Dual reservoir positive displacement pump mechanism

Abstract

Disclosed herein is a dual reservoir configuration for a space-efficient pump mechanism comprising an outer reservoir and an inner reservoir, where linear translation of the inner reservoir causes the inner reservoir to move into the outer reservoir and act as a plunger for the outer reservoir to force fluid contained therein through a first fluid port. A static plunger disposed within the inner reservoir forces fluid disposed within the inner reservoir through a second fluid port. Also disclosed are various drive mechanisms for causing linear movement of the first reservoir into the second reservoir.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 304,270, filed January 28, 2022, the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] Many conventional automated drug delivery systems are known, including, for example, a wearable drug delivery device of the type shown in FIG. 2. The drug delivery device 102 can be designed to deliver any type of liquid drug to a user. In certain embodiments, the drug delivery device 102 can be, for example, an OmniPod® drug delivery device manufactured by Insulet, Inc. of Acton, Massachusetts. The drug delivery device 102 can be a drug delivery device such as those described in U.S. Pat. No. 7,303,549, U.S. Pat. No. 7,137,964, or U.S. Pat. No. 6,740,059, each of which is incorporated herein by reference in its entirety.

[0003] The drug delivery device 102 typically includes a positive displacement pump mechanism. Typically, the pump mechanism includes a reservoir that stores a liquid drug. The liquid drug stored in the reservoir can be delivered to a user by forcing the drug out of the reservoir using a drive plunger that translates longitudinally through the reservoir and expelling the liquid drug through a fluid port defined in the reservoir. The plunger can be translated longitudinally through the reservoir, for example, by a rigid lead screw that pushes the plunger forward during pumping. When the reservoir is filled, the lead screw moves rearward with the plunger. The lead screw extends beyond the back of the plunger a distance equal to the stroke of the plunger plus an additional amount to allow engagement with the drive mechanism. This creates space efficiency constraints when scaling the design. As the stroke of the plunger increases, the length of the lead screw must also increase by the same amount.

[0004] In a body worn device, it is desirable to keep the pump mechanism, as well as the drug delivery device 102 as a whole, as small as possible to minimize shock to the wearer. In addition, because such drug delivery devices are typically powered by on-board batteries, it is desirable to minimize the power required to operate the device.

[0005] It is therefore desirable to replace the prior art pump mechanisms with positive displacement pumps having a more space efficient pump mechanism to allow for smaller devices to reduce strain on the user.

[0006] definition As used herein, the term "liquid medication" should be taken to include any medication in liquid form that can be administered by a medication delivery device via a subcutaneous cannula, including, for example, insulin, GLP-1, pramlintide, morphine, blood pressure medications, chemotherapy medications, fertility medications, etc., or co-formulations of two or more of GLP-1, pramlintide, and insulin. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Pat. No. 7,303,549 [Patent Document 2] U.S. Pat. No. 7,137,964 [Patent Document 3] U.S. Patent No. 6,740,059 Summary of the Invention

[0008] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. It is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

[0009] The primary embodiment of the invention disclosed herein uses a dual reservoir configuration having a relatively large outer reservoir and a relatively small inner reservoir, the inner reservoir having a slightly smaller cross-sectional shape than the outer reservoir so that the inner reservoir, acting as a plunger for the outer reservoir, can move linearly through the outer reservoir. The two reservoirs are in fluid communication with each other through a rigid hollow rod that is disposed between the inner and outer reservoirs and supports a static plunger against the inner reservoir such that as the inner reservoir moves linearly into the outer reservoir, the inner reservoir forces fluid from the outer reservoir through the hollow rod and into the inner reservoir. The static plunger in the inner reservoir acts to force fluid out of the inner reservoir through a fluid exhaust port as the inner reservoir is moved linearly into the outer reservoir.

[0010] The dual reservoir configuration utilizes a second reservoir and a static plunger to utilize the space occupied by the lead screw in prior art examples of drug delivery devices. This makes embodiments using the dual reservoir configuration more space efficient than prior art examples. Variations on the primary embodiment are directed to different methods of driving the inner reservoir into the outer reservoir and are described in detail below.

[0011] In the drawings, like reference numbers generally refer to the same parts throughout the different views.In the following description, various embodiments of the present invention are described with reference to the following drawings, in which: [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 illustrates a functional block diagram of an exemplary system suitable for implementing the systems and methods disclosed herein. [Diagram 2] FIG. 2 is an illustration of a prior art wearable drug delivery device of the type in which the inventions disclosed herein may be used. [Figure 3A-3D] 3A-3D are schematic cross-sectional views of a primary embodiment of the present invention, showing the outer reservoir, the inner reservoir, the hollow connecting rod and the static plunger when the device is filled with fluid and when fluid is being dispensed. [Figure 4A-4B] 4A-4B are opaque perspective views of a first variation of the primary embodiment, in which a lead screw coupled to an inner reservoir is rotated by a tube nut to drive the inner reservoir into the outer reservoir. [Figure 5A-5C] 5A-5C are opaque perspective views of a second variant of the primary embodiment, in which the lead screw is threadedly engaged with a pushing element that, when the lead screw rotates, pushes on the rear surface of the inner reservoir to drive the inner reservoir into the outer reservoir. [Figure 6A-6B]6A-6B are opaque perspective views of a third variant of the primary embodiment, in which a lead screw is threadedly engaged with the inner reservoir such that rotation of the lead screw drives the inner reservoir into the outer reservoir. [Figure 7A-7B] 7A-7B are opaque perspective views of a fourth variant of the primary embodiment in which a rack and pinion arrangement is used to move the outer reservoir towards the inner reservoir so as to drive the inner reservoir into the outer reservoir. [Figure 8A-8B] 8A-8B are opaque perspective views of a fifth variant of the primary embodiment, in which two lead screws are threadedly engaged with the inner reservoir such that synchronous rotation of the lead screws drives the inner reservoir into the outer reservoir. [Figure 9] FIG. 9 is a schematic cross-sectional view of a secondary embodiment in which the inner reservoir is driven into the outer reservoir using a central lead screw, requiring two fluid ports. [Figure 10A-10B] 10A-10B are opaque cutaway views of a second embodiment of the invention in which a central lead screw in the inner reservoir is used to drive the inner reservoir into the outer reservoir. [Figures 11A-11C] 11A-11C show different exemplary embodiments of reservoirs having different cross-sectional shapes. [Figure 12A-12B] 12A-12B show two possible embodiment plunger configurations suitable for use in all embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention provides various systems, components, and methods for transferring a liquid medication from a liquid reservoir in a medication delivery device to a patient interface, such as a needle or cannula. The embodiments described herein provide one or more advantages over conventional prior art systems, components, and methods, namely, an overall smaller packaging area for the medication delivery device.

[0014] Various embodiments of the present disclosure include systems and methods for delivering medication to a user using a medication delivery device (sometimes referred to herein as a "pod"), either autonomously or according to a wireless signal received from an electronic device. In various aspects, the electronic device may be a smartphone, a smart watch, a smart necklace, a user device with a module attached to the medication delivery device, or any other type or kind of electronic device that may be carried by a user or worn on the user's body and that executes an algorithm to calculate the number and dosage of medication deliveries.

[0015] For example, the user device may execute an "artificial-pancreas" (AP) algorithm that calculates the frequency and dosage of insulin deliveries. The user device may also communicate with a sensor, such as a glucose sensor or continuous glucose monitor (CGM), that collects data regarding the user's physical characteristics or condition, such as glucose concentration. The sensor may be placed in or on the user's body and may be part of the drug delivery device or may be a separate device.

[0016] Alternatively, the drug delivery device may communicate with the sensor instead of or in addition to communication between the sensor and the user device. This communication may be direct (e.g., if the sensor is integrated or otherwise part of the drug delivery device) or remote / wireless (e.g., if the sensor is located in a separate housing from the drug delivery device). In these embodiments, the drug delivery device includes computer hardware (e.g., processor, memory, firmware, etc.) that executes some or all of the algorithms to calculate the time and dosage of drug delivery.

[0017] 1 shows a functional block diagram of an exemplary drug delivery system 100 suitable for implementing the systems and methods described herein. The drug delivery system 100 may implement drug delivery algorithms (and / or provide functionality), such as for artificial pancreas (AP) applications, to manage or control the automatic delivery of a drug or medication, such as insulin, to a user (e.g., to maintain euglycemia-normal blood sugar levels in the blood). The drug delivery system 100 may be an automatic drug delivery system that may include a drug delivery device 102 (which may be wearable), an analyte sensor 108 (which may be wearable), and a user device 105 (which may be wearable).

[0018] The drug delivery system 100 may also include an accessory device 106, such as a smart watch, personal assistant device, etc., in any example, that can communicate with other components of the system 100 via either wired or wireless communication links 191-193.

[0019] User Device The user device 105 may be a computing device such as a smartphone, a smartwatch, a tablet, a personal diabetes management (PDM) device, a dedicated diabetes care management device, etc. For example, the user device 105 may have a processor 151, a device memory 153, a user interface 158, and a communication interface 154. The user device 105 may also include analog and / or digital circuitry that may be implemented as the processor 151 to execute processing based on program code stored in the device memory 153, such as a user application 160, to manage the user's blood glucose level, to control the delivery of medication, drugs or therapeutics to the user, and to provide other functions such as calculation of carbohydrate compensation amounts, correction bolus amounts, etc., as described below. The user device 105 may be used to activate, deactivate, trigger, needle / cannulate, program, adjust settings, and / or control operations of the medication delivery device 102 and / or analyte sensor 103 and optional smart accessory device 106.

[0020] The processor 151 may also be configured to execute programming code stored in the device memory 153, such as a user application 160. The user application 160 may be a computer application operable to deliver medication based on information received from the analyte sensor 103, the cloud-based service 111, and / or the user device 105 or the optional accessory device 106. The memory 153 may also store programming code for operating a user interface 158 (e.g., a touch screen device, a camera, etc.), a communication interface 154, etc. When executing the user application 160, the processor 151 may be configured to implement indicators and notifications regarding meal intake, blood glucose measurements, etc. The user interface 158 is under the control of the processor 151 and may be configured to present a graphical user interface, such as to enable input of meal announcements, adjust setting selections, etc., as described herein.

[0021] In a specific example, when the user application 160 is for an artificial pancreas (AP) application, the processor 151 is also configured to execute a diabetes treatment plan (which may be stored in memory) managed by the user application 160. In addition to the above-mentioned functions, when the user application 160 is for an artificial pancreas (AP) application, it may further provide functionality for determining carbohydrate compensation doses, correction bolus doses, and determining real-time basal doses according to the diabetes treatment plan. Furthermore, as an artificial pancreas (AP) application, the user application 160 provides functionality for outputting signals to the drug delivery device 102 via the communication interface 154 to deliver the determined bolus and basal doses.

[0022] Communications interface 154 includes one or more transceivers that operate according to one or more radio frequency protocols. In one embodiment, the transceivers may include a cellular transceiver and a Bluetooth transceiver. Communications interface 154 may be configured to receive and transmit signals containing information usable by user applications 160.

[0023] The user device 105 may further include one or more output devices 155, which may be, for example, speakers or vibration transducers, for providing various signals to the user.

[0024] Drug Delivery Devices In various exemplary embodiments, the drug delivery device 102 may have a reservoir 124 and a drive mechanism 125 controllable by a controller 121, which executes a drug delivery algorithm (MDA) 129 stored in memory 123 and may perform some or all of the functions of the AP application described above, such that the user device 105 may not need the drug delivery and control performed by the drug delivery device 102. Alternatively, the controller 121 may act to control the reservoir 124 and the drive mechanism 125 based on signals received from a user application 160 executing on the user device 105 and communicated to the drug delivery device 102 via communication line 194. The drive mechanism 125 operates to translate a plunger longitudinally through the reservoir to force the liquid drug through a fluid exit port and into the needle / cannula 186.

[0025] In alternative embodiments, the drug delivery device 102 may also have an optional second reservoir 124-2 and second drive mechanism 125-2, allowing for independent delivery of two different liquid drugs. For example, the reservoir 124 may be filled with insulin and the reservoir 124-2 may be filled with pramlintide or GLP-1. In some embodiments, each of the reservoirs 124, 124-2 may be configured with a separate drive mechanism 125, 125-2, respectively, which may be separately controllable by the controller 121 under the direction of the MDA 129. Both reservoirs 124, 124-2 may be connected to a common needle / cannula 186.

[0026] The drug delivery device 102 may optionally be configured with a user interface 127 providing means for receiving input from a user and for outputting information to the user. The user interface 127 may comprise, for example, a light emitting diode, a button on the housing of the drug delivery device 102, an acoustic transducer, a microdisplay, a microphone, an accelerometer for detecting device movement or a user gesture (e.g. tapping on the housing of the device), or any other type of interface device configured to allow a user to input information and / or enable the drug delivery device 102 to emit information for presentation to a user (e.g. an alarm signal, etc.).

[0027] The drug delivery device 102 has a patient interface 186 for mating with a user to deliver a liquid drug. The patient interface may be, for example, a needle or cannula for delivering the drug to the user's body (which may be subcutaneous, intraperitoneal, or intravenous). The drug delivery device 102 further has a mechanism for inserting the needle / cannula 186 into the user's body, which may be integral to the drug delivery device 102 or may be attachable thereto. The insertion mechanism may, in one embodiment, comprise an actuator that inserts the needle / cannula 186 beneath the user's skin and then retracts the needle, leaving the cannula in place. The actuator may be triggered by the user device 105 or may be a manual firing mechanism with a spring or other energy storage mechanism that causes the needle / cannula 186 to pierce the user's skin.

[0028] In one embodiment, the medication delivery device 102 has a communication interface 126, which may be a transceiver operating according to one or more radio frequency protocols such as Bluetooth, Wi-Fi, near field communication, cellular, etc. The controller 121 may communicate with the user device 105 and the analyte sensor 108, for example, via the communication interface 126.

[0029] In some embodiments, the drug delivery device 102 may include one or more sensors 184. The sensors 184 may include one or more of a pressure sensor, a power sensor, etc. communicatively coupled to the controller 121 and providing various signals. For example, the pressure sensor may be configured to provide an indication of fluid pressure detected in a fluid path between the patient interface 186 and the reservoir 124. The pressure sensor may be coupled to or integrated with an actuator for inserting the patient interface 186 into a user. In one example, the controller 121 may be operable to determine a rate of drug infusion based on the indication of fluid pressure. The rate of drug infusion may be compared to an infusion rate threshold, and the comparison may be usable in determining an insulin payload (IOB) or a total daily insulin (TDI) amount. In one embodiment, the analyte sensor 108 may be integrated with the drug delivery device 102.

[0030] The drug delivery device 102 further includes a power source 128, such as a battery, a piezoelectric device, an energy harvesting device, etc., for powering the control unit 121, the memory 123, the drive mechanism 125, and / or other components of the drug delivery device 102.

[0031] The medication delivery device 102 may be configured to implement and perform the processes required to deliver multiple doses of medication to a user without input from the user device 105 or optional accessory device 106. As will be described in more detail, the MDA 129 may be operable to determine, for example, the amount of insulin to be delivered, the IOB, remaining insulin, etc., and to cause the controller 121 to actuate the drive mechanism 125 to deliver medication from the reservoir 124. The MDA 129 may obtain as input data received from the analyte sensor 108 or a user application 160.

[0032] The reservoirs 124, 124-2 may be configured to store a pharmaceutical, drug or therapeutic agent suitable for automated delivery, such as insulin, pramlintide, GLP-1, co-formulations of insulin and GLP-1, morphine, blood pressure medications, chemotherapy medications, fertility medications, and the like.

[0033] The drug delivery device 102 may be a wearable device that may be attached to the body of a user, such as a patient or diabetic, at an attachment location and may deliver any therapeutic agent, including any drug or medication, such as insulin, to the user at or about the attachment location. The surface of the drug delivery device 102 may have an adhesive to facilitate attachment to the skin of a user.

[0034] When the drug delivery device 102 is configured to communicate with an external device, such as a user device 105 or an analyte sensor 108, the drug delivery device 102 can receive signals from the user device 105 or the analyte sensor 108 via a wired or wireless link 194. A controller 121 of the drug delivery device 102 can receive and process the signals from the respective external device and effectuate delivery of the drug to the user in accordance with a diabetes treatment plan or other drug delivery regimen.

[0035] Accessory Devices The optional accessory device 107 may be a wearable smart device, such as a smart watch (e.g., an Apple Watch®), smart glasses, smart jewelry, a Global Positioning System (GPS)-enabled wearable, a wearable fitness device, smart clothing, and the like. Similar to the user device 105, the accessory device 107 may also be configured to perform various functions, including controlling the drug delivery device 102. For example, the accessory device 107 may have a communication interface 174, a processor 171, a user interface 178, and a memory 173. The user interface 178 may be a graphical user interface presented on a touchscreen display of the smart accessory device 107. The memory 173 may store programming code for operating various functions of the smart accessory device 107, as well as an instance of the user application 160, or a simplified version of the user application 160 with reduced functionality. In some examples, the accessory device 107 may also have various types of sensors.

[0036] Analyte Sensors The analyte sensor 108 may include a controller 131, a memory 132, a detection / measurement device 133, an optional user interface 137, a power / energy harvesting circuit 134, and a communication interface 135. The analyte sensor 108 may be communicatively coupled to a processor 151 of the management device 105 or controller 121 of the medication delivery device 102. The memory 132 may be configured to store information and programming code 136.

[0037] The analyte sensor 108 may be configured to detect one or more different analytes, such as glucose, lactate, ketones, uric acid, sodium, potassium, and alcohol levels, and output a detection result, such as a measurement. In an exemplary embodiment, the analyte sensor 108 may be configured as a continuous glucose monitor (CGM) for measuring blood glucose levels at predetermined time intervals, such as every 5 minutes, every minute, and the like. The communication interface 135 of the analyte sensor 108 may include circuitry that operates as a transceiver to communicate the measured blood glucose levels to the user device 105 via wireless link 195 or to the drug delivery device 102 via wireless communication link 108. Although referred to herein as the analyte sensor 108, the detection / measurement device 133 of the analyte sensor 108 may include one or more additional sensing elements, such as a glucose measuring element, a heart rate monitor, a pressure sensor, and the like. The controller 131 may include separate dedicated logic and / or components, application specific integrated circuits, and microcontrollers or processors that execute software instructions, firmware, programming instructions stored in a memory (such as memory 132), or any combination thereof.

[0038] Similar to the controller 121 of the drug delivery device 102, the controller 131 of the analyte sensor 108 may be operable to perform a number of functions. For example, the controller 131 may be configured by programming code 136 to manage the collection and analysis of data detected by the detection and measurement device 133.

[0039] 1 as being separate from the drug delivery device 102, in various aspects the analyte sensor 108 and the drug delivery device 102 may be incorporated into the same unit. That is, in various embodiments the analyte sensor 108 may be part of and integral with the drug delivery device 102 and may be included in the same housing as or in a housing attachable to the drug delivery device 102. In such an exemplary configuration, the controller 121 may perform the functions required for proper delivery of the drug alone, without any external input from the user device 105, the cloud-based service 111, another sensor (not shown), the optional accessory device 106, etc.

[0040] Cloud-based services The drug delivery system 100 can communicate with or receive services from a cloud-based service 111. The services provided by the cloud-based service 111 can have a data memory that stores personalized or anonymized data, such as blood glucose measurements, past IOB or TDI, prior carbohydrate compensation doses, and other forms of data. Additionally, the cloud-based service 111 can process anonymized information from multiple users to provide generalized information related to TDI, insulin sensitivity, IOB, etc. The communication link 115 that couples the cloud-based service 111 to each device 102, 105, 106, 108 of the system 100 can be a cellular link, a Wi-Fi link, a Bluetooth link, or a combination thereof.

[0041] Communication Links The wireless communication links 115 and 191-196 may be any type of wireless link operating using a known wireless communication standard or a proprietary standard. By way of example, the wireless communication links 191-196 may provide a communication link based on Bluetooth, Zigbee, Wi-Fi, a short-range communication standard, a cellular standard, or any other wireless protocol via the respective communication interfaces 126, 135, 154, and 174.

[0042] Example of operation In an operational example, the user application 160 implements a graphical user interface that is the primary interface with the user and is used to start and stop the drug delivery device 102, program basal and bolus calculator settings for manual mode, as well as program settings specific to automatic mode (hybrid closed loop or closed loop).

[0043] The user application 160 provides a graphical user interface 158 that allows the use of large text, graphics, and on-screen instructions to prompt the user through the set-up process and use of the system 100. It is also used to program the user's custom basal insulin delivery profile, check the status of the drug delivery device 102, initiate an insulin bolus, change the patient's insulin delivery profile, handle system alerts and alarms, and allow the user to switch between automatic and manual modes.

[0044] The user application 160 can be configured to operate in a manual mode in which the user application 160 delivers insulin at a programmed basal rate and a user-defined bolus amount with the option to set a temporary basal profile. The controller 121 also has the capability to function as a sensor-enhanced pump in manual mode, using sensor glucose data provided by the analyte sensor 108 to feed into a bolus calculator.

[0045] The user application 160 may be configured to operate in an automatic mode that supports the user application 160 to use multiple target blood glucose values. For example, in one embodiment, the target blood glucose values ​​may be in the range of 110 mg / dL to 150 mg / dL, in 10 mg / dL increments, in 5 mg / dL increments, or other increments, preferably in 10 mg / dL increments. The user experience mirrors the current setup flow, whereby the healthcare provider assists the user in programming the basal rate, glucose goal, and bolus calculator setup. These inform the user application 160 about the insulin dosing parameters. The insulin dosing parameters are adapted over time based on the total daily insulin (TDI) delivered during each use of the drug delivery device 102. The hypoglycemic protection mode may be implemented by the user for various durations in the automatic mode. In the hypoglycemic protection mode, the algorithm reduces insulin delivery and is intended to be used for a hypoglycemic duration when insulin sensitivity is expected to be higher (e.g., during exercise).

[0046] The user application 160 (or MDA 129) may provide periodic insulin microboluses based on past glucose measurements and / or predicted glucose over a predicted period (e.g., 60 minutes). Optimal post-prandial control may require the user to deliver meal boluses in the same manner as current pump therapy, but normal operation of the user application 160 compensates for missed meal boluses and mitigates prolonged hyperglycemia. The user application 160 uses a control-to-goal strategy that attempts to achieve and maintain set target blood glucose levels, thereby reducing the duration of prolonged hyperglycemia and hypoglycemia.

[0047] In some embodiments, the user device 105 and the analyte sensor 108 may not communicate directly with each other. Instead, data from the analyte sensor (e.g., blood glucose level) may be communicated to the medication delivery device 102 via link 196 and then relayed to the user device 105 via link 194. In some embodiments, the analyte sensor serial number must be entered into the user application 160 to enable communication between the analyte sensor 108 and the user device 105.

[0048] The user application 160 may provide the ability to calculate a suggested bolus dose through the use of a bolus calculator. The bolus calculator is provided as a user convenience to help determine a suggested bolus dose based on ingested carbohydrates, the most recent blood glucose reading (or blood glucose reading if using a fingertip), a programmable correction factor, insulin to carbohydrate ratio, target blood glucose level, and on-board insulin (IOB). The user application 160 estimates the IOB, taking into account manual boluses and insulin.

[0049] Description of the embodiments A primary embodiment of the present invention is shown diagrammatically in Figures 3A-3C. Figure 3A shows the dual reservoirs in an empty configuration with the inner reservoir 304 linearly moved all the way into the outer reservoir 302. The outer reservoir 302 is fixed relative to the housing of the drug delivery device 102, and the inner reservoir 304 can be linearly moved in and out of the outer reservoir 302 using an external or internal drive mechanism. A static plunger 306 is fixed to the outer reservoir 302 via a hollow tube 308.

[0050] 3A shows a hollow tube 308 rigidly attached to a central portion of the back wall of the outer reservoir 302. The hollow tube 308 defines fluid ports 314, 316 at either end thereof so that fluid within the outer reservoir 302 can be forced through the hollow tube 308 and into the inner reservoir 304. A static plunger 306 is disposed within the inner reservoir 304 and acts to push fluid out of the inner reservoir 304 through the fluid port 310 as the inner reservoir 304 moves into the outer reservoir 302.

[0051] Preferably, there is a fluid seal 318 defined around the outer surface of the inner reservoir 304 to form a fluid seal between the outer surface of the inner reservoir 302 and the inner surface of the outer reservoir 304 to prevent any fluid contained within the outer reservoir 302 from leaking outward. Similarly, the static plunger 306 is configured with a fluid seal around its outer periphery to form a seal between the plunger 306 and the inner wall of the inner reservoir 304 to contain the fluid within the inner reservoir 304. To prevent leakage between the inner reservoir 304 and the outer reservoir 302 and between the hollow tube 308 and the end wall of the inner reservoir 304, additional seals (not shown) can be provided between the static plunger 306 and the hollow tube 308, which acts as a plunger as the inner reservoir 304 moves in direction "B" into the outer reservoir 302.

[0052] 3B illustrates the process of filling the dual reservoirs 302, 304. Adding fluid to the system through a fluid port 312 defined in the end wall of the outer reservoir 302 results in a pressure increase inside the outer reservoir 302. A hollow tube 308 fluidly connects the outer reservoir 302 with the inner reservoir 304, so that fluid travels through the hollow tube 308 from the outer reservoir 302 to the inner reservoir 304, causing an increase in pressure inside the inner reservoir 304. Note that the hollow tube 308 extends through the static plunger 306 to allow fluid to enter the sealed end of the inner reservoir 304. As the reservoirs continue to fill, the generated fluid pressure inside both reservoirs overcomes system friction and begins to move the inner reservoir 304 in direction "A" out of the outer reservoir 302 until it reaches the fully filled configuration shown in FIG. 3C when the end wall of the inner reservoir 304 contacts the static plunger 306. In an alternative embodiment, the reservoirs 302, 304 may be separated in the position shown in FIG. 3C prior to filling and then filled when separated. In this case, filling of the reservoirs does not urge the inner reservoir 304 in direction "A". When a user inserts liquid medication into either or both of the reservoirs 302, 304, air is forced out.

[0053] From the fully filled configuration shown in FIG. 3C, the fluid contained in both reservoirs can then be dispensed. FIG. 3D illustrates the process of dispensing fluid. The inner reservoir 304 is linearly displaced into the outer reservoir 302 in a manner controlled by an external driving force, which causes the inner reservoir 304 to move linearly in direction "B" and into the outer reservoir 302. Several exemplary driving mechanisms for providing the external driving force are disclosed herein. Forcing the inner reservoir 304 into the outer reservoir 302 reduces the available volume in both reservoirs 302, 304 and pressurizes the contained fluid. When the fluid pressure exceeds the applied back pressure, the fluid exits the pump mechanism through the fluid exhaust port 310 and is defined on the wall of the inner reservoir 304. The dispensing of fluid continues until both reservoirs reach the empty configuration shown in FIG. 3A when the end wall of the inner reservoir 304 contacts the end wall of the outer reservoir 302.

[0054] The location of both the fluid fill port 312 and the fluid drain port 310 are flexible so that they can be located on either the inner reservoir 304 or the outer reservoir 302. The option that best fits the system requirements can be selected for implementation. For example, having a fluid port on the moving inner reservoir 304 can create challenges regarding integration of the pump system with other subsystems of the drug delivery device 102. In various aspects, either of the fluid ports 310, 312 can serve as an inlet fluid port for the fluid drain port. In such cases, it may be necessary to seal the fluid port that acts as the drain port during filling of the reservoir and seal the fluid port that acts as the inlet port during delivery of fluid. In some embodiments, the pump mechanism can be configured with only one of the fluid ports 310, 312 acting as both an inlet fluid port and a fluid drain port.

[0055] As mentioned above, precise delivery of fluid requires precisely controlled movement of the inner reservoir 304 into the outer reservoir 302. In some embodiments, a clutch may be provided between the drive mechanism and the reservoir to which it is connected. This allows the drive mechanism to disengage from the reservoir to allow the user to fill the reservoir (e.g., during the filling process, when the reservoir is required, it moves in the opposite direction from its motion during the delivery process). Once filling is complete, the clutch is engaged to connect the drive mechanism to the reservoir, after which fluid can be delivered through actuation of the drive mechanism. Several variations of the primary embodiment featuring different drive mechanisms are now disclosed.

[0056] 4A-4B show a first extension of the primary embodiment in which the inner reservoir 304 is linearly moved into the outer reservoir 302 using a lead screw 406. The lead screw 406 is attached to the inner reservoir 304 as shown in FIG. 4A. Overmolding, heat sticking, or adhesives can be used to ensure a secure connection between the lead screw 406 and the inner reservoir 304. A tube nut 404, which is an elongated tube with internal threads for the lead screw 406, engages the end of the lead screw 406 opposite the end that engages the inner reservoir 304. The pumping action is produced by rotating the tube nut 404 in direction "D", as shown in FIG. 4B, which causes the inner reservoir 304 to be linearly moved in direction "E" into the outer reservoir 302. Axial movement of the tube nut 404 is restricted so that rotation of the tube nut 404 results in axial movement of the lead screw 406 and inner reservoir 304 via the threaded engagement between the lead screw 406 and the tube nut 404 .

[0057] 4A-4B also show a fluid seal 402 that extends around the circumference of the moving plunger 307 and forms a fluid seal between the outer surface of the inner reservoir 304 and the inner surface of the outer reservoir 302. The fluid seal 402 prevents the fluid contained in the outer reservoir 302 from escaping through the space between the outer reservoir 302 and the inner reservoir 304. FIGS. 4A-4B show that the plunger 306 is fitted with an O-ring around its circumference to form a fluid seal between the plunger 306 and the inner surface of the inner reservoir 304 to prevent the fluid contained in the inner reservoir 304 from escaping. Additionally, a fluid seal (not shown) may be provided between the hollow tube 308 and the moving plunger 307 to prevent leakage between the inner reservoir 304 and the outer reservoir 302.

[0058] 5A-5C show a second extension of the primary embodiment in which a lead screw 510 threadably engages the pusher member 502 via a threaded through hole 506 defined in the pusher member 502. As the lead screw 510 rotates, the pusher member 502 moves axially along the lead screw 510, but rotation of the pusher element 502 about the axis of the lead screw 510 is restricted. FIG. 5A shows an initial state in which none of the reservoirs are filled. The reservoirs 304 do not contact the pusher member 502 in the initial unfilled state. As the reservoirs 302, 304 fill, the inner reservoir 304 moves in the direction "F" and eventually engages the pusher member 502, as shown in FIG. 5B. Note that the reservoir 304 moves in the direction "F" due to the pressure generated by the filling of the reservoirs 302, 304, and not due to the action of the lead screw 510 or the movement of the pusher member 508. Once the reservoirs 302, 304 are in a filled condition as shown in FIG. 5B, the action of the lead screw 510 causes the inner reservoir 304 to move in the direction "E" as shown in FIG. 5C.

[0059] The lead screw 510 can be rotated by any known means. For example, the tube nut 404 shown in Figures 4A-4B can also be used in this variation, where alternatively or additionally, a motor can be used. Rotation of the lead screw 510 in direction "D" results in linear movement of the pushing member 502 in direction "E" along the longitudinal axis of the lead screw 510. In some embodiments, the pushing member 502 can be configured with a protruding feature 504 that engages with a recess 508 defined on the exterior of the end wall of the inner reservoir 304. In some embodiments, the protruding feature 504 can be hemispherical in shape and the recess 508 can be concave, or vice versa. In still other embodiments, any other type of engagement between the pushing member 502 and the exterior of the end wall of the inner reservoir 304 can be used. As the pushing member 502 is translated in direction "E" by rotation of the lead screw 510 in direction "D", the pushing member 502 engages the outer end wall of the inner reservoir 304, causing the inner reservoir 304 to move in direction "E" into the outer reservoir 302. A significant advantage of this embodiment compared to the embodiment shown in Figures 4A-4B is that no off-axis loads are applied to the inner reservoir 304. Thus, the inner reservoir 304 remains coaxially aligned with the outer reservoir 302 at all times.

[0060] 6A-6B show a third extension of the primary embodiment in which the pusher member 502 of the extension shown in FIGS. 5A-5B is integrated with the body of the inner reservoir 304, indicated by reference number 602. In the variation shown in FIG. 6A, the pusher member 602 is also integrated with the fluid port 310, although it should be noted that the pusher member 602 may be defined on the inner reservoir 304 separate from the fluid port 310, as will be understood. The pusher member 602 defines a through hole 604 having an internal thread. The pusher member 602 is in threaded engagement with the lead screw 510 such that rotation of the lead screw 510 in direction "D" causes a controlled linear movement of the inner reservoir 304 in direction "E" into the outer reservoir 302. As with the previous embodiment, the lead screw 510 may be rotated via a tube nut of the type shown in FIGS. 4A-4B as reference numeral 404, or by any other known means.

[0061] 7A-7B show a fourth extension of the primary embodiment. In this embodiment, the inner reservoir 304 is preferably rigidly attached to the housing of the drug delivery device 102, and the outer reservoir 302 is linearly moved to move over the inner reservoir 304, thereby linearly moving the inner reservoir 304 into the outer reservoir 302. In this variation, the drive mechanism is a rack and pinion arrangement. The outer reservoir 302 is configured with a rack gear 702 on its outer surface. The pinion gear 704 is rotated in the direction "F" by any known means, moving the outer reservoir 302 in the direction "F", thereby linearly moving the inner reservoir 304 into the outer reservoir 302 due to the linear movement of the outer reservoir 302 in the direction "F".

[0062] The lead screw / tube nut mechanism shown in the variation of Figures 4-6 provides precisely controlled axial displacement of the inner reservoir 304 and introduces a mechanical advantage into the system, but can reduce the energy efficiency of the system due to additional friction caused by off-axis loads between the lead screw threads and the tube nut threads, a limitation that is not present in this variation.

[0063] 8A-8B show a fifth extension of the primary embodiment. Lead screws are not a perfect mechanism for off-axis loads since friction losses increase exponentially as off-axis loads are applied to the system. To minimize the effect of off-axis loads on the lead screws, this variation uses two lead screws 802, 804. The lead screws 802, 804 are threadedly engaged with a pushing member 602 of the type shown in FIGS. 6A-6B, which is integral with the inner reservoir 304 and is located on either side of the inner reservoir 304. Thus, synchronous rotation of the lead screws 802, 804 in direction "D" causes linear movement of the reservoir 304 in direction "E", thereby driving the inner reservoir 304 into the outer reservoir 302. The lead screws 802, 804 can be rotated using a tube nut of the type shown in FIGS. 4A-4B as reference numeral 404 or any other known means. An alternative to using two lead screws (not shown) is to use a lead screw on one side and a smooth cylindrical rod on the other over which slides one of the pusher members 602. In this way, only one lead screw needs to be rotated while still overcoming the challenge of off-axis loads.

[0064] The use of dual lead screws not only increases the energy efficiency of the system by minimizing or eliminating off-axis moments applied to the lead screw / tube nut interface, but also improves alignment between the inner reservoir 304 and the outer reservoir 302. The variation using two lead screws (or one lead screw and a smooth cylindrical rod) can be applied to any of the variations of the invention shown in Figures 4-6 above. With respect to the embodiment shown in Figures 7A-7B, a dual rack and pinion mechanism can be used in a similar manner to the dual lead screw variation to achieve the same results.

[0065] FIG. 9 shows in schematic form a secondary embodiment of the invention using a dual reservoir configuration with central actuation. As discussed with respect to the previous embodiment and variations, side actuation has drawbacks such as misalignment between the inner reservoir 304 and the outer reservoir 302 and additional friction losses at the lead screw / tube nut interface. The embodiment shown in FIG. 9 overcomes these drawbacks by using a central actuation mechanism in which the lead screw 902 is located inside the inner reservoir 304 and contacts the end wall of the inner reservoir 304. As such, the lead screw 902 is positioned coaxially with the reservoirs 302, 304. In this case, the load is aligned with the desired direction of motion of the inner reservoir 304, preventing misalignment between the reservoirs 302, 304 and reducing friction losses in the lead screw 902.

[0066] 9 is a schematic diagram of a dual reservoir embodiment with central actuation, in which a lead screw 902 with an external thread is threadedly engaged with a tube nut 904 with an internal thread. A plunger tube 908 is rigidly attached to the housing of the drug delivery device 102 and supports a static plunger 906. In this embodiment, the outer reservoir 302 is also rigidly attached to the housing of the drug delivery device 102, and the tube nut 904 is restricted from moving axially but is free to rotate about its longitudinal axis in direction "C". The lead screw 902 is moved axially by its threaded engagement with the tube nut 904 to push the inner reservoir 304 into the outer reservoir 302 by engagement of the lead screw 902 with the end wall of the inner reservoir 304. In this embodiment, the interfaces between the inner reservoir 304 and the outer reservoir 302, the static plunger 906 and the inner reservoir 304, and the inner reservoir 304 and the plunger tube 908 are fluidly sealed by the means described above with respect to the other variations. Note that in this embodiment, because fluid is prevented from moving between the inner reservoir 304 and the outer reservoir 302, each of the inner reservoir 304 and the outer reservoir 302 must have individual fluid ports. The connection of the respective fluid ports from the inner reservoir 304 and the outer reservoir 302 is made external to the pump mechanism at any convenient location between the pump mechanism and the patient interface.

[0067] 10A-10B show cutaway views of this embodiment of the invention. Due to the threaded engagement between the lead screw 902 and the tube nut 904, rotation of the tube nut 904 causes the lead screw 902 to move in the direction "E" and push on the end wall of the inner reservoir 304, thereby moving the inner reservoir 304 into the outer reservoir 302.

[0068] Exemplary embodiments of the invention disclosed herein are presented with a reservoir having a circular cross-sectional shape. However, the invention is not so limited. In alternative embodiments, reservoirs having different cross-sectional shapes can be used, examples of which are shown in Figures 11A-11C. In a primary embodiment, the reservoir may have a circular cross-sectional shape, but other cross-sectional shapes such as a rectangle with rounded edges (Figure 11A), a flattened circle (Figure 11B), an ellipse (Figure 11C), etc. may be implemented without departing from the intended technical scope of the invention. Although a rectangular cross-sectional shape may provide increased volumetric efficiency over a circular cross-sectional shape, a rectangular cross-sectional shape also increases the risk of seal failure due to sharper corners. Ideally, a combination of rectangular and elliptical shapes may be a preferred option to achieve both reasonable sealing quality and volumetric efficiency, as shown in Figures 11A-11C.

[0069] As described with respect to the embodiments and variations disclosed herein, some interfaces, such as the interface between the inner reservoir 304 and the outer reservoir 302, need to be sealed to achieve the expected performance of the pump mechanism. In these cases, as shown in FIG. 12A, an O-ring can be used, which can be placed in a groove defined on the circumferential surface of the plunger 306 to maintain a dynamic seal between the plunger 306 and the inner surface of the inner reservoir 304. Alternatively, as shown in FIG. 12B, a two-shot molding technique can be used to bond a silicone rubber sealing element to the plunger 306. Two-shot molding simplifies the assembly process.

[0070] The following examples relate to various embodiments of the systems and methods disclosed herein for implementation of an automated drug delivery system having a dual reservoir pump mechanism.

[0071] Example 1 is a first embodiment of a pump mechanism comprising an outer reservoir and an inner reservoir configured for linear movement into and out of the outer reservoir, a static plunger disposed within the inner reservoir, a hollow tube supporting the static plunger fluidly connecting the inner reservoir and the outer reservoir, one or more fluid ports, and a drive mechanism for linearly moving the inner reservoir into the outer reservoir.

[0072] Example 2 is an extension of Example 1, or any other example disclosed herein, where the pump mechanism further comprises a fluid seal between the inner reservoir and the outer reservoir.

[0073] Example 3 is an extension of Example 1, or any other example disclosed herein, where the external reservoir is rigidly attached to a structure external to the pump mechanism.

[0074] Example 4 is an extension of Example 3, or any other example disclosed herein, where the inner reservoir defines a through hole, and the drive mechanism comprises a lead screw that engages with the through hole such that linear translation of the lead screw causes linear translation of the inner reservoir into the outer reservoir.

[0075] Example 5 is an extension of example 4, or any other example disclosed herein, where the drive mechanism further comprises a tube nut that threadably engages the lead screw such that rotation of the tube nut causes linear movement of the lead screw.

[0076] Example 6 is an extension of Example 1, or any other example disclosed herein, where the outer surface of the inner reservoir defines a recess, and the drive mechanism includes a pusher member defining an internal threaded portion with a through hole and a protrusion, and a lead screw that threadably engages with the through hole of the pusher member, and where rotation of the lead screw causes linear translation of the pusher member to engage the recess and protrusion on the inner reservoir and push the inner reservoir into the outer reservoir.

[0077] Example 7 is an extension of Example 6, or any other example disclosed herein, where the protrusions are hemispherical in shape and the depressions are concave.

[0078] Example 8 is an extension of Example 1, or any other example disclosed herein, where the drive mechanism includes a pusher element integral with the inner reservoir and defining a through hole having an internal thread, and a lead screw that threadably engages with the through hole such that rotation of the lead screw causes linear movement of the pusher element and linear movement of the inner reservoir into the outer reservoir.

[0079] Example 9 is an extension of example 1, or any other example disclosed herein, wherein the drive mechanism includes a rack gear disposed on an outer surface of the outer reservoir and a pinion gear engaged with the rack gear such that rotation of the pinion gear causes linear movement of the outer reservoir toward an end of the outer reservoir.

[0080] Example 10 is an extension of Example 7, or any other example disclosed herein, wherein the inner reservoir defines a second through hole disposed on an outer surface of the inner reservoir opposite the through hole, and the drive mechanism further comprises a second lead screw engaging the second through hole such that synchronous linear movement of the lead screw and the second lead screw causes linear movement of the inner reservoir into the outer reservoir.

[0081] Example 11 is an extension of Example 8, or any other example disclosed herein, wherein the drive mechanism further comprises a second pushing element integral with the inner reservoir defining a through hole having an internal thread, and a second lead screw threadably engaging with the through hole of the second pushing element, wherein synchronous rotation of the lead screws causes linear movement of the inner reservoir into the outer reservoir.

[0082] Example 12 is an extension of Example 9, or any other example disclosed herein, wherein the drive mechanism further includes a second rack gear disposed on an outer surface of the outer reservoir opposite the rack gear, and a second pinion gear engaging the second rack gear such that synchronous rotation of the pinion gears causes linear movement of the outer reservoir toward the inner reservoir.

[0083] Example 13 is an extension of Example 1, or any other example disclosed herein, wherein the inner and outer reservoirs have a cross-sectional shape selected from the group consisting of an oval, a flattened circle, and a rectangle with rounded corners.

[0084] Example 14 is an extension of example 1 or any other example disclosed herein, wherein the pump mechanism further includes a fluid seal disposed on a circumferential surface of the static plunger to create a fluid seal between the plunger and an inner surface of the inner reservoir.

[0085] Example 15 is an extension of example 1 or any other example disclosed herein, wherein the pump mechanism further comprises a fluid seal between an inner surface of the outer reservoir and an outer surface of the inner reservoir.

[0086] Example 16 is an extension of example 1 or any other example disclosed herein, wherein the pump mechanism further comprises a fluid seal between the hollow tube within the static plunger.

[0087] Example 17 is a second embodiment of a pump mechanism comprising an outer reservoir, an inner reservoir configured for linear movement into and out of the outer reservoir, a static plunger disposed within the inner reservoir, and a lead screw disposed within the inner reservoir coaxially with the longitudinal axis of the inner reservoir, the lead screw extending through the static plunger to contact an end wall of the inner reservoir and a tube nut engaged with the lead screw, such that rotation of the tube nut causes linear movement of the lead screw that pushes the inner reservoir into the outer reservoir.

[0088] Example 18 is an extension of Example 17, or any other example disclosed herein, where the external reservoir is rigidly attached to a structure external to the pump mechanism.

[0089] Example 19 is an extension of example 18, or any other example disclosed herein, wherein the pump mechanism further comprises a hollow tube including a tube nut, the hollow tube being rigidly attached to an external structure of the pump mechanism and supporting the static plunger.

[0090] Example 20 is an extension of example 19 or any other example disclosed herein, wherein the pump mechanism further comprises a drive mechanism for rotating the tube nut.

[0091] Example 21 is an extension of Example 20, or any other example disclosed herein, wherein the pump mechanism further comprises a first fluid port defined in a wall of the outer reservoir and a second fluid port defined in a wall of the inner reservoir.

[0092] Example 22 is an extension of example 21, or any other example disclosed herein, where the first fluid port and the second fluid port are fluidly coupled external to the pump mechanism.

[0093] Example 23 is an extension of example 17, or any other example disclosed herein, wherein the pump mechanism further includes a fluid seal disposed on a circumferential surface of the static plunger to form a fluid seal between the plunger and an inner surface of the inner reservoir.

[0094] Example 24 is an extension of example 17 or any other example disclosed herein, wherein the pump mechanism further comprises a fluid seal between the inner reservoir and the outer reservoir.

[0095] Example 25 is an extension of example 17, or any other example disclosed herein, wherein the inner reservoir and the outer reservoir have a cross-sectional shape selected from the group consisting of an oval, a flattened circle, and a rectangle with rounded corners.

[0096] Example 26 is a third embodiment of a pump mechanism comprising an outer reservoir, an inner reservoir configured to move linearly into the outer reservoir, and a drive mechanism for linearly moving the inner reservoir, wherein a portion of the inner reservoir acts as a plunger within the outer reservoir to push a drug contained in the outer reservoir through a first fluid port.

[0097] Software-related implementations of the techniques described herein may include, but are not limited to, firmware, application-specific software, or any other type of computer-readable instructions that may be executed by one or more processors. The computer-readable instructions may be provided via a non-transitory computer-readable medium. Hardware-related implementations of the techniques described herein include, but are not limited to, integrated circuits (ICs), application-specific integrated circuits (ASICs), field programmable arrays (FPGAs), and / or programmable logic devices (PLDs). In some examples, the techniques described herein and / or any systems or components described herein may be implemented using a processor executing computer-readable instructions stored on one or more memory components.

[0098] Those skilled in the art to which the present invention pertains may appreciate many modifications and adaptations of the present invention. The embodiments provided herein, including the dimensions, shapes, ratings and specifications of the various components or component arrangements, as well as a description of a specific manufacturing process, are merely illustrative and are not meant to limit the present invention in any way. As those skilled in the art will appreciate, many variations of the forms discussed herein are possible that fall within the scope of the present invention. Furthermore, it should be understood that the features of the various aspects described herein are not mutually exclusive and can exist in various combinations and permutations without departing from the spirit and scope of the present invention, even if such combinations or permutations are not expressly stated herein. Thus, the methods and apparatus disclosed herein should be construed as illustrative rather than limiting the present invention. The scope of the present invention is defined by the following claims.

Claims

1. In the pump mechanism, The pump mechanism includes: An outer reservoir; and an inner reservoir configured for linear movement into the outer reservoir; a static plunger disposed within the internal reservoir; a hollow tube supporting the static plunger and extending between the inner reservoir and the outer reservoir, thereby fluidly connecting the inner reservoir to the outer reservoir; one or more fluid ports defined in either or both of the inner and outer reservoirs; a drive mechanism for linearly moving the inner reservoir into the outer reservoir.

2. The pump mechanism includes: The pump mechanism of claim 1 , further comprising a fluid seal between an inner surface of the outer reservoir and an outer surface of the inner reservoir.

3. The pump mechanism of claim 1 , wherein the external reservoir is rigidly attached to a structure external to the pump mechanism.

4. a portion attached to the inner reservoir defining a throughbore; 2. The pump mechanism of claim 1, wherein the drive mechanism comprises a lead screw engaging the throughbore such that linear translation of the lead screw causes linear translation of the inner reservoir into the outer reservoir.

5. The pump mechanism of claim 4 , wherein the drive mechanism further comprises a tube nut in threaded engagement with the lead screw such that rotation of the tube nut causes linear translation of the lead screw.

6. 6. The pump mechanism of claim 5, wherein the tube nut is received within the hollow tube, the hollow tube being rigidly attached to a structure external to the pump mechanism and supporting the stationary plunger.

7. The pump mechanism of claim 1 , wherein the one or more fluid ports comprise a first fluid port defined in a wall of the outer reservoir and a second fluid port defined in a wall of the inner reservoir.

8. The pump mechanism of claim 7 , wherein the first fluid port and the second fluid port are fluidly connected to an exterior of the pump mechanism.

9. The drive mechanism includes: a pusher member defining a throughbore having an internally threaded portion; a lead screw that is screwed into the through hole of the pushing member; 2. The pump mechanism of claim 1, wherein rotation of the lead screw causes linear movement of the pushing member such that the pushing member pushes the inner reservoir into the outer reservoir.

10. The pump mechanism of claim 9 , wherein a mating element is defined on the pusher member and a corresponding mating element is defined on an outer surface of the inner reservoir.

11. The drive mechanism includes: a rack gear disposed on an outer surface of the outer reservoir; a pinion gear engaged with the rack gear, The pump mechanism of claim 1 , wherein rotation of the pinion gear causes linear movement of the outer reservoir towards the inner reservoir, thereby causing linear movement of the inner reservoir into the outer reservoir.

12. The drive mechanism includes: a second rack gear disposed on an outer surface of the outer reservoir opposite the rack gear; a second pinion gear engaged with the second rack gear, 12. The pump mechanism of claim 11, wherein synchronous rotation of the pinion gear and the second pinion gear causes linear movement of the outer reservoir towards the inner reservoir, thereby causing linear movement of the inner reservoir into the outer reservoir.

13. The drive mechanism includes: a pusher member integral with or attached to the internal reservoir, the pusher member defining a throughbore having an internal thread; a lead screw that is screwed into the through hole of the pushing member; The pump mechanism of claim 1 , wherein rotation of the lead screw causes linear movement of the pusher element and linear movement of the inner reservoir into the outer reservoir.

14. the inner reservoir defines a second through hole disposed on the outer surface of the inner reservoir opposite the through hole; The drive mechanism includes:

14. The pump mechanism of claim 13, further comprising a second lead screw engaging a second through hole in the inner reservoir, wherein synchronous linear movement of the lead screw and the second lead screw causes linear movement of the inner reservoir into the outer reservoir.

15. The drive mechanism includes: a second pusher member integral with or attached to the internal reservoir, the second pusher member defining a through hole; 14. The pump mechanism of claim 13, further comprising a cylindrical rod disposed within the throughbore of the second pushing member.

16. 2. The pump mechanism of claim 1, wherein the inner and outer reservoirs have a cross-sectional shape selected from the group consisting of an oval, a flattened circle, and a rectangle with rounded corners.

17. The pump mechanism of claim 1 , further comprising a fluid seal disposed on a circumferential surface of the static plunger to create a fluid seal between the static plunger and an inner surface of the inner reservoir.

18. The pump mechanism of claim 1 , further comprising a fluid seal between an inner surface of the outer reservoir and an outer surface of the inner reservoir.

19. The pump mechanism of claim 1 , further comprising a fluid seal between the hollow tube and the static plunger.

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