Patent Publication Number: US-9839741-B2

Title: Flanged sealing element and needle guide pin assembly for a fluid infusion device having a needled fluid reservoir

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/728,796, filed Dec. 27, 2012 (the parent application). The parent application Ser. No. 13/728,796 is a continuation-in-part of U.S. patent application Ser. No. 13/399,851, filed Feb. 17, 2012 (now abandoned), which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,857, filed Feb. 17, 2012, which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,863, filed Feb. 17, 2012 (now abandoned), which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,865, filed Feb. 17, 2012 (issued on Dec. 2, 2014 as U.S. Pat. No. 8,900,206, which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,870, filed Feb. 17, 2012 (issued on Oct. 21, 2014 as U.S. Pat. No. 8,864,726), which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,874, filed Feb. 17, 2012 (issued on Oct. 28, 2014 as U.S. Pat. No. 8,870,829), which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). The parent application Ser. No. 13/728,796 is also a continuation-in-part of U.S. patent application Ser. No. 13/399,878, filed Feb. 17, 2012 (issued on Feb. 3, 2015 as U.S. Pat. No. 8,945,068), which claims the benefit of U.S. provisional patent application No. 61/445,393, filed Feb. 22, 2011 (now expired). 
    
    
     TECHNICAL FIELD 
     Embodiments of the subject matter described herein relate generally to fluid infusion devices for delivering a medication fluid to the body of a user. More particularly, embodiments of the subject matter relate to a sealing element that provides a fluid seal between a fluid delivery needle and a removable fluid reservoir. 
     BACKGROUND 
     Certain diseases or conditions may be treated, according to modern medical techniques, by delivering a medication or other substance to the body of a patient, either in a continuous manner or at particular times or time intervals within an overall time period. For example, diabetes is commonly treated by delivering defined amounts of insulin to the patient at appropriate times. Some common modes of providing insulin therapy to a patient include delivery of insulin through manually operated syringes and insulin pens. Other modern systems employ programmable fluid infusion devices (e.g., insulin pumps) to deliver controlled amounts of insulin to a patient. 
     A fluid infusion device suitable for use as an insulin pump may be realized as an external device or an implantable device, which is surgically implanted into the body of the patient. External fluid infusion devices include devices designed for use in a generally stationary location (for example, in a hospital or clinic), and devices configured for ambulatory or portable use (to be carried by a patient). External fluid infusion devices may establish a fluid flow path from a fluid reservoir to the patient via, for example, a suitable hollow tubing. The hollow tubing may be connected to a hollow fluid delivery needle that is designed to pierce the patient&#39;s skin to deliver an infusion medium to the body. Alternatively, the hollow tubing may be connected directly to the patient&#39;s body through a cannula or set of micro-needles. 
     The fluid reservoir of an external fluid infusion device may be realized as a single-use prefilled disposable unit, a patient-filled unit, a refillable unit, or the like. The fluid reservoir for a typical fluid infusion device is implemented as a removable and replaceable component. To this end, the fluid infusion device includes structure, features, and/or elements that are designed to establish the fluid flow path with the fluid reservoir. For example, a fluid seal between the fluid reservoir and a hollow fluid delivery needle may be established when the fluid reservoir is properly installed in the fluid infusion device. When the fluid reservoir is removed (for purposes of replacement, to allow certain activities such as swimming or bathing, or the like), the fluid delivery needle should be protected against contamination. 
     Accordingly, it is desirable to implement a sealing element that creates a seal between a removable fluid reservoir and a delivery needle of a fluid infusion device. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     BRIEF SUMMARY 
     Various embodiments of a fluid infusion device, along with related fluid reservoirs and sealing elements for fluid reservoirs, are provided here. For example, an embodiment of a sealing element for a fluid infusion device is provided. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, and a needle cavity formed in the retractable body section. The needle cavity continues through the base section to define a needle opening in the base section, and the needle cavity is sized to receive the hollow fluid delivery needle. The sealing element also includes a self-sealing slit formed in the tip section to accommodate the hollow fluid delivery needle when the sealing element is in a retracted position. 
     Another embodiment of a sealing element for a fluid infusion device is also provided. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, and a needle cavity formed in the retractable body section and continuing through the base section to define a needle opening in the base section. The needle cavity is sized to receive the hollow fluid delivery needle, and the needle cavity defines internal relief features of the retractable body section. The internal relief features cause the sealing element to deform and retract over the hollow fluid delivery needle in response to a longitudinal force applied to the tip section. In addition, the internal relief features cause the sealing element to regain a nominal shape, extend over the hollow fluid delivery needle, and enclose the hollow fluid delivery needle in response to removal of the longitudinal force. 
     An embodiment of a sealing assembly for a fluid infusion device is also provided. The fluid infusion device cooperates with a fluid reservoir having a fluid delivery port. The sealing assembly includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path from the fluid reservoir to a user of the fluid infusion device, and a sealing element coupled to the base plate and overlying at least a portion of the hollow fluid delivery needle. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, a needle cavity formed in the retractable body section and continuing through the base section to define a needle opening in the base section, and a self-sealing slit formed in the tip section. The needle cavity is sized to receive the hollow fluid delivery needle, and the self-sealing slit accommodates the hollow fluid delivery needle when the sealing element is in a retracted position. 
     Another embodiment of a sealing assembly for a fluid infusion device is also provided. The sealing assembly includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path from the fluid reservoir to a user of the fluid infusion device, and a sealing element coupled to the base plate and overlying at least a portion of the hollow fluid delivery needle. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, and a needle cavity formed in the retractable body section and continuing through the base section to define a needle opening in the base section. The needle cavity is sized to receive the hollow fluid delivery needle, and the needle cavity defines internal relief features of the retractable body section. The internal relief features promote deformation of the sealing element and retraction of the sealing element over the hollow fluid delivery needle in response to a longitudinal force applied to the tip section of the sealing element. Moreover, the internal relief features cause the sealing element to automatically extend over the hollow fluid delivery needle into a nominal state in response to removal of the longitudinal force. 
     Also presented here is an embodiment of a fluid infusion device to deliver a fluid to a user. The fluid infusion device includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path from the fluid infusion device to the user, and a sealing element coupled to the base plate and overlying at least a portion of the hollow fluid delivery needle. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, a needle cavity formed in the retractable body section and continuing through the base section to define a needle opening in the base section, the needle cavity sized to receive the hollow fluid delivery needle, and a self-sealing slit formed in the tip section. The fluid infusion device also includes a removable fluid reservoir having a fluid delivery port to receive a tip of the hollow fluid delivery needle. When the removable fluid reservoir is removed from the hollow fluid delivery needle, the retractable body section extends such that the hollow fluid delivery needle is enclosed by the sealing element and such that the self-sealing slit forms a fluid seal to inhibit fluid ingress into the needle cavity. When the removable fluid reservoir is installed on the hollow fluid delivery needle, the tip of the hollow fluid delivery needle extends from the tip section and into the fluid reservoir, and the retractable body section deforms to create a radial seal with an interior of the fluid delivery port. 
     Another embodiment of a fluid infusion device is also presented here. The fluid infusion device includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path from the fluid infusion device to the user, and a sealing element coupled to the base plate and overlying at least a portion of the hollow fluid delivery needle. The sealing element includes a base section, a tip section extending from the base section, a retractable body section between the base section and the tip section, and a needle cavity formed in the retractable body section and continuing through the base section to define a needle opening in the base section. The needle cavity is sized to receive the hollow fluid delivery needle, and the needle cavity defines internal relief features of the retractable body section. The fluid infusion device also includes a removable fluid reservoir comprising a fluid delivery port to receive a tip of the hollow fluid delivery needle. The internal relief features promote deformation of the sealing element and retraction of the sealing element over the hollow fluid delivery needle when the removable fluid reservoir is engaged with the sealing element and the hollow fluid delivery needle. The internal relief features also cause the sealing element to automatically extend over the hollow fluid delivery needle, and cause the sealing element to assume a nominal state when the removable fluid reservoir is removed from the sealing element and the hollow fluid delivery needle. 
     Yet another embodiment of a fluid infusion device is also provided here. The fluid infusion device includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path for the medication fluid, and a sealing element coupled to the base plate and overlying at least a portion of the hollow fluid delivery needle. The sealing element includes a base section, a tip section extending from the base section, and a retractable body section between the base section and the tip section. The fluid infusion device also includes a fluid reservoir having a fluid chamber, a fluid delivery port coupled to the fluid chamber, and at least one vent hole formed in the fluid delivery port. The at least one vent hole provides a venting conduit from inside the fluid chamber to outside the fluid chamber. The fluid delivery port engages and cooperates with the sealing element and the hollow fluid delivery needle such that the tip section of the sealing element is urged against the fluid delivery port to seal the at least one vent hole. 
     An alternative embodiment of a fluid reservoir is also presented here. The fluid reservoir includes a main body section that defines a fluid chamber for the medication fluid, a fluid delivery port coupled to and extending from the main body section, the fluid delivery port having a fluid conduit and a pressure vent defined therein, and a septum located in the fluid delivery port and having a nominal non-pierced state forming a fluid seal within the fluid conduit. The pressure vent provides a venting conduit from inside the fluid chamber to outside the fluid chamber, and the pressure vent terminates at an exterior surface of the fluid delivery port. The exterior surface is contoured to mate with a resilient sealing element of the fluid infusion device to seal the pressure vent. 
     Also disclosed here is an embodiment of a sealing assembly for a fluid infusion device having a hollow fluid delivery needle, a retractable sealing element surrounding the hollow fluid delivery needle, and a fluid reservoir. The sealing assembly includes a fluid delivery port for the fluid reservoir, the fluid delivery port comprising a first sealing surface, a pressure vent formed in the fluid delivery port to provide a venting conduit for a fluid chamber of the fluid reservoir, the pressure vent terminating at the first sealing surface, and a tip section for the retractable sealing element. The tip section has a second sealing surface to mate with the first sealing surface, wherein the first sealing surface and the second sealing surface are urged together to form a fluid seal for the pressure vent when the fluid reservoir is engaged with the hollow fluid delivery needle and the sealing element. 
     Another alternative embodiment of a fluid reservoir is presented here. The fluid reservoir includes a main body section that defines a fluid chamber for the medication fluid, and a fluid delivery port coupled to and extending from the main body section. The fluid delivery port includes a fluid conduit that communicates with the fluid chamber, and the fluid delivery port terminates at a port opening. The fluid reservoir also includes a septum movably coupled to the fluid delivery port. The septum is movable between a sealed position where the septum forms a circumferential seal around the port opening, and a vented position that permits fluid to flow out of the fluid delivery port via the port opening. 
     Yet another alternative embodiment of a fluid reservoir is presented here. The fluid reservoir includes a main body section that defines a fluid chamber for the medication fluid, and a fluid delivery port coupled to and extending from the main body section. The fluid delivery port has a fluid conduit that communicates with the fluid chamber, and the fluid delivery port terminates at a port opening. The fluid reservoir also includes a valve sleeve movably coupled to the fluid delivery port, wherein the fluid delivery port and the valve sleeve cooperate to accommodate translational movement of the valve sleeve relative to the fluid delivery port. A septum is located within the valve sleeve and is movable in concert with the valve sleeve between a sealed position and a vented position. 
     Also provided here is another alternative embodiment of a fluid infusion device that delivers a medication fluid to a body. The fluid infusion device includes a base plate, a hollow fluid delivery needle coupled to the base plate to provide a fluid flow path for the medication fluid, and a fluid reservoir. The fluid reservoir includes a main body section that defines a fluid chamber for the medication fluid, a fluid delivery port coupled to and extending from the main body section, and a septum coupled to the fluid delivery port. The fluid delivery port has a fluid conduit that communicates with the fluid chamber, and the fluid delivery port terminates at a port opening. The septum translates relative to the port opening and is movable between a sealed position and a vented position. In the sealed position, the hollow fluid delivery needle engages the septum and urges the septum against the port opening to form a circumferential seal around the port opening. In the vented position, the hollow fluid delivery needle is disengaged from the septum. 
     Yet another embodiment of a fluid infusion device is also provided here. The fluid infusion device includes a fluid reservoir having a main body section that defines a fluid chamber for the medication fluid, and also having a fluid delivery port coupled to and extending from the main body section. The fluid delivery port has a fluid conduit that communicates with the fluid chamber, and the fluid delivery port terminates at an unsealed port opening. The fluid infusion device also includes a self-sealing reservoir port receptacle for the fluid delivery port. The port receptacle has an inlet to receive the fluid delivery port, a valve chamber in fluid communication with the inlet, a valve element located in the valve chamber, and an outlet in fluid communication with the valve chamber. The valve element is biased toward the inlet into a sealed position to form a fluid seal between the valve element and the inlet, and the outlet provides a fluid flow path for the medication fluid. Engagement of the fluid delivery port with the inlet causes an end of the fluid delivery port to move the valve element from the sealed position to an opened position to accommodate flow of the medication fluid into the valve chamber. 
     An alternative embodiment of a sealing assembly for a fluid infusion device is also presented here. The sealing assembly includes a reservoir port receptacle, an inlet formed in the reservoir port receptacle to receive a fluid delivery port of a fluid reservoir that contains the medication fluid, and a valve chamber formed in the reservoir port receptacle and in fluid communication with the inlet, a valve element located in the valve chamber, a resilient compression element located in the valve chamber to bias the valve element toward the inlet, and an outlet formed in the reservoir port receptacle to provide a fluid flow path for the medication fluid. 
     Another embodiment of a fluid infusion device is also presented here. The fluid infusion device includes a base plate, a delivery conduit coupled to the base plate, wherein the delivery conduit provides the medication fluid to the body, and a self-sealing reservoir port receptacle located on the base plate. The self-sealing reservoir port receptacle includes an inlet to receive a fluid delivery port of a fluid reservoir, a valve chamber in fluid communication with the inlet, a valve element located in the valve chamber, and an outlet between the valve chamber and the delivery conduit. When the fluid delivery port is disengaged from the self-sealing reservoir port receptacle, the valve element is biased toward the inlet into a sealed position to form a fluid seal between the valve element and the inlet. The outlet provides a fluid flow path for the medication fluid. When the fluid delivery port is engaged with the self-sealing reservoir port receptacle, an end of the fluid delivery port moves the valve element from the sealed position to an opened position to accommodate flow of the medication fluid from the fluid reservoir into the valve chamber. 
     Also presented here is an alternative embodiment of a fluid reservoir for a fluid infusion device that delivers a medication fluid to a body. The fluid reservoir includes a main body section that defines a fluid chamber for the medication fluid, a hollow needle extending from the main body section and defining a fluid conduit that communicates with the fluid chamber, the hollow needle terminating at a needle end, and a needle hood extending from the main body section and at least partially surrounding the hollow needle. The needle hood terminates at a lip that extends further from the main body section than the needle end. 
     Yet another alternative embodiment of a fluid infusion device is also provided here. The fluid infusion device includes a base plate, a delivery conduit coupled to the base plate, wherein the delivery conduit provides the medication fluid to the body, and a fluid reservoir. The fluid reservoir has a main body section that defines a fluid chamber for the medication fluid, a hollow needle extending from the main body section and in fluid communication with the fluid chamber, and a needle hood extending from the main body section and at least partially surrounding the hollow needle. The fluid infusion device also includes a reservoir port receptacle located on the base plate and comprising mating structure to engage and mate with the needle hood, a sealing element to receive the hollow needle and form a seal around an exterior surface of the hollow needle, and an outlet conduit at least partially defined by the sealing element, wherein the outlet conduit is coupled to the delivery conduit. 
     Also presented here is another embodiment of a fluid infusion device that delivers a medication fluid to a body. The fluid infusion device includes a fluid reservoir having a main body section that defines a fluid chamber for the medication fluid, and having a hollow needle extending from the main body section and in fluid communication with the fluid chamber. The fluid infusion device also includes a reservoir port receptacle having a sealing element, and having mating structure to engage the fluid reservoir in an aligned orientation for introducing the hollow needle into the sealing element to form a seal around an exterior surface of the hollow needle. 
     A sealing assembly in accordance with another embodiment is also presented here. The sealing assembly is designed for a fluid infusion device that cooperates with a fluid reservoir having a reservoir port and a hollow fluid reservoir needle at least partially located within the reservoir port. The sealing assembly includes a reservoir port receptacle to receive the reservoir port. The reservoir port receptacle has a proximal end, a distal end extending from the proximal end, and a needle entry formed in the distal end to receive the hollow fluid reservoir needle. The sealing assembly also includes a fluid chamber located at least partially in the reservoir port receptacle, and a sealing component positioned in the reservoir port receptacle to cooperate with the fluid chamber. The sealing component has a needle guide pin protruding from the proximal end of the reservoir port receptacle, wherein an end section of the needle guide pin is sized to fit within the hollow fluid reservoir needle. The sealing component also has a needle sealing element that cooperates with the hollow fluid reservoir needle and with the needle guide pin. The needle sealing element includes a base section adjacent to the fluid chamber, an end section opposite the base section, a neck section between the base section and the end section, and a needle opening extending through the neck section. When the reservoir port is engaged with reservoir port receptacle, the end section of the needle guide pin resides within the hollow fluid reservoir needle, a portion of the hollow fluid reservoir needle resides within the needle opening, and the needle sealing element forms a first seal around an exterior surface of the hollow fluid reservoir needle. When the reservoir port is disengaged from the reservoir port receptacle, the hollow fluid reservoir needle is decoupled from the sealing component, a portion of the end section of the needle guide pin resides within the needle opening, and the needle sealing element forms a second seal around an exterior surface of the needle guide pin. 
     Also presented here is a sealing assembly in accordance with yet another embodiment. The sealing assembly is utilized with a fluid infusion device that cooperates with a fluid reservoir having a reservoir port and a hollow fluid reservoir needle at least partially located within the reservoir port. The sealing assembly includes a base plate and a reservoir port receptacle on the base plate to receive the reservoir port. The reservoir port receptacle has a proximal end, a distal end extending from the proximal end, and a needle entry formed in the distal end to receive the hollow fluid reservoir needle. The sealing assembly also includes a flow base component coupled to the base plate and to the reservoir port receptacle. The flow base component has an inlet structure extending therefrom to define a fluid chamber, and the flow base component also has a needle guide pin protruding therefrom. An end section of the needle guide pin is sized to fit within the hollow fluid reservoir needle. The sealing component also includes a needle sealing element having a proximal flange adjacent to the inlet structure, a distal flange opposite the proximal flange, a neck section between the proximal flange and the distal flange, and a needle opening extending through the neck section. The needle sealing element is positioned within the reservoir port receptacle such that the neck section surrounds the end section of the needle guide pin. 
     Another embodiment of a fluid infusion device is also presented here. The fluid infusion device includes a removable fluid reservoir having a reservoir port and a hollow fluid reservoir needle, a base plate having a reservoir port receptacle to receive the reservoir port and the fluid reservoir needle, and an inlet structure located in the reservoir port receptacle. The inlet structure defines at least a portion of a fluid chamber. The fluid infusion device also includes a needle guide pin protruding from the inlet structure, wherein an end section of the needle guide pin is sized to fit within the hollow fluid reservoir needle. The fluid infusion device also includes a needle sealing element having a base section adjacent to the inlet structure, an end section opposite the base section, a neck section between the base section and the end section, and a needle opening extending through the neck section. When the reservoir port is engaged with reservoir port receptacle, the end section of the needle guide pin resides within the hollow fluid reservoir needle, a portion of the hollow fluid reservoir needle resides within the needle opening, and the needle sealing element forms a first seal around an exterior surface of the hollow fluid reservoir needle. When the reservoir port is disengaged from the reservoir port receptacle, the hollow fluid reservoir needle is decoupled from the sealing component, a portion of the end section of the needle guide pin resides within the needle opening, and the needle sealing element forms a second seal around an exterior surface of the needle guide pin. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the subject matter may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures. 
         FIG. 1  is a perspective view of an embodiment of a fluid infusion device; 
         FIG. 2  is a perspective view that depicts internal structure of the durable housing of the fluid infusion device shown in  FIG. 1 ; 
         FIG. 3  is a perspective view that depicts internal structure of the base plate of the fluid infusion device shown in  FIG. 1 ; 
         FIG. 4  is a perspective view that depicts the reservoir port receptacle and a sealing element of the fluid infusion device shown in  FIG. 1 ; 
         FIG. 5  is a cross-sectional and partially phantom view of a portion of the fluid infusion device, corresponding to a view along line  5 - 5  in  FIG. 4 ; 
         FIG. 6  is an exploded perspective view of a sealing assembly suitable for use with the fluid infusion device shown in  FIG. 1 ; 
         FIG. 7  is a plan view of the sealing element shown in  FIG. 6 , as viewed from its base end; 
         FIG. 8  is a side elevation view of the sealing element shown in  FIG. 6 ; 
         FIG. 9  is a front elevation view of the sealing element shown in  FIG. 6 ; 
         FIG. 10  is a perspective view of the sealing element shown in  FIG. 6 ; 
         FIG. 11  is a longitudinal cross-sectional view of the sealing element shown in  FIG. 6 ; 
         FIG. 12  is a cross-sectional and partially phantom view of a portion of the fluid infusion device, in a state where the fluid reservoir is fully engaged with the sealing element; 
         FIG. 13  is a perspective view of an alternate embodiment of a sealing element; 
         FIG. 14  is a phantom side view that depicts a portion of an alternative embodiment of a sealing element; 
         FIG. 15  is a phantom perspective view that depicts a portion of an alternative embodiment of a sealing element; 
         FIG. 16  is a phantom side view that depicts a portion of an alternative embodiment of a sealing element; 
         FIG. 17  is a schematic side view of an embodiment of a vented fluid reservoir; 
         FIG. 18  is a top view of an embodiment of a vented fluid reservoir; 
         FIG. 19  is a phantom side view of an embodiment of a fluid reservoir that includes a septum that serves as a pressure relief valve; 
         FIG. 20  is a phantom side view of the fluid reservoir shown in  FIG. 19  in a sealed state; 
         FIG. 21  is a longitudinal cross-sectional view of a fluid reservoir and a self-sealing reservoir port receptacle suitable for use with a fluid infusion device; 
         FIG. 22  is an end view of the fluid reservoir as viewed from the perspective of line  22 - 22  in  FIG. 21 ; 
         FIG. 23  is a perspective view of a first embodiment of a fluid reservoir that includes a needle; 
         FIG. 24  is a cross-sectional view of a portion of the fluid reservoir, as viewed from the perspective of line  24 - 24  in  FIG. 23 ; 
         FIG. 25  is a perspective view of a section of a fluid infusion device, including a reservoir port receptacle suitable for engagement with the fluid reservoir shown in  FIG. 23 ; 
         FIG. 26  is a perspective view of a sealing and conduit component suitable for use with the fluid infusion device shown in  FIG. 25 ; 
         FIG. 27  is a cross-sectional view of the section of the fluid infusion device, as viewed from the perspective of line  27 - 27  in  FIG. 25 ; 
         FIG. 28  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 23 ) before engagement with the section of the fluid infusion device (shown in  FIG. 25 ); 
         FIG. 29  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 23 ) after engagement with the section of the fluid infusion device (shown in  FIG. 25 ); 
         FIG. 30  is a cross-sectional view of a portion of a second embodiment of a needled fluid reservoir; 
         FIG. 31  is a cross-sectional view of a section of a fluid infusion device that is designed to accommodate the needled fluid reservoir shown in  FIG. 30 ; 
         FIG. 32  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 30 ) before engagement with the section of the fluid infusion device (shown in  FIG. 31 ); 
         FIG. 33  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 30 ) after engagement with the section of the fluid infusion device (shown in  FIG. 31 ); 
         FIG. 34  is a perspective view of a third embodiment of a needled fluid reservoir; 
         FIG. 35  is a cross-sectional view of a portion of the fluid reservoir, as viewed from the perspective of line  35 - 35  in  FIG. 34 ; 
         FIG. 36  is a perspective view of a section of a fluid infusion device, including a reservoir port receptacle suitable for engagement with the fluid reservoir shown in  FIG. 34 ; 
         FIG. 37  is a cross-sectional view of the section of the fluid infusion device, as viewed from the perspective of line  37 - 37  in  FIG. 36 ; 
         FIG. 38  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 34 ) before engagement with the section of the fluid infusion device (shown in  FIG. 36 ); 
         FIG. 39  is a cross-sectional and partially phantom view that illustrates the fluid reservoir (shown in  FIG. 34 ) after engagement with the section of the fluid infusion device (shown in  FIG. 36 ); 
         FIG. 40  is a cross-sectional view of a portion of a fluid infusion device, showing a sealing structure prior to engagement with a fluid reservoir needle; 
         FIG. 41  is a cross-sectional view of the portion of the fluid infusion device shown in  FIG. 40 , showing the sealing structure after engagement with the fluid reservoir needle; 
         FIG. 42  is a cross-sectional view of a portion of a base plate utilized by the fluid infusion device shown in  FIG. 40 ; 
         FIG. 43  is a perspective view of a flow base component utilized by the fluid infusion device shown in  FIG. 40 ; 
         FIG. 44  is a perspective view of the flow base component shown in  FIG. 43 , with a portion removed to better illustrate its internal structure; 
         FIG. 45  is a perspective view of the flow base component shown in  FIG. 43 , with a portion removed to better illustrate its internal structure; 
         FIG. 46  is a perspective view of a needle sealing element utilized by the fluid infusion device shown in  FIG. 40 ; 
         FIG. 47  is a front end view of the needle sealing element shown in  FIG. 46 ; and 
         FIG. 48  is a side view of the needle sealing element shown in  FIG. 46 , with a spacer installed thereon. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Certain terminology may be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” could be used to refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “side”, “outboard”, and “inboard” could be used to describe the orientation and/or location of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second”, and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
     Various embodiments presented here are related to a sealing element suitable for use with a fluid reservoir and a fluid delivery needle of the type found in fluid infusion systems. In certain embodiments, the sealing element includes at least one slit formed in its tip to accommodate a hollow needle. When a fluid reservoir is introduced and coupled to the needle, the port of the fluid reservoir and/or another structural feature of the reservoir urges the sealing element to retract over the needle such that the end of the needle penetrates the slit, protrudes from the tip of the sealing element, and enters the fluid reservoir. Upon fluid connection in this manner, the needle penetrates the tip of the sealing element, which in turn outwardly expands the material (e.g., silicone) of the sealing element near the tip. The reservoir port that receives the sealing element is sized and configured such that expansion of the sealing element forms a radial seal between the inner surface of the reservoir port and the sealing element. Further and complete installation of the reservoir onto the needle also creates a secondary backup face seal between the opening of the reservoir port and the sealing element. 
     Additional embodiments of various fluid reservoir configurations, needle sealing arrangements, and fluid interface designs are also presented here. For example, a number of vented fluid reservoir embodiments are described below, where a pressure vent is incorporated into the fluid reservoir to facilitate the equalization of pressure that may otherwise be present inside of the fluid reservoir and, therefore, to reduce the likelihood of accidental fluid delivery caused by the build-up of internal pressure. 
     In addition, a “needleless” embodiment is presented here. In lieu of a fluid delivery needle, a fluid reservoir is suitably configured to interact with a sealing component or feature of a base plate of the fluid infusion device. The sealing component includes a valve member (e.g., a ball valve) that opens to accommodate fluid delivery from the fluid reservoir when the reservoir is introduced to the base plate. When the reservoir is removed, the valve member automatically seals the flow path. 
     Various embodiments of a fluid reservoir having a “hooded” or shielded needle or needle-like structure are also provided. The reservoir needle is designed to deliver the medication fluid to a corresponding fluid receptacle of the fluid infusion device. The fluid receptacle includes a sealing element that receives the reservoir needle and creates a fluid seal with the reservoir. 
     The following description relates to a fluid infusion device of the type used to treat a medical condition of a patient. The infusion device is used for infusing fluid into the body of a user. The non-limiting examples described below relate to a medical device used to treat diabetes (more specifically, an insulin pump), although embodiments of the disclosed subject matter are not so limited. Accordingly, the infused medication fluid is insulin in certain embodiments. In alternative embodiments, however, many other fluids may be administered through infusion such as, but not limited to, disease treatments, drugs to treat pulmonary hypertension, iron chelation drugs, pain medications, anti-cancer treatments, medications, vitamins, hormones, or the like. For the sake of brevity, conventional features and characteristics related to infusion system operation, insulin pump and/or infusion set operation, fluid reservoirs, and fluid syringes may not be described in detail here. Examples of infusion pumps and/or related pump drive systems used to administer insulin and other medications may be of the type described in, but not limited to: United States patent application number 2009/0299290 A1; United States patent application number 2008/0269687; U.S. Pat. Nos. 7,828,764; and 7,905,868 (the entire content of these patent documents is incorporated by reference herein). 
     Retractable Needle Sealing Element 
       FIG. 1  is a perspective view of an exemplary embodiment of a fluid infusion device  100 . The fluid infusion device  100  includes two primary components that are removably coupled to each other: a durable housing  102 ; and a base plate  104 . The fluid infusion device  100  also includes or cooperates with a removable/replaceable fluid reservoir  106 . For the illustrated embodiment, the fluid reservoir  106  mates with, and is received by, the durable housing  102 . In alternate embodiments, the fluid reservoir  106  mates with, and is received by, the base plate  104 .  FIG. 2  is a perspective view that depicts internal structure of the durable housing  102 ,  FIG. 3  is a perspective view that depicts internal structure of the base plate  104 , and  FIG. 4  is a perspective view that depicts a reservoir port receptacle  108  and a sealing element  110  of the fluid infusion device  100 . 
     The base plate  104  is designed to be temporarily adhered to the skin of the patient using, for example, an adhesive layer of material. After the base plate is affixed to the skin of the patient, a suitably configured insertion device or apparatus may be used to insert a fluid delivery needle or cannula  112  (see  FIG. 1 ) into the body of the patient. The cannula  112  functions as one part of the fluid delivery path associated with the fluid infusion device  100 , as is well understood. 
       FIG. 1  depicts the durable housing  102  and the base plate  104  coupled together. In practice, the durable housing  102  and/or the base plate  104  may include features, structures, or elements to facilitate removable coupling (e.g., pawls, latches, rails, slots, keyways, buttons, or the like). As shown in  FIG. 2 , the durable housing  102  is designed to receive the removable fluid reservoir  106  and to retain the fluid reservoir  106  in a particular position and orientation. Moreover, the durable housing  102  is configured to secure to the base plate  104  in a specified orientation to engage the fluid reservoir  106  with the reservoir port receptacle  108  (see  FIG. 3 ). For this particular embodiment, the durable housing  102  contains, among other components, a drive motor, a battery, a threaded drive shaft for the fluid reservoir, one or more integrated circuit chips and/or other electronic devices (not shown). In particular embodiments, the fluid infusion device  100  includes certain features to orient, align, and position the durable housing  102  relative to the base plate  104  such that when the two components are coupled together the fluid reservoir  106  is urged into the reservoir port receptacle  108  to engage the sealing assembly and establish a fluid seal, as described in more detail below. 
     The durable housing  102  and the base plate  104  are cooperatively configured to accommodate removable coupling of the durable housing  102  to the base plate  104 . The removable nature of the durable housing  102  enables the patient to replace the fluid reservoir  106  as needed. Moreover, the durable housing  102  can be removed (while leaving the base plate  104  adhered to the patient) to allow the patient to swim, shower, bathe, and participate in other activities that might otherwise damage or contaminate the durable housing  102 . When the durable housing  102  is removed from the base plate  104 , the fluid reservoir  106  is disengaged from the reservoir port receptacle  108 , the fluid flow path is broken, and the base plate  104  will appear as shown in  FIG. 4 . 
     The fluid reservoir  106  includes a fluid delivery port  114  that cooperates with the reservoir port receptacle  108 .  FIG. 3  depicts the fully installed position of the fluid reservoir  106  relative to the base plate  104  and the reservoir port receptacle  108  (for ease of illustration, the durable housing  102  is not shown in  FIG. 3 ). The fluid delivery port  114  may include a pierceable septum if the fluid reservoir  106  is a prefilled unit. Alternatively, the fluid delivery port  114  may include a vented opening to accommodate filling of the fluid reservoir  106  by the patient, a doctor, a caregiver, or the like. The fluid delivery port  114  has an interior  116  defined therein. As shown in  FIG. 5 , the interior  116  is shaped, sized, and otherwise configured to receive the sealing element  110  when the fluid reservoir  106  is engaged with the reservoir port receptacle  108 . In certain embodiments, the interior  116  is conical, tapered, and/or funnel-shaped, as best shown in  FIG. 5 . This preferred shape of the interior  116  makes it easy for the sealing element  110  to mate with the fluid delivery port  114  when the durable housing  102  is coupled to the base plate  104 . 
     The sealing element  110  forms part of a sealing assembly  130  for the fluid infusion device  100 . The sealing assembly  130  as referred to here may also include the base plate  104  (or a portion thereof) and/or other structure or elements that cooperate with the sealing element  110 . These additional components will be described with reference to  FIG. 5 , which is a cross-sectional and partially phantom view of a portion of the fluid infusion device  100  (corresponding to the view taken from line  5 - 5  in  FIG. 4 ) and with reference to  FIG. 6 , which is an exploded perspective view of the sealing assembly  130 . The illustrated embodiment of the sealing assembly  130  generally includes, without limitation: the sealing element  110 ; a mounting cap  132 ; and a hollow fluid delivery needle  134 . It should be appreciated that a portion of the base plate  104  (e.g., the reservoir port receptacle  108  and/or the end portion of the base plate  104  that receives the sealing element  110  and the mounting cap  132 ) may be considered to be part of the sealing assembly  130 . 
     The sealing assembly  130  may be formed by coupling the sealing element  110  and the hollow fluid delivery needle  134  to the mounting cap  132 . In turn, the mounting cap  132  may be secured to the base plate  104  (see  FIG. 1  and  FIG. 3 ). The sealing element  110  and the hollow fluid delivery needle  134  may be secured to the mounting cap  132  using an adhesive, a bonding or welding agent, by a compression or snap fitting arrangement, or the like. The bottom surface  136  of the sealing element  110  (see  FIG. 6 ) forms a fluid seal with a mating surface of the mounting cap  132 . In certain embodiments, the mounting cap  132  includes a hollow protrusion  138  (which may be conical in shape) that extends into, and forms a fluid seal with, the base section of the sealing element  110 , as shown in  FIG. 5 . A portion of the hollow fluid delivery needle  134  extends through the hollow protrusion  138  and into the sealing element  110 . As shown in  FIG. 6 , the hollow fluid delivery needle  134  for this particular embodiment is “J” shaped to provide a fluid flow path from the sealing element  110 , across the length of the mounting cap  132 , and into an outlet port  140  of the mounting cap  132 . The outlet port  140  leads to a second sealing element  142  (which may be integrally formed with the sealing element  110 , as shown), which in turn leads into a fluid chamber  144  defined in the base plate  104 . The fluid chamber  144  is fluidly coupled to the cannula  112  ( FIG. 1 ) such that when a plunger of the fluid reservoir  106  is actuated, the fluid is expelled from the fluid reservoir  106 , through the hollow fluid delivery needle  134 , into the fluid chamber  144 , and into the body of the patient via the cannula  112 . 
       FIGS. 7-10  show the sealing element  110  and the second sealing element  142  in more detail, and  FIG. 11  shows the sealing element  110  by itself in cross-section. The sealing element  110  and the second sealing element  142  may be integrally formed as a one-piece component from a resilient and deformable material, such as rubber, urethane, or the like. In certain embodiments, the sealing element  110  and the second sealing element  142  are formed from a pliable silicone material. The material used for the sealing element and the second sealing element  142  is selected to be resistant to the fluid being delivered, biocompatible, and capable of being sterilized after manufacturing. The following description focuses on the configuration, characteristics, and functionality of the sealing element  110  (the figures include the second sealing element  142  for the sake of completeness and for consistency with the exemplary embodiment). 
     The sealing element  110  includes a base section  150 , a tip section  152  extending from the base section  150 , and a retractable body section  154  between the base section  150  and the tip section  152 . In practice, the sealing element  110  is a one-piece component and, accordingly, the base section  150 , the tip section  152 , and the retractable body section  154  are integrally formed and continuous with one another. Referring to  FIG. 11 , the sealing element  110  includes a needle cavity  155  formed therein. More specifically, the needle cavity  155  is formed within the retractable body section  154 , and it continues through the base section  150  to define a needle opening  156  in the base section  150 . The exemplary embodiment depicted in the figures includes a tapered or conical shaped needle opening  156  that mates with the outer contour of the hollow protrusion  138  (see  FIG. 5 ), which in turn accommodates the hollow fluid delivery needle  134 . As shown in  FIG. 5 , the needle cavity  155  is shaped, sized, and configured to receive the hollow fluid delivery needle  134 . 
     The base section  150  generally corresponds to the portion of the sealing element  110  that is coupled to the base plate  104  (by way of the mounting cap  132 ). Notably, the mounting cap  132  and the hollow fluid delivery needle  134  are coupled to the base plate  104  in a substantially fixed and rigid manner such that the hollow fluid delivery needle  134  protrudes from the mounting cap  132  and extends within the reservoir port receptacle  108  (see  FIG. 4 ). The sealing element  110 , however, is a pliable and deformable feature.  FIG. 4  depicts the sealing element  110  in its natural nominal state without the fluid reservoir  106  in place. In this nominal state, the tip section  152  of the sealing element  110  extends slightly beyond the lip of the reservoir port receptacle  108 . The sealing element  110  is configured to retract over the hollow fluid delivery needle  134  when the fluid reservoir  106  engages the base plate  104  (in  FIG. 3  the fluid reservoir  106  is fully engaged with the reservoir port receptacle  108 ). 
     The tip section  152  may be mushroom or barb shaped in various embodiments, as shown in  FIGS. 8-11 . The barbed shape of the tip section  152  promotes entry and seating of the sealing element  110  into the fluid delivery port  114  of the fluid reservoir  106 . Moreover, the barbed shape configuration helps to establish a good radial seal between the sealing element  110  and the interior  116  of the fluid delivery port  114  (described in more detail below). 
     Referring to  FIG. 5  and  FIG. 11 , the sealing element  110  may also include at least one self-sealing slit  160 , slot, opening, or hole formed in the tip section  152  to accommodate the hollow fluid delivery needle  134  when the sealing element is in a retracted position. The self-sealing slit  160  may be realized as a very fine slice or puncture formed in the tip section  152  for purposes of guiding the end of the hollow fluid delivery needle  134  through the material of the sealing element  110  as needed. The self-sealing slit  160  is preferred over an embodiment that relies on repeated punctures of the tip section  152  with a sharp or pointed needle. For this particular embodiment, a flat or blunt ended hollow fluid delivery needle  134  can be utilized because the self-sealing slit  160  provides a pre-existing pathway through the tip section  152 . 
     The self-sealing slit  160  expands to accommodate passage of the hollow fluid delivery needle  134 , and it automatically returns to a “closed” and sealed state when the fluid reservoir  106  is removed from the base plate  104 . The sealed state is depicted in  FIG. 5 —the hollow fluid delivery needle  134  is fully enclosed within the sealing element  110  and the end of the hollow fluid delivery needle  134  is positioned behind the self-sealing slit  160 . More specifically, the sealing element  110  is overlying the protruding portion of the hollow fluid delivery needle  134 , which is located within the retractable body section  154 . In this state, the self-sealing slit  160  closes to inhibit fluid ingress into the needle cavity  155  and to protect the hollow fluid delivery needle  134  from contamination. 
     The illustrated embodiment of the sealing element  110  also includes an integral guide channel  162  formed in the tip section  152 . The guide channel  162  is in communication with the needle cavity  155  and the self-sealing slit  160 , as best shown in  FIG. 11 . The guide channel  162  may be realized as an opening or neck region having a smaller dimension (e.g., diameter) than the end of the needle cavity  155 , but a larger dimension than the self-sealing slit  160 . This arrangement and configuration enables the guide channel  162  to guide/lead the tip of the hollow fluid delivery needle  134  into the self-sealing slit  160  during retraction of the sealing element  110  over the hollow fluid delivery needle  134 . In practice, the guide channel  162  increases the likelihood of the hollow fluid delivery needle  134  entering the self-sealing slit  160  rather than “catching” and puncturing the material forming the tip section  152 . 
     Referring to  FIG. 11 , the needle cavity  155  is suitably configured such that it defines internal relief features  164  and/or an internal relief structure of the retractable body section  154 . In operation, the internal relief features  164  facilitate retraction of the sealing element  110  over the hollow fluid delivery needle  134  in response to a longitudinal force applied to the tip section  152 . Longitudinal force of this type may be imparted to the tip section  152  when the durable housing  102  is coupled to the base plate  104  and, consequently, when the fluid delivery port  114  of the fluid reservoir  106  engages the reservoir port receptacle  108  of the base plate  104  (see  FIG. 3 ). The internal relief features  164  also cause the sealing element  110  to be self-biasing or spring-like such that the sealing element  110  extends over and covers the hollow fluid delivery needle  134  in response to the removal of the longitudinal force. This extended position is depicted in  FIGS. 5-11 . 
     The internal relief features  164  allow the sealing element  110  to compress and deform easily when the fluid reservoir  106  is introduced. Moreover, the internal relief features  164  function as a spring when under compression. In this regard, the internal relief features  164  urge the tip section  152  outward and beyond the end of the hollow fluid delivery needle  134  when the fluid reservoir  106  is withdrawn. The specific configuration of the internal relief features  164  may vary from one embodiment to another, and the exemplary arrangement depicted in  FIG. 11  is not intended to be exhaustive or otherwise limiting. As shown in  FIG. 11 , the internal relief features  164  may include or be arranged as an accordion structure within the needle cavity  155 . Alternatively (or additionally), the internal relief features  164  may include one or a plurality of internal annular channels formed within the needle cavity  155 . Alternatively (or additionally), the internal relief features  164  may include one or a plurality of internal annular ridges or ribs within the needle cavity  155 . Alternatively (or additionally), the internal relief features  164  may include one or a plurality of bottleneck structures resident within the needle cavity  155 . The embodiment shown in  FIG. 11  includes a number of annular channels alternating with a plurality of annular ridges. This arrangement of channels and ridges results in a plurality of bottleneck regions, which in turn form the spring-like accordion structure. 
     The mechanical characteristics, sealing characteristics, and functional aspects of the sealing element  110  will now be described with primary reference to  FIGS. 4, 5, 11, and 12 . The fluid infusion device  100  and, more specifically, the sealing element  110  may be manipulated into various states associated with the coupling status of the fluid reservoir  106  relative to the sealing assembly  130  ( FIG. 6 ), the sealing element  110 , the reservoir port receptacle  108 , etc. The different states may also be specified with respect to the coupling status of the durable housing  102  relative to the base plate  104 . In this regard, one state may be defined as the “separated” or “disconnected” or “disengaged” state where the durable housing  102  and the base plate  104  are separated from each other (or are otherwise decoupled) such that the fluid delivery port  114  is fully disengaged from the sealing element  110 .  FIG. 4  depicts the base plate  104  in its disconnected state. Another state may be defined as the “connected” or “engaged” state where the durable housing  102  and the base plate  104  are fully coupled together, as depicted in  FIG. 1 . This description assumes that the fluid reservoir  106  is properly located and installed within the durable housing  102  (see  FIG. 2 ). Consequently, when the fluid infusion device  100  is in the connected state, the fluid delivery port  114  is received within the reservoir port receptacle  108 , and the interior  116  of the fluid delivery port  114  engages the sealing element  110 .  FIG. 12  is a longitudinal cross-sectional view that schematically depicts the connected state of the fluid infusion device  100 . In contrast,  FIG. 5  shows the fluid infusion device  100  in an intermediate state where the durable housing  102  and the base plate  104  have been introduced to one another and oriented for coupling together. In this intermediate state, the fluid delivery port  114  has partially engaged the reservoir port receptacle  108 , but the sealing element  110  has not yet been retracted over the hollow fluid delivery needle  134 . 
     The sealing element  110  has a nominal state, which is depicted in  FIGS. 4-11 , and a retracted state, which is depicted in  FIG. 12 . The sealing element  110  naturally assumes its nominal state when the fluid infusion device  100  is in the disconnected state, and when the fluid infusion device  100  is in the intermediate state described above. When in the nominal state, the tip of the hollow fluid delivery needle  134  resides within the needle cavity  155  (see  FIG. 5 ). In other words, the sealing element  110  encloses the hollow fluid delivery needle  134  when the sealing element  110  is in the nominal state. Consequently, the self-sealing slit  160  is free to return to its natural position to form a fluid seal for the needle cavity  155 . Thus, when the sealing element  110  is in the nominal state, the self-sealing slit  160  inhibits fluid ingress into the needle cavity, which is desirable to prevent or minimize contamination of the hollow fluid delivery needle  134 . 
     In contrast, the sealing element  110  is urged into its retracted state when the fluid infusion device  100  is in the connected state. The transition from the intermediate state to the connected state is associated with the application of longitudinal force (imparted by the fluid delivery port  114 ) to the tip section  152  of the sealing element  110 . The longitudinal force is imparted to the tip section  152  when the durable housing  102  is coupled to the base plate  104 —the action of coupling the durable housing  102  to the base plate  104  causes the fluid delivery port  114  to move toward the mounting cap  132 , which in turn reduces the distance between the interior  116  of the fluid delivery port  114  and the mounting cap  132 . In response to this reduction in distance, the sealing element  110  is deformed and crushed such that it retracts over the hollow fluid delivery needle  134 . Notably, the internal relief features  164  promote the deformation and retraction of the sealing element  110  over the hollow fluid delivery needle  134  in response to force applied to the tip section  152 , which is caused by forward movement of the fluid reservoir  106 . Retraction of the sealing element  110  causes the tip  172  of the hollow fluid delivery needle  134  to be led through the guide channel  162  and into the self-sealing slit  160 , such that the tip  172  protrudes from the tip section  152  (see  FIG. 12 ) and such that an end section  173  of the hollow fluid delivery needle  134  resides in the self-sealing slit  160 . Thus, when the removable fluid reservoir  106  is installed on the hollow fluid delivery needle  134 , the tip  172  extends from the tip section  152  of the sealing element  110  and into the fluid reservoir  106 . 
     The sealing element  110  interacts with the fluid delivery port  114  to establish a fluid seal. Referring to  FIG. 11  and  FIG. 12 , the retractable body section  154  of the sealing element  110  has an exterior surface  174 . When the sealing element  110  is in its nominal state ( FIGS. 4-11 ), the exterior surface  174  is “relaxed” and it resembles a smooth cylindrical surface. Due to the deformable characteristics of the sealing element  110 , however, the exterior surface  174  moves outward when the sealing element  110  is retracting over the hollow fluid delivery needle  134 , especially when the hollow fluid delivery needle  134  protrudes from the tip section  152  and displaces the seal material. This outward movement of the exterior surface  174  corresponds to an outward expansion of the retractable body section  154 . The retractable body section  154  continues to expand in this manner until it abuts the interior  116  of the fluid delivery port  114 , as depicted in  FIG. 12 . Thus, as the tip section  152  engages the fluid delivery port  114 , the sealing element  110  creates an initial seal with the fluid delivery port  114 . In addition, the retractable body section  154  expands to form a radial seal with the interior  116  when the fluid reservoir  106  engages the sealing element  110  and the hollow fluid delivery needle  134 . The tip section  152  of the sealing element  110  also abuts the interior  116  of the fluid delivery port  114 , which enhances the fluid seal. 
     The internal relief features  164  facilitate compression of the sealing element  110  into the retracted state shown in  FIG. 12 . The internal relief features  164  also provide resiliency to enable the sealing element  110  to regain its nominal shape when the durable housing  102  is removed and, consequently, the fluid delivery port  114  is disengaged from the sealing element  110  and the hollow fluid delivery needle  134 . In other words, the sealing element  110  automatically and naturally springs back into its nominal position, and extends over and covers the hollow fluid delivery needle  134 , when the fluid infusion device  100  transitions from the connected state to the disconnected state. For this reason, the internal relief features  164  are preferably designed, arranged, and configured to provide spring-like characteristics to the sealing element  110 . 
       FIGS. 13-16  depict sealing elements configured in accordance with three alternate embodiments. Any of these alternative embodiments could be utilized in lieu of the sealing element  110  described above. These alternate embodiments share many features, characteristics, and functions with the sealing element  110 . For the sake of brevity, common aspects of these sealing elements will not be described in detail here. 
       FIG. 13  is a perspective view of an alternate embodiment of a sealing element  200 , which may be suitable for use in lieu of the sealing element  110 . The sealing element  200  shares many features and characteristics with the sealing element  110  and, indeed, the internal structures of the sealing elements  110 ,  200  may be similar or identical. For example, the sealing element  200  also includes a self-sealing slit  201  to accommodate a needle. The sealing element  200  employs a gradually tapered retractable body section  202  that transitions smoothly and continuously with a tip section  204 . In contrast, the sealing element  110  employs a barbed tip section  152 . 
       FIG. 14  is a phantom side view that depicts a portion of an alternate embodiment of a sealing element  300 . The sealing element  300  includes a relatively straight and smooth cylindrical retractable body section  302  that transitions to a tip section  304 . In contrast to the embodiments described previously, the sealing element  300  also includes a circumferential compression element  306  coupled around the tip section  304 . The circumferential compression element  306  is suitably designed, shaped, and sized to impart an inward biasing force to a self-sealing slit  308  formed in the tip section  304 . Consequently, when the sealing element  300  is in its natural and nominal state (as depicted in  FIG. 14 ), the circumferential compression element  306  urges the self-sealing slit  308  closed to enhance the seal for the needle cavity  310 . 
     In certain embodiments, the circumferential compression element  306  is realized as a physically distinct and separate component that is attached to the material that forms the bulk of the sealing element  300 . For example, the circumferential compression element  306  could be affixed to the tip section  304  using an adhesive, a bonding agent, or the like. Alternatively, the circumferential compression element  306  could be coupled to the tip section  304  by way of a compression fit and/or by way of structural features that secure the circumferential compression element  306  to the tip section  304  (e.g., keyway features, tabs, ridges, or the like). In accordance with one exemplary embodiment, the circumferential compression element  306  is realized as a resilient band that resists deformation more than the material that forms the tip section  304 . 
       FIG. 15  is a phantom perspective view that depicts a portion of another alternate embodiment of a sealing element  400 . The sealing element  400  is similar to the sealing element  300  in that it also includes a circumferential compression element  406 . For this embodiment, however, the circumferential compression element  406  is realized as a rigid ring that encircles most if not all of the tip section  404 . In accordance with one exemplary embodiment, the circumferential compression element  406  is realized as a metal compression ring that can be installed over the tip section  404  by bending or deforming it to achieve the desired amount of compression. 
       FIG. 16  is a phantom side view that depicts a portion of yet another alternate embodiment of a sealing element  500 . The sealing element  500  includes a tip section  504  having a different shape and profile (relative to the embodiments described previously). The shape of the tip section  504  is similar to the shape of the tip section  152  in that it is wider than the retractable body section  502 . This wide tip section  504  is desirable to establish a good fluid seal with the fluid reservoir. Moreover, the additional material that is used to form the wide tip section  504  serves to enhance the integrity of the self-sealing slit  508 . 
     It should be appreciated that the specific features and characteristics shown and described above for the various exemplary embodiments are neither exclusive nor required for any given embodiment. For example, any of the exemplary sealing elements described above could be provided with or without a circumferential compression element for the tip section. As another example, the specific shape and configuration of the tip section may vary from one embodiment to another. Thus, the individual features and elements shown and described may be implemented and deployed in an embodiment of a fluid infusion device as desired to suit the needs of the particular application. 
     Vented Fluid Reservoirs 
     An open or vented fluid reservoir may be utilized to reduce or eliminate excess pressure that might otherwise be introduced into the fluid chamber of the reservoir during a filling operation. In this regard, a vented fluid reservoir allows the pressure to equalize before the reservoir is coupled to the fluid infusion device and, therefore, reduces or eliminates the likelihood of unintended fluid delivery. To this end, one embodiment described here includes a vented port or funnel to relieve the pressure in the reservoir. Another embodiment described below employs a movable septum that functions as a pressure relief valve for the fluid reservoir. 
       FIG. 17  depicts a schematic side view representation of a vented fluid reservoir  600 , and  FIG. 18  is a top view of an exemplary embodiment of the vented fluid reservoir  600 . For ease of understanding and illustration,  FIG. 17  depicts some structure in cross section and some structure in phantom. The fluid reservoir  600  may be utilized with the fluid infusion device  100  (or a slightly modified version thereof) described above with reference to  FIGS. 1-6 . Accordingly, common features, structures, elements, and functionality will not be redundantly described here in the context of the fluid reservoir  600 . 
     Referring to  FIG. 17 , the fluid reservoir  600  may cooperate with a fluid infusion device (not shown) having a hollow fluid delivery needle  602  and a sealing element  604  overlying at least a portion of the hollow fluid delivery needle  602 . The sealing element  604  may exhibit any of the features, structures, or elements described above, as appropriate for the particular embodiment. As described above for the previous embodiments, the sealing element  604  may terminate at a tip section  606  through which a tip  608  of the hollow fluid delivery needle penetrates when the fluid reservoir  600  is engaged with the hollow fluid delivery needle  602  and with the sealing element  604  (see, for example,  FIG. 12 ). For this particular embodiment, the tip section  606  is barbed or mushroom shaped such that it has a tapered convex exterior surface  610 . 
     The fluid reservoir  600  generally includes, without limitation: a main body section  620 ; a filling port  621 ; a fluid delivery port  622 ; a funnel element  623 ; and a septum  624 . The main body section defines a fluid chamber  626  for the medication fluid that is to be delivered by the fluid infusion device. The filling port  621  is in fluid communication with the fluid chamber  626  to accommodate filling of the fluid chamber  626  with the desired medication fluid (using a syringe or fill needle, as is well understood). The fluid delivery port  622  is coupled to, and extends from, the main body section  620 . The fluid delivery port  622  is in fluid communication with the fluid chamber  626  to provide a fluid flow path from inside the fluid chamber  626  to the hollow fluid delivery needle  602  (this fluid flow path is established and maintained when the fluid reservoir  600  is engaged with the base plate of the fluid infusion device). 
     The funnel element  623  is coupled within the fluid delivery port  622 . In certain embodiments, the main body section  620  and the fluid delivery port  622  are formed from a first material (such as plastic) and the funnel element  623  is formed from a second material (such as metal). The funnel element  623  may be implemented as an insert that can be seated within and coupled to the fluid delivery port  622  in any suitable manner such that the funnel element  623  remains in a fixed position. Notably, the funnel element  623  includes a tapered, conical, or convex interior surface  628 . This interior surface  628  represents one surface of the receptacle that is defined by the funnel element  623 . As schematically illustrated in  FIG. 17 , the funnel element  623  is shaped, sized, and configured in accordance with the sealing element  604 . This enables the interior surface  628  of the funnel element  623  and the exterior surface  610  of the sealing element  604  to mate with one another and cooperate to form a fluid tight seal when they are forced together. 
     The septum  624  is located and held in place in the funnel element  623 . The septum  624  may be formed from a soft, resilient, and pliable material that has certain self-sealing or self-restoring properties. For example, the septum  624  may be formed from a silicone rubber material in certain embodiments. Depending upon the embodiment, the septum  624  may be provided in a solid and continuous form, or it may be provided with a slit, a cut, or an equivalent feature that makes it easier to pierce while still maintaining at least a nominal seal. The septum  624  has a nominal non-pierced state (depicted in  FIG. 17 ) where the needle does not protrude through the septum  624 . In the non-pierced state, the septum  624  forms a fluid seal within a fluid conduit  630  defined by the fluid reservoir  600 . Thus, the medication fluid inside the fluid chamber  626  cannot flow within the fluid conduit  630  when the fluid reservoir  600  is in the disengaged state shown in  FIG. 17 . However, when the fluid reservoir  600  is properly engaged with the hollow fluid delivery needle  602  and with the sealing element  604 , the tip  608  of the hollow fluid delivery needle  602  penetrates the septum  624  to create a fluid flow path from the fluid chamber  626  through the septum  624 . Accordingly, the hollow fluid delivery needle  602  pierces the septum  624  to facilitate delivery of the medication fluid from the fluid chamber to the hollow fluid delivery needle  602 . 
     In various embodiments, the fluid delivery port  622  and/or the funnel element  623  include a pressure vent formed therein. The pressure vent may take any suitable form or arrangement. For example, the pressure vent may be realized with one or more vent holes. As another example, the pressure vent may be realized with one or more slits or any other opening formed within the funnel element  623 . The exemplary embodiments shown in  FIG. 17  and  FIG. 18  employ small diameter vent holes  640  formed in the funnel element  623 . As shown in  FIG. 18 , the vent holes  640  may be arranged around the perimeter of the fluid delivery port and/or around the perimeter of the funnel element  623 . As depicted in  FIG. 17 , the vent holes  640  may be located around the outer perimeter of the septum  624 . Thus, the vent holes  640  create venting conduits that pass around the septum  624  and pass around the fluid conduit  630 . In practice, the vent holes  640  are sized to minimize leakage of the medication fluid caused by gravity or handling of the fluid reservoir  600 . Of course, if the fluid chamber  626  is highly pressurized, then some medication fluid may be forced out of the vent holes  640  while the fluid chamber  626  equalizes. 
     Each vent hole  640  provides a venting conduit from inside the fluid chamber  626  to outside the fluid chamber  626 . More specifically, each vent hole  640  is realized as a fluid conduit that communicates at one end with the fluid chamber  626  and at the other end with the interior surface  628  of the funnel element  623 . Thus, each vent hole  640  terminates at the interior surface  628 . When the fluid reservoir  600  is disengaged from the fluid infusion device, the vent holes  640  may be visible from the top of the fluid reservoir  600 , as shown in  FIG. 18 . 
     In operation, the fluid delivery port  622  and the funnel element  623  engage and cooperate with the sealing element  604  and with the hollow fluid delivery needle  602  in the manner generally described above with reference to the fluid infusion device  100 . When the fluid delivery port  622  is installed and pressed over the sealing element  604 , the tip section  606  of the sealing element  604  is urged against the contoured interior surface  628  of the funnel element  623 . This action causes the exterior surface  610  of the sealing element  604  to contact and mate with the interior surface  628  of the funnel element  623 . In turn, the tip section  606  (which may deform or expand in response to the coupling) covers and seals the vent holes  640 . As mentioned previously, the tip  608  of the hollow fluid delivery needle pierces the septum  624  when the fluid reservoir  600  is introduced. In certain embodiments, the fluid delivery port  622 , the funnel element  623 , the sealing element  604 , and the hollow fluid delivery needle  602  are cooperatively configured such that the tip section  606  of the sealing element  604  seals the vent holes  640  before the hollow fluid delivery needle  602  pierces the septum  624 . This reduces or eliminates leakage of the medication fluid. The vent holes  640  remain sealed in this manner during operation of the fluid infusion device, such that the medication fluid is forced from the fluid chamber  626  and through the hollow fluid delivery needle  602  in the intended manner. 
     Another embodiment of a vented fluid reservoir will now be described with reference to  FIG. 19  and  FIG. 20 .  FIG. 19  is a phantom side view of a fluid reservoir  700  in an open or vented state, and  FIG. 20  is a phantom side view of the fluid reservoir  700  in a sealed state. It should be appreciated that the fluid reservoir  700  may be utilized with the fluid infusion device  100  (or a slightly modified version thereof) described above with reference to  FIGS. 1-6 . Accordingly, common features, structures, elements, and functionality will not be redundantly described here in the context of the fluid reservoir  700 . 
     The illustrated embodiment of the fluid reservoir  700  generally includes, without limitation: a main body section  702 ; a fluid delivery port  704 ; a valve sleeve  706 ; and a septum  708 . The main body section  702  includes a fluid chamber  710  defined therein. The fluid chamber  710  accommodates the medication fluid to be delivered to the patient. The fluid delivery port  704  is coupled to and extends from the main body section  702 . In certain embodiments, the fluid delivery port  704  is integrally formed with the main body section  702 . For example, the fluid delivery port  704  and the main body section  702  may be fabricated from a molded plastic material. The fluid delivery port  704  includes or defines a fluid conduit  712  that communicates with the fluid chamber  710 . 
     This particular embodiment of the fluid delivery port  704  has a generally cylindrical shape that resembles a neck region extending from the main body section  702 . The fluid delivery port  704  terminates at a port opening  714 . The port opening  714  is realized as a round rim or lip at the end of the fluid delivery port  704 . As shown in  FIG. 19  and  FIG. 20 , the perimeter edge of the fluid delivery port  704  may be beveled or “pointed” if so desired (beveling in this manner may be desirable for purposes of creating a good seal with the septum  708 ). 
     Although not always required, the illustrated embodiment of the fluid delivery port  704  includes a circumferential groove  716  formed therein (around the outer surface). The groove  716  may be defined as a region between a shoulder  718  of the main body section  702  and a barb portion  720  of the fluid delivery port  704 . For this embodiment, the barb portion  720  is located at or near the port opening  714 . In alternative embodiments, the groove  716  could be positioned anywhere along the length of the fluid delivery port  704 . The groove  716  receives an interior ridge  724  of the valve sleeve  706 , which is formed within an attachment receptacle of the valve sleeve  706 . This attachment receptacle is generally defined by the interior region below the septum  708  in  FIG. 19  and  FIG. 20 . The attachment receptacle is shaped, sized, and otherwise configured to receive the fluid delivery port  704  as shown in the figures. The interior ridge  724  may be implemented as a continuous protrusion positioned within the attachment receptacle such that it completely encircles the fluid delivery port  704 . The dimensions of the interior ridge  724  and the groove  716  are selected such that the valve sleeve  706  can be “snapped” into place and retained on the fluid delivery port  704  in a manner that accommodates translational movement of the valve sleeve  706  relative to the fluid delivery port  704 . 
     Notably, the groove  716  allows the valve sleeve  706  to move toward the fluid chamber  710  until movement is inhibited by the shoulder  718  and/or by other structure of the fluid reservoir  700 , or until movement is inhibited by engagement between the septum  708  and the port opening  714  (see  FIG. 20 ). Similarly, the groove  716  allows the valve sleeve  706  to move away from the fluid chamber  710  until movement of the interior ridge  724  is inhibited by the barb portion  720  of the fluid delivery port  704  (see  FIG. 19 ). Thus, the valve sleeve  706  is movably coupled to the fluid delivery port  704 , and the attachment receptacle of the valve sleeve  706  is sized to accommodate translation of the valve sleeve  706  relative to the fluid delivery port  704  and, more particularly, relative to the port opening  714 . 
     The septum  708  is located within a septum receptacle  728  defined within the valve sleeve  706 . The septum receptacle  728  may be realized as an interior groove or channel formed in the inner wall of the valve sleeve  706 . In the illustrated embodiment, the septum receptacle  728  is adjacent to the attachment receptacle, such that one surface of the septum  708  (i.e., the lower surface in  FIG. 19  and  FIG. 20 ) defines a boundary of the attachment receptacle. The septum receptacle  728  receives and holds the septum  708  in a fixed position relative to the valve sleeve  706 . In other words, the septum receptacle  728  maintains the septum  708  in place such that the septum  708  translates in concert with the valve sleeve  706 . In this regard, the septum  708  is movably coupled to the fluid delivery port  704  by way of the valve sleeve  706 . 
     The valve sleeve  706  also includes a sleeve opening  730  that is adjacent to the septum receptacle  728 . The sleeve opening  730  is arranged such that at least a portion of the septum  708  is accessible via the sleeve opening  730 . As shown in  FIG. 19  and  FIG. 20 , the upper surface of the septum  708  is exposed in the sleeve opening  730 . The sleeve opening  730  allows a hollow fluid delivery needle of the fluid infusion device to pierce or otherwise pass through the septum  708  to gain entry to the fluid conduit  712 . 
     The valve sleeve  706  and the septum  708  are movable between a sealed position (shown in  FIG. 20 ) and an open or vented position (shown in  FIG. 19 ). The sealed position is achieved when the fluid reservoir  700  is engaged with the fluid delivery needle of the fluid infusion device. More specifically, the septum  708  and the valve sleeve  706  are urged into the sealed position when the fluid delivery needle is forced against and through the septum  708 . Additionally or alternatively, the septum  708  could be urged into the sealed position when the valve sleeve  706  abuts structure of the base plate. When in the sealed position, the surface of the septum  708  contacts the port opening  714  to form a circumferential seal around the port opening  714 . This seal inhibits fluid flow between the fluid delivery port  704  and the septum  708  during a delivery cycle (which is intended to force the medication fluid through the delivery needle). For simplicity, the needle and its associated base plate mounting structure are not shown in  FIG. 20 . 
     When the fluid reservoir  700  is removed from the fluid infusion device and, therefore, is disengaged from the fluid delivery needle, the valve sleeve  706  and the septum  708  are free to move relative to the fluid delivery port  704 . Accordingly, the valve sleeve  706  and the septum  708  are free to move into the vented position in response to a pressure differential condition where pressure in the fluid chamber  710  exceeds the ambient pressure. Under these conditions, the excess pressure inside the fluid chamber  710  can be released through the port opening  714  because the valve sleeve  706  and the septum  708  function as a pressure relief valve. When subjected to excess pressure in this manner, the septum  708  moves slightly upward, which creates a gap between the bottom surface of the septum  708  and the port opening  714 . Consequently, the septum  708  permits fluid to flow out of the fluid delivery port  704  via the port opening  714  when the valve sleeve  706  is in the vented position. After the pressure is equalized, however, the valve sleeve  706  and the septum  708  might naturally return to the sealed position shown in  FIG. 20 , especially if the fluid reservoir  700  is held in the depicted orientation (where the force of gravity may cause the valve sleeve  706  to fall into the sealed position). 
     Needleless Fluid Reservoir Interface 
     The embodiments described above utilize a hollow needle that engages the fluid reservoir during operation of the fluid infusion device. An alternative needleless implementation will now be described with reference to  FIG. 21  and  FIG. 22 .  FIG. 21  is a longitudinal cross-sectional view of a fluid reservoir  800  and a self-sealing reservoir port receptacle  802  suitable for use with a fluid infusion device, and  FIG. 22  is an end view of the fluid reservoir  800  as viewed from the perspective of line  22 - 22  in  FIG. 21 . The fluid reservoir  800  and the self-sealing reservoir port receptacle  802  may be utilized with the fluid infusion device  100  (or a slightly modified version thereof) described above with reference to  FIGS. 1-6 . Accordingly, common features, structures, elements, and functionality will not be redundantly described here in the context of the fluid reservoir  800  and the self-sealing reservoir port receptacle  802 . 
     The fluid reservoir  800  may be intended to be a user-filled or refillable unit, or it could be designed to be a disposable pre-filled unit, depending upon the particular application. The fluid reservoir  800  includes a main body section  804  that defines an interior fluid chamber  806  for holding the desired fluid, e.g., a medication fluid such as insulin. The fluid reservoir  800  also includes a fluid delivery port  808  that is coupled to, and extends from, the main body section  804 . The fluid delivery port  808  includes or otherwise defines a fluid conduit  810  that communicates with the fluid chamber  806 . The fluid conduit  810  is used to deliver the fluid from the fluid chamber  806 . In certain embodiments, the fluid conduit  810  may also be used as the fill port of the fluid reservoir  800 . 
     Notably, the fluid reservoir  800  is “unsealed” in that the fluid delivery port  808  terminates at an unsealed port opening  812 . In this regard, the fluid delivery port  808  does not include a septum or any equivalent form of fluid seal that remains in place during use of the fluid infusion device. That said, the fluid reservoir  800  could be manufactured and provided with a protective seal or film that is removed prior to use. For instance, a prefilled version of the fluid reservoir  800  may include a temporary cover, lid, or cap that can be removed prior to use. In the context of a user-filled unit, the unsealed nature of the fluid reservoir  800  allows the fluid chamber  806  to be filled in a manner that inherently equalizes the pressure. Consequently, the fluid chamber  806  will not be over-pressurized when the fluid reservoir  800  is introduced to the fluid infusion device. 
     The fluid delivery port  808  and the port opening  812  are shaped and sized in accordance with the dimensions of the self-sealing reservoir port receptacle  802 . More specifically, the fluid delivery port  808  and the port opening  812  are shaped and dimensioned to facilitate mating and engagement with the self-sealing reservoir port receptacle  802 . In this regard, the fluid delivery port  808  is inserted into the self-sealing reservoir port receptacle  802  to enable the fluid reservoir  800  to provide the medication fluid to the body of the patient via the self-sealing reservoir port receptacle  802 . 
     In certain embodiments, the port opening  812  includes at least one flow path  814  (see  FIG. 22 ) that allows the medication fluid to flow from the fluid conduit  810  and into the self-sealing reservoir port receptacle  802  when the fluid reservoir  800  is engaged with and coupled to the self-sealing reservoir port receptacle  802 . The illustrated embodiment employs five channels formed in the exposed rim  816  of the fluid delivery port  808 . The fluid is able to flow through these channels during a delivery cycle of the fluid infusion device (as described in more detail below). In alternative embodiments, the at least one flow path  814  may be realized as through holes, slits, or any suitably configured conduit to pass the medication fluid. Moreover, the port opening  812  could be shaped (e.g., to resemble a crown) in any desired way to enable the medication fluid to flow from the fluid conduit  810  during use. 
     In various embodiments, the self-sealing reservoir port receptacle  802  is coupled to, provided with, or incorporated into a base plate of the fluid infusion device (see, for example, a similar arrangement depicted in  FIG. 1  and  FIG. 3 ). As mentioned previously, the fluid infusion device may include a suitable delivery conduit, such as the cannula  112  shown in  FIG. 1 , wherein the delivery conduit provides the medication fluid to the body. Accordingly, the self-sealing reservoir port receptacle  802  may be located on the base plate to establish a flow path for the medication fluid from the fluid reservoir  800  to the delivery conduit. 
     The illustrated embodiment of the self-sealing reservoir port receptacle  802  is implemented as a needleless component. In other words, a delivery needle is not utilized with either the self-sealing reservoir port receptacle  802  or the fluid reservoir  800 . Rather, the self-sealing reservoir port receptacle  802  incorporates a biased valve element  830  that is nominally closed in its natural state, but is opened in response to engagement of the fluid reservoir  800 . Referring to  FIG. 21 , the exemplary embodiment of the self-sealing reservoir port receptacle  802  generally includes, without limitation: an inlet  832 ; a valve chamber  834  for the valve element  830 ; and an outlet  836 . For this particular embodiment, the inlet  832 , the valve chamber  834 , and the outlet  836  are joined together to define a continuous hollow interior pathway. 
     The inlet  832  is suitably configured, shaped, and sized to receive the fluid delivery port  808  of the fluid reservoir  800 . For this embodiment, the inlet  832  includes an interior  838  that is sized to receive the fluid delivery port  808 . In alternative embodiments, the inlet  832  may be sized to fit inside the fluid conduit  810 . The inlet  832  may also include or cooperate with a sealing element  840  that forms a seal with the outer surface of the fluid delivery port  808  when the fluid delivery port  808  is engaged with the inlet  832 . In various embodiments, the sealing element  840  is realized as a resilient gasket, o-ring, washer, or the like. Moreover, although the depicted embodiment has the sealing element  840  incorporated into the inlet  832 , the sealing element  840  may alternatively (or additionally) be incorporated into the fluid delivery port  808 . When the fluid delivery port  808  is engaged with the inlet  832 , the sealing element  840  inhibits leakage of fluid from the port opening  812  and from the valve chamber  834 . 
     The valve chamber  834  is in fluid communication with the inlet  832 . For this particular embodiment, the downstream end of the inlet  832  corresponds to the upstream end of the valve chamber  834 , as shown in  FIG. 21 . The valve chamber  834  is shaped, sized, and otherwise configured to retain the valve element  830  while allowing the valve element  830  to translate in the upstream and downstream directions within the valve chamber  834 . The upstream end of the valve chamber  834  may include a retaining shoulder  844  formed therein. The retaining shoulder  844  may be defined as the transition from a relatively small inner dimension corresponding to the inlet  832  to a relatively large inner dimension corresponding to the valve chamber  834 . In other words, the retaining shoulder  844  represents a neck region that prevents the valve element  830  from completely entering the inlet  832 . 
     The self-sealing reservoir port receptacle  802  also includes a resilient compression element  846  located in the valve chamber  834 . The resilient compression element  846  can be positioned between the valve element  830  and the downstream end of the valve chamber  834 . The resilient compression element  846  is sized and configured to bias the valve element  830  toward the inlet  832  (as shown in  FIG. 21 ). In other words, the resilient compression element  846  naturally urges the valve element  830  against the retaining shoulder  844  and into a sealed position to form a fluid seal between the valve element  830  and the inlet  832 . In certain embodiments, the resilient compression element  846  is realized as a spring. Alternatively, the resilient compression element  846  could be realized as a compressible plug, an accordion-like member, or the like. 
     The valve element  830  may be shaped and sized as appropriate for the particular embodiment.  FIG. 21  depicts one exemplary embodiment where the valve element  830  is realized as a ball valve, i.e., the valve element  830  includes a spherical component. Thus, the valve chamber  834  may be fabricated as a cylindrical cavity to accommodate the round profile of the valve element  830 . Alternatively, the valve element  830  could be realized as a cylindrical plug. Various shapes and configurations could be utilized for the valve element  830 , and the ball valve implementation is merely one suitable embodiment. 
     The downstream end of the valve chamber  834  is in fluid communication with the outlet  836  such that medication fluid can pass through the valve chamber  834  and into the outlet  836 . The outlet  836  provides a fluid flow path  848  for the medication fluid. In this regard, the fluid flow path  848  may be routed through the base plate and/or through other structure of the fluid infusion device, and to the delivery conduit that leads to the body of the user, as described previously. In other words, the outlet  836  can be positioned between the valve chamber  834  and the delivery conduit. 
       FIG. 21  shows the self-sealing reservoir port receptacle  802  in its sealed position. The sealed state is automatically assumed in the absence of the fluid reservoir  800 . In other words, when the fluid delivery port  808  is disengaged from the inlet  832  of the self-sealing reservoir port receptacle  802 , the resilient compression element  846  forces the valve element  830  toward the inlet  832  and against the retaining shoulder  844 , which in turn forms a fluid seal between the valve element  830  and the inlet  832 . This seal is desirable to prevent backflow leakage of the medication fluid and to reduce the likelihood of contamination of the fluid path. 
     Engagement of the fluid delivery port  808  with the inlet  832  causes the end of the fluid delivery port  808  to contact the valve element  830 . Further engagement and complete coupling of the fluid delivery port  808  within the inlet  832  causes the end of the fluid delivery port  808  to move the valve element  830  from the sealed position (shown in  FIG. 21 ) to an opened position. In the opened position, the valve element  830  is forced in the downstream direction toward the outlet  836 . As a result of this movement, the resilient compression element  846  becomes compressed and compacted within the valve chamber  834 . Retraction of the valve element  830  in this manner also enables the fluid delivery port  808  to gain access to the valve chamber  834 , which in turn accommodates flow of the medication fluid from the fluid reservoir  800  and into the valve chamber  834 . Referring again to  FIG. 22 , the at least one flow path  814  in the exposed rim  816  ensures that the medication fluid can flow into the valve chamber  834  (even though the end of the fluid delivery port  808  is in contact with the valve element  830 ). 
     Needled Fluid Reservoir for a Fluid Infusion Device 
     Most of the embodiments described previously employ a hollow fluid delivery needle that is provided with a base plate of a fluid infusion device (see, for example,  FIGS. 1-5 ). The needle in such embodiments cooperates with a sealed or an open fluid reservoir, wherein the needle is introduced into the fluid chamber of the fluid reservoir to accommodate delivery of the medication fluid from the fluid chamber, through the needle, and to the body of the patient. 
     Alternatively, the embodiments presented in this section utilize a needled fluid reservoir, i.e., a fluid reservoir having a hollow fluid delivery needle incorporated therein. The hollow needle engages a suitably configured reservoir port receptacle, which may be located on the base plate of the fluid infusion device. The reservoir port receptacle includes a fluid conduit that is used to deliver the medication fluid to the body of the patient. In certain embodiments, the reservoir needle is unsealed and, therefore, open to ambient pressure. Accordingly, the fluid infusion device includes an appropriate sealing arrangement to establish a fluid seal with the hollow needle when the fluid reservoir is engaged with the reservoir port receptacle. 
       FIGS. 23-29  relate to a first embodiment of a needled fluid reservoir  900  that is suitable for use with a compatible fluid infusion device.  FIG. 23  is a perspective view of the fluid reservoir  900 , and  FIG. 24  is a cross-sectional view of an end portion  902  of the fluid reservoir  900 . It should be appreciated that the fluid reservoir  900  could be utilized with a modified version of the fluid infusion device  100  described above with reference to  FIGS. 1-6 . Accordingly, common features, structures, elements, and functionality will not be redundantly described here with reference to  FIGS. 23-29 . Moreover, the fluid reservoir  900  shares a number of features and elements with some of the fluid reservoirs described previously. For the sake of brevity, such common features and elements will not be described in detail again in the context of the fluid reservoir  900 . 
     Referring to  FIG. 23  and  FIG. 24 , the fluid reservoir  900  includes a main body section  904  that defines an interior fluid chamber  906  for a fluid to be delivered, such as a medication fluid. The fluid reservoir  900  also includes a hollow needle  908  extending from the main body section  904  and defining a fluid conduit  910  (see  FIG. 24 ) that communicates with the fluid chamber  906 . Although not always required, the illustrated embodiment of the hollow needle  908  is realized as a separate component that is physically coupled to the main body section  904  (and/or to a structural feature defined in the main body section  904 ) in an appropriate manner to communicate with the fluid chamber  906 . In this regard, the hollow needle  908  and the main body section  904  in this particular embodiment are realized as two physically distinct and separate components that are assembled together into the configuration shown in the figures. For example, the main body section  904  could be fabricated from a molded plastic material, and the hollow needle  908  could be fabricated from a metal material, as appropriate to the specific embodiment. In practice, the hollow needle  908  is coupled to the main body section  904  in a way that prevents leakage of fluid between the main body section  904  and the outer surface of the hollow needle  908 . 
     As best shown in  FIG. 24 , the hollow needle  908  terminates at a needle end  912  that forms or otherwise defines a blunt tip  914 . The blunt tip  914  may be flat (as shown), rounded, mushroom-shaped, or otherwise contoured in a way that does not result in a sharp or pointed needle end  912 . Moreover, the hollow needle  908  may be unsealed such that the fluid conduit  910  remains open to ambient or atmospheric pressure, which is desirable to enable the fluid reservoir  900  to equalize its internal pressure inside the fluid chamber  906  via the hollow needle  908 . The fluid conduit  910  is preferably sized to inhibit or prevent natural leakage of the fluid, while still accommodating the delivery of the medication fluid from the fluid chamber  906 . Moreover, for embodiments where the hollow needle  908  also serves as the fill needle, the fluid conduit  910  is sized to enable quick and easy filling of the fluid reservoir  900 . As described in more detail below, the blunt tip  914  is suitably sized, shaped, and configured to engage a sealing element of the fluid infusion device. 
     Various embodiments of the fluid reservoir  900  include a needle hood  916  that at least partially covers the hollow needle  908 . The needle hood  916  extends from the main body section  904  to at least partially surround the hollow needle  908 , while still providing access to the hollow needle  908  from the end, as best shown in  FIG. 23 . As depicted in  FIG. 24 , the illustrated embodiment of the needle hood  916  is integrated with the main body section  904 . Thus, the needle hood  916  can be molded together with the main body section  904  as a unitary component. The needle hood  916  terminates at a lip  918 . In certain embodiments, the lip  918  extends further from the main body section  904  than the needle end  912 . In other words, the blunt tip  914  of the hollow needle  908  does not protrude from the lip  918  (see  FIG. 24 ). This arrangement is desirable to protect the hollow needle  908  from damage and contamination. This arrangement also protects the user if the hollow needle  908  is provided with a sharp tip. 
     The fluid reservoir  900  may also include an alignment structure that mates with cooperating structure of the reservoir port receptacle of the fluid infusion device (see  FIG. 25  and related description). Although not always required, at least a portion of the alignment structure may be integrally formed with the needle hood  916 . For example, the illustrated embodiment of the fluid reservoir  900  utilizes opposing guide rails  920  and a particular shape for the needle hood  916  (e.g., an inverted “U” shape when viewed from the perspective of  FIG. 23 ) that cooperate to provide the desired alignment features. The guide rails  920  and the shape of the needle hood  916  have corresponding mating features on the reservoir port receptacle shown in  FIG. 25 . 
       FIG. 25  is a perspective view of a section  922  of a fluid infusion device, including a reservoir port receptacle  924  suitable for engagement with the fluid reservoir  900 . The section  922  may represent a portion of a base plate of the fluid infusion device (see  FIGS. 3-6 , which show the base plate  104  with a similarly configured section for the fluid infusion device  100 ).  FIG. 26  is a perspective view of a sealing and conduit component  926  suitable for use in the section  922  shown in  FIG. 25 , and  FIG. 27  is a cross-sectional view of the section  922 , as viewed from the perspective of line  27 - 27  in  FIG. 25 . 
     The reservoir port receptacle  924  includes suitably designed mating structure  928  that is intended to engage and mate with the needle hood  916  and, more particularly, to engage with the alignment structure of the needle hood  916 . For this particular embodiment, the mating structure  928  is realized as two shoulders or channels that cooperate with the guide rails  920  when the fluid reservoir  900  is coupled to the reservoir port receptacle  924 . Moreover, the overall outer shape and contour of the reservoir port receptacle  924  can be shaped and sized to match the interior space defined by the needle hood  916 . These features cooperate to orient, align, and guide the needle hood  916  over the reservoir port receptacle  924 . Accordingly, the alignment structure of the fluid reservoir  900  cooperates with the mating structure  928  to align and orient the hollow needle  908  relative to the reservoir port receptacle  924 . This facilitates proper introduction and insertion of the hollow needle  908  into a sealing element  930  of the reservoir port receptacle  924 . 
     The sealing and conduit component  926  may be realized as an insert or a plug that is received within the section  922 , as shown in  FIG. 27 . The sealing element  930  may be coupled to or integrally formed with the sealing and conduit component  926 , as shown in  FIG. 26  and  FIG. 27 . The embodiment of the sealing element  930  shown in  FIG. 27  includes a self-sealing opening  932  to receive the hollow needle  908 . Notably, the self-sealing opening  932  is particularly suitable for use with the blunt tip  914 , which is not designed to pierce or puncture the sealing element  930 . Rather, the blunt tip  914  can pass through the self-sealing opening  932  when the fluid reservoir  900  is urged into the reservoir port receptacle  924  (as depicted in  FIG. 29 ). 
       FIG. 28  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  900  before engagement with the section  922  of the fluid infusion device, and  FIG. 29  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  900  after engagement with the section  922 . In  FIG. 28 , the needle end  912  has not yet contacted the sealing element  930 . Accordingly, the self-sealing opening  932  exhibits a sealed or compressed state to prevent fluid ingress into an outlet conduit  934  of the reservoir port receptacle  924 . In  FIG. 29 , however, engagement of the fluid reservoir  900  with the reservoir port receptacle  924  causes the blunt tip  914  to penetrate the self-sealing opening  932  such that the needle end  912  resides within the outlet conduit  934 . Accordingly, fluid communication is established from the fluid chamber  906  to the outlet conduit  934 , via the hollow needle  908 . In this state, the sealing element  930  forms a seal around the exterior surface of the hollow needle  908  to inhibit fluid leakage from the outlet conduit  934 . 
     As shown in  FIGS. 27-29 , the outlet conduit  934  may be at least partially defined by the sealing element  930 . For this particular embodiment, the outlet conduit  934  is integrally formed within the sealing and conduit component  926  to provide a fluid flow path from the self-sealing opening  932 , across a span of the section  922  (see  FIG. 27 ) and into a fluid chamber  936  defined in the base plate. The fluid chamber  936  may be fluidly coupled to a delivery conduit such as a cannula (see  FIG. 1 , which shows the cannula  112  for the fluid infusion device  100 ) for purposes of fluid delivery to the body of the patient. Thus, the sealing and conduit component  926  may be employed instead of a “J” shaped hollow needle as described above with reference to  FIG. 6 . 
     It should be appreciated that the needle hood  916  and/or the alignment structure of the fluid reservoir  900  may also be designed to mate and cooperate with corresponding structure of a reservoir filling apparatus. In this regard, the alignment structure could also serve to align and orient the hollow needle  908  relative to the reservoir filling apparatus to facilitate insertion of the hollow needle  908  into a sealing element or entry port of the reservoir filling apparatus. This dual-purpose nature of the needle hood  916  and alignment structure may be desirable for embodiments of the fluid reservoir  900  that use the same hollow needle  908  for both filling and delivery of the medication fluid. 
       FIGS. 30-33  relate to a second embodiment of a needled fluid reservoir  940  that is suitable for use with a compatible fluid infusion device. The fluid reservoir  940  and the related features of the fluid infusion device are similar in many respects to that described above for the fluid reservoir  900 . Accordingly, for the sake of brevity and clarity, the following description referring to  FIGS. 30-33  is abbreviated in nature. 
     The fluid reservoir  940  is very similar to the fluid reservoir  900 , except for its use of a hollow needle  942  terminating at a sharp tip  944  (rather than a blunt or rounded tip). Likewise, the sealing and conduit component  946  shown in  FIG. 31  is substantially identical to the sealing and conduit component  926  described above. Notably, however, the sealing and conduit component  946  includes a pierceable sealing element  948  (rather than a self-sealing element having a predefined slit, hole, or slot formed therein) that is suitably configured to accommodate the sharp tip  944 . Thus, the sharp tip  944  pierces the sealing element  948  when the fluid reservoir  940  is coupled to the reservoir port receptacle  950 . 
       FIG. 32  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  940  before engagement with the reservoir port receptacle  950 , and  FIG. 33  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  940  after engagement with the reservoir port receptacle  950 . In  FIG. 32 , the hollow needle  942  has not yet contacted the sealing element  948 , which remains solid and intact. In  FIG. 33 , however, engagement of the fluid reservoir  940  with the reservoir port receptacle  950  causes the sharp tip  944  to pierce the sealing element  948  such that the end of the hollow needle  942  resides within the outlet conduit  952 . Accordingly, fluid communication is established from the fluid chamber  954  of the fluid reservoir  940  to the outlet conduit  952 , via the hollow needle  942 . In the state depicted in  FIG. 33 , the sealing element  948  forms a seal around the exterior surface of the hollow needle  942  to inhibit fluid leakage from the outlet conduit  952 . 
       FIGS. 34-39  relate to a third embodiment of a needled fluid reservoir  960  that is suitable for use with a compatible fluid infusion device. The fluid reservoir  960  and the related features of the fluid infusion device are similar in many respects to that described above for the fluid reservoir  900 . Accordingly, for the sake of brevity and clarity, the following description referring to  FIGS. 34-39  is abbreviated in nature. 
     The fluid reservoir  960  is very similar to the fluid reservoir  900 , except for its use of an integrated hollow needle  962  rather than a physically distinct and separate needle component. In this regard, the hollow needle  962  is integrated and contiguous with the main body section  964  of the fluid reservoir  960 . In certain embodiments, the hollow needle  962  and the main body section  964  are molded together from the same material (e.g., a plastic material) to create a unitary single component. The integrated nature of the hollow needle  962  is depicted in  FIG. 35 , which shows how the base  966  of the hollow needle  962  blends with (and is continuous with) the main body section  964 . Although not always required, the illustrated embodiment of the hollow needle  962  terminates at a rounded, blunt tip  968 . Alternatively, a pointed, angled, or sharp tip could be utilized. 
       FIG. 36  depicts a section  970  of the fluid infusion device; the section  970  may represent a portion of the base plate (as described above). The section  970  houses a sealing and conduit component  972 , which has the general characteristics and functionality described above for the previous two embodiments. The sealing and conduit component  972  includes or cooperates with a sealing element  974 , which is accessible via a reservoir port receptacle  976 . Notably, the sealing element  974  has an unsealed (open) inlet end  978  that is sized, shaped, and otherwise configured to receive the hollow needle  962 . Moreover, the illustrated embodiment of the sealing element  974  has an outlet end  980  that is downstream from the inlet end  978 . The outlet end  980  includes, cooperates with, or defines a pressure valve  982  that actuates in response to a fluid delivery action of the fluid infusion device, to accommodate flow of the medication fluid from the hollow needle to an outlet conduit  984 . Consequently, even though the inlet end  978  of the sealing element  974  is open and exposed, the outlet conduit  984  is protected by the pressure valve  982  when the fluid reservoir  960  is removed from the reservoir port receptacle  976 . 
       FIG. 38  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  960  before engagement with the reservoir port receptacle  976 , and  FIG. 39  is a cross-sectional and partially phantom view that illustrates the fluid reservoir  960  after engagement with the reservoir port receptacle  976 . In  FIG. 38 , the hollow needle  962  has not yet entered the sealing element  974 . In  FIG. 39 , however, engagement of the fluid reservoir  960  with the reservoir port receptacle  976  urges the hollow needle  962  into the inlet end  978  of the sealing element  974  such that the end of the hollow needle  962  resides within a valve chamber  986  defined within the sealing element  974 . Accordingly, fluid communication is established from the fluid chamber  988  of the fluid reservoir  960  to the valve chamber  986 , via the hollow needle  962 . In the state depicted in  FIG. 39 , the sealing element  974  forms a seal around the exterior surface of the hollow needle  962  to inhibit fluid leakage from the valve chamber  986 . 
       FIG. 39  depicts the pressure valve  982  in a closed state, which is indicative of a lack of sufficient fluid pressure within the valve chamber  986 . In contrast, when the plunger (not shown) of the fluid reservoir  960  is activated for a fluid delivery pulse, cycle, or action, the pressure valve  982  actuates and opens to accommodate flow of the medication fluid from the hollow needle  962  and through the pressure valve  982 , by way of the valve chamber  986 . The medication fluid is also urged through the outlet conduit  984 , which may lead to a cannula that provides the medication fluid to the body of the patient. 
     Sealing Arrangement for a Needled Fluid Reservoir 
     As described previously (with reference to  FIGS. 1-3  and  FIGS. 34-39 ), a fluid infusion device may cooperate with a needled fluid reservoir that engages a sealing arrangement to provide a fluid delivery flow path from the fluid infusion device to the body of the patient.  FIGS. 40 and 41  depict (in cross-section) a portion of a fluid infusion device  1000  that incorporates another exemplary embodiment of a sealing assembly  1002  that cooperates with a fluid reservoir  1004  to form a sealed fluid flow path from the fluid reservoir  1004  to the patient. A number of features and aspects of the fluid infusion device  1000  and the sealing assembly  1002  are similar to that described above for the embodiments depicted in  FIGS. 1-3, 25-29, and 36-39 . For the sake of brevity and ease of description, shared or common features, structure, and functionality will not be redundantly described here with reference to the fluid infusion device  1000  and the sealing assembly  1002 . 
     The fluid infusion device  1000  generally includes a durable housing that engages and couples with a base plate, as described above with reference to  FIGS. 1-3 . In certain embodiments, the fluid reservoir  1004  is installed onto the durable housing such that the fluid reservoir  1004  couples with the sealing assembly  1002  when the durable housing is introduced to the base plate. In this regard,  FIG. 40  shows the fluid infusion device  1000  before the fluid reservoir  1004  mates with the sealing assembly  1002 , and  FIG. 41  shows the fluid infusion device  1000  after the fluid reservoir  1004  is engaged with the sealing assembly  1002 . 
     A portion of a base plate  1006  of the fluid infusion device  1000  is depicted in  FIGS. 40-42 . The illustrated embodiment of the fluid infusion device  1000  includes a reservoir port receptacle  1008  that is integrated with, coupled to, or implemented with the base plate  1006 . The reservoir port receptacle  1008  may be considered to be part of the sealing assembly  1002 . Accordingly, the sealing assembly  1002  as referred to here may include the base plate  1006  (or a portion thereof) and/or other structure or elements that cooperate with the reservoir port receptacle  1008 . The reservoir port receptacle  1008  is shaped, sized, and otherwise configured to accommodate and receive a reservoir port  1010  and a hollow fluid reservoir needle  1012  of the fluid reservoir  1004 . For this particular embodiment, the hollow fluid reservoir needle  1012  is located within the reservoir port  1010 , which may serve as a needle hood as described above for the fluid reservoir  900  (see  FIG. 23 ). In this regard, the reservoir port  1010  may extend further than a blunt tip  1014  of the hollow fluid reservoir needle  1012 . In other words, the blunt tip  1014  of the hollow fluid reservoir needle  1012  does not protrude from the end of the reservoir port  1010 . In alternative embodiments, a longer reservoir needle that extends beyond the end of the reservoir port  1010  could be utilized if so desired to suit the needs of the given application or system. 
     In certain embodiments, the fluid reservoir  1004  includes a diffuser (not shown) positioned within the fluid path of the fluid reservoir needle  1012 . The diffuser may be realized as a porous and fluid permeable membrane or material that impedes fluid flow to inhibit leakage of fluid out of the fluid reservoir  1004  due to excess pressure that may be present inside of the fluid reservoir  1004 . The diffuser is suitably designed to accommodate the desired flow rate as intended during controlled fluid delivery operations. 
     The reservoir port receptacle includes a proximal end  1016 , an opposing distal end  1018  extending from the proximal end  1016 , and a needle entry  1020  (i.e., an opening as shown in  FIG. 42 ) formed in the distal end  1018 . The needle entry  1020  is shaped and sized to accommodate and receive the hollow fluid reservoir needle  1012 , as shown in  FIG. 41 . Although not always required, the exterior surface of the reservoir port receptacle  1008  may be cylindrical. Moreover, although not always required, the needle entry  1020  in the illustrated embodiment is realized as a circular hole formed in the distal end  1018 . The reservoir port receptacle  1008  may also include or cooperate with a retaining structure, feature, or element to maintain a needle sealing element  1022  and a spacer  1023  between the distal end  1018  and the proximal end  1016  of the reservoir port receptacle  1008 . In certain embodiments, the retaining structure is realized as an inwardly protruding collar  1024 , which may be integrally formed in the distal end  1018  of the reservoir port receptacle  1008  (see  FIG. 42 ). The collar  1024  may be shaped, sized, and contoured as desired to maintain the needle sealing element  1022  and the spacer  1023  in position within the reservoir port receptacle  1008 . In practice, the needle entry  1020  is large enough to accommodate the insertion of the needle sealing element  1022  and the spacer  1023  into the reservoir port receptacle  1008 , and to facilitate positioning and seating of the needle sealing element  1022  and the spacer  1023  into the nominal position shown in  FIG. 40 . Alternatively, the needle sealing element  1022  and the spacer  1023  could be inserted from the rear of the base plate  1006  and secured in place by a flow base component  1030 . 
     The illustrated embodiment of the sealing assembly  1002  includes the flow base component  1030 , which may be a one-piece element or an assembly that includes two or more subcomponents.  FIG. 43  is a perspective view of one exemplary embodiment of the flow base component  1030 , which is realized as a composite component having a primary cap portion  1032  and a hollow needle  1034  (not shown in  FIG. 43 , but depicted in  FIG. 40  and  FIG. 41 ) coupled to the primary cap portion  1032 . In certain implementations, the hollow needle  1034  is sealed in a cavity formed within the primary cap portion  1032  (using a curable adhesive, an epoxy, or the like). The sealing material maintains the hollow needle  1034  in position and inhibits fluid leakage. The hollow needle  1034  represents one exemplary embodiment of an outlet conduit for the sealing assembly  1002 . In alternative embodiments, the outlet conduit may be integrally formed in the flow base component  1030 . 
     The flow base component  1030  is coupled to the reservoir port receptacle  1008  to provide a fluid flow path from the fluid reservoir  1004  to a delivery conduit of the fluid infusion device  1000 . More specifically, the hollow needle  1034  has a first end  1038  that is configured for selective fluid communication with the fluid reservoir needle  1012 , that is, when the fluid infusion device  1000  is in the state depicted in  FIG. 41 . In certain embodiments, the flow base component  1030  includes a fluid pathway  1039  formed therein (which is described in more detail below), and the first end  1038  of the hollow needle is in fluid communication with the fluid pathway  1039 , as shown in the cross-sectional views of  FIG. 40  and  FIG. 41 , and as shown in the partially cutaway views of  FIGS. 44 and 45 . More specifically, the first end  1038  extends into the fluid pathway  1039  to receive fluid dispensed from the fluid reservoir needle  1012 . 
     As shown in  FIG. 40  and  FIG. 41 , the hollow needle  1034  for this particular embodiment is “C” or “J” shaped to provide a fluid flow path from the first end  1038  of the hollow needle  1034 , across the length of the flow base component  1030 , and to a second end  1040  of the hollow needle  1034 . The second end  1040  leads to a fluid chamber  1044  defined in the base plate  1006 . The fluid chamber  1044  is fluidly coupled to a delivery conduit of the fluid infusion device, e.g., the cannula  112  ( FIG. 1 ), such that when a plunger of the fluid reservoir  1004  is actuated, the fluid is expelled from the fluid reservoir  1004 , through the fluid pathway  1039 , into the first end  1038  of the hollow needle, through the hollow needle  1034 , into the fluid chamber  1044 , and into the body of the patient via the cannula  112 . 
     Referring to  FIG. 42  and  FIG. 43 , the base plate  1006  is shaped and sized to mate with the flow base component  1030 . For example, the illustrated embodiment of the flow base component  1030  includes an inlet structure  1046  positioned near the first end  1038  of the hollow needle  1034 , and an outlet structure  1048  positioned near the second end  1040  of the hollow needle  1034 . The inlet structure  1046  and the outlet structure  1048  both extend and protrude from the primary body section  1050  of the flow base component  1030 . These extending features of the flow base component  1030  fit into corresponding features of the base plate  1006 , as shown in  FIG. 40  and  FIG. 41 . In particular, the inlet structure  1046  fits into a section of the reservoir port receptacle  1008 . When assembled as depicted in  FIG. 40  and  FIG. 41 , the inlet structure  1046  may be coupled to an interior surface  1052  of the reservoir port receptacle  1008  (see  FIG. 42 ). 
     The base plate  1006  may include a suitably shaped and sized fluid chamber  1056  defined therein. In operation, fluid expelled from the fluid reservoir  1004  enters the fluid chamber  1056  and passes into the first end  1038  of the hollow needle  1034 , which is in fluid communication with the fluid chamber  1056  (via the fluid pathway  1039 ). For the illustrated embodiment, the fluid chamber  1056  is located at least partially in the reservoir port receptacle  1008 . More specifically, the fluid chamber  1056  is at least partially defined in the flow base component  1030 . For example, the fluid chamber  1056  may be generally defined as an interior area within the inlet structure  1046 , which terminates at an abutment surface  1058  of the flow base component  1030  (see  FIG. 43 ). Referring to  FIG. 40  and  FIG. 41 , the needle sealing element  1022  is positioned between the distal end  1018  of the reservoir port receptacle  1008  and the fluid chamber  1056 . More specifically, the needle sealing element  1022  is held in place between the collar  1024  ( FIG. 42 ) and the abutment surface  1058  ( FIG. 43 ). As shown in  FIG. 40  and  FIG. 41 , the base section of the needle sealing element  1022  contacts the abutment surface  1058 , and the opposing end section of the needle sealing element  1022  contacts the collar  1024 . 
     As mentioned above, a portion of the flow base component  1030  terminates at the abutment surface  1058 . This portion extends from the flow base component  1030  to form the inlet structure  1046  (see  FIG. 43 ). For this particular embodiment, the fluid chamber  1056  is defined by the inlet structure  1046  and by a needle guide pin  1064  that protrudes from the proximal end  1016  of the reservoir port receptacle  1008 . Referring to  FIGS. 43-45 , the needle guide pin  1064  may be integrated with the flow base component  1030 , i.e., the needle guide pin  1064  may be fabricated as a feature or element of the flow base component  1030 . In this regard,  FIG. 43  and  FIG. 44  depict how the needle guide pin  1064  extends and protrudes from the flow base component  1030 . 
     The needle guide pin  1064  includes a support area  1066  and an opposing end section  1068 . The support area  1066  is attached to (or, in this embodiment, is integrated with) the primary body section  1050  of the flow base component  1030 , and the end section  1068  extends from the support area  1066 . The end section  1068  of the needle guide pin  1064  is suitably shaped, sized, and otherwise configured to fit within the hollow fluid reservoir needle  1012  (see  FIG. 41 ). In certain embodiments where the end section  1068  of the needle guide pin  1064  and the interior of the fluid reservoir needle  1012  are cylindrical in shape, the outer diameter of the end section  1068  is less than the inner diameter of the fluid reservoir needle  1012 . In practice, the needle guide pin  1064  and the fluid reservoir needle  1012  are sized such that fluid can effectively flow past the needle guide pin  1064  during fluid delivery operations. In other words, an amount of clearance is provided such that a fluid flow gap is maintained between the outer surface of the needle guide pin  1064  and the interior of the fluid reservoir needle  1012  when the fluid infusion device is in the state shown in  FIG. 41 . 
     As described previously, certain embodiments of the flow base component  1030  utilize a fluid pathway  1039  to direct fluid from the fluid chamber  1056  to the first end  1038  of the hollow needle  1034 . In accordance with the illustrated embodiment, the fluid pathway  1039  is formed in the flow base component  1030  such that the fluid chamber  1056  is in fluid communication with the fluid pathway  1039 . Moreover, at least a portion of the fluid pathway  1039  may be formed in the needle guide pin  1064 . More specifically, a portion of the fluid pathway  1039  is formed in the support area  1066  of the needle guide pin  1064 , as shown in  FIGS. 43-45 . In practice, the fluid pathway  1039  may be realized as one or more slots, slits, or holes that are accessible from inside the fluid chamber  1056 . 
     As shown in  FIGS. 40 and 41 , the needle sealing element  1022  is located between the distal end  1018  of the reservoir port receptacle  1008  and the abutment surface  1058 . Thus, the needle sealing element  1022  can be held in place by the abutment surface  1058  in cooperation with the collar  1024 . Alternatively, any suitably configured abutment structure could be implemented to maintain the needle sealing element  1022  in place. For example, the interior of the reservoir port receptacle  1008  could be fabricated with protruding features or a shoulder that functions as an abutment structure. Notably, the abutment surface  1058  provides support around the perimeter of the needle sealing element  1022  to allow entry of the fluid reservoir needle  1012  into the fluid chamber  1056 , as needed. In other words, the abutment surface  1058  does not interfere with the desired travel of the fluid reservoir needle  1012  (see  FIG. 41 ). 
     One suitable embodiment of the needle sealing element  1022  is depicted in  FIGS. 46-48 . ( FIG. 48  also shows the spacer  1023  installed on the needle sealing element  1022 ). The needle sealing element  1022  may be integrally formed as a one-piece component from a resiliently deformable material, such as rubber, urethane, or the like. In certain embodiments, the needle sealing element  1022  is formed from a pliable silicone material. The illustrated embodiment of the needle sealing element  1022  includes, without limitation: a base section  1070 ; a neck section  1072 ; an end section  1074 ; and a needle opening  1078 . When assembled as shown in  FIG. 40  and  FIG. 41 , the base section  1070  is adjacent to the fluid chamber  1056 . In certain embodiments, the base section  1070  contacts and cooperates with the abutment surface  1058  to form a seal against the inlet structure  1046 . The end section  1074  is opposite the base section  1070 , and the neck section  1072  is located between the base section  1070  and the end section  1074 . 
     The needle opening  1078  is formed in the needle sealing element  1022  such that it extends through the neck section  1072 . Depending upon the particular configuration of the needle sealing element  1022 , the needle opening  1078  may also extend through some or all of the base section  1070  and/or through some or all of the neck section  1072 . When the needle sealing element  1022  is in the state shown in  FIG. 40 , the end section  1068  of the needle guide pin  1064  resides within the needle opening  1078 . In contrast, when the needle sealing element  1022  is in the state shown in  FIG. 41 , the needle opening  1078  expands to accommodate the fluid reservoir needle  1012 . Thus, when the needle sealing element  1022  is in its natural and uncompressed state (shown in  FIG. 46 ), the needle opening  1078  has a nominal diameter or size that is smaller than the outer diameter or dimension of the needle guide pin  1064 . 
     The needle sealing element  1022  may include a proximal flange  1082  formed at the base section  1070 , and a distal flange  1084  formed at the end section  1074 . The proximal flange  1082  has an outer sealing surface  1086  that cooperates with the interior surface  1052  ( FIG. 42 ) of the reservoir port receptacle  1008 . Similarly, the distal flange  1084  has an outer sealing surface  1088  that cooperates with the interior surface  1052  of the reservoir port receptacle  1008 .  FIG. 40  and  FIG. 41  depict the manner in which these outer sealing surfaces  1086 ,  1088  contact the interior surface  1052 . As described in more detail below, the needle sealing element  1022  cooperates with the hollow fluid reservoir needle  1012  and/or with the needle guide pin  1064  as needed to maintain fluid seals for the fluid infusion device  1000 . 
     Referring now to  FIG. 48 , and with continued reference to  FIG. 40  and  FIG. 41 , the fluid infusion device  1000  may also include a suitably shaped, sized, and configured spacer  1023 . The spacer  1023  may be coupled around the neck section  1072  of the needle sealing element  1022  such that the spacer  1023  “floats” within the reservoir port receptacle  1008 . As shown in  FIG. 48 , the spacer  1023  is located and maintained in position between the proximal flange  1082  and the distal flange  1084  (i.e., between the base section  1070  and the end section  1074  of the needle sealing element  1022 ). The spacer  1023  may be formed from a stiff and rigid material such as a metal, a hard plastic, nylon, or the like. In certain embodiments, the spacer  1023  can be realized as a split ring to facilitate installation over the needle sealing element  1022 . 
     The spacer  1023  functions as a support member for the needle sealing element  1022 . More specifically, the spacer  1023  inhibits flexing, deformation, and compression of the flanges  1082 ,  1084  toward one another during insertion and removal of the fluid reservoir needle  1012 . In other words, the spacer  1023  keeps the flanges  1082 ,  1084  in a spaced-apart relationship relative to one another, which in turn enables the flanges  1082 ,  1084  to maintain contact with the interior surface  1052  of the reservoir port receptacle. 
     It should be appreciated that the combination of the needle sealing element  1022 , the needle guide pin  1064 , and the spacer  1023  represents one suitable embodiment of a sealing component for the base plate  1006 . Moreover, certain features or elements of the base plate  1006  and/or certain features or elements of the flow base component  1030  may also form a portion of the sealing component. In practice, the sealing component is positioned in the reservoir port receptacle  1008  to cooperate with the fluid chamber  1056  during different operating states of the fluid infusion device  1000 . Of course, the sealing component could be realized and implemented in an alternative manner than that described here. 
     Operation of the sealing component will now be described with reference to  FIGS. 40 and 41 .  FIG. 40  depicts the fluid infusion device  1000  in a disengaged state, where the reservoir port  1010  is not yet fully engaged with or mated to the reservoir port receptacle  1008 . In contrast,  FIG. 41  depicts the fluid infusion device  1000  in an engaged state, where the reservoir port  1010  is engaged with and mated to the reservoir port receptacle  1008 . When the fluid infusion device  1000  is in the disengaged state, the fluid reservoir needle  1012  is decoupled from the needle sealing element  1022  and is decoupled from the needle guide pin  1064 . Consequently, the needle sealing element  1022  assumes the position shown in  FIG. 40 : the needle sealing element  1022  is positioned within the reservoir port receptacle such that the neck section  1072  surrounds the end section  1068  of the needle guide pin  1064 . 
     When the fluid infusion device  1000  is in the disengaged state shown in  FIG. 40 , the fluid reservoir needle  1012  is decoupled from the sealing component, and a portion of the end section  1068  of the needle guide pin  1064  resides within the needle opening  1078 . Accordingly, the needle opening  1078  is blocked by the needle guide pin  1064  in response to retraction and removal of the fluid reservoir needle  1012  from the needle sealing element  1022 , and the needle sealing element  1022  forms a seal around the exterior surface of the needle guide pin  1064 . In practice, the neck section  1072  squeezes and pinches around the end section  1068  of the needle guide pin  1064  with sufficient force to maintain a fluid tight seal between the needle sealing element  1022  and the needle guide pin  1064 . This seal inhibits leakage of fluid from the fluid chamber  1056 , and inhibits ingress of contaminants into the fluid chamber  1056 . Thus, any fluid contained in the fluid chamber  1056  remains trapped and does not leak beyond the needle sealing element  1022 . Moreover, when the fluid infusion device  1000  is in the disengaged state, the outer sealing surfaces  1086 ,  1088  (see  FIG. 46  and  FIG. 48 ) contact the interior surface  1052  ( FIG. 42 ) of the reservoir port receptacle  1008  to inhibit leakage of fluid and ingress of contaminants around the outer perimeter of the needle sealing element  1022 . 
     Coupling of the reservoir port  1010  to the reservoir port receptacle  1008  causes the hollow fluid reservoir needle  1012  to be urged toward the needle sealing element  1022 . Eventually, the blunt tip  1014  of the fluid reservoir needle  1012  is guided toward the end section  1068  of the needle guide pin  1064 . The reservoir port receptacle  1008  and the needle guide pin  1064  are cooperatively configured for compatibility with the reservoir port  1010  such that the fluid reservoir needle  1012  is automatically aligned with the needle guide pin  1064  when the reservoir port  1010  is introduced to the reservoir port receptacle  1008 . Accordingly, continued engagement of the reservoir port  1010  with the reservoir port receptacle  1008  causes the needle guide pin  1064  to enter the interior of the fluid reservoir needle  1012 , as depicted in  FIG. 41 . In this regard, the wall of the hollow fluid reservoir needle  1012  forces the neck section  1072  of the needle sealing element  1022  outward such that the needle sealing element  1022  can accommodate full insertion of the fluid reservoir needle  1012 . 
     When the fluid infusion device  1000  is in the engaged state shown in  FIG. 41 , the end section  1068  of the needle guide pin  1064  resides within the fluid reservoir needle  1012 , and a portion of the fluid reservoir needle  1012  resides within the needle opening  1078 . More specifically, a portion of the fluid reservoir needle  1012  is located within the neck section  1072  of the needle sealing element  1022 . In addition, the needle sealing element  1022  forms a seal around the exterior surface of the fluid reservoir needle  1012 . As shown in  FIG. 41 , the blunt tip  1014  of the fluid reservoir needle  1012  moves past the neck section  1072  and into the fluid chamber  1056 , which establishes fluid communication from the fluid reservoir  1004  to the fluid chamber  1056 . In response to entry of the fluid reservoir needle  1012 , the needle opening  1078  expands and the needle sealing element  1022  is deformed and outwardly compressed within the reservoir port receptacle  1008 . 
     Notably, the needle sealing element  1022  inhibits leakage of fluid from the fluid chamber  1056  during operation of the fluid infusion device  1000 , e.g., during fluid delivery operations. In addition, the flanges  1082 ,  1084  of the needle sealing element  1022  are further compressed to enhance the fluid seal between the needle sealing element  1022  and the interior surface  1052  of the reservoir port receptacle. Consequently, fluid expelled from the fluid reservoir needle  1012  during a fluid delivery operation is forced into the fluid chamber  1056 , through the fluid pathway  1039 , and through the hollow needle  1034 , and little to no fluid leaks past the exterior surface of the fluid reservoir needle  1012 . 
     To summarize, when the fluid reservoir  1004  urged into a mated position with the reservoir port receptacle  1008 , the fluid reservoir needle  1012  receives and slides over the needle guide pin  1064 , and the wall of the fluid reservoir needle  1012  fits between the needle guide pin  1064  and the neck section  1072  of the needle sealing element  1022 . The needle sealing element  1022  responds by creating a seal with the exterior surface of the fluid reservoir needle  1012 . Once properly seated, the end of the fluid reservoir needle  1012  extends into (or near) the fluid chamber  1056  to facilitate delivery of medication fluid to the body of the user. Thereafter, when the fluid reservoir  1004  is decoupled from the reservoir port receptacle  1008 , the fluid reservoir needle  1012  withdraws from the needle sealing element  1022 , and the neck section  1072  closes around the outer surface of the needle guide pin  1064  to inhibit fluid egress from the fluid chamber  1056 , and to inhibit the entry of contaminants into the fluid chamber  1056 . 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.