Dispensing fluid from an infusion pump system

Some embodiments of an infusion pump device may include a drive system that accurately and incrementally dispenses fluid from the pump device in a controlled manner. Particular embodiments of the drive system may include a rotational motor that is coupled to a string member, which is used to adjust a pawl relative to a ratchet body. In such circumstances, the drive system can provide a reliable and compact infusion pump device that accurately dispenses the desired volume of fluid.

TECHNICAL FIELD

This document relates to an infusion pump system, such as a medical infusion pump system.

BACKGROUND

Pump devices are commonly used to deliver one or more fluids to a targeted individual. For example, a medical infusion pump device may be used to deliver a medicine to a patient as part of a medical treatment. The medicine that is delivered by the infusion pump device can depend on the condition of the patient and the desired treatment plan. For example, infusion pump devices have been used to deliver insulin to the vasculature of diabetes patients so as to regulate blood-glucose levels.

A number of factors may affect the design of infusion pump devices. One such factor is the size of the device. The device may be sized to house the various pump components, yet a large device may reduce the portability for the user. Another factor that may affect the design of an infusion pump device is the convenience to the user. For example, if the device is designed to be a reusable dispenser having high-cost components, it may be expensive and inconvenient for the user to replace such a device that has been lost or damaged. A number of infusion pump components can impact the overall size of the device and the convenience to the user.

SUMMARY

Some embodiments of an infusion pump device may include a drive system that accurately and incrementally dispenses fluid from the pump device in a controlled manner. Particular embodiments of the drive system may include a rotational motor that is coupled to a string member, which is used to adjust a pawl member relative to a ratchet body. This operation of the drive system may cause incremental longitudinal advancement of a piston rod in the infusion pump device, which forces a controlled amount of fluid from the pump device. In such circumstances, the drive system can be part of a reliable and compact infusion pump device that accurately dispenses the desired volume of fluid.

In some embodiments, a medical infusion pump system may include a pump device having a drive system to cause dispensation of a medicine. The drive system may include a pawl that is adjustable relative to a ratchet body. The pawl may engage one or more teeth of the ratchet body to incrementally advance the ratchet body. The drive system may also include a string member coupled to the pawl. The string member may be arranged in a loop around two or more guide structures. The drive system may further include a rotational motor coupled to the string member so that rotation by the motor causes the string member to adjust the pawl relative to the ratchet body. In certain aspects, the medical infusion pump system may include a removable controller device that is mechanically and electrically connectable to the pump device.

Particular embodiments of a medical infusion pump system may include a pump device having a drive system to cause dispensation of a medicine. The drive system may include a pawl that is adjustable relative to a ratchet body. The pawl may engage one or more teeth of the ratchet body to incrementally advance the ratchet body. The drive system may also include a flexible member coupled to the pawl and a spindle coupled to the flexible member. The drive system may further include a rotational motor coupled to the spindle so that rotation by the motor causes the flexible member to wind or unwind around spindle to thereby adjust the pawl relative to the ratchet body.

Some embodiments of a medical infusion pump system may include a pump device and a controller device that is electrically connectable to the pump device to control operation of the drive system. The pump device may include a housing that defines a cavity to receive a medicine and a drive system to cause dispensation of the medicine when the medicine is received in the cavity. The drive system may include a rotational motor and a string member coupled to the motor. The string member may comprise braided filaments.

In certain embodiments, a method for dispensing medicine from an infusion pump system includes rotating a motor one or more full rotations in a first rotational direction to unwind a string member from a spindle and thereby adjust a ratchet mechanism coupled to a piston rod. The adjustment of the ratchet mechanism may incrementally advance the piston rod in a forward direction to force medicine from a wearable medicine dispenser device. The method may also include continuing to rotate the motor in the first rotational direction so that the string member winds around the spindle and thereby applies a tension force to reset the ratchet mechanism. The method may include, in a next dispensing cycle, rotating the motor one or more full rotations in an opposite, second rotational direction to unwind the string member from the spindle and thereby adjust the ratchet mechanism coupled to the piston rod. The adjustment of the ratchet mechanism may incrementally advance the piston rod in the forward direction to force medicine from the wearable medicine dispenser device.

Some embodiments of a method for dispensing medicine from an infusion pump system may include rotating a motor to unwind a string member from a spindle and thereby adjust a ratchet mechanism coupled to a piston rod. The adjustment of the ratchet mechanism may incrementally advance the piston rod in a forward direction to force medicine from a wearable medicine dispenser device. The method may also include rotating the motor to wind the string member around the spindle and thereby apply a tension force to reset the ratchet mechanism.

These and other embodiments may provide one or more of the following advantages. First, the drive system of the pump device can provide a reliable and consistent configuration for accurately dispensing the desired volume of fluid from the pump device. Second, some embodiments of the drive system may comprise few, if any, high-cost components, thereby facilitating the production of a disposable infusion pump device. Third, the pump device may house the drive system in a compact manner so that the pump device is portable, wearable, and readily concealable by the user. As such. a user can conveniently wear the pump device on the user's skin underneath clothing or carry the pump device in the user's pocket (or other portable location) while receiving the medicine dispensed from the pump device. Fifth, in some embodiments, a string member of the drive system can be arranged in a loop around two or more guides so as to optimize the location and direction of the force applied by the string member and to provide a force amplification effect. Sixth, the string member of the driver system may comprise braided filaments that are capable of enduring the torsion and frictional forces associated with undergoing a multitude of motion cycles. Seventh, some embodiments of the infusion pump system may include a removable controller device having a user interface. Such a configuration may provide the user with the ability to monitor the device settings by simply viewing the pump device (e.g., no need for a separate device for reviewing the pump settings). Moreover, the removable controller configuration may provide the user with the ability to dispose of the pump body while reusing the removable controller with a new, subsequent pump body (e.g., maintaining the previous user settings while receiving a new supply of medicine). Eighth, the pump device can be configured to receive a preloaded medicine cartridge (e.g., preloaded with insulin or another medicine for use in the treatment of Diabetes) so as to facilitate low manufacturing costs and high speed assembly.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring toFIG. 1, some embodiments of an infusion pump system10include a pump device100that can communicate with a controller device200. The pump device100includes a housing structure110that defines a cavity116in which a fluid cartridge120is received. In this embodiment, the pump system10in a medical infusion pump system that is configured to controllably dispense a medicine from the cartridge120. As such, the fluid cartridge120may contain a medicine to be infused into the tissue or vasculature of a targeted individual, such as a human or animal patient. For example, the pump device100can be adapted to receive a medicine cartridge120in the form of carpule that is preloaded with insulin or another medicine for use in the treatment of Diabetes (e.g., BYETTA, SYMLIN, or others). Such a cartridge120may be supplied, for example, by Eli Lilly and Co. of Indianapolis, Ind. Other examples of medicines contained in the fluid cartridge120include: pain relief drugs, hormone therapy, blood pressure treatments, anti-emetics, osteoporosis treatments, or other injectable medicines.

As described in more detail below, the pump device100includes a drive system that causes controlled dispensation of the medicine or other fluid from the cartridge120. In some embodiments, the drive system (not shown inFIG. 1) incrementally advances a piston rod longitudinally into the cartridge120so that the fluid is forced out of the output end122(described below). In this embodiment, the septum at the output end122can be pierced to permit fluid outflow when a cap member (not shown inFIG. 1, refer to cap member315inFIG. 5for one example) is connected to the pump housing structure110.

The drive system may be housed in the housing structure110of the pump device in a compact manner so that the pump device100is portable, wearable, concealable, or a combination thereof. For example, in the circumstances in which the medicine cartridge120has a length of about 6 cm to about 7 cm (about 6.4 cm in this embodiment), the overall length of the pump housing structure110(which contains medicine cartridge and the drive system) can be about 7 cm to about 9 cm (about 8.3 cm or less in this embodiment). In addition, the pump housing structure110may have an overall height of about 1.5 cm to about 4 cm (about 2.9 cm or less in this embodiment) and an overall thickness of about 8 mm to about 20 mm (about 14.5 mm or less in this embodiment). Accordingly, a user can conveniently wear the pump device100on the user's skin (e.g., skin adhesive) underneath the user's clothing or carry the pump device100in the user's pocket (or other portable location) while receiving the medicine dispensed from the pump device.

For example, in the circumstances in which the medicine cartridge120has a length of about 6 cm to about 7 cm (about 6.4 cm in this embodiment), the overall length of the pump housing structure110(which contains medicine cartridge and the drive system) can be about 7 cm to about 9 cm (about 8.3 cm or less in this embodiment). In addition, the pump housing structure110may have an overall height of about 1.5 cm to about 4 cm (about 2.9 cm or less in this embodiment) and an overall thickness of about 8 mm to about 20 mm (about 14.5 mm or less in this embodiment). In such circumstances, the controller device200can be figured to mate with the compact pump housing110so that, when removably attached to one another, the components define a portable infusion pump unit that stores a relatively large quantity of medicine compared to the overall size of the unit. For example, in this embodiment, the infusion pump system10(including the pump device100attached to the removable controller device200) may have an overall length of about 7 cm to about 9 cm (about 8.5 cm or less in this embodiment), an overall height of about 1.5 cm to about 4 cm (about 3.5 cm or less in this embodiment),and an overall thickness of about 8 mm to about 20 mm (about 15 mm or less in this embodiment).

Still referring toFIG. 1, the drive system of the pump device100may be continuously or intermittently controlled by pump controller device200. In this embodiment, the controller device200is configured to removably attach to the pump device100, When attached, the controller device200communicates electronic control signals via hard-wire-connection to the drive system or other components of the pump device100. The controller device200can include a controller housing structure210that is configured to mate with a complementary portion of the pump housing structure110so as to form a releasable mechanical connection. For example, the pump housing structure110may define a cavity118that mates with a complementary protruding face (not show inFIG. 1) of the controller housing structure210for a friction fit engagement. Also, the controller housing structure210may include a channel212that mates with a curved surface117of the pump housing structure110when the controller device200is attached to the pump device. In addition, one or more releasable connector devices (e.g., mating tongues and grooves, mounting protrusions friction fit into mating cavities, or the like) can be used to further implement the releasable securement of the controller device200to the pump device100. Furthermore, the pump device100may include one or more electrical contacts118that are exposed to the controller device200and that mate with opposing electrical contacts (e.g., conductive pads, pins, and the like) on the adjacent face of the controller device200. As such, the controller device200is in electrical communication with the pump device100and is capable of transmitting electrical signals to the pump device100and receiving feedback signals (e.g., sensor signals) from components within the pump device100.

The pump controller device200includes a user interface220that permits a user to monitor the operation of the pump device100. In this embodiment, the user interface includes a display222and one or more user-selectable buttons224,226, and228. The display222may be used to communicate a number of settings or menu options for the infusion pump system10. For example, the user may press one or more of the buttons224,226, and228to shuffle through a number of menus or program screens that show particular settings and data (e.g., review data that shows the medicine dispensing rate or the total amount of medicine dispensed in a given time period). Also, in some embodiments, the user can adjust the settings or otherwise program the controller device200by pressing one or more buttons224,226, and228of the user interface220. In embodiments of the infusion pump system10configured to dispense insulin, the user may press one or more of the buttons224,226, and228to change the dispensation rate of insulin or to request that a bolus of insulin be dispensed. In some embodiments, the user interface220may include tactile buttons, a touch screen, audio inputs or outputs, or a combination thereof. Previously incorporated U.S. Provisional Application Ser. No. 60/721,267 also describes a number of configurations for a removable controller device in addition to the configuration illustrated inFIG. 1herein.

Accordingly, when the controller device200is connected to the pump device100, the user is provided with the opportunity to readily monitor infusion pump operation by simply viewing the user interface210connected to the pump device100. Such monitoring capabilities may provide comfort to a user who may have urgent questions about the current operation of the pump device100(e.g., the user may be unable to receive immediate answers if wearing an infusion pump device having no user interface attached thereto). Also, there is no need for the user to carry and operate a separate device to monitor the operation of the infusion pump device100, thereby simplifying the monitoring process and reducing the number of devices that must be carried by the user.

Referring toFIG. 2, the pump device100includes a drive system105that accurately and incrementally dispenses fluid from the pump device100in a controlled manner. In this embodiment, the pump housing structure110includes a detachable shell112that covers at least a portion of the drive system105and includes a frame portion114to which at least a portion of the drive system105is mounted. The detachable shell112may include an inner curved surface against which a curved section of a piston rod170rests. The frame portion114define a the cavity116that receives the fluid cartridge120. One or both of the detachable shell112and the frame portion114can be molded from polymer material, such as Polycarbonate, Acrylonitrile Butadiene Styrene, or Acrylic. As previously described, in some embodiments, the fluid cartridge120may occupy a majority of the length of the pump device110(with the drive system105being arranged in a compact manner) so that the pump device100is wearable and portable.

In some embodiments, the drive system105may include a rotational motor130that is coupled to a string member140, which is used to adjust a ratchet mechanism150. Briefly, the rotational motor130can be used to act upon the string member140, thereby causing the string member140to adjust a pawl member152relative to a ratchet body155. In this embodiment, the ratchet body155is in the form of a ratchet wheel. The ratchet wheel155can be integrally formed with, or mounted to, a worm gear156. Incremental rotation of the ratchet wheel155causes rotation of a drive wheel160(due to engagement with the worm gear156), which causes the incremental longitudinal advancement of a flexible piston rod170. As the piston rod170is advanced into plunger chamber126of the fluid cartridge120(e.g., defined in this embodiment by the circumferential wall124of the fluid cartridge120), the fluid in the cartridge120is forced from the septum at the output end122. It should be understood from the description herein that, when the pump device100is in use, the septum at the output end122may be pierced by a cap member (not shown inFIG. 2) mounted to the housing structure110, which allows fluid to exit from the cartridge120and enter a tube of an infuision set attached to the patient. Accordingly, the drive system105can provide a reliable and compact configuration for accurately dispensing the desired volume of fluid from the pump device100. Moreover, the drive system105may comprise few, if any, high-cost actuator components or electronics, thereby facilitating the relatively low-cost production of a disposable and reliable pump device100.

Referring now to the components of the drive system105in more detail, the rotational motor130may comprise a battery powered actuator having a rotatable output shaft132. In this embodiment, the rotational motor130can receive signals that cause the output shaft to rotate in a first rotational direction or in a second, opposite rotational direction. One example of a suitable rotational motor130is a coreless DC motor supplied by Jinlong Machinery of China.

The rotational motor130can be mounted to the frame portion114of the pump housing structure110so that the motor130remains in a substantially stationary position relative to the electrical contacts119of the pump device100. As such, the operation of the rotational motor130can be controlled by the control device200(FIG. 1) via electrical signals communicated through one or more of the electrical contacts119. In some embodiments, one or more of the electrical contacts119may be directly connected to the inputs of the rotation motor130, for example, to deliver control signals from a control circuit or to deliver electrical current from a battery, capacitor, or other power source disposed in the controller device200or disposed in the pump device100. In other embodiments, the electrical contacts119may be connected to an electrical circuit (e.g., an integrated circuit implemented on a small printed circuit board) onboard the pump device100(e.g., mounted to the frame portion114). In such circumstances, the control device200may deliver control signals via the electrical contacts119to the electrical circuit onboard the pump device100, which then opens a gate or a circuit pathway to permit the electrical current to pass to the rotational motor130(e.g., from a battery or other power source disposed in the pump device100).

Referring to FIGS.2and3A-C, the string member140may be coupled to the rotational motor130so that actuation by the motor130causes the string member140to act upon the ratchet mechanism150. For example, one or more full rotations of the motor130can be translated into a tension force in the string member140that is applied to a pawl member152, which (in this embodiment) is pivotable to a reset position by the tension force from the string member140. As such, the string member140is coupled between the rotational motor130and the ratchet mechanism150so as to provide a reliable and consistent adjustment of the ratchet mechanism150. In some embodiments, the string member140may comprise a flexible member capable of transmitting a tension force, for example, a braided string structure (some examples are described below in connection withFIG. 3B), a monofilament string structure, a flexible tape or ribbon structure, or the like.

The string member140can be arranged in a loop around two or more guides (e.g., two guides142and144are shown in this embodiment). Such a loop arranged can be used to optimize the location and direction of the tension force in the string member140that is applied to the ratchet mechanism150. Moreover, the loop arrangement of the string member may provide a force amplification effect when the string member140is wound using the rotational motor130, which may permit the use of a smaller-sized motor in the pump design. Previously incorporated U.S. Provisional Application Ser. No. 60/720,411 also describes a number of loop arrangements for the string member140in addition to the illustrative example depicted inFIGS. 3A-Cherein.

In the embodiment shown inFIGS. 3A-C, the string member140starts at the shaft132of the rotational motor130, passes around a stationary guide142, around a second guide144connected to the pawl member152, and then back to the motor130to form a loop arrangement. The motor130spins such that a portion145the string member140winds upon itself, thus drawing the two guides142and144together with a force amplification effect. In some circumstances, the force amplification effect of the winding string member140can be approximated as:
F(string)=T(motor)/r(string),
where T(motor) is the torque rating of the motor, r(string) is the radius of the string and F(string) is the subsequent pulling force on the string. To find the total force upon the guide coupled to the pawl (F(guide)):
F(guide)=F(string)+F(String)cos(θ)−L(friction)
or reducing
F(guide)=T(motor)/r(string)[1+cos(θ)]−L(friction),
where cos(θ) describes the angle of the string with respect to parallel to the axis of the stationary guide and the drive guide and L(friction) represents the total losses associated with friction within the system.

As shown inFIG. 3B, the string member140may comprise braided filaments that are capable of enduring repeated twisting sequences of the string member140. For example, the braided filaments may comprise one or more polymer materials, such as PET (e.g., DTex Dyneema material available from Honeywell, Inc.). Such braided filament string members are capable of enduring the torsion and frictional forces associated with undergoing thousands of cycles of twisting as described above in connection withFIGS. 2 and 3A. The string member140can be formed to have an outer diameter of about 0.02 mm to about 0.07 mm, and preferably about 0.05 mm. Also, in some embodiments, the string member140may comprise braided filaments that are arranged around a centrally disposed thin wire filament having a diameter of about 0.02 mm or less. The thin wire filament may comprise a polymer material a metallic material having a non-coarse outer surface. Such materials may also be capable of enduring the repeated twisting sequences of the string member140. Such a construction may permit the outer filament surfaces to frictionally engage one another during the twisting process while the filament surfaces contacting the centrally disposed thin wire are exposed to a reduced friction load.

Referring again toFIG. 2, the string member140is coupled to the ratchet mechanism150, which provides incremental motion to thereby advance the piston rod170. The ratchet mechanism150includes the pawl member152and the ratchet body155, which in this embodiment is a ratchet wheel having a number of teeth along its circumferential surface. The pawl member that is adjustable between a reset position and a forward position. For example, the rotational motor130may be activated to twist the string member140(as previously described), and the string member140then applies a tension force that adjusts the pawl member152to the reset position where the pawl member152engages one or more new teeth of the ratchet wheel155. A spring device154is also coupled to the pawl member so as to urge the pawl member152toward the forward position. This spring bias causes the pawl member152to drive the ratchet wheel155an incremental amount in a forward rotational direction as the string member140is untwisted.

Referring again toFIGS. 3A-3C, the adjustable pawl member152is constructed in such a way as to engage the teeth of the ratchet wheel155in a single direction (e.g., in the forward rotational direction of the ratchet wheel155). In the reverse direction, a locking pawl159prevents the ratchet wheel155from reverse motion. As such, the adjustable pawl member152can adjust from the forward position to the reset position (shown inFIG. 3A) to engage a new tooth of the ratchet wheel155while the ratchet wheel155remains in position due to the locking pawl159. In this embodiment, the adjustable pawl member152is pivotably coupled to a support plate151at so that the string member140and the spring device154can act to pivot the pawl member between the reset position and the forward position. In particular, a first end portion of the pawl member152may be fixedly or hingedly mounted to the support plate154while a free end portion of the pawl member152engages the ratchet wheel155. Also, in this embodiment, the locking pawl159is fixedly coupled to the support plate151.

The ratchet mechanism150can employ a set of stopper pins153aand153bthat limit the motion of the adjustable pawl member152. In some embodiments, the stopper pins153aand153bcan serve as location sensors to detect when the pawl member152has reached the reset position (e.g., adjacent the stopper pin153a) or the forward position (e.g., adjacent the stopper pin153b). For example, these sensors can be optical, magnetic, or contact type sensors. The sensors may be capable of transmitting signals that indicate when the location of the pawl member152is detected. Such sensor signals may be transmitted to the motor130, to the controller device200(FIG. 1), or a combination thereof. Accordingly, when the pawl member152reaches the stopper pin153a(e.g., by rotation of the motor130that causes the string member140to adjust the pawl member152), a signal can indicate that the pawl member152has reached the limit of its travel and the motor130will cease rotation in that direction (e.g., end the twisting process on the string member140in that direction).

Referring again toFIG. 2andFIGS. 3A-C, the driving force of the ratchet mechanism150can be provided by energy stored in a potential energy storage device, such as the spring device154. Thus, when the adjustable pawl152is driving the ratchet wheel155in the forward rotational direction, the potential energy of the spring device154is being translated to kinetic energy for the motion of the pawl member152and the ratchet wheel155. For example, in one incremental motion cycle, the pawl member152may start at the reset position (as shown inFIG. 3A) with the string member140in a twisted configuration. In response to the controller device200(FIG. 1) transmitting a signal to initiate the cycle, the rotational motor130may begin to rotate in a first rotational direction that unwinds the string member140, thereby permitting the spring device154to drive the pawl member152toward the forward position. The rotational motor130continues to rotate in the first direction so that after the pawl member152reaches the forward position (e.g., adjacent the stopper pin153b), the string member140begins to twist in the opposite orientation. Such twisting of the string member140causes a tension force that overcomes the bias of the spring device154and adjusts the pawl member152toward the reset position. After the pawl member152reaches the reset position (e.g., adjacent the stopper pin153a), the rotational motor130stops rotating in the first rotational direction and the pawl member152remains at rest in the reset position. In the event of a second cycle, the rotational motor130would begin the cycle by rotating in a second rotational direction (opposite the first rotational direction) so as to unwind the string member140yet again. This pattern of cycles may continue until the piston rod170has reached the limit of its longitudinal travel (described in more detail below).

In other embodiments, the incremental motion cycle may begin with the pawl member152starting at the forward position (e.g., adjacent the stopper pin153b). In such circumstances, the rotation motor130would rotate in a first rotational direction to twist the string until the pawl member is moved to the reset position (as shown inFIG. 3A), and then the rotational motor130would rotate in a second, opposite rotational direction to unwind the string member140until the pawl member152returns to the forward position.

As shown inFIG. 2, the spring device154can be coupled to the pawl member152at a first end portion and coupled to the support plate151at a second end portion. Alternatively, as shown inFIG. 3A, the spring device154can be to the pawl member152at a first end portion and coupled to a part of the frame portion114(not directly joined to the support plate151).

Referring again toFIG. 2, in some embodiments the ratchet wheel155can be coupled with a worm gear156so that the incremental rotation of the ratchet wheel155is translated to the worm gear156. Such rotation of the worm gear156causes a rotation of a drive wheel160, which is rotatably mounted to the frame portion114of the pump device100. The drive wheel160includes a central aperture having an internal thread pattern therein (not shown inFIG. 2). The internal thread pattern of the drive wheel160mates is an external thread pattern on the flexible piston rod170so that the piston rod170is longitudinally advanced inside the plunger chamber126of the fluid cartridge120. Thus, the incremental motion of provided by the ratchet mechanism150, the string member140, and the motor130causes the drive wheel160to incrementally rotate, which in turn translates to a longitudinal advancement of the flexible piston rod170. In one example, the drive system105can advance the piston rod170an increment of about 16 microns or less (about 4 microns to about 12 microns, and preferably about 7 microns to about 8 microns) for each incremental motion cycle of the motor130, string member140, and ratchet mechanism150as previously described.

In some embodiments, the flexible piston rod170comprises a plurality of segments172serially connected by hinge portions so that the flexible piston rod170is adjustable from a curved shape to a noncurved shape. The plurality of segments172and the interconnecting hinge portions can be integrally formed in one piece from a moldable material, including a number of polymer materials such as Nylon or POM. In this embodiment, the plurality of segments172comprise generally cylindrical segments that each include an exterior thread pattern along at least one cylindrical surface portion. A plunger connector178may be coupled to the leading end of the flexible piston rod170so as to abut against the plunger (not shown inFIG. 2) in the plunger chamber126of the fluid cartridge120.

Still referring toFIG. 2, the flexible piston rod170can include an anti-rotation structure that hinders the piston rod170from rotating with drive wheel160(thereby allowing the rotation of the drive wheel160to translate into a longitudinal motion of the piston rod170). For example, in this embodiment, the flexible piston170includes a longitudinal channel173extending through each of the segments172. The longitudinal channel173can engage a complementary protrusion on the frame portion114(not shown inFIG. 2) proximate the drive wheel160so that the flexible piston rod170is hindered from rotating when the drive wheel160turns relative to the frame portion114. Accordingly, the longitudinal channel in each segment172aligns to form a keyway that receives a mating key (e.g., a protrusion) on the frame portion114. In other embodiments, the anti-rotation structure may include a plurality of longitudinal channels173(with each channel capable of engaging an associated protrusion that acts as a key to hinder rotation while permitting longitudinal motion), one or more flat surfaces along each segment172(with the flat surface slidably engaging a complementary flat surface on the frame portion114), or the like.

In the configuration illustrated inFIG. 2, the flexible piston rod170is in a retracted state so that it has a generally curved shape, with some or all of the cylindrical segments172hinged away from the adjacent segments172. As the rod segments172are advanced through the drive wheel160, the segments172abut one another end-to-end so as to form a generally rigid, noncurved shape. Previously incorporated U.S. Provisional Application Ser. No. 60/720,405 also describes a number of configurations for the flexible piston rod170in addition to the configuration illustrated inFIG. 2herein.

Because the flexible piston rod170is adjustable from a curved shape to a noncurved shape, the overall length of the pump device can be reduced in some embodiments. For example, in a typical infusion pump that houses a straight and rigid rod, the typical infusion pump requires a package or housing having a linear dimension sufficient to accommodate the length of the rigid piston rod when it is at its limit of travel in which it is fully withdrawn from the container or cylinder. This requirement for a large linear dimension can make it difficult to make the overall size of the typical infusion pump small enough for certain desired applications, such as, for example, wearable or implantable pumps. In a typical infusion pump having a rigid piston rod, the space required to house the rigid piston rod can be described by the following equation:
L=2t+y,(1)
where:“L” is the minimum overall linear dimension or length required to support the driven member part of the device;“t” is the required linear travel of an equivalent rigid driven member; and“y” is an added sum for the space required to support the driving member part of the device.

It can be seen, therefore, that if the piston rod is a rigid, linear element, the relative length of unused piston rod travel can potentially double the overall length of the typical infusion pump housing.

In the embodiment depicted inFIG. 2, the space requirement of pump device100having the flexible piston rod170is substantially less than the space requirement of a similar device actuated by a rigid piston rod. This can be explained by referencing the original “space requirement” equation set forth above as Equation (1). In contrast to the space requirement of a dispensing device containing a rigid pushrod, the equation for the space required for a dispensing device containing a flexible pushrod is as follows:
L=t+y+z,(2)
where:“L” is the minimum overall linear dimension or length required to support the driven member part of the device;“t” is the required travel of the flexible driven member (flexible pushrod);“y” is an added sum for the space required to support the driving member; and“z” is the space required to house the unused portion of the flexible driving member.

The space required under component “z’ is a function of the properties of the flexible piston rod170(e.g., the curved portion of the flexible piston rod170before it is advanced toward the fluid cartridge120). Thus, the pump device100incorporating the flexible piston rod170would require less space than the same device if it were to incorporate a non-flexible, rigid rod. In such circumstances, the overall length of the pump housing structure110can be less than twice the push rod travel length.

It should be understood that the flexible piston rod170may include segments that have a shape other than the generally cylindrical segments172. For example, in an alternative to the embodiment illustrated inFIG. 2, the segments of the flexible piston rod170can have a generally a square or rectangular cross-section (rather than a cylindrical shape), with teeth or a thread pattern on at least one surface thereof. In these circumstances, the flexible piston rod170may pass through a carrier in which the drive wheel160is rotatably mounted. The drive wheel160can have a threaded edge, that engages the teeth of the rod segments. Thus, rotation of the drive wheel160causes a linear advancement of the flexible piston rod170along an axis that is parallel to the axis of rotation of the drive wheel160, while the passage of the rod segments through the carrier aligns the segments into a linear orientation.

Referring now to another embodiment of a pump device300as shown inFIG. 4, the drive system305can include a string member340in a loop arrangement around more than two guides, such as four guide structures342,344,346, and348. In these circumstances, the motion path of the string member340and the orientation of the string member340can be configured to provide an efficient mechanical advantage orientation during the desired motion of the adjustable pawl member352. One of the guide structures348may be coupled to the adjustable pawl member352while the remaining guide structures342,344, and346are coupled to the frame portion314of the pump device314. Accordingly, the string member340may have a loop configuration with more directional changes compared to the embodiments previously described in connection withFIGS. 2 and 3A.

Similar to the previously described embodiments, the pump device300includes a housing structure310that defines a cavity316capable of receiving a fluid cartridge320. The housing structure310may include a frame portion314and a detachable shell portion312(refer toFIG. 5) so that, when assembled, the pump device300can have an outer configuration that mates with a removable controller device390(refer toFIGS. 6-7). In these embodiments, the drive system305can be contained in the housing structure310of the pump device300in a compact manner so that the pump device300is portable, wearable, concealable, or a combination thereof. Accordingly, a user can conveniently wear the pump device300on the user's skin (e.g., skin adhesive) underneath the user's clothing or carry the pump device100in the user's pocket (or another portable location) while receiving the medicine dispensed from the pump device300.

Referring toFIGS. 5-7, the pump device300can be part of an infusion pump system20in which the pump device300communicates with a controller device, including but not limited to the removable controller device390depicted inFIGS. 6-7. In this embodiment, the controller device390includes a user interface391so that the operation of the pump device300can be readily monitored by a user. For example, the user interface391may include a display392and two or more buttons (e.g., two buttons394aand394bare provided in this embodiment). The pump system20can be a medical infusion pump system that is configured to controllably dispense a medicine from the cartridge320. As such, the pump device300can be adapted to receive a medicine cartridge320in the form of a preloaded carpule that contains insulin or another medicine for use in the treatment of Diabetes (e.g., BYETTA, SYMLIN, or others) or other injectable medicines. Similar to previously described embodiments, the pump device300includes a drive system305that causes controlled dispensation of the medicine or other fluid from the cartridge320. For example, the drive system305may incrementally advance a flexible piston rod370into a plunger chamber326of the cartridge320so that the fluid is force out the septum at the output end322.

In those embodiments in which the pump device300is connected to a removable controller device390, the controller device390can communicate control signals to the drive system305or other components of the pump device300. Similar to the previously described embodiments, the controller device390can include a controller housing structure that is configured to mate with a complementary portion of the pump housing structure310so as to form a mechanical connection. For example, the controller housing structure may include a cavity that mates with a portion of the pump housing structure310when the controller device390is attached to the pump device300. In addition, the controller device390may include a flexible finger317to mate with an complementary surface of the pump housing structure310. Further, as shown for example inFIG. 5, the pump device300may include one or more magnetically attractable devices318aand318bthat engage with complementary magnetically attractable devices of the controller device390(not shown inFIGS. 6-7). As such, the magnetically attractable devices318aand318bmay contribute to releasably secure the pump device300to the controller device390. Other mechanical connectors (e.g., snap-fit connectors, magnetic connectors, surface protrusions that mate with female cavities, or the like) can also be implemented to join pump housing structure310with the controller device.

Still referring theFIGS. 5-7, the pump device300may include on or more electrical contacts319that are exposed to the controller device390and that mate with opposing electrical contacts (e.g., pads, pins, or the like) on the adjacent face of the controller device390. In this embodiment, the electrical contacts319are disposed on the detachable shell portion312of the pump housing structure310(refer toFIG. 5) and are aligned with an electrical contact device309mounted in the frame portion314. It should be understood that, in other embodiments, the electrical contacts319may be arranged on the frame portion314rather than on the detachable shell portion312. In this embodiment, the frame portion314of the pump device may define a space315(refer toFIG. 4) that is capable of receiving a connection circuit306(refer toFIG. 5). The connection circuit306may be simple and inexpensive so as to facilitate a low-cost pump device300that is disposable. The connection circuit306may include a battery307or other power source and, optionally, a gateway circuit device308. In some circumstances, the gateway circuit device308may be under the control of and directed by the control circuit in the controller device390. The connection circuit306provides the electrical contact device309so as to facilitate electrical communication with the removable controller device390. As such, the controller device390capable of transmitting electrical signals to the pump device300and is capable of receiving feedback signals (e.g., sensor signals) from the components in the pump device300. For example, the gateway circuit device308of the circuit309may be in electrical communication (e.g., via one or more electrical wires or electrically conductive traces) with a force sensor377(refer toFIG. 8) arranged between the plunger connector378that the plunger321. The force sensor377may comprise a force transducer or load cell that is capable of electrically communicating an applied force. As such, the force sensor377can provide feedback signals to the circuit309(or to the control device390via the electrical contacts) so as to monitor the force transmitted to the plunger321of the medicine cartridge320. Such information can be used, for example, to detect if an occlusion exists in the medicine flow path. Other sensors (e.g., a pressure sensor, a flow sensor, a rotation sensor, a displacement sensor, or the like) may be electrically connected to the circuit306to provide feedback signals to the circuit306(or to the control device390via the electrical contacts). It should be understood that, in other embodiments, the connection circuit306may be configured to operate without the gateway circuit device308. For example, the control circuit in the removable controller device200may communicate via the electrical contacts directly with a portion of the drive system305(e.g., direct electrical communication with the motor330), with one or more sensors disposed in the pump device300, and with the battery307.

Referring toFIGS. 4-5and8, the pump device300includes a drive system305that is capable of accurately and incrementally dispensing fluid from the fluid cartridge320in a controlled manner. Similar to the previously described embodiments, the drive system305may include the rotational motor330that is coupled to the string member340. Briefly, the rotational motor330can be used to act upon the string member340, thereby causing the string member340to adjust a pawl member352relative to a ratchet body355. In this embodiment, the ratchet body355is in the form of a ratchet wheel that is integrally formed with a worm gear356. Incremental rotation of the ratchet wheel355causes rotation of a drive wheel360, which causes the incremental longitudinal advancement of a flexible piston rod370. As the piston rod370is advanced into plunger chamber326(e.g., defined in this embodiment by the circumferential wall324of the fluid cartridge320), the fluid in the cartridge320is forced from septum at the output end322. As shown inFIG. 5, when the pump device300is in use, the septum at the output end322may be pierced by a cap member315mounted to the housing structure310, which can provide fluid communication from the cartridge320to an infusion set tube attached to the patient. For example, the cap member315may include a penetrator device316athat provides fluid communication from the medicine cartridge320to a tube connection end316b. Accordingly, the drive system305can provide a reliable and compact configuration for accurately dispensing the desired volume of fluid from the pump device300. Moreover, the drive system305may comprise few, if any, high-cost actuator components or electronics, thereby facilitating the production of a disposable and reliable pump device300. (It should be understood thatFIG. 5depicts the drive system305mounted to the frame portion314of the pump device300, andFIG. 8shows a similar view with the frame portion314removed for purposes of illustrating the drive system305and the fluid cartridge320.)

As shown inFIG. 4, some components of the drive system305can be retained by the frame portion314, a cover mount311that is assembled to the frame portion314, or a combination thereof. For example, the rotational motor330, the string member340, and the spring device354can be assembled into the frame portion314and then retained by the cover mount311. The adjustable pawl member352, the ratchet wheel355, and the worm gear356can be assembled onto and axle351that is integrally formed with the frame portion314and then retained by the cover mount311. A locking pawl359can be integrally formed with the frame portion314so as to align with the ratchet wheel355when the ratchet wheel355is assembled onto the axle351. Also, the drive wheel360and an adjacent bearing365(to facilitate rotation of the drive wheel360relative to the frame portion314) can be received in annular channels363and367, respectively, of the frame portion314. When the cover mount311is assembled to the frame portion314, the cover mount311can restrict the radial or axial movement of the drive wheel360while permitting forward rotation of the drive wheel360. In another example, the “unused” or retracted portion of the piston rod370may rest in a channel313defined in the top of the cover mount311. In such a construction, the cover mount311and the frame portion314can collectively permit the desired motion of the components of the drive system305while reducing the likelihood of “backlash” movement or component dislodgement (which might otherwise occur, for example, when the pump device300is dropped to the ground).

Referring now in more detail to the components of the drive system305depicted inFIGS. 9-10, the rotational motor330may comprise an electrically power actuator having a rotatable output shaft332. In this embodiment, the rotational motor330can receive signals that cause the output shaft to rotate in a first rotational direction or in a second, opposite rotational direction. As previously described, one example of a suitable rotational motor330is a coreless DC motor supplied by Jinlong Machinery of China. Also as previously described, the operation of the rotational motor330can be controlled by a control device (e.g., removable control device200as described in connection withFIG. 1or the like) via electrical signals communicated through one or more electrical contacts.

Still referring toFIGS. 9-10, the string member340may be coupled to the rotational motor330so that actuation by the motor330causes the string member to act upon the ratchet mechanism350. One or more full rotations of the motor330can be translated into a tension force in the string member340that is applied to a pawl member352, which (in this embodiment) is pivoted to a reset position by the tension force from the string member140. As such, the string member340is coupled between the rotational motor330and the ratchet mechanism350so as to provide a reliable and consistent adjustment of the ratchet mechanism350. In this embodiment, the string member340is coupled to the motor shaft332using a mechanical connector333. Similar to previously described embodiments, the string member140may comprise a flexible member capable of transmitting a tension force, for example, a braided string structure, a monofilament string structure, a flexible tape or ribbon structure, or the like.

The string member340can be arranged in a loop around two or more guide structures (e.g., four guide structures342,344,346, and348are shown in this embodiment). The motion path of the string member340and the orientation of the string member340can be configured to provide an efficient mechanical advantage orientation during the desired motion of the adjustable pawl member352. In this embodiment, one of the guide structures348is coupled to the adjustable pawl member352while the remaining guide structures342,344, and346are integrally formed with the frame portion314of the pump device300(guide structures342,344, and346are shown in dotted lines to represent their location on the frame portion314(not shown inFIGS. 9-10)). Also, the guide structure346exemplifies how a single guide structure can have two sliding surfaces that oppose one another, thereby functioning similar to a configuration having two different guides. As described in connection with previous embodiments, the loop arrangement of the string member340may provide a force amplification effect when the string member340is wound using the rotational motor330.

In the embodiment shown inFIGS. 9-10, the string member340starts at the shaft332of the rotational motor330, passes around a first sliding surface of the guide structure346, around a second guide structure342, around a third guide structure348connected to the adjustable pawl member352, around a fourth guide structure344, around a second sliding surface of the guide structure346, and then back to the motor330to form the loop arrangement. As shown inFIG. 10, when the motor330rotates, a portion345the string member340twists upon itself, thus drawing the guide structure348toward the stationary guide structures342and344. The orientation of the stationary guide structures342and344relative to the guide structure348(connected to the pawl member352) can be configured to provide an efficient mechanical advantage for the tension force applied by the string member340during the desired motion of the adjustable pawl member352.

The string member340is coupled to the ratchet mechanism350, which provides incremental motion to thereby advance the piston rod370. The ratchet mechanism350includes the pawl member352and the ratchet body355, which in this embodiment is a ratchet wheel having a number of teeth along its circumferential surface. The pawl member352is adjustable between a reset position (refer toFIG. 10) and a forward position (refer toFIG. 9). For example, the rotational motor330may be activated to twist the string member340, and the string member340then applies a tension force that adjusts the pawl member352to the reset position in which the pawl member352grabs a new tooth of the ratchet wheel155(refer toFIG. 10). In this embodiment, the adjustable pawl member352is pivotably coupled to about the axis of the axle351(refer toFIG. 4) that receives the ratchet wheel355and the worm gear356.

A spring device354is also coupled to the pawl member352so as to urge the pawl member352toward the forward position (refer toFIG. 9). In this embodiment, the spring device354is in the form of a leaf spring that is fixed to the frame portion314(refer toFIG. 4) at a first end portion and that is engaged with an abutment protrusion357of the pawl member352at a second end portion. Thus, as shown inFIG. 10, when the pawl member352is adjusted to the reset position, the spring device354is flexed and stores potential energy that urges the pawl member152to return to the forward position (refer toFIG. 9) and thereby drive the ratchet wheel355in a forward rotational direction. As previously described, a locking pawl359coupled to the frame portion314(refer toFIG. 4) prevents the ratchet wheel355from reverse motion. As such, the adjustable pawl member352can adjust from the forward position (refer toFIG. 9) to the reset position (refer toFIG. 10) to engage a new tooth of the ratchet wheel355while the ratchet wheel355remains in position due to the locking pawl359.

It should be understood that the drive system305can employ a set of stopper pins (similar to previously described embodiments) that limit the motion of the adjustable pawl member352or that serve as location sensors to indicate when the pawl member352has reach the reset position or the forward position. For example, these sensors can be optical, magnetic, or contact type sensors. The sensors may be capable of transmitting signals that indicate when the location of the guide structure348or the pawl member352is detected. Such sensor signals may be transmitted to the motor330, to the controller device, or a combination thereof.

Still referring toFIGS. 9-10, in some embodiments the ratchet wheel355can be integrally formed with the worm gear356so that the incremental rotation of the ratchet wheel355is translated to the worm gear356. Such rotation of the worm gear356causes a rotation of a drive wheel360, which is rotatably mounted to the frame portion314of the pump device300. Similar to previously described embodiments, the drive wheel360includes a central aperture having an internal thread pattern therein (not shown inFIGS. 9-10), which mates is an external thread pattern on the flexible piston rod370. Thus, the incremental motion provided by the ratchet mechanism350, the string member340, and the motor330causes the drive wheel360to incrementally rotate, which in turn translates to a linear advancement of the flexible piston rod370.

Accordingly, in some embodiments, the piston rod370may undergo only forward or positive displacement as a result of drive system305. For example, the drive system305substantially hinders the piston rod370from retracting or “backing up” in response to fluid pressure in the medicine cartridge320or other reversal forces. In such circumstances, the flexible piston rod370can be retracted only upon disassembly of the pump device300(e.g., to disengage the gears or the ratchet mechanism). In those embodiments in which the pump device300is intended to be disposable, the non-retractable piston rod configuration (due to the drive system305) may facilitate a “one time use” disposable pump device, thereby reducing the likelihood of failure due to non-intended repeated use of the disposable pump device.

The flexible piston rod370comprises a plurality of segments372serially connected by hinge portions so that the flexible piston rod370is adjustable from a curved shape to a noncurved shape. As previously described, the plurality of segments372and the interconnecting hinge portions can be integrally formed in one piece from a moldable material, including one or more polymer materials such as Nylon or POM. In this embodiment, the plurality of segments372comprise generally cylindrical segments that each include an exterior thread pattern along at least one cylindrical surface portion. A plunger connector378may be coupled to the leading end of the flexible piston rod370so as to abut against or connect with the plunger321in the plunger chamber326of the fluid cartridge320. Previously incorporated U.S. Provisional Application Ser. No. 60/720,405 also describes a number of configurations for the flexible piston rod370in addition to the configuration illustrated inFIGS. 9-10herein.

Referring now toFIGS. 11A-C, the incremental motion cycle of the drive system305may include rotation of the motor330so that the string member340transitions from a twisted state, to an untwisted state, and then again to a twisted state. Such a transition of the string member340can cause the pawl member330to adjust from the reset position (refer toFIG. 11A), to the forward position (refer toFIG. 11B), and back to the reset position (refer toFIG. 11C). The adjustment of the pawl member352from the reset position to the forward position drives the ratchet wheel355and worm gear356, which incrementally rotates the drive wheel360and thereby advances the flexible piston rod370a longitudinal increment distance379(refer toFIG. 11B). In one example, the drive system305can advance the piston rod370a longitudinal increment distance379of about 16 microns or less (about 4 microns to about 12 microns, and preferably about 7 microns to about 8 microns) for each incremental motion cycle of the motor330, string member340, and ratchet mechanism350as previously described herein.

As shown inFIGS. 11A-C, some embodiments of the motor330may include a mandrel334extending axially from the mechanical connector33or the motor shaft332. The mandrel can be arranged so that the string member340is configured to twist around the mandrel334in response to rotation by the motor shaft332. The frictional wear upon the string material may be reduced because the string member engages and twists around the mandrel334rather than engaging an opposing string material surface and twisting upon itself.

Referring to nowFIG. 11A, in this embodiment of the incremental motion cycle, the pawl member352begins at the reset position with the string member340in a twisted configuration at string portion345. As previously described, the string portion345is twisted around the mandrel334that extends axially from the motor330. When the adjustable pawl member352is in the reset position as shown inFIG. 11A, it is capable of engaging a tooth of the ratchet wheel355.

Referring toFIG. 11B, in response to the controller device transmitting a signal to initiate the cycle, the rotational motor330may begin to rotate in a first rotational direction that unwinds the string member340, thereby permitting the spring device354to drive the pawl member152toward the forward position (refer toFIG. 11B). When the adjustable pawl352is driving the ratchet wheel355in the forward rotational direction, the potential energy of the spring device354is being translated to kinetic energy for the motion of the pawl member352and the ratchet wheel355. Such an adjustment of the pawl member352from the reset position to the forward position drives the ratchet wheel355and the integrally formed worm gear356. The incremental rotation of the worm gear356results in an incremental rotation by the drive wheel360, which advances the flexible piston rod370the longitudinal increment distance379. Such an incremental advancement of the flexible piston rod370may cause a predetermined volume of fluid to be dispensed from the cartridge320(FIG. 4).

Referring toFIG. 11C, the rotational motor330continues to rotate in the first rotational direction so that after the pawl member352reaches the forward position, the string member340begins to twist in the opposite orientation. As previously described, the string member340is twisted around the mandrel334that extends axially from the motor330. Such twisting of the string member340causes a tension force that overcomes the bias of the spring device354and adjusts the pawl member352toward the reset position. When the adjustable pawl member352reaches the reset position, as shown inFIG. 11C, the pawl member is capable of engaging a new tooth of the ratchet wheel355. The locking pawl359(shown inFIG. 4) prevents the ratchet wheel355from rotating in a reverse (non-forward) rotational direction while the adjustable pawl member352is shifting back to the reset position. Such an adjustment of the pawl member352back to the reset position causes the spring device354to flex (as shown inFIG. 11C), thereby storing potential energy to drive the adjustable pawl member352and ratchet wheel355in a subsequent cycle. After the pawl member352reaches the reset position, the rotational motor330stops rotating in the first rotational direction and the pawl member352remains at rest in the reset position (refer toFIG. 11C). In the event of a subsequent cycle, the rotational motor330would begin the cycle by rotating in a second rotational direction (opposite the first rotational direction) so as to unwind the string member340yet again. This pattern of cycles may continue until the piston rod370has reached the limit of its longitudinal travel.

It should be understood, that in other embodiments, the incremental motion cycle may begin with the pawl member352starting at the forward position (refer toFIG. 11B). In such circumstances, the rotation motor330would rotate in a first rotational direction to twist the string until the pawl member is moved to the reset position (refer toFIG. 11C), and then the rotational motor330would rotate in a second, opposite rotational direction to unwind the string member340until the pawl member352returns to the forward position (refer again toFIG. 11B).

Similar to the previously described embodiments, the string member340may comprise braided filaments that are capable of enduring repeated twisting sequences of the string member340. The braided filaments may comprise a polymer such as PET. Such braided filament string members are capable of enduring the torsion and frictional forces associated with undergoing thousands of cycles of twisting as described above in connection withFIGS. 11A-C. The string member340can be formed to have an outer diameter of about 0.02 mm to about 0.07 mm, and preferably about 0.05 mm. Also, in some embodiments, the string member340may comprise braided filaments that are arranged around a centrally disposed thin wire filament (e.g., comprising a polymer material or a metallic material) having a diameter of about 0.02 mm or less, which is also capable of enduring the repeated twisting sequences of the string member340. Such a construction may permit the outer filament surfaces to frictionally engage one another during the twisting process while the filament surfaces contacting the centrally disposed thin wire are exposed to a reduced friction load.

Referring now toFIGS. 12-14, some embodiments of a pump device400can include a string member and a rotational motor like the previously described embodiments, except that the string member440is configured to wind (or unwind or both) around a spindle device. Such a configuration may reduce the torsion and friction loads upon the string member material while providing a tension force to adjust the ratchet mechanism. Moreover, the spindle configuration may further reduce the space requirements for drive system in the pump housing, thereby providing a reliable and compact infusion pump system that is portable and wearable by the user.

Referring toFIG. 12, a ratchet mechanism450that is configured to assemble within a pump device (similar to the ratchet mechanism150in pump device100described in connection withFIG. 3A) is adjusted by a string member440that can wind around a spindle device442. The ratchet mechanism450, string member440, spindle device442, and motor430can be part of a drive system for the pump device (similar to the drive system105of the pump device100described in connection withFIG. 2) that provides a reliable and consistent configuration for accurately dispensing the desired volume of fluid from the infusion pump device. Also, similar to the previously described embodiments, the drive system including the string member440, the motor430, and the spindle device442may comprise few, if any, high-cost components, thereby facilitating the production of a disposable infusion pump device. Because the pump device may house the drive system in a compact manner, the pump device can be portable, wearable, and readily concealable by the user.

As shown inFIG. 12, the spindle device442can be coupled to a rotational motor430so that the spindle device442rotates with the motor shaft. A string member440can be attached to the spindle device442so that the string member440winds or unwinds around the spindle device442in response to the rotation of the motor430. Similar to previously described embodiments, the string member440may comprise a flexible member capable of transmitting a tension force, for example, a braided filament structure, a monofilament string structure, a flexible tape or ribbon structure, or the like. For example, in some embodiments, the string member440may comprise a flexible tape material having generally flat opposing surfaces, thereby permitting the tape material to be wrapped around itself when being wound on the spindle device442.

The string member440is also coupled to the ratchet mechanism450, which provides incremental motion to thereby advance the piston rod (not shown inFIG. 12). The ratchet mechanism450includes the pawl member452and the ratchet body455, which in this embodiment is a ratchet wheel having a number of teeth along its circumferential surface. The pawl member452is adjustable between a reset position (refer toFIG. 12) and a forward position. For example, the rotational motor430may be activated to rotate the spindle device442and thereby wind the string member440(as previously described), and the string member440then applies a tension force that adjusts the pawl member452to the reset position. In the reset position, the pawl member452can engage one or more new teeth of the ratchet wheel455. A spring device454is also coupled to the pawl member452so as to urge the pawl member452toward the forward position. This spring force causes the pawl member452to drive the ratchet wheel455an incremental amount in a forward rotational direction. Similar to the embodiments previously described in connection withFIG. 3A, a locking pawl459prevents the ratchet wheel455from reverse motion. As such, the adjustable pawl member452can adjust from the forward position to the reset position (shown inFIG. 12) to engage a new tooth of the ratchet wheel455while the ratchet wheel455remains in position due to the locking pawl459.

In this embodiment, the ratchet mechanism450can employ a set of stopper pins (as previously described) that limit the motion of the adjustable pawl member452. In some embodiments, the stopper pins can serve as location sensors to detect when the pawl member has reach the reset position or the forward position. For example, these sensors can be optical, magnetic, or contact type sensors.

Accordingly, in one incremental motion cycle, the pawl member452may start at the reset position (as shown inFIG. 12) with the string member440wound around the spindle device442. In response to the controller device (not shown inFIG. 12) transmitting a signal to initiate the cycle, the rotational motor430may begin to rotate in a first rotational direction that unwinds the string member440from the spindle device442, thereby permitting the spring device454to force the pawl member452toward the forward position. The rotational motor430continues to rotate in the first rotational direction so that after the pawl member452reaches the forward position, the string member440begins to wind around the spindle device442in the opposite orientation. Such winding of the string member440causes a tension force that overcomes the bias of the spring device454and adjusts the pawl member452toward the reset position. After the pawl member reaches the reset position, the rotational motor430stops rotating in the first rotational direction and the pawl member452remains at rest in the reset position. In the event of a second cycle, the rotational motor430would begin the cycle by rotating in a second rotational direction (opposite the first rotational direction) so as to unwind the string member440from the spindle device442yet again.

In other embodiments, the incremental motion cycle may begin with the pawl member452starting at the forward position. In such circumstances, the rotational motor430would rotate in a first rotational direction to wind the string member440around the spindle device until the pawl member452is moved to the reset position (as shown inFIG. 12), and then the rotational motor430would rotate in a second, opposite rotational direction to unwind the string member440from the spindle device442until the pawl member452returns to the forward position.

Referring now to another embodiment of a pump device500as shown inFIGS. 13-14, the drive system505can include a string member540that is configured to be wrapped around a spindle device542. In these circumstances, the orientation of the string member540can be configured to provide an efficient mechanical advantage during the desired motion of the adjustable pawl member552. Moreover, such a configuration may reduce the torsion and friction loads upon the string member material and may further reduce the space requirements for drive system505of the pump device500. Similar to previously described embodiments, the string member540may comprise a flexible member capable of transmitting a tension force, for example, a braided filament structure, a monofilament string structure, a flexible tape or ribbon structure, or the like. For example, in some embodiments, the string member540may comprise a flexible tape material having generally flat opposing surfaces, thereby permitting the tape material to be wrapped around itself when being wound on the spindle device542.

Similar to the previously described embodiments, the pump device500includes a housing structure510that defines a cavity516capable of receiving a fluid cartridge (not shown inFIGS. 13-14). The housing structure510may include a frame portion514and a detachable shell portion (removed fromFIGS. 13-14for purposes of illustration) so that, when assembled, the pump device500can have an outer appearance similar to that of pump device300depicted inFIG. 5. In these embodiments, the drive system505can be contained in the housing structure510of the pump device500in a compact manner so that the pump device500is portable, wearable, concealable, or a combination thereof. Similar to previously described embodiments, the pump device500can be part of an infusion pump system in which the pump device communicates with a controller device, including but not limited to the removable controller device390described in connection withFIG. 6. The controller device can communicate control signals to the drive system505or other components of the pump device500. For example, the pump device500may include on or more electrical contacts that are exposed to the controller device and that mate with opposing electrical contacts (e.g., pads, pins, or the like) on the adjacent end of the controller device. In this embodiment, the pump system is a medical infusion pump system that is configured to controllably dispense a medicine. As such, the pump device500can be adapted to receive a medicine cartridge in the form of carpule that contains insulin or another medicament for use in the treatment of Diabetes (e.g., exenatide, BYETTA, or others), or other injectable medicines.

Still referring toFIGS. 13-14, the pump device500includes a drive system505that is capable of accurately and incrementally dispensing fluid from the fluid cartridge in a controlled manner. Similar to the previously described embodiments, the drive system505may include a rotational motor530that is coupled to a string member540. Briefly, the rotational motor530can be used to wind (or unwind or both) the string member540around a spindle device542, which causes the string member540to adjust a pawl member552relative to a ratchet body555. In this embodiment, the ratchet body555is in the form of a ratchet wheel that is integrally formed with a worm gear556. Incremental rotation of the ratchet wheel555causes rotation of a drive wheel560, which causes the incremental linear advancement of a flexible piston rod570. As the piston rod570is advanced in the forward longitudinal direction, fluid dispenses from the pump device500. Accordingly, the drive system505can provide a reliable and compact configuration for accurately dispensing the desired volume of fluid from the pump device500. Moreover, the drive system505may comprise few, if any, high-cost actuator components or electronics, thereby facilitating the production of a disposable and reliable pump device500.

Referring toFIG. 14(note that the frame portion514has been removed fromFIG. 14for purposes of illustration), the string member540is coupled to the ratchet mechanism, which provides incremental motion to thereby advance the piston rod570. The ratchet mechanism includes the pawl member552and the ratchet body555, which in this embodiment is a ratchet wheel having a number of teeth along its circumferential surface. The pawl member552is adjustable between a reset position and a forward position (refer toFIG. 14). For example, the rotational motor530may be activated to wind the string member540around the spindle device542, and the string member540then applies a tension force that adjusts the pawl member552to the reset position in which the pawl member552grabs a new tooth of the ratchet wheel555. A spring device554is also coupled to the pawl member552so as to urge the pawl member552toward the forward position. In this embodiment, the spring device554is a leaf spring that is fixed to the frame portion514(refer toFIG. 13) at a first end portion and that is engaged with an abutment protrusion557of the pawl member552at a second end portion. Thus, when the pawl member552is adjusted to the reset position, the spring device554is increasingly flexed and thereby stores potential energy that urges the pawl member552to return to the forward position. Similar to previously described embodiments, a locking pawl coupled to the frame portion514(refer toFIG. 13) prevents the ratchet wheel555from reverse motion. As such, the adjustable pawl member552can adjust from the forward position to the reset position to engage a new tooth of the ratchet wheel555while the ratchet wheel555remains in position due to the locking pawl559.

In this embodiment, the ratchet wheel555is integrally formed with the worm gear556so that the incremental rotation of the ratchet wheel555is translated to the worm gear556. Such rotation of the worm gear556causes a rotation of a drive wheel560, which is rotatably mounted to the frame portion514using a bearing565. Similar to previously described embodiments, the drive wheel560includes a central aperture having an internal thread pattern therein (not shown inFIGS. 13-14), which mates with an external thread pattern on the flexible piston rod570. Thus, the incremental motion provided by the ratchet mechanism550, the string member540, and the motor530causes the drive wheel560to incrementally rotate, which in turn translates to a linear advancement of the flexible piston rod570. A plunger connector578may be coupled to the leading end of the flexible piston rod570so as to abut against or connect with the plunger in the fluid cartridge.

Still referring toFIG. 14, the incremental motion cycle of the drive system505may include rotation of the motor530so that the string member540transitions from a wrapped state (e.g., wound around the spindle device542), to an unwrapped state, and then to a wrapped state. Such a transition of the string member540can cause the adjustable pawl member552to transition from the reset position, to the forward position (refer toFIG. 14), and back to the reset position. As previously described, the adjustment of the pawl member552from the reset position to the forward position drives the incremental rotation of the drive wheel560, which advances the flexible piston rod570a longitudinal increment distance. In one example, the drive system505can advance the piston rod570a longitudinal increment distance of about 16 microns or less (about 4 microns to about 12 microns, and preferably about 7 microns to about 8 microns) for each incremental motion cycle of the motor530, string member540, and ratchet mechanism550as previously described herein. It should be understood, that in other embodiments, the incremental motion cycle may begin with the pawl member552starting at the forward position (refer toFIG. 14). In such circumstances, the rotation motor530would rotate in a first rotational direction to wind the string member540around the spindle device542until the pawl member552is moved to the reset position, and then the rotational motor530would rotate in a second, opposite rotational direction to unwind the string member540until the pawl member552returns to the forward position.