Patent Publication Number: US-10322231-B2

Title: Drive mechanism for drug delivery pumps with integrated status indication

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/163,690, filed on Jan. 24, 2014, which is a continuation-in-part of U.S. application Ser. No. 13/600,114, filed on Aug. 30, 2012, now U.S. Pat. No. 8,939,935, which claims the benefit of U.S. Provisional Application No. 61/530,788, filed on Sep. 2, 2011. U.S. application Ser. No. 14/163,690 claims the benefit of U.S. Provisional Application No. 61/756,667, filed on Jan. 25, 2013, and U.S. Provisional Application No. 61/912,642, filed on Dec. 6, 2013. Each of these applications is included by reference herein in its entirety for all purposes. 
    
    
     FIELD 
     THIS INVENTION relates to drug delivery pumps. More particularly, this invention relates to drive mechanisms with integrated status indication, drug delivery pumps with status integrated drive mechanisms, the methods of operating such devices, and the methods of assembling such devices. 
     BACKGROUND 
     Parenteral delivery of various drugs, i.e., delivery by means other than through the digestive track, has become a desired method of drug delivery for a number of reasons. This form of drug delivery by injection may enhance the effect of the substance being delivered and ensure that the unaltered medicine reaches its intended site at a significant concentration. Similarly, undesired side effects associated with other routes of delivery, such as systemic toxicity, can potentially be avoided through parenteral delivery. By bypassing the digestive system of a mammalian patient, one can avoid degradation of the active ingredients caused by the catalytic enzymes in the digestive tract and liver and ensure that a necessary amount of drug, at a desired concentration, reaches the targeted site. 
     Traditionally, manually operated syringes and injection pens have been employed for delivering parenteral drugs to a patient. More recently, parenteral delivery of liquid medicines into the body has been accomplished by administering bolus injections using a needle and reservoir, continuously by gravity driven dispensers, or via transdermal patch technologies. Bolus injections often imperfectly match the clinical needs of the patient, and usually require larger individual doses than are desired at the specific time they are given. Continuous delivery of medicine through gravity-feed systems compromises the patient&#39;s mobility and lifestyle, and limits the therapy to simplistic flow rates and profiles. Another form of drug delivery, transdermal patches, similarly has its restrictions. Transdermal patches often require specific molecular drug structures for efficacy, and the control of the drug administration through a transdermal patch is severely limited. 
     Ambulatory infusion pumps have been developed for delivering liquid medicaments to a patient. These infusion devices have the ability to offer sophisticated fluid delivery profiles accomplishing bolus requirements, continuous infusion and variable flow rate delivery. These infusion capabilities usually result in better efficacy of the drug and therapy and less toxicity to the patient&#39;s system. Currently available ambulatory infusion devices are expensive, difficult to program and prepare for infusion, and tend to be bulky, heavy and very fragile. Filling these devices can be difficult and require the patient to carry both the intended medication as well as filling accessories. The devices often require specialized care, maintenance, and cleaning to assure proper functionality and safety for their intended long-term use, and are not cost-effective for patients or healthcare providers. 
     As compared to syringes and injection pens, pump type delivery devices can be significantly more convenient to a patient, in that doses of the drug may be calculated and delivered automatically to a patient at any time during the day or night. Furthermore, when used in conjunction with metabolic sensors or monitors, pumps may be automatically controlled to provide appropriate doses of a fluidic medium at appropriate times of need, based on sensed or monitored metabolic levels. As a result, pump type delivery devices have become an important aspect of modern medical treatments of various types of medical conditions, such as diabetes, and the like. 
     While pump type delivery systems have been utilized to solve a number of patient needs, manually operated syringes and injection pens often remain a preferred choice for drug delivery as they now provide integrated safety features and can easily be read to identify the status of drug delivery and the end of dose dispensing. However, manually operated syringes and injections pens are not universally applicable and are not preferred for delivery of all drugs. There remains a need for an adjustable (and/or programmable) infusion system that is precise and reliable and can offer clinicians and patients a small, low cost, light weight, simple to use alternative for parenteral delivery of liquid medicines. 
     SUMMARY 
     The present invention provides drive mechanisms with integrated status indication, drug delivery pumps which incorporate such drive mechanisms, the methods of operating such devices, and the methods of assembling such devices. The drive mechanisms of the present invention provide integrated status indication features which provide feedback to the user before, during, and after drug delivery. For example, the user may be provided an initial feedback to identify that the system is operational and ready for drug delivery. Upon activation, the system may then provide one or more drug delivery status indications to the user. At completion of drug delivery, the drive mechanism and drug pump may provide an end-of-dose indication. As the end-of-dose indication is tied to the piston reaching the end of its axial translation, the drive mechanism and drug pump provide a true end-of-dose indication to the user. Additionally, the embodiments of the present invention provide end-of-dose compliance to ensure that substantially the entire drug dose has been delivered to the user and that the status indication features have been properly contacted to provide accurate feedback to the user. Through these mechanisms, confirmation of drug dose delivery can accurately be provided to the user or administrator. Accordingly, the novel devices of the present invention alleviate one or more of the problems associated with prior art devices, such as those referred to above. 
     In a first embodiment, the present invention provides a drive mechanism having integrated status indication which includes: a drive housing, a status switch interconnect, a drive biasing member, a piston, and a drug container having a cap, a pierceable seal, a barrel, and a plunger seal. The drive biasing member may be configured to bear upon an interface surface of the piston. The drug container may preferably contain a drug fluid for delivery to the user. The drive mechanism may further include a connection mount attached to the pierceable seal. A cover sleeve may be utilized between the drive biasing member and the interface surface of the piston to, for example, provide more even distribution of force from the biasing member to the piston. A contact sleeve may be slidably mounted to the drive housing through an axial aperture of the drive housing, such that sleeve hooks at a distal end of the contact sleeve are caused to contact the piston between interface surface and a contact protrusion near the proximal end of the piston. The piston may also include a locking groove, between contact protrusion and the proximal end of the piston. The contact sleeve may have a radially extending ring at its proximal end, upon which reside one or more flex prongs. 
     The drive mechanism may further include one or more contact surfaces located on corresponding components. Such contact surfaces may be electrical contact surfaces, mechanical contact surfaces, or electro-mechanical contact surfaces. Such surfaces may initially be in contact and caused to disengage, or initially be disconnected and caused to engage, to permit a signal to be sent to and/or from the power control system. In at least one embodiment, as described further herein, the contact surfaces may be electrical contact surfaces which are initially disconnected and caused to come into engagement whereby, upon such engagement, contact surfaces are capable of continuing an energy pathway or otherwise relaying a signal to the power and control system. In another embodiment of the present invention, the contact surfaces are mechanical contact surfaces which are initially in contact and caused to disengage whereby, upon such disengagement, such disengagement is communicated to the power and control system. Such signals may be transferred across one or more interconnects to the power and control system or by mechanical action to the power and control system. Such components may be utilized within the drive mechanism to measure and relay information related to the status of operation of the drive mechanism, which may be converted by the power and control system into tactile, auditory, and/or visual feedback to the user. Regardless of the electrical or mechanical nature of the contact surfaces, the motion of the components which permits transmission of a signal to the power control system is enabled by a biasing member axially translating a contact sleeve in the distal direction during operation of the device. 
     The drive mechanism may include a piston extension slidably mounted at a distal end and within an axial pass-through of piston; a piston extension biasing member, which is mounted within the axial pass-through of piston and initially compressed between piston extension and piston; and, optionally, a piston biasing member support between piston extension biasing member and piston extension. The piston extension is retained within piston by interaction between one or more extension arms of the piston extension and one or more corresponding connection slots of piston. The piston extension may be utilized to perform a compliance push of drug fluid from the drug container. Additionally or alternatively, the drive mechanism may utilize a compressible plunger seal, wherein such compression capacity or distance permits a compliance push of drug fluid from the drug container. Other compliance features are described further herein. 
     In another embodiment of the present invention, a drive mechanism having integrated incremental status indication includes a drive housing, a drive biasing member, a piston, an incremental status stem having a stem interconnect mounted, affixed, printed, or otherwise attached thereon, and a drug container having a cap, a pierceable seal, a barrel, and a plunger seal, wherein the incremental status stem resides within axial pass-throughs of the drive housing and the piston. The incremental status stem may have one or more interconnects which contact one or more contacts on the piston to provide incremental status feedback to the user. The incremental status embodiment may similarly utilize the electrical, mechanical, or electro-mechanical interconnects and contacts, and/or one or more of the compliance features, described above. 
     In a further embodiment, the present invention provides a drug delivery pump with integrated status indication. The drug pump includes a housing and an assembly platform, upon which an activation mechanism, an insertion mechanism, a fluid pathway connection, a power and control system, and a drive mechanism having a drug container may be mounted. The drive biasing member may be configured to bear upon an interface surface of the piston. The drug container may preferably contain a drug fluid for delivery to the user. The drive mechanism may further include a connection mount attached to the pierceable seal. A cover sleeve may be utilized between the drive biasing member and the interface surface of the piston to, for example, provide more even distribution of force from the biasing member to the piston. A contact sleeve may be slidably mounted to the drive housing through an axial aperture of the drive housing, such that sleeve hooks at a distal end of the contact sleeve are caused to contact the piston between interface surface and a contact protrusion near the proximal end of the piston. The piston may also include a locking groove, between contact protrusion and the proximal end of the piston. The contact sleeve may have a radially extending ring at its proximal end, upon which reside one or more flex prongs. The drive mechanism may further include one or more contact surfaces located on corresponding components. Such contact surfaces may be electrical contact surfaces, mechanical contact surfaces, or electro-mechanical contact surfaces. Such surfaces may initially be in contact and caused to disengage, or initially be disconnected and caused to engage, to permit a signal to be sent to and/or from the power control system. In at least one embodiment, as described further herein, the contact surfaces may be electrical contact surfaces which are initially disconnected and caused to come into engagement whereby, upon such engagement, contact surfaces are capable of continuing an energy pathway or otherwise relaying a signal to the power and control system. In another embodiment of the present invention, the contact surfaces are mechanical contact surfaces which are initially in contact and caused to disengage whereby, upon such disengagement, such disengagement is communicated to the power and control system. Regardless of the electrical or mechanical nature of the contact surfaces, the motion of the components which permits transmission of a signal to the power control system is enabled by a biasing member axially translating a contact sleeve in the distal direction during operation of the device. 
     In yet another embodiment, the present invention provides a drug delivery pump with incremental status indication. The drug pump includes a housing and an assembly platform, upon which an activation mechanism, an insertion mechanism, a fluid pathway connection, a power and control system, and a drive mechanism having a drug container may be mounted, and further includes an incremental status stem having a stem interconnect mounted, affixed, printed, or otherwise attached thereon, wherein the incremental status stem resides within axial pass-throughs of the drive housing and the piston, and wherein the incremental status stem has one or more interconnects which contact one or more contacts on the piston to complete an transmission to the power and control system to provide incremental feedback to the user. The drug delivery pump with incremental status indication may similarly utilize the electrical, mechanical, or electro-mechanical interconnects and contacts, and/or one or more of the compliance features, described above. 
     The present invention further provides a method of assembly. The drug container may first be assembled and filled with a drug fluid. The drug container includes a cap, a pierceable seal, a barrel, and a plunger seal. The pierceable may be fixedly engaged between the cap and the barrel, at a distal end of the barrel. The barrel may be filled with a drug fluid through the open proximal end prior to insertion of the plunger seal from the proximal end of the barrel  58 . An optional connection mount may be mounted to a distal end of the pierceable seal. The connection mount to guide the insertion of the piercing member of the fluid pathway connection into the barrel of the drug container. The drug container may then be mounted to a distal end of drive housing. 
     Prior to mounting the drug container to the housing, a switch status interconnect may be mounted to a proximal end of drive housing. A contact sleeve, having one or more sleeve hooks at a distal end and a ring at a proximal end having an electrical contact thereon, may be mounted to the drive housing through an axial pass-through from the proximal end of the drive housing. A drive biasing member may be inserted into a distal end of the drive housing. Optionally, a cover sleeve may be inserted into a distal end of the drive housing to substantially cover biasing member. A piston may be inserted into the distal end of the drive housing and through an axial pass-through of contact sleeve, such that a contact protrusion of piston is proximal to the sleeve hooks of contact sleeve. The piston and drive biasing member, and optional cover sleeve, may be compressed into the drive housing. Such assembly positions the drive biasing member in an initial compressed, energized state and preferably places a piston interface surface in contact with the proximal surface of the plunger seal within the proximal end of barrel. When a piston extension is employed, the piston extension and piston extension biasing member, and optional piston biasing member support, may be compressed into an axial pass-through of piston prior to compression of the components. Prior to, or after, installing these components into the drive mechanism housing, the primary container may be attached. 
     When one or more interconnects or contacts are utilized for status indication, such components may be mounted, connected, printed, or otherwise attached to their corresponding components prior to assembly of such components into the drive mechanism. When a separate incremental status stem and a corresponding stem interconnect are utilized for such incremental status indication, the stem interconnect may be mounted, affixed, printed, or otherwise attached to incremental status stem prior to assembly of the incremental status stem to the proximal end of the contact sleeve and/or the proximal end of the drive housing in a manner such that the incremental status stem resides within an axial pass-through of contact sleeve and drive housing. The incremental status stem is further mounted to reside within an axial pass-through of piston. 
     The disclosure describes, in one aspect, a drug pump drive mechanism for use in cooperation with a drug container including a plunger seal. The drive mechanism has an axis and includes a drive housing, a piston adapted to impart movement to the plunger seal within the drug container, a plurality of biasing members disposed in parallel, and a retainer. The piston is disposed for movement from a retracted first position along the axis to an extended second position. The biasing members are adapted to move from an energized first position to a deenergized second position as a result of the release of energy. The biasing members are disposed to cause movement of the piston from the retracted first position to the extended second position as the biasing members move from the energized first position to the deenergized second position. The retainer is disposed to maintain the biasing members in the energized first position when the retainer is in a retaining first position, and to release the biasing members from the first energized position when the retainer moves to a releasing second position. 
     In at least one embodiment, the plurality of biasing members includes at least one of a tension spring or a compression spring. In at least one embodiment, the plurality of biasing members includes a pair of springs, in at least one embodiment of which the springs are compression springs. In at least embodiment, the compression springs are concentrically disposed, and disposed about at least a portion of the piston. In at least one embodiment, the retainer engages at least a portion of the piston to retain the piston in its retracted position when the retainer is in its retaining first position. At least one embodiment further includes a sleeve assembly disposed about at least one of the plurality of biasing members. In at least one embodiment, the sleeve assembly includes a plurality of telescoping sleeves, and the sleeve assembly is disposed to move to axially with the piston. At least one embodiment further includes at least one window and at least a portion of the sleeve assembly is visible through the window with at least a portion of the sleeve assembly being visible through said window until the piston is in the extended second position. At least one embodiment further includes an end-of-dose indicator disposed substantially adjacent the window, the end-of-dose indicator being adapted to identify at least one of when the sleeve assembly is disposed subjacent the window and when the sleeve assembly is not disposed subjacent the window, the relative motion of the sleeve assembly with reference to the window or another reference component, the stoppage of such motion, and the rate or change of rate of motion. In at least one embodiment, the end-of-dose indicator includes a sensor disposed to sense at least one of when the sleeve assembly is disposed subjacent the window and when the sleeve assembly is not disposed subjacent the window. In at least one embodiment, the sensor is a mechanical sensor, an electrical sensor, an ultrasonic sensor, a capacitive sensor, a magnetic sensor, or an optical sensor. In at least one embodiment, the sensor is a mechanical sensor disposed to bear against the sleeve assembly when the sleeve assembly is disposed subjacent the window. 
     In another aspect of the disclosure, there is provided a drug pump drive mechanism for use in cooperation with a drug container including a plunger seal; the drive mechanism has an axis and includes a drive housing, a piston adapted to impart movement to the plunger seal within the drug container, at least one biasing member, a retainer, a sleeve assembly, and an end-of-dose indicator. The piston is disposed for movement from at least a retracted first position to an extended second position along said axis. The at least one biasing member is disposed and adapted to move from an energized first position to a deenergized second position as a result of the release of energy. The biasing member is disposed to cause movement of the piston from the retracted first position to the extended second position as the biasing member moves from the energized first position to the deenergized second position. The retainer disposed to maintain the biasing member in the energized first position when the retainer is in a retaining first position, and to release the biasing member from the first energized position when the retainer moves to a releasing second position. The sleeve assembly is adapted to move along the axis with the piston. The sleeve assembly is disposed at least partially within the drive housing, and at least a portion of the sleeve assembly being visible through a window in the housing when the piston is one of the retracted first position or the extended second position. The sleeve assembly is not visible through said window when the piston is in the other of the retracted first position or the extended second position. The end-of-dose indicator is disposed substantially adjacent the window. The end-of-dose indicator is adapted to identify at least one of when the sleeve assembly is disposed subjacent the window and when the sleeve assembly is not disposed subjacent the window. 
     In at least one embodiment, the sleeve assembly is disposed about the at least one biasing member and includes a plurality of telescoping sleeves. In an embodiment, the sleeve assembly is disposed about the biasing member(s). In at least one embodiment, the at least one biasing member includes a plurality of biasing members. A particular embodiment includes at least two compression springs disposed in parallel. In at least on embodiment, the end-of-dose indicator includes a sensor disposed to sense at least one of when the sleeve assembly is disposed subjacent the window and when the sleeve assembly is not disposed subjacent the window. In at least one embodiment, the sensor is at least one of a mechanical sensor, a mechanical sensor, an electrical sensor, an ultrasonic sensor, a capacitive sensor, a magnetic sensor, or an optical sensor. In a particular embodiment, the sensor is a mechanical sensor disposed to bear against the sleeve assembly when the sleeve assembly is disposed subjacent the window. In some embodiments, at least a portion of a distal end of the piston is adapted to be disposed within the drug container when the piston is disposed in the retracted first position and the drug pump drive mechanism is disposed for use in cooperation with the drug container. 
     At least some embodiments of the present invention provide the necessary drive force to push a plunger seal and a drug fluid within a drug container, while reducing or minimizing the drive mechanism and overall device footprint. Accordingly, the present invention may provide a drive mechanism which may be utilized within a more compact drug delivery pump device. Some embodiments of the present invention may similarly be utilized to provide additional force, as may be needed for highly viscous drug fluids or for larger volume drug containers. 
     The novel embodiments of the present invention provide drive mechanisms with integrated status indication, which are capable of provide incremental status of the drug delivery before, during, and after operation of the device, and provides means for ensuring drug dose compliance, i.e., ensuring substantially the entire drug dose has been delivered to the user. Throughout this specification, unless otherwise indicated, “comprise,” “comprises,” and “comprising,” or related terms such as “includes” or “consists of,” are used inclusively rather than exclusively, so that a stated integer or group of integers may include one or more other non-stated integers or groups of integers. As will be described further below, the embodiments of the present invention may include one or more additional components which may be considered standard components in the industry of medical devices. The components, and the embodiments containing such components, are within the contemplation of the present invention and are to be understood as falling within the breadth and scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following non-limiting embodiments of the invention are described herein with reference to the following drawings, wherein: 
         FIG. 1A  shows an isometric view of a drug delivery pump having safety integrated insertion mechanisms, according to one embodiment of the present invention; 
         FIG. 1B  shows an isometric view of the interior components of the drug delivery pump shown in  FIG. 1A ; 
         FIG. 1C  shows an isometric view of the bottom of the drug delivery pump shown in  FIG. 1A ; 
         FIG. 2  shows an isometric view of a drive mechanism, according to at least one embodiment of the present invention; 
         FIG. 3  shows an exploded view, along an axis “A,” of the drive mechanism shown in  FIG. 2 , 
         FIG. 4A  shows a cross-sectional view of the drive mechanism shown in  FIG. 2  in an initial inactive state; 
         FIG. 4B  shows a cross-sectional view of the drive mechanism shown in  FIG. 2  in an actuated state; 
         FIG. 4C  shows a cross-sectional view of the drive mechanism shown in  FIG. 2  in a further actuated state as drug delivery from the mechanism continues; 
         FIG. 4D  shows a cross-sectional view of the drive mechanism shown in  FIG. 2  as the mechanism nears completion of drug delivery; 
         FIG. 4E  shows a cross-sectional view of the drive mechanism shown in  FIG. 2  as the mechanism performs a compliance push to ensure completion of drug delivery; 
         FIG. 5  shows an isometric view of a drive mechanism, according to a second embodiment of the present invention; 
         FIG. 6  shows an exploded view, along an axis “A,” of the drive mechanism shown in  FIG. 5 ; 
         FIG. 7  shows a cross-sectional view of the drive mechanism shown in  FIG. 5  in an actuated state; 
         FIG. 8  shows an isometric view of the drive mechanism according to a further embodiment of the present invention; 
         FIG. 9A  shows a cross-sectional view of the drive mechanism shown in  FIG. 8  in an initial inactive state; 
         FIG. 9B  shows a cross-sectional view of the drive mechanism shown in  FIG. 8  in an actuated state and as the mechanism nears completion of drug delivery; 
         FIG. 9C  shows a cross-sectional view of the drive mechanism shown in  FIG. 8  as the mechanism completes drug delivery and triggers an end-of-dose signal. 
         FIG. 10A  is an isometric view of yet another embodiment of a drug delivery pump having safety integrated insertion mechanisms in accordance with teachings of the present invention; 
         FIG. 10B  is an isometric view of the interior components of the drug delivery pump shown in  FIG. 10A ; 
         FIG. 10C  is an isometric view of the bottom of the drug delivery pump shown in  FIG. 10A ; 
         FIG. 11  is an isometric view of a drive mechanism, according to at the embodiment of  FIGS. 10A-10C ; 
         FIG. 12  is an exploded view, along an axis “A,” of the drive mechanism shown in  FIG. 11 , 
         FIG. 13A  is a cross-sectional view of the drive mechanism shown in  FIG. 11  in an initial inactive state; 
         FIG. 13B  is a cross-sectional view of the drive mechanism shown in  FIG. 11  in an actuated state; 
         FIG. 13C  is a cross-sectional view of the drive mechanism shown in  FIG. 11  at the completion of drug delivery; 
         FIG. 14A  is a cross-sectional view of the drive mechanism taken along line  14 - 14  in  FIG. 11 ; and 
         FIG. 14B  is a cross-sectional view of the drive mechanism similar to  FIG. 14A , but after the activation of the sensor. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein to describe the drive mechanisms, drug delivery pumps, or any of the relative positions of the components of the present invention, the terms “axial” or “axially” refer generally to a longitudinal axis “A” around which the drive mechanisms are preferably positioned, although not necessarily symmetrically there-around. The term “radial” refers generally to a direction normal to axis A. The terms “proximal,” “rear,” “rearward,” “back,” or “backward” refer generally to an axial direction in the direction “P”. The terms “distal,” “front,” “frontward,” “depressed,” or “forward” refer generally to an axial direction in the direction “D”. As used herein, the term “glass” should be understood to include other similarly non-reactive materials suitable for use in a pharmaceutical grade application that would normally require glass, including but not limited to certain non-reactive polymers such as cyclic olefin copolymers (COC) and cyclic olefin polymers (COP). The term “plastic” may include both thermoplastic and thermosetting polymers. Thermoplastic polymers can be re-softened to their original condition by heat; thermosetting polymers cannot. As used herein, the term “plastic” refers primarily to moldable thermoplastic polymers such as, for example, polyethylene and polypropylene, or an acrylic resin, that also typically contain other ingredients such as curatives, fillers, reinforcing agents, colorants, and/or plasticizers, etc., and that can be formed or molded under heat and pressure. As used herein, the term “plastic” is not meant to include glass, non-reactive polymers, or elastomers that are approved for use in applications where they are in direct contact with therapeutic liquids that can interact with plastic or that can be degraded by substituents that could otherwise enter the liquid from plastic. The term “elastomer,” “elastomeric” or “elastomeric material” refers primarily to cross-linked thermosetting rubbery polymers that are more easily deformable than plastics but that are approved for use with pharmaceutical grade fluids and are not readily susceptible to leaching or gas migration under ambient temperature and pressure. “Fluid” refers primarily to liquids, but can also include suspensions of solids dispersed in liquids, and gasses dissolved in or otherwise present together within liquids inside the fluid-containing portions of syringes. According to various aspects and embodiments described herein, reference is made to a “biasing member”, such as in the context of one or more biasing members for insertion or retraction of the needle, trocar, and/or cannula. It will be appreciated that the biasing member may be any member that is capable of storing and releasing energy. Non-limiting examples include a spring, such as for example a coiled spring, a compression or extension spring, a torsional spring, and a leaf spring, a resiliently compressible or elastic band, or any other member with similar functions. In at least one embodiment of the present invention, the biasing member is a spring, preferably a compression spring. 
     The novel devices of the present invention provide drive mechanisms with integrated status indication and drug delivery pumps which incorporate such drive mechanisms. Such devices are safe and easy to use, and are aesthetically and ergonomically appealing for self-administering patients. The devices described herein incorporate features which make activation, operation, and lock-out of the device simple for even untrained users. The novel devices of the present invention provide these desirable features without any of the problems associated with known prior art devices. Certain non-limiting embodiments of the novel drug delivery pumps, drive mechanisms, and their respective components are described further herein with reference to the accompanying figures. 
     As used herein, the term “pump” is intended to include any number of drug delivery systems which are capable of dispensing a fluid to a user upon activation. Such drug delivery systems include, for example, injection systems, infusion pumps, bolus injectors, and the like.  FIGS. 1A-1C  show an exemplary drug delivery device according to at least one embodiment of the present invention. The drug delivery device may be utilized to administer delivery of a drug treatment into a body of a user. As shown in  FIGS. 1A-1C , the drug pump  10  includes a pump housing  12 . Pump housing  12  may include one or more housing subcomponents which are fixedly engageable to facilitate easier manufacturing, assembly, and operation of the drug pump. For example, drug pump  10  includes a pump housing  12  which includes an upper housing  12 A and a lower housing  12 B. The drug pump may further include an activation mechanism  14 , a status indicator  16 , and a window  18 . Window  18  may be any translucent or transmissive surface through which the operation of the drug pump may be viewed. As shown in  FIG. 1B , drug pump further includes assembly platform  20 , sterile fluid conduit  30 , drive mechanism  100  having drug container  50 , insertion mechanism  200 , fluid pathway connection  300 , and power and control system  400 . One or more of the components of such drug pumps may be modular in that they may be, for example, pre-assembled as separate components and configured into position onto the assembly platform  20  of the drug pump  10  during manufacturing. 
     The pump housing  12  contains all of the device components and provides a means of removably attaching the device  10  to the skin of the user. The pump housing  12  also provides protection to the interior components of the device  10  against environmental influences. The pump housing  12  is ergonomically and aesthetically designed in size, shape, and related features to facilitate easy packaging, storage, handling, and use by users who may be untrained and/or physically impaired. Furthermore, the external surface of the pump housing  12  may be utilized to provide product labeling, safety instructions, and the like. Additionally, as described above, housing  12  may include certain components, such as status indicator  16  and window  18 , which may provide operation feedback to the user. 
     In at least one embodiment, the drug pump  10  provides an activation mechanism  14  that is displaced by the user to trigger the start command to the power and control system  400 . In a preferred embodiment, the activation mechanism is a start button  14  that is located through the pump housing  12 , such as through an aperture between upper housing  12 A and lower housing  12 B, and which contacts a control arm  40  of the power and control system  400 . In at least one embodiment, the start button  14  may be a push button, and in other embodiments, may be an on/off switch, a toggle, or any similar activation feature known in the art. The pump housing  12  also provides a status indicator  16  and a window  18 . In other embodiments, one or more of the activation mechanism  14 , the status indicator  16 , the window  18 , and combinations thereof may be provided on the upper housing  12 A or the lower housing  12 B such as, for example, on a side visible to the user when the drug pump  10  is placed on the body of the user. Housing  12  is described in further detail hereinafter with reference to other components and embodiments of the present invention. 
     Drug pump is configured such that, upon activation by a user by depression of the activation mechanism, the drug pump is initiated to: insert a fluid pathway into the user; enable, connect, or open necessary connections between a drug container, a fluid pathway, and a sterile fluid conduit; and force drug fluid stored in the drug container through the fluid pathway and fluid conduit for delivery into a user. One or more optional safety mechanisms may be utilized, for example, to prevent premature activation of the drug pump. For example, an optional on-body sensor  24  (shown in  FIG. 1C ) may be provided in one embodiment as a safety feature to ensure that the power and control system  400 , or the activation mechanism, cannot be engaged unless the drug pump  10  is in contact with the body of the user. In one such embodiment, the on-body sensor  24  is located on the bottom of lower housing  12 B where it may come in contact with the user&#39;s body. Upon displacement of the on-body sensor  24 , depression of the activation mechanism is permitted. Accordingly, in at least one embodiment the on-body sensor  24  is a mechanical safety mechanism, such as for example a mechanical lock out, that prevents triggering of the drug pump  10  by the activation mechanism  14 . In another embodiment, the on-body sensor may be an electro-mechanical sensor such as a mechanical lock out that sends a signal to the power and control system  400  to permit activation. In still other embodiments, the on-body sensor can be electrically based such as, for example, a capacitive- or impedance-based sensor which must detect tissue before permitting activation of the power and control system  400 . These concepts are not mutually exclusive and one or more combinations may be utilized within the breadth of the present invention to prevent, for example, premature activation of the drug pump. In a preferred embodiment, the drug pump  10  utilizes one or more mechanical on-body sensors. Additional integrated safety mechanisms are described herein with reference to other components of the novel drug pumps. 
     Power and Control System: 
     The power and control system  400  includes a power source, which provides the energy for various electrical components within the drug pump, one or more feedback mechanisms, a microcontroller, a circuit board, one or more conductive pads, and one or more interconnects. Other components commonly used in such electrical systems may also be included, as would be appreciated by one having ordinary skill in the art. The one or more feedback mechanisms may include, for example, audible alarms such as piezo alarms and/or light indicators such as light emitting diodes (LEDs). The microcontroller may be, for example, a microprocessor. The power and control system  400  controls several device interactions with the user and interfaces with the drive mechanism  100 . In one embodiment, the power and control system  400  interfaces with the control arm  40  to identify when the on-body sensor  24  and/or the activation mechanism  14  have been activated. The power and control system  400  may also interface with the status indicator  16  of the pump housing  12 , which may be a transmissive or translucent material which permits light transfer, to provide visual feedback to the user. The power and control system  400  interfaces with the drive mechanism  100  through one or more interconnects to relay status indication, such as activation, drug delivery, and end-of-dose, to the user. Such status indication may be presented to the user via auditory tones, such as through the audible alarms, and/or via visual indicators, such as through the LEDs. In a preferred embodiment, the control interfaces between the power and control system and the other components of the drug pump are not engaged or connected until activation by the user. This is a desirable safety feature that prevents accidental operation of the drug pump and may additionally maintain the energy contained in the power source during storage, transportation, and the like. 
     The power and control system  400  may be configured to provide a number of different status indicators to the user. For example, the power and control system  400  may be configured such that after the on-body sensor and/or trigger mechanism have been pressed, the power and control system  400  provides a ready-to-start status signal via the status indicator  16  if device start-up checks provide no errors. After providing the ready-to-start status signal and, in an embodiment with the optional on-body sensor, if the on-body sensor remains in contact with the body of the user, the power and control system  400  will power the drive mechanism  100  to begin delivery of the drug treatment through the fluid pathway connection  300  and sterile fluid conduit  30 . In a preferred embodiment of the present invention, the insertion mechanism  200  and the fluid pathway connection  300  may be caused to activate directly by user operation of the activation mechanism  14 . During the drug delivery process, the power and control system  400  is configured to provide a dispensing status signal via the status indicator  16 . After the drug has been administered into the body of the user and after the end of any additional dwell time, to ensure that substantially the entire dose has been delivered to the user, the power and control system  400  may provide an okay-to-remove status signal via the status indicator  16 . This may be independently verified by the user by viewing the drive mechanism and drug dose delivery through the window  18  of the pump housing  12 . Additionally, the power and control system  400  may be configured to provide one or more alert signals via the status indicator  16 , such as for example alerts indicative of fault or operation failure situations. 
     Other power and control system configurations may be utilized with the novel drug pumps of the present invention. For example, certain activation delays may be utilized during drug delivery. As mentioned above, one such delay optionally included within the system configuration is a dwell time which ensures that substantially the entire drug dose has been delivered before signaling completion to the user. Similarly, activation of the device may require a delayed depression (i.e., pushing) of the activation mechanism  14  of the drug pump  10  prior to drug pump activation. Additionally, the system may include a feature which permits the user to respond to the end-of-dose signals and to deactivate or power-down the drug pump. Such a feature may similarly require a delayed depression of the activation mechanism, to prevent accidental deactivation of the device. Such features provide desirable safety integration and ease-of-use parameters to the drug pumps. An additional safety feature may be integrated into the activation mechanism to prevent partial depression and, therefore, partial activation of the drug pumps. For example, the activation mechanism and/or power and control system may be configured such that the device is either completely off or completely on, to prevent partial activation. Such features are described in further detail hereinafter with regard to other aspects of the novel drug pumps. 
     Fluid Pathway Connection: 
     The fluid pathway connection  300  includes a sterile fluid conduit  30 , a piercing member, a connection hub, and a sterile sleeve. The fluid pathway connection may further include one or more flow restrictors. Upon proper activation of the device  10 , the fluid pathway connection  300  is enabled to connect the sterile fluid conduit  30  to the drug container of the drive mechanism  100 . Such connection may be facilitated by a piercing member, such as a needle, penetrating a pierceable seal of the drug container of the drive mechanism  100 . The sterility of this connection may be maintained by performing the connection within a flexible sterile sleeve. Upon substantially simultaneous activation of the insertion mechanism, the fluid pathway between drug container and insertion mechanism is complete to permit drug delivery into the body of the user. 
     In at least one embodiment of the present invention, the piercing member of the fluid pathway connection is caused to penetrate the pierceable seal of the drug container of the drive mechanism by direct action of the user, such as by depression of the activation mechanism by the user. For example, the activation mechanism itself may bear on the fluid pathway connection such that displacement of the activation mechanism from its original position also causes displacement of the fluid pathway connection. In a preferred embodiment, this connection is enabled by the user depressing the activation mechanism and, thereby, driving the piercing member through the pierceable seal, because this prevents fluid flow from the drug container until desired by the user. In such an embodiment, a compressible sterile sleeve may be fixedly attached between the cap of the drug container and the connection hub of the fluid pathway connection. The piercing member may reside within the sterile sleeve until a connection between the fluid connection pathway and the drug container is desired. The sterile sleeve may be sterilized to ensure the sterility of the piercing member and the fluid pathway prior to activation. 
     The drug pump is capable of delivering a range of drugs with different viscosities and volumes. The drug pump is capable of delivering a drug at a controlled flow rate (speed) and/or of a specified volume. In one embodiment, the drug delivery process is controlled by one or more flow restrictors within the fluid pathway connection and/or the sterile fluid conduit. In other embodiments, other flow rates may be provided by varying the geometry of the fluid flow path or delivery conduit, varying the speed at which a component of the drive mechanism advances into the drug container to dispense the drug therein, or combinations thereof. Still further details about the fluid pathway connection  300  and the sterile fluid conduit  30  are provided hereinafter in later sections in reference to other embodiments. 
     Insertion Mechanism: 
     A number of insertion mechanisms may be utilized within the drug pumps of the present invention. In at least one embodiment, the insertion mechanism  200  includes an insertion mechanism housing having one or more lockout windows, and a base for connection to the assembly platform and/or pump housing (as shown in  FIG. 1B  and  FIG. 1C ). The connection of the base to the assembly platform  20  may be, for example, such that the bottom of the base is permitted to pass-through a hole in the assembly platform to permit direct contact of the base to the body of the user. In such configurations, the bottom of the base may include a scaling membrane that is removable prior to use of the drug pump  10 . The insertion mechanism may further include one or more insertion biasing members, a needle, a retraction biasing member, a cannula, and a manifold. The manifold may connect to sterile fluid conduit  30  to permit fluid flow through the manifold, cannula, and into the body of the user during drug delivery. 
     As used herein, “needle” is intended to refer to a variety of needles including but not limited to conventional hollow needles, such as a rigid hollow steel needles, and solid core needles more commonly referred to as a “trocars.” In a preferred embodiment, the needle is a 27 gauge solid core trocar and in other embodiments, the needle may be any size needle suitable to insert the cannula for the type of drug and drug administration (e.g., subcutaneous, intramuscular, intradermal, etc.) intended. A sterile boot may be utilized within the needle insertion mechanism. The sterile boot is a collapsible sterile membrane that is in fixed engagement at a proximal end with the manifold and at a distal end with the base. In at least on embodiment, the sterile boot is maintained in fixed engagement at a distal end between base and insertion mechanism housing. Base includes a base opening through which the needle and cannula may pass-through during operation of the insertion mechanism, as will be described further below. Sterility of the cannula and needle are maintained by their initial positioning within the sterile portions of the insertion mechanism. Specifically, as described above, needle and cannula are maintained in the sterile environment of the manifold and sterile boot. The base opening of base may be closed from non-sterile environments as well, such as by for example a sealing membrane  254  (shown in  FIG. 1C ). 
     According to at least one embodiment of the present invention, the insertion mechanism is initially locked into a ready-to use-stage by lockout pin(s) which are initially positioned within lockout windows of the insertion mechanism housing. In this initial configuration, insertion biasing member and retraction biasing member are each retained in their compressed, energized states. As shown in  FIG. 1B , the lockout pin(s)  208  may be directly displaced by user depression of the activation mechanism  14 . As the user disengages any safety mechanisms, such as an optional on-body sensor  24  (shown in  FIG. 1C ), the activation mechanism  14  may be depressed to initiate the drug pump. Depression of the activation mechanism  14  may directly cause translation or displacement of control arm  40  and directly or indirectly cause displacement of lockout pin(s)  208  from their initial position within locking windows  202 A of insertion mechanism housing  202 . Displacement of the lockout pin(s)  208  permits insertion biasing member to decompress from its initial compressed, energized state. This decompression of the insertion biasing member drives the needle and the cannula into the body of the user. At the end of the insertion stage, the retraction biasing member is permitted to expand in the proximal direction from its initial energized state. This axial expansion in the proximal direction of the retraction biasing member retracts the needle, while maintaining the cannula in fluid communication with the body of the user. Accordingly, the insertion mechanism may be used to insert a needle and cannula into the user and, subsequently, retract the needle while retaining the cannula in position for drug delivery to the body of the user. 
     Drive Mechanism: 
     With reference to the embodiments shown in  FIGS. 2 and 3 , drive mechanism  100  includes a drive housing  130 , a status switch interconnect  132 , and a drug container  50  having a cap  52 , a pierceable seal  56 , a barrel  58 , and a plunger seal  60 . The drug container may contain a drug fluid, within the barrel between the pierceable seal and the plunger seal, for delivery through the insertion mechanism and drug pump into the body of the user. The seals described herein may be comprised of a number of materials but are, in a preferred embodiment, comprised of one or more elastomers or rubbers. The drive mechanism may further include a connection mount  54  to guide the insertion of the piercing member of the fluid pathway connection into the barrel  58  of the drug container  50 . The drive mechanism  100  may further contain one or more drive biasing members, one or more release mechanisms, and one or more guides, as are described further herein. The components of the drive mechanism function to force a fluid from the drug container out through the pierceable seal, or preferably through the piercing member of the fluid pathway connection, for delivery through the fluid pathway connection, sterile fluid conduit, and insertion mechanism into the body of the user. 
     The drive mechanism may further include one or more contact surfaces located on corresponding components. Such contact surfaces may be electrical contact surfaces, mechanical contact surfaces, or electro-mechanical contact surfaces. Such surfaces may initially be in contact and caused to disengage, or initially be disconnected and caused to engage, to permit a signal to be sent to and/or from the power control system  400 . In at least one embodiment, as described further herein, the contact surfaces may be electrical contact surfaces which are initially disconnected and caused to come into engagement whereby, upon such engagement, contact surfaces are capable of continuing an energy pathway or otherwise relaying a signal to the power and control system  400 . In another embodiment of the present invention, the contact surfaces are mechanical contact surfaces which are initially in contact and caused to disengage whereby, upon such disengagement, such disengagement is communicated to the power and control system  400 . Such signals may be transferred across one or more interconnects  132  to the power and control system  400  or by mechanical action to the power and control system  400 . Such components may be utilized within the drive mechanism to measure and relay information related to the status of operation of the drive mechanism, which may be converted by the power and control system  400  into tactile, auditory, and/or visual feedback to the user. Such embodiments are described further herein. Regardless of the electrical or mechanical nature of the contact surfaces, the motion of the components which permits transmission of a signal to the power control system  400  is enabled by a biasing member  122  axially translating a contact sleeve  140  in the distal direction during operation of the device. 
     In one particular embodiment, the drive mechanism  100  employs one or more compression springs as the biasing member(s). Upon activation of the drug pump by the user, the power and control system may be actuated to directly or indirectly release the compression spring(s) from an energized state. Upon release, the compression spring(s) may bear against and act upon the plunger seal to force the fluid drug out of the drug container. The fluid pathway connection may be connected through the pierceable seal prior to, concurrently with, or after activation of the drive mechanism to permit fluid flow from the drug container, through the fluid pathway connection, sterile fluid conduit, and insertion mechanism, and into the body of the user for drug delivery. In at least one embodiment, the fluid flows through only a manifold and a cannula of the insertion mechanism, thereby maintaining the sterility of the fluid pathway before and during drug delivery. Such components and their functions are described in further detail hereinafter. 
     Referring now to the embodiment of the drive mechanism shown in  FIG. 3 , the drive mechanism  100  includes a drug container  50  having a cap  52 , a pierceable seal  56 , a barrel  58 , and a plunger seal  60 , and optionally a connection mount  54 . The drug container  50  is mounted to a distal end of a drive housing  130 . Compressed within the drive housing  130 , between the drug container  50  and the proximal end of the housing  130 , are a drive biasing member  122  and a piston  110 , wherein the drive biasing member  122  is configured to bear upon an interface surface  110 C of the piston  110 , as described further herein. Optionally, a cover sleeve  120  may be utilized between the drive biasing member  122  and the interface surface  110 C of the piston  110  to, for example, promote more even distribution of force from the drive biasing member  122  to the piston  110 , prevent buckling of the drive biasing member  122 , and/or hide biasing member from user view. Interface surface  110 C of piston  110  is caused to rest substantially adjacent to, or in contact with, a proximal end of seal  60 . 
     The drive mechanism  100  further includes, mounted at a distal end, a status switch interconnect  132 . A contact sleeve  140  is slidably mounted to the drive housing  130  through an axial aperture of the housing  130 , such that sleeve hooks  140 B at a distal end of the contact sleeve  140  are caused to contact the piston  110  between interface surface  110  and a contact protrusion  110 B near the proximal end of the piston  110 . Piston  110  also includes a locking groove  110 A, between contact protrusion  110 B and the proximal end of the piston  110 . Contact sleeve  140  has a radially extending ring  140 C at its proximal end, upon which resides one or more flex prongs  140 A. An electrical contact  134  may be connected, mounted, printed, or otherwise mounted to ring  140 C which, during operation of the drive mechanism, may come in contact with corresponding status switch interconnect  132  to complete an electrical circuit or otherwise permit a transmission to the power and control system to provide feedback to the user. 
     The components of the drive mechanism  100 , upon activation, may be used to drive axial translation in the distal direction of the plunger seal  60  of the drug container  50 . Optionally, the drive mechanism  100  may include one or more compliance features which enable additional axial translation of the plunger seal  60  to, for example, ensure that substantially the entire drug dose has been delivered to the user and make sure that the feedback contact mechanisms have connected. For example, in one embodiment of the present invention, the sleeve hooks  140 B are flex arms which may permit, upon sufficient application of force by the drive biasing member  122  on the piston  110 , to allow interface surface  110 C to translate axially beyond sleeve hooks  140 B to drive further axial translation of the plunger seal  60  for a compliance push of drug fluid from the drug container. Additionally or alternatively, the plunger seal  60 , itself, may have some compressibility permitting a compliance push of drug fluid from the drug container. 
     In at least one embodiment of the present invention, a compliance push of drug fluid from the drug container is enabled by a piston extension  102 . In such embodiments, the drive mechanism  100  further includes a piston extension  102  slidably mounted at a distal end and within an axial pass-through of piston  110 . The piston extension  102  may be retained within piston  110  by interaction between extension arms  102 B of the piston extension  102  and connection slots  110 D of piston  110 , as shown in  FIGS. 4A-4E . Piston extension may be driven by a piston extension biasing member  106 , which is mounted within the axial pass-through of piston  110  and initially compressed between piston extension  102  and piston  110 . An optional piston biasing member support  104  may be utilized between piston extension biasing member  106  and piston extension  102  to, for example, promote more uniform distribution of force from piston extension biasing member  106  to piston extension  102 . The function of the optional piston extension is described in further detail hereinafter. 
     The novel drive mechanisms of the present invention integrate status indication into the drug dose delivery. By use of one or more status switch interconnects and one or more corresponding electrical contacts, the status of the drive mechanism before, during, and after operation can be relayed to the power and control system to provide feedback to the user. Such feedback may be tactile, visual, and/or auditory, as described above, and may be redundant such that more than one signals or types of feedback are provided to the user during use of the device. For example, the user may be provided an initial feedback to identify that the system is operational and ready for drug delivery. Upon activation, the system may then provide one or more drug delivery status indications to the user. At completion of drug delivery, the drive mechanism and drug pump may provide an end-of-dose indication. As the end-of-dose indication is tied to the piston reaching the end of its axial translation, the drive mechanism and drug pump provide a true end-of-dose indication to the user. 
     In at least one embodiment, as shown in  FIG. 2  and  FIG. 3 , an end-of-dose status indication may be provided to the user once the status switch interconnect  132  is caused to contact electrical contact  134  at the end of axial travel of the piston  110  and plunger  60  within the barrel  58  of the drug container  50 . In a further embodiment, incremental status indication relaying various stages of drug delivery can be communicated to the user during operation. In one such embodiment, sleeve hooks  140 B of cover sleeve  120  may have one or more interconnects which come into contact with one or more electrical contacts on the outer surface of piston  110  during operation. As piston  110  translates axially in the distal direction to push plunger seal  60  distally, thereby pushing fluid out of the drug container through the pierceable seal end, the electrical contacts of the piston  110  may sequentially contact the interconnect on the sleeve hooks  140 B to relay the incremental status of operation. Depending on the number of electrical contacts located on the outer surface of the piston  110 , the frequency of the incremental status indication may be varied as desired. The location of the contacts and interconnects may be interchanged or in a number of other configurations which permit completion of an electrical circuit or otherwise permit a transmission between the components. 
     In another embodiment of the drive mechanism  500 , shown in  FIGS. 5 and 6 , incremental status indication may be measured and relayed by a separate incremental status stem  650  and a corresponding stem interconnect  652 . The stem interconnect  652  may be mounted, affixed, printed, or otherwise attached to incremental status stem  650 . Incremental status stem  650  may be a static component, i.e., it does not move or translate, that is mounted to the distal end of contact sleeve  640  and/or the distal end of drive housing  630  such that the incremental status stem  650  resides within an axial pass-through of contact sleeve  640  and drive housing  630 . The incremental status stem  650  further resides within an axial pass-through of piston  610 . In such embodiments of the present invention, one or more contacts may be located on an inner surface of the piston  610  such that they sequentially interface with one or more corresponding interconnects on the incremental status stem  650 . As piston  610  translates axially in the distal direction to push plunger seal  60  distally, thereby pushing fluid out of the drug container through the pierceable seal end, the electrical contacts of the piston  610  may sequentially contact the interconnect on the incremental status stem  650  to relay the incremental status of operation. Depending on the number of electrical contacts, the frequency of the incremental status indication may be varied as desired. The location of the contacts and interconnects may be interchanged or in a number of other configurations which permit completion of an electrical circuit or otherwise permit a transmission between the components. 
       FIG. 7  shows a cross-sectional view of the embodiment of the drive mechanism shown in  FIG. 5  during operation of the drive mechanism. As shown, incremental status stem  650  may be a static component that is mounted to the distal end of contact sleeve  640  and/or the distal end of drive housing  630  such that the incremental status stem  650  resides within an axial pass-through of contact sleeve  640  and drive housing  630 . As piston  610  translates axially in the distal direction (i.e., in the direction of the solid arrow) to push plunger seal  60  distally, the electrical contacts of the piston  610  may sequentially contact the interconnect on the incremental status stem  650  to relay the incremental status of operation through stem interconnect  652 . Accordingly, incremental status of the drive mechanism, and therefore status of drug delivery, may be conveyed to the user during use of the device. 
     Returning now to the embodiment shown in  FIGS. 2-3 , further aspects of the novel drive mechanism will be described with reference to  FIGS. 4A-4E . One or more of these aspects may similarly be utilized in the embodiment shown in  FIG. 5 , or any other variation captured by the embodiments described herein.  FIG. 4A  shows a cross-sectional view of the drive mechanism, according to at least a first embodiment, during its initial locked stage. A fluid, such as a drug fluid, may be contained within barrel  58 , between plunger seal  60  and pierceable seal  56 , for delivery to a user. Upon activation by the user, a fluid pathway connection may be connected to the drug container through the pierceable seal  56 . As described above, this fluid connection may be facilitated by a piercing member of the fluid pathway connection which pierces the pierceable seal and completes the fluid pathway from the drug container, through the fluid pathway connection, the fluid conduit, the insertion mechanism, and the cannula for delivery of the drug fluid to the body of the user. Initially, one or more locking mechanisms (not shown) may reside within the locking grooves  110 A of piston  110 . Directly or indirectly upon activation of the device by the user, the locking mechanism may be removed from the locking grooves  110 A of piston  110 , to permit operation of the drive mechanism. 
     As shown in  FIG. 4A , the piston extension biasing member  106  and drive biasing member  122  are both initially in a compressed, energized state. The drive biasing member  122  may be maintained in this state until activation of the device between internal features of drive housing  130  and interface surface  110 C of piston  110 . As the locking mechanism is removed from the locking groove  110 A of piston  110 , drive biasing member  122  is permitted to expand (i.e., decompress) axially in the distal direction (i.e., in the direction of the solid arrow). Such expansion causes the drive biasing member  122  to act upon and distally translate interface surface  110 C and piston  110 , thereby distally translating plunger  60  to push drug fluid out of the barrel  58 . Distal translation of the piston  110  causes distal translation of the piston extension biasing member  106  and piston extension  102 , when such optional features are incorporated into the device. As shown in  FIG. 4B , such distal translation of the piston  110  and plunger seal  60  continues to force fluid flow out from barrel  58  through pierceable seal  56 . Status switch interconnect  132  is prevented from prematurely contacting electrical contact  134  by one or more flex prongs  140 A, as shown in  FIG. 4C . Alternatively, low force springs or other resistance mechanisms may be utilized in addition to or alternatively from flex prongs  140 A to achieve the same functions. During distal translation of the piston  110 , sleeve hooks  140 B may slidably contact the outer surface of piston  110 . As described above, interconnects and electrical contacts may be located on these components to provide incremental status indication during operation of the drive mechanism. 
     As the drive mechanism  100  nears or reaches end-of-dose, flex prongs  140 A may be caused to flex outwards (i.e., in the direction of the hollow arrows) by the decompression force of drive biasing member  122 . Such flexion of the flex prongs  140 A may permit status switch interconnect  132  to contact electrical contact  134 , completing a circuit or otherwise permitting a transmission to the power and control system to provide feedback to the user. At this stage, one or more delivery compliance mechanisms may be utilized to ensure that the status switch interconnect  132  has contacted electrical contact  134  and/or that substantially the entire drug dose has been delivered. For example, in one embodiment of the present invention, the sleeve hooks  140 B are flex arms which may permit, upon sufficient application of force by the drive biasing member  122  on the piston  110 , to allow interface surface  110 C to translate axially beyond sleeve hooks  140 B to drive further axial translation of the plunger seal  60  for a compliance push of drug fluid from the drug container. Additionally or alternatively, the plunger seal  60 , itself, may have some compressibility permitting a compliance push of drug fluid from the drug container. For example, when a pop-out plunger seal is employed, i.e., a plunger seal that is deformable from an initial state, the plunger seal may be caused to deform or “pop-out” to provide a compliance push of drug fluid from the drug container. 
     In at least one embodiment of the present invention, a compliance push of drug fluid from the drug container is enabled by a piston extension  102 . In such embodiments, the drive mechanism  100  further includes a piston extension  102  slidably mounted at a distal end and within an axial pass-through of piston  110 . The piston extension  102  may be retained within piston  110  by interaction between extension arms  102 B of the piston extension  102  and connection slots  110 D of piston  110 , as shown in  FIG. 4D . Piston extension may be driven by a piston extension biasing member  106 , which is mounted within the axial pass-through of piston  110  and initially compressed between piston extension  102  and piston  110 . An optional piston biasing member support  104  may be utilized between piston extension biasing member  106  and piston extension  102  to, for example, promote more uniform distribution of force from piston extension biasing member  106  to piston extension  102 . 
     As the piston  110  reaches its end of travel within barrel  58 , piston extension  102  may be permitted to axially travel in the distal direction by the force exerted by piston extension biasing member  106 . At this stage, the piston extension biasing member  106  is permitted to expand (i.e., decompress) axially in the distal direction such that extension arms  102 B of the piston extension  102  may translate distally (i.e., in the direction of the solid arrow) within connection slots  110 D of piston  110 , as shown in  FIG. 4D . As shown in  FIG. 4E , such distal translation (i.e., in the direction of the hatched arrow) of the piston extension  102  enables a compliance push (shown by dimension “C” in  FIG. 4E ) of drug fluid from the drug container. Piston extension  102  may be configured such that extension arms  102 B may contact and apply force upon a distal end of connections slots  110 D to distally translate piston  110  further (i.e., in the direction of the hatched arrow). This further distal translation of the piston  110  may be utilized to ensure that status switch interconnect  132  has engaged contact  134 . 
     As described above, the novel drive mechanisms of the present invention integrate status indication into the drug dose delivery. Through integration of the end-of-dose status indication mechanisms to the axial translation of the piston, and thereby the plunger seal, true and accurate end-of-dose indication may be provided to the user. By use of one or more contact surfaces on corresponding components, the status of the drive mechanism before, during, and after operation can be relayed to the power and control system to provide feedback to the user. Such feedback may be tactile, visual, and/or auditory, as described above, and may be redundant such that more than one signals or types of feedback are provided to the user during use of the device.  FIGS. 4A-4E  above show an arrangement which provide end-of-dose status indication to the user once the status switch interconnect  132  is caused to contact electrical contact  134  at the end of axial travel of the piston  110  and plunger  60  within the barrel  58  of the drug container  50 . As described above, the novel devices described herein may additionally provide incremental status indication to relay various stages of drug delivery to the user during operation. In one such embodiment, sleeve hooks  140 B of cover sleeve  120  may have one or more interconnects which come into contact with one or more electrical contacts on the outer surface of piston  110  during operation. A redundant end-of-dose indication may be utilized upon contact between sleeve hooks  140 B of contact sleeve  140  and contact protrusion  110 B of piston  110 . Electrical contacts or interconnects along piston  110  may sequentially contact the corresponding interconnects or contacts on the sleeve hooks  140 B to relay the incremental status of operation. Depending on the number of electrical contacts located on the outer surface of the piston  110 , the frequency of the incremental status indication may be varied as desired. The location of the contacts and interconnects may be interchanged or in a number of other configurations which permit completion of an electrical circuit or otherwise permit a transmission between the components. 
     In another embodiment of the drive mechanism  500 , shown in  FIGS. 5-7 , incremental status indication may be measured and relayed by a separate incremental status stem  650  and a corresponding stem interconnect  652 . As shown in  FIG. 7 , incremental status stem  650  may be a static component that is mounted to the distal end of contact sleeve  640  and/or the distal end of drive housing  630  such that the incremental status stem  650  resides within an axial pass-through of contact sleeve  640  and drive housing  630 . As piston  610  translates axially in the distal direction (i.e., in the direction of the solid arrow) to push plunger seal  60  distally, the electrical contacts of the piston  610  may sequentially contact the interconnect on the incremental status stem  650  to relay the incremental status of operation through stem interconnect  652 . Depending on the number of electrical contacts, the frequency of the incremental status indication may be varied as desired. The location of the contacts and interconnects may be interchanged or in a number of other configurations which permit completion of an electrical circuit or otherwise permit a transmission between the components. Accordingly, incremental status of the drive mechanism, and therefore status of drug delivery, may be conveyed to the user during use of the device. 
     In a further embodiment of the drive mechanism, shown in  FIGS. 8 and 9A-9C , drive mechanism  1000  may be similar to mechanism  100  or mechanism  500 , and incorporate the respective components and functions of such embodiments, but utilize mechanical contact surfaces instead of electrical contact surfaces, as described above.  FIG. 8  shows an isometric view of the drive mechanism  1000  according to a further embodiment of the present invention.  FIGS. 9A-9C  show cross-sectional views of the drive mechanism shown in  FIG. 8  in an initial inactive state, an actuated state and as the mechanism nears completion of drug delivery, and as the mechanism completes drug delivery and triggers an end-of-dose signal. In such embodiments, the status switch interconnect is a mechanical trigger  1150  and the contact surface is a pin  1140 P. As shown in  FIG. 9A , the optional piston extension biasing member  1106  and drive biasing member  1122  are both initially in a compressed, energized state. The drive biasing member  1122  may be maintained in this state until activation of the device between internal features of drive housing  1130  and interface surface  1110 C of piston  1110 . As the locking mechanism is removed from the locking groove  1110 A of piston  1110 , drive biasing member  1122  is permitted to expand (i.e., decompress) axially in the distal direction (i.e., in the direction of the solid arrow). Such expansion causes the drive biasing member  1122  to act upon and distally translate interface surface  1110 C and piston  1110 , thereby distally translating plunger  1060  to push drug fluid out of the barrel  1058 . Distal translation of the piston  1110  causes distal translation of the piston extension biasing member  1106  and piston extension  1102 , when such optional features are incorporated into the device. 
     As shown in  FIG. 9B , such distal translation of the piston  1110  and plunger seal  1060  continues to force fluid flow out from barrel  1058  through pierceable seal  1056 . As described above, interconnects and electrical contacts may be located on these components to provide incremental status indication during operation of the drive mechanism. As shown in  FIG. 9C , as the drive mechanism  1000  reaches end-of-dose, pin  1140 P disengages from mechanical trigger  1150  to permit a transmission to the power and control system  400  to provide feedback to the user. In one such embodiment, disengagement of the pin  1140 P from the mechanical trigger  1150  permits the trigger to rotate as it is biased by a biasing member, such as a constant-force spring  1170 . Initially, the constant-force spring  1170  biases the mechanical trigger  1150  against the pin  1140 P. Upon axial translation of the pin  1140 P, as described above, pin  1140 P disengages from mechanical trigger  1150  which then rotates or is otherwise displaced to permit transmission of feedback to the user. At this stage, one or more delivery compliance mechanisms, as described above, may be utilized to ensure that the pin  1140 P has disengaged mechanical trigger  1150  and/or that substantially the entire drug dose has been delivered. 
     Assembly and/or manufacturing of drive mechanism  100 , drug delivery pump  10 , or any of the individual components may utilize a number of known materials and methodologies in the art. For example, a number of known cleaning fluids such as isopropyl alcohol and hexane may be used to clean the components and/or the devices. A number of known adhesives or glues may similarly be employed in the manufacturing process. Additionally, known siliconization and/or lubrication fluids and processes may be employed during the manufacture of the novel components and devices. Furthermore, known sterilization processes may be employed at one or more of the manufacturing or assembly stages to ensure the sterility of the final product. 
     The drive mechanism may be assembled in a number of methodologies. In one method of assembly, the drug container  50  may first be assembled and filled with a fluid for delivery to the user. The drug container  50  includes a cap  52 , a pierceable seal  56 , a barrel  58 , and a plunger seal  60 . The pierceable seal  56  may be fixedly engaged between the cap  52  and the barrel  58 , at a distal end of the barrel  58 . The barrel  58  may be filled with a drug fluid through the open proximal end prior to insertion of the plunger seal  60  from the proximal end of the barrel  58 . An optional connection mount  54  may be mounted to a distal end of the pierceable seal  56 . The connection mount  54  to guide the insertion of the piercing member of the fluid pathway connection into the barrel  58  of the drug container  50 . The drug container  50  may then be mounted to a distal end of drive housing  130 . 
     One or more switch status interconnects  132  may be mounted to a proximal end of drive housing  130 . A contact sleeve  140 , having one or more sleeve hooks  140 B at a distal end and a ring  140 C at a proximal end having an electrical contact  134  thereon, may be mounted to the drive housing  130  through an axial pass-through from the proximal end of the drive housing  130 . A drive biasing member  122  may be inserted into a distal end of the drive housing  130 . Optionally, a cover sleeve  120  may be inserted into a distal end of the drive housing  130  to substantially cover biasing member  122 . A piston may be inserted into the distal end of the drive housing  130  and through an axial pass-through of contact sleeve  140 , such that a contact protrusion  110 B of piston  110  is proximal to the sleeve hooks  140 B of contact sleeve  140 . The piston  110  and drive biasing member  122 , and optional cover sleeve  120 , may be compressed into drive housing  130 . Such assembly positions the drive biasing member  122  in an initial compressed, energized state and preferably places a piston interface surface  110 C in contact with the proximal surface of the plunger seal  60  within the proximal end of barrel  58 . When a piston extension  102  is employed, the piston extension  102  and piston extension biasing member  106 , and optional piston biasing member support, may be compressed into an axial pass-through of piston  110 . The piston, piston biasing member, contact sleeve, and optional components, may be compressed and locked into the ready-to-actuate state within the drive housing  130  prior to attachment or mounting of the drug container  50 . 
     When one or more interconnects or contacts are utilized for status indication, such components may be mounted, connected, printed, or otherwise attached to their corresponding components prior to assembly of such components into the drive mechanism  100 . When a separate incremental status stem  650  and a corresponding stem interconnect  652  are utilized for such incremental status indication, the stem interconnect  652  may be mounted, affixed, printed, or otherwise attached to incremental status stem  650 . The incremental status stem  650  and stem interconnect  652  to the proximal end of the contact sleeve  640  and/or the proximal end of the drive housing  630  in a manner such that the incremental status stem  650  resides within an axial pass-through of contact sleeve  640  and drive housing  630 . The incremental status stem  650  is further mounted to reside within an axial pass-through of piston  610 . 
     It will be appreciated that the end-of-dose indicator or interconnects/contact may include any appropriate arrangement, including, for example, mechanical, electrical, electromechanical, ultrasonic, capacitive or magnetic arrangements. Similarly, the drive mechanism may be of any appropriate design. 
     Alternate arrangements of both the drive mechanism and end-of-dose indicator or interconnects/contact are illustrated, for example, in  FIGS. 10A-14B . For the sake of clarity, the reference numbers utilized in  FIGS. 10A-14B  are similar to those of the embodiment of  FIGS. 1A-4C , only preceded by the number “2” or “20” as appropriate to provide a reference number having four digits, i.e., 2XXX. For example, the drug pump and drive mechanism of  FIGS. 10A-14B  will be designated by the numbers  2010  and  2100 , respectively, as opposed to the drug pump  10  and drive mechanism  100  of  FIGS. 1A-4E . This correlation, however, should not be taken as an indication that the components of  FIGS. 10A-14B  with reference numbers similar to those of the embodiment of  FIGS. 1A-4E  are exactly the same as the respective components of  FIGS. 1A-4E . 
     As shown in  FIGS. 10A-10C , the drug pump  2010  includes a drive mechanism  2100  for receiving a drug container  2050 , an insertion mechanism  2200 , a fluid pathway connection  2300  including a fluid conduit  2030 , and a power and control system  2400 , all residing within a housing  2012 , and an activation mechanism  2014  actuable by a user from the outside of the housing  2012 . The housing  2012  may take any number of configurations and be facilitated by any number of components, such as a single-body or multi-component housing  2012 . Certain other components, such as electronics for power and signaling, activation buttons, and safety sensors are also omitted for clarity, but are understood to be standard components within such drug pump devices. While the housing  2012 , insertion mechanism  2200 , fluid pathway connection  2300 , and power and control system  2500 , as well as the activation mechanism  2014  are not discussed in detail, those of skill in the art will appreciate that they may be the same or similar to the components and systems discussed in detail with regard to the other embodiments disclosed herein. 
     The drive mechanism  2100 , primary drug container  2050 , and a portion of the fluid pathway connection  2300  are shown isometrically in  FIG. 11  and exploded form in  FIG. 12 .  FIGS. 13A-13C  illustrate the drive mechanism  2100  in cross-section as it progresses through several stages of operation.  FIGS. 14A-14B  illustrate a lateral cross-section of the drive mechanism  2100  at several stages of operation. 
     The primary drug container  2050  retains the drug treatment that is to be injected or infused into the patient, and may be a vial or similar container from which a drug treatment can be dosed. To provide a sterile environment for the drug treatment, the drug container  2050  may include a cylindrical barrel  2058  with a pierceable seal  2056  disposed in a distal end and a plunger seal  2060  disposed within a proximal end. The pierceable seal  2056  and plunger seal  2060  may be formed of a number of materials, such as one or more elastomeric materials, and are sized and formulated to maintain a seal with the barrel  2058 . 
     The portion of the fluid pathway connection  2300  illustrated in  FIGS. 11-13C  includes a connection mount  2054 , a sterile boot  2310 , and a piercing assembly  2320 . The piercing assembly  2320  includes a piercing member  2322  extending from a hub  2324  which supports the piercing member  2322 , and provides a fluid connection  2326  (see  FIG. 11 ) to which the fluid conduit  2030  or other fluid connector may be fluidly coupled to fluidly couple the drug container  2050  to the insertion mechanism  2200 . The connection mount  2054  is disposed adjacent the pierceable seal  2056  and includes an aperture adapted to guide the insertion of the piercing member  2322  of the fluid pathway connection into the pierceable seal  2056  of the drug container  2050 . The sterile boot  2310  is disposed about the piercing assembly  2320  and provides a sterile environment for the completion of the fluid coupling of the fluid pathway connection  2300 . A collar  2052  may be provided in order to secure a flange of the sterile boot  2310 , the connection mount  2054 , the pierceable seal, and the barrel  2058  in fixed relation to one another. 
     Referring to  FIGS. 1A and 1B , in operation, when a user activates the activation mechanism  2014 , as by depressing the illustrated start button, an arm  2015  coupled to the activation mechanism  2014  exerts an axial force on the piercing assembly  2320  to move the piercing member  2322  axially to pierce the pierceable seal  2056 . The drive mechanism  2100  is adapted for use in cooperation with the proximal end of the drug container  2050  to axially advance the plunger seal  2060  within the barrel  2058  to dispense the drug treatment through the fluid pathway connection  2300  once the pierceable seal  2056  has been pierced by the piercing member  2322 . 
     The drive mechanism  2100  includes a drive housing  2130  having an axis that is coincident with the axis A of the drive mechanism  2100  (see  FIG. 11 ). The axis A may be disposed in coincident with axes in the container  2050  and the plunger seal  2060 . A piston  2110  is at least partially disposed within the drive housing  2130  for longitudinal movement along the axis of the drive mechanism  2100 . It will be appreciated that the term “axis” when used in connection with the drive housing  2130  is not intended to require the axis to be in a central location of the drive housing  2130  or that the drive housing  2130  be round. 
     The piston  2110  is mounted to move between a retracted first position (illustrated in  FIG. 13A ), wherein the piston  2110  is at least partially disposed within the drive housing  2130 , and an extended second position (illustrated in  FIGS. 13B and 13C ), wherein the piston  2110  extends axially outward from drive housing  2130 . The piston  2110  includes an interface surface  2110 C that is disposed to either directly confront the plunger seal  2060  when assembled with a drug container  2050 , or to otherwise transmit an actuating force to the plunger seal  2060 . In other words, the piston  2110  of the drive mechanism  2100  of  FIGS. 10A-14B  is adapted to exert a dispensing force on the plunger seal  2060  of the drug container  2050  and to translate outward from a distal end of a housing  2012  to advance the plunger seal  2060  within the drug container  2050  to dispense the drug. While the initial position shown in  FIG. 13A  illustrates the interface surface  2110 C of the piston  2110  as disposed substantially adjacent the distal end of the housing  2012 , it will be appreciated that, in alternate embodiments, the piston may be initially disposed in a position extending outside of the drive housing  2130 . In such an arrangement, in initial assembly of the drive mechanism  2100  with a drug container  2050 , the piston  2110  may be initially at least partially disposed within proximal end of the drug container  2050 . 
     In order to impart axial movement to the piston  2010 , the drive mechanism  2100  further includes a plurality of piston biasing members  2106 ,  2122  disposed to move from an energized first position when the piston  2110  is in the retracted first position to a deenergized second position when the piston  2110  is in an extended second position. It will be appreciated that, for the purposes of this disclosure and the accompanying claims, the term “deenergized second position” is a relative term. That is, the piston biasing members  2106 ,  2122  in the “deenergized second position” have less energy than the piston biasing members  2106 ,  2122  in the “energized first position.” That is not to say, however, that the piston biasing members  2106 ,  2122  in the “deenergized second position” are necessarily completely deenergized or storing no energy. 
     So long as the piston  2110  is maintained in the retracted first position, biasing members  2106 ,  2122  are maintained in their energized first position (see  FIG. 13A ). The piston  2110  is maintained in the retracted first position by a retaining element or clip  2115 . While any appropriate arrangement may be utilized to retain the piston  2110  in the retracted first position, the clip  2115  may bear against an outside surface of the drug pump housing  2012  and be received in a locking groove  2110 A of the piston  2110 .  FIG. 13A  illustrates the clip  2115  disposed in such a retaining first position. It will thus be appreciated by those of skill in the art that the engagement of the retaining element or clip  2115  to maintain the piston  2110  in its retracted first position with the biasing members  2106 ,  2122  in their energized first position, allows the drive mechanism  2100  to be handled as a self-contained unit such that it may be assembled into the drug pump  2010  or in cooperation with a drug container  2050 . In operation, however, once the clip  2115  is removed or moved to a releasing second position (see  FIGS. 12B and 13C ), the piston biasing members  2106 ,  2122  exert an axial dispensing force on the piston  2110  as they move to a deenergized second position and the piston moves to its extended second position. In at least one embodiment, clip  2115  may be removed through an action caused, directly or indirectly, by movement of the activation mechanism  2014 . The action removing clip  2115  can be achieved in a number of ways. For example, with reference to  FIG. 12 , the action removing clip  2114  is a linear, perpendicular movement relative to the axis “A” of the drug container  2050 . 
     In accordance with an aspect of the invention as illustrated in the embodiment of  FIGS. 10A-31C , the drive mechanism  2100  is small in size and/or device footprint, yet capable of providing the dispensing force needed to push a drug fluid from a drug container  2050  through a fluid conduit  2030  for drug delivery via an insertion mechanism  2200 . In this embodiment of the drive mechanism  2100 , the piston biasing members  2106 ,  2122  are disposed in parallel, in contrast to the series disposal of the embodiments of  FIGS. 1A-9C . It will thus be appreciated by those of skill in the art that the drive mechanism  2100  of  FIGS. 10A-14B  yields a significantly smaller footprint than prior art devices or even the drive mechanisms  100 ,  500 ,  1000  of the other embodiments herein. 
     For the purposes of this disclosure and its claims, when used in connection with biasing members, be it a specific embodiment of biasing members, such as springs, or the general use of the term “biasing members,” the terms “parallel” are to be interpreted as they would by those of skill in the art. That is, the terms “series,” “in series,” or “disposed in series” is to be interpreted as springs disposed and operating as they would when connected end to end, and the terms “parallel,” “in parallel,” or “disposed in parallel” is to be interpreted as springs disposed and operating as they would in a side-by-side relationship. 
     Those of skill in the art will appreciate that for biasing members disposed in series, the inverse of equivalent spring constant will equal the sum of the respective inverses of the spring constants of the individual biasing members. In contrast, the equivalent spring constant of biasing members  2106 ,  2122  in a parallel relationship will be the sum of the spring constants of the individual biasing members. Similarly, the dispensing force exerted by the biasing members  2106 ,  2122  in a parallel relationship will be the sum of the forces exerted by the biasing members  2106 ,  2122  individually. As a result, the use of biasing members  2106 ,  2122  disposed in parallel provides the desired dispensing force in a substantially more compact package, allowing the drive mechanism  2100  to be more compact than the embodiments of  FIGS. 1A-9C . By extension, the use of biasing members  2106 ,  2122  disposed in parallel may allow the entire drug pump  2010  to be substantially more compact than an arrangement wherein the biasing members are disposed in series. 
     In this embodiment, the biasing members  2106 ,  2122  are in the form of a pair of concentrically disposed compression springs. Alternate arrangements are envisioned, however. For example, one or more of the biasing members could alternately, for example, be tension springs, depending upon the structure of the components of the drive mechanism. Moreover, in the illustrated drive mechanism  2100 , the biasing members  2106 ,  2122  are disposed concentrically with respect to each other and the piston  2100 . In an alternate embodiment, however, the biasing members may be alternately disposed, as, by way of example only, in a side by side arrangement, or on opposite sides of the piston. In still further embodiments, three or more biasing members could be provided and disposed in parallel in any appropriate configuration. It will further be appreciated, that an additional biasing member may be provided and disposed in series with one or more of the parallelly disposed biasing members. For example, in an embodiment where the piston includes an extension, similar to the piston extension  102  of the embodiment of  FIGS. 1A-4E , for example, an additional biasing member may be provided to engage the piston extension. 
     Returning now to the embodiment of  FIGS. 10A-14B , the drive mechanism  2100  includes an end-of-dose indicator  2133 . The end-of-dose indicator  2133  includes a switch interconnect  2132  and a contact sleeve assembly  2120  adapted for movement with the piston  2110 . Piston  2110  has an interface surface  2112  that is capable of contacting or otherwise bearing upon plunger seal  2060  to force drug fluid out of barrel  2058  through the fluid pathway connection  2300  for delivery to a patient. In order to provide access of the end-of-dose indicator  2133  to the interior of the drive housing  2130  includes an access window  2131 , the significance of which will be described further below. 
     The contact sleeve assembly  2120  of the embodiment illustrated in  FIGS. 11-13C  includes a pair of telescoping sleeves  2124 ,  2126 . The first sleeve  2124  is adapted for movement with the piston  2110  as the piston biasing members  2106 ,  2122  are deenergized. A distal, generally radially extending flange  2124 A of the first sleeve  2124  is disposed subjacent the head  2111  of the piston  2110 . In this way, one or both of the biasing members  2106 ,  2122  bear against the flange  2124 A, which bears against the piston head  2111  to impart axial movement to the piston  2110 . The second sleeve  2126  is slidably coupled to the first sleeve  2124 , the first sleeve  2124  sliding distally outward from the second sleeve  2126 . In order to permit the second sleeve  2126  to travel with the first sleeve  2124  when the first sleeve  2124  is fully extended from the second sleeve  2126 , a coupling structure is provided. In the illustrated embodiment the sleeves  2124 ,  2126  include respective flanges  2124 B,  2126 A that engage as the proximal end of the first sleeve  2124  approaches the distal end of the second sleeve  2126  (see  FIG. 13A ) to cause the second sleeve  2126  to likewise move in an axial direction with the piston  2110  (see  FIG. 13C ). 
     It will be appreciated, however, that alternate arrangements are envisioned. By way of example only, the first sleeve  2124  could alternatively be integrally formed with the piston  2110 . In this way, the first sleeve  2124  formed with the piston  2110  would telescope outward from a second sleeve  2126  in a manner similar to that described above. Moreover, while the sleeve assembly  2120  has been described as including a pair of telescoping sleeves, alternate numbers of sleeves may be used, such as three or more telescoping sleeves. The number of sleeves may be dependent upon the cooperative structures, however, such as the relative dimensions of the drive housing  2130 , and the travel of the piston  2110 . For example, in an embodiment utilizing a smaller drive housing, but having a similar piston travel, three or more telescoping sleeves may be desirable. In some embodiments where multiple sleeves are provided about the biasing members  2106 ,  2122 , and the biasing members  2106 ,  2122  are in the form of compression springs, such as shown in the illustrated embodiment, the springs in a compressed, energized state may have a length equal to the untelescoped sleeves  2124 ,  2126 , yet have an uncompressed, deenergized length that is equal to the length of the telescoped sleeves. Further, while the end-of-dose indicator  2133  is described in connection with a drive mechanism  2100  including a plurality of biasing members disposed in parallel, those of skill in the art will appreciate that the end-of-dose indicator  2133  could also be utilized in connection with a drive mechanism including a single biasing device or a plurality of biasing members disposed in series and/or parallel. 
     As the sleeve assembly  2120  moves axially outward, the proximal end  2126 B of the sleeve assembly  2120  passes the window  2131  of the drive housing  2130 . In the illustrated embodiment in particular, as the second sleeve  2126  moves axially outward, the proximal end  2126 B of the second sleeve  2126  passes the window  2131  of the drive housing  2130 . 
     The switch interconnect  2132  includes a sensor  2134  and an electronic coupling  2136  to the power and control system  2400 . At least a portion of the sensor  2134  is disposed adjacent the window  2131 , and is adapted to identify a change in the presence of the contact sleeve assembly  2120  proximal to the window  2131  within the drive housing  2130 . For example, in the illustrated embodiment, the sensor  2134  may read that the sleeve assembly  2120  is no longer present proximal to the window  2131 . 
     In order to better illustrate the relationship of the sensor  2134  and the sleeve assembly  2120  during movement of the sleeve assembly  2120 , portions of the sleeve assembly  2120  are broken away in  FIGS. 13A-13B ; in  FIGS. 14A-14B , the housing  2130 , sleeve  2126 , biasing members  2106 ,  2122 , and end-of-dose indicator  2133  are shown in cross-section taken along line  14 - 14  in  FIG. 11 . In the illustrated embodiment, the sleeve assembly  1120  is disposed adjacent the window  2131  when the piston  2110  is in the retracted first position (see  FIG. 13A ), and as the sleeve assembly  1120  begins to telescope outward with the piston  2110  (see  FIGS. 13B and 14A ). Conversely, the sleeve assembly  1120  is not disposed adjacent the window  2131  when the piston  2110  is in a fully extended second position (see  FIGS. 13C and 14B ). As the proximal end  2126 B of the second sleeve  2126  passes the window, the switch interconnect  2132  identifies that the sleeve assembly has passed the window  2131 , and that the end of dose has occurred, and provides that information to the power and control system  2400 . The electronic coupling  2136  may be of any appropriate design. In the illustrated embodiment, for example, the sensor  2134  connects directly to a PCB board  2138 . 
     The switch interconnect  2132  illustrated includes a mechanical sensor  2134  in the form of a pivotably mounted trigger  2135 , in essence, an on/off mechanical switch. The trigger  2135  is disposed in a first position in contact with the sleeve assembly  2120  when the piston  2110  is in a retracted first position. As the piston  2110  moves outward from the drive housing  2130 , the trigger  2135  slides along the telescoping sleeve assembly  2120  until such time as the proximal end  2126 B of the second sleeve  2126  passes the window  2131 , that is, the trigger  2135 . As the second sleeve  2126  passes the trigger  2135 , the trigger  2135  moves to a second position. The movement of the trigger  2135  to the second position results in the electronic coupling  2135  providing a signal indicating the end of dose to the power and control system  2400 . 
     The switch interconnect  2132  may be of any appropriate design, however. For example, the switch interconnect  2132  may include a sensor of an electromechanical nature, such as the one illustrated in  FIGS. 10A-14B , or a sensor of an electrical nature, such as, for example, an optical reader or sensor. Additionally or alternatively, the switch interconnect  2132  may utilize an ultrasonic sensor, a capacitive sensor, a magnetic sensor, or a number of other types of sensors. Accordingly, the sensor may not require physical contact with the corresponding reference component. In an embodiment including an optical sensor, the sensor may read when the presence or absence of the sleeve assembly  2120 , for example, reading the interior of the drive housing  2130  opposite the window  2131 . The sensor may be configured to additionally or alternatively identify at least one of when the sleeve assembly is disposed subjacent the window and when the sleeve assembly is not disposed subjacent the window, the relative motion of the sleeve assembly with reference to the window or another reference component, the stoppage of such motion, and the rate or change of rate of motion. 
     Although illustrated as an electromechanical arrangement that reads the position of a telescoping sleeve, any appropriate arrangement may be provided to read the relative position of any appropriate component, the end-of-dose indicator providing a signal to the power and control system to indicate that all of the drug has been administered. Additionally, the switch interconnects and corresponding contacts and/or reference component may be utilized to provide incremental status indication in addition to an end-of-dose indication. For example, in the switch interconnect arrangement described above with reference to  FIGS. 10A-13C , the switch interconnect  2132  may be an electromechanical sensor configured to recognize a number of bumps, ridges, or grooves, in the corresponding sleeve  2126  or any other reference component, the contact with which permits the switch interconnect to signal an incremental status indication (e.g., delivery initiation, amount of volumes delivered, duration of plunger travel, etc.) and a final end-of-dose indication. As described herein, similar incremental status indication may be provided in this configuration by utilizing a different type of sensor arrangement. For example, the switch interconnect  2132  may be an optical sensor configured to recognize a number of markings on the corresponding sleeve  2126  or any other reference component. As the optical sensor recognizes the number of markings, it permits the switch interconnect to signal an incremental status indication (e.g., delivery initiation, amount of volumes delivered, duration of plunger travel, etc.) and a final end-of-dose indication. Any appropriate arrangement may be provided to read the relative position of a number of markings, ridges, grooves, or respective indicators on any appropriate reference component, and recognition of such indicators by the switch interconnect permits it to provide a signal to the power and control system to indicate the incremental status of drug delivery, including the final status that all of the drug has been administered. As would be appreciated by an ordinarily skilled artisan in the relevant arts, the indicators may not necessarily be defined aspects on a reference component, and the switch interconnects may be configured to recognize the actual travel of the reference component itself. The switch interconnects may thus be configured to recognize the rate of change, the distance of travel, or other related measurements in the actual travel of the reference components and enable a signal to the power and control system to provide the user with such information or feedback. 
     It will be appreciated by those of skill in the art that the embodiments of the present invention provide the necessary drive force to push a plunger seal and a drug fluid within a drug container, while reducing or minimizing the drive mechanism and overall device footprint. Accordingly, the present invention provides a drive mechanism which may be utilized within a more compact drug delivery pump device. The embodiments of the present invention may similarly be utilized to provide additional force, as may be needed for highly viscous drug fluids or for larger volume drug containers. 
     The embodiments shown and detailed herein disclose only a few possible variations of the present invention; other similar variations are contemplated and incorporated within the breadth of this disclosure. 
     The drive mechanism may further include one or more contact surfaces located on corresponding components. Such contact surfaces may be electrical contact surfaces, mechanical contact surfaces, or electro-mechanical contact surfaces. Such surfaces may initially be in contact and caused to disengage, or initially be disconnected and caused to engage, to permit a signal to be sent to and/or from the power control system  2400 . 
     A fluid pathway connection, and specifically a sterile sleeve of the fluid pathway connection, may be connected to the cap and/or pierceable seal of the drug container. A fluid conduit may be connected to the other end of the fluid pathway connection which itself is connected to the insertion mechanism such that the fluid pathway, when opened, connected, or otherwise enabled travels directly from the drug container, fluid pathway connection, fluid conduit, insertion mechanism, and through the cannula for drug delivery into the body of a user. The components which constitute the pathway for fluid flow are now assembled. These components may be sterilized, by a number of known methods, and then mounted either fixedly or removably to an assembly platform or housing of the drug pump, as shown in  FIG. 1B . 
     Certain optional standard components or variations of drive mechanism  100  or drug pump  10  are contemplated while remaining within the breadth and scope of the present invention. For example, upper or lower housings may optionally contain one or more transparent or translucent windows  18 , as shown in  FIG. 1A , to enable the user to view the operation of the drug pump  10  or verify that drug dose has completed. Additionally, the drug pump  10  may contain an adhesive patch  26  and a patch liner  28  on the bottom surface of the housing  12 . The adhesive patch  26  may be utilized to adhere the drug pump  10  to the body of the user for delivery of the drug dose. As would be readily understood by one having ordinary skill in the art, the adhesive patch  26  may have an adhesive surface for adhesion of the drug pump to the body of the user. The adhesive surface of the adhesive patch  26  may initially be covered by a non-adhesive patch liner  28 , which is removed from the adhesive patch  26  prior to placement of the drug pump  10  in contact with the body of the user. Removal of the patch liner  28  may further remove the sealing membrane  254  of the insertion mechanism  200 , opening the insertion mechanism to the body of the user for drug delivery (as shown in  FIG. 1C ). 
     Similarly, one or more of the components of drive mechanism  100  and drug pump  10  may be modified while remaining functionally within the breadth and scope of the present invention. For example, as described above, while the housing of drug pump  10  is shown as two separate components upper housing  12 A and lower housing  12 B, these components may be a single unified component. Similarly, while electrical contact  134  is shown as a separate component from contact sleeve  140 , it may be a unified component printed onto the ring surface of the contact sleeve  140 . As discussed above, a glue, adhesive, or other known materials or methods may be utilized to affix one or more components of the drive mechanism and/or drug pump to each other. Alternatively, one or more components of the drive mechanism and/or drug pump may be a unified component. For example, the upper housing and lower housing may be separate components affixed together by a glue or adhesive, a screw fit connection, an interference fit, fusion joining, welding, ultrasonic welding, and the like; or the upper housing and lower housing may be a single unified component. Such standard components and functional variations would be appreciated by one having ordinary skill in the art and are, accordingly, within the breadth and scope of the present invention. 
     It will be appreciated from the above description that the drive mechanisms and drug pumps disclosed herein provide an efficient and easily-operated system for automated drug delivery from a drug container. The novel embodiments described herein provide integrated status indication to provide feedback to the user. The novel drive mechanisms of the present invention may be directly or indirectly activated by the user. For example, in at least one embodiment the lockout pin(s) which maintain the drive mechanism in its locked, energized state are directly displaced from the corresponding lockout grooves of the piston  110  by user depression of the activation mechanism. Furthermore, the novel configurations of the drive mechanism and drug pumps of the present invention maintain the sterility of the fluid pathway during storage, transportation, and through operation of the device. Because the path that the drug fluid travels within the device is entirely maintained in a sterile condition, only these components need be sterilized during the manufacturing process. Such components include the drug container of the drive mechanism, the fluid pathway connection, the sterile fluid conduit, and the insertion mechanism. In at least one embodiment of the present invention, the power and control system, the assembly platform, the control arm, the activation mechanism, the housing, and other components of the drug pump do not need to be sterilized. This greatly improves the manufacturability of the device and reduces associated assembly costs. Accordingly, the devices of the present invention do not require terminal sterilization upon completion of assembly. A further benefit of the present invention is that the components described herein are designed to be modular such that, for example, housing and other components of the pump drug may readily be configured to accept and operate drive mechanism  100 , drive mechanism  500 , or a number of other variations of the drive mechanism described herein. 
     Manufacturing of a drug pump includes the step of attaching both the drive mechanism and drug container, either separately or as a combined component, to an assembly platform or housing of the drug pump. The method of manufacturing further includes attachment of the fluid pathway connection, drug container, and insertion mechanism to the assembly platform or housing. The additional components of the drug pump, as described above, including the power and control system, the activation mechanism, and the control arm may be attached, preformed, or pre-assembled to the assembly platform or housing. An adhesive patch and patch liner may be attached to the housing surface of the drug pump that contacts the user during operation of the device. 
     A method of operating the drug pump includes the steps of: activating, by a user, the activation mechanism; displacing a control arm to actuate an insertion mechanism; and actuating a power and control system to activate a drive control mechanism to drive fluid drug flow through the drug pump. The method may further include the step of: engaging an optional on-body sensor prior to activating the activation mechanism. The method similarly may include the step of: establishing a connection between a fluid pathway connection to a drug container. Furthermore, the method of operation may include translating a plunger seal within the drive control mechanism and drug container to force fluid drug flow through the drug container, the fluid pathway connection, a sterile fluid conduit, and the insertion mechanism for delivery of the fluid drug to the body of a user. The method of operation of the insertion mechanism and the drug pump may be better appreciated with reference to  FIGS. 4A-4E , as described above. 
     Throughout the specification, the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention. The disclosure of each patent and scientific document, computer program and algorithm referred to in this specification is incorporated by reference in its entirety.