended expressions and can be used interchangeably herein. 
     The phrases “at least one”, “one or more”, and “and/or”, as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
     All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of this disclosure. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. 
     Furthermore, identification references (e.g., primary, secondary, first, second, third, fourth, etc.) are not intended to connote importance or priority but are used to distinguish one feature from another. The drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary. 
     Furthermore, the terms “substantial” or “substantially,” as well as the terms “approximate” or “approximately,” can be used interchangeably in some embodiments, and can be described using any relative measures acceptable by one of ordinary skill in the art. For example, these terms can serve as a comparison to a reference parameter, to indicate a deviation capable of providing the intended function. Although non-limiting, the deviation from the reference parameter can be, for example, in an amount of less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, and so on. 
     Still furthermore, although the various methods disclosed herein are described as a series of acts or events, the present disclosure is not limited by the illustrated ordering of such acts or events unless specifically stated. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein, in accordance with the disclosure. In addition, not all illustrated acts or events may be required to implement a methodology in accordance with the present disclosure. Furthermore, the methods may be implemented in association with the formation and/or processing of structures illustrated and described herein as well as in association with other structures not illustrated. 
     The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Furthermore, the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose. Those of ordinary skill in the art will recognize the usefulness is not limited thereto and the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Thus, the claims set forth below are to be construed in view of the full breadth and spirit of the present disclosure as described herein.