Patent Description:
Many conventional wearable drug delivery systems include either a fully rigid reservoir or a fully flexible reservoir for storing a liquid drug. Each type of reservoir includes one or more advantages and disadvantages over the other type of reservoir. Fully rigid reservoirs take up space that may be better used. While fully flexible reservoirs may be space efficient and may require relatively lower pumping pressures, the flexible reservoirs present challenges compared to fully rigid reservoirs. For example, the expansion and collapse of earlier flexible reservoirs may be unpredictable, thereby leading to undesirable hold up volumes and difficulties in determining stored fluid volumes (e.g., inaccurate fill gauging). Flexible reservoirs also present challenges related to vapor transmissivity. In some instances, a small volume of fluid is spread across a large surface area on a thin flexible membrane. This may lead to higher vapor transmission rates and may negatively impact medication concentration/potency. <CIT> discloses a reservoir for storing a liquid drug, the reservoir comprising a shell component and a flexible component coupled thereto. A similar reservoir is known from <CIT>, which represents prior art under Article <NUM>(<NUM>) EPC. In both cases, the flexible component does not deflate and conform to the inner surface of the shell component.

The invention comprises a reservoir for storing a liquid drug as defined in claim <NUM>. Additional features of preferred embodiments are defined in the dependent claims. Disclosed is an example of a reservoir for storing a liquid drug. The reservoir includes a shell component, a flexible component and a port. The flexible component is coupled to the shell component. The coupling is a hermetic seal. The port is configured to enable filling of emptying of the reservoir.

An example of a reservoir system is disclosed that includes a flexible reservoir and an exoskeleton. The flexible reservoir is configured to expand when filled with a liquid drug. The exoskeleton is coupled to the flexible reservoir.

A system example is disclosed in which the system include a reservoir, one or more peel-able restraints positioned on the flexible reservoir. The one or more peel-able restraints are configured to seal off one or more corresponding sections of the flexible reservoir, and sequentially break to allow a liquid to fill a next corresponding section of the one or more corresponding sections of the flexible reservoir as the flexible reservoir is filled with the liquid.

Various systems, components, and methods related to drug delivery devices are disclosed. Each of the systems, components, and methods disclosed herein provides one or more advantages over conventional systems, components, and methods.

In order to mitigate the foregoing disadvantages of flexible reservoirs, a need therefore exists for a drug delivery device that includes a drug reservoir or reservoir that combines the advantages of fully flexible and fully rigid reservoirs while mitigating one or more disadvantages of fully flexible and fully rigid reservoirs. In addition, there is a need for a flexible reservoir system that may expand and collapse in a more predictable manner, to reduce hold up volumes and enable accurate stored fluid volume determinations, while retaining the advantages of flexible reservoirs such as high space efficiency or low pumping pressure. A further need exists for a flexible reservoir for use with a drug delivery device that has reduced holdup volume, reduced vapor transmission, and improved fill sensing capabilities.

<FIG> illustrates a cross-sectional side view of a first example of a drug reservoir in a filled state and an unfilled state. The combination of components for forming the reservoir (or hybrid reservoir) may, for example, allow the liquid drug to be stored and then expelled from the reservoir with relatively lower pumping pressures (as compared to fully rigid drug reservoirs) and without the need for a plunger as well as other apparent advantages.

As shown, the drug reservoir <NUM> includes a shell component <NUM> that may be rigid or semi-rigid and a flexible component <NUM>. The shell component <NUM> may be formed from a variety of materials including, for example, plastic or metal, or any combination thereof. The flexible component <NUM> may be formed from a variety of flexible materials including, for example, a flexible plastic film. The flexible component <NUM> has greater flexibility than the shell component <NUM>. <FIG> shows the drug reservoir <NUM> in an unfilled state and in a filled state. When filled, the flexible component <NUM> expands in response to a liquid drug (not shown) filling the drug reservoir <NUM> from a port (shown in other examples). The expansion of the flexible component <NUM> and the hermetic coupling or seal to the shell component <NUM> enables the drug reservoir <NUM> to contain a liquid drug (or other fluid or therapeutic agent) <NUM>. The shell component <NUM> is an open shell. In some examples of a wearable drug delivery device, the shell component <NUM> may be integrated into other parts, such as a housing or chassis thereby enabling a rigid or semi-rigid shell component <NUM> to serve multiple purposes, such as part of a housing for the wearable drug delivery device, a structure element of another part (e.g. a battery clip or retainer) of the wearable drug delivery device, or the like.

The flexible component <NUM> may be coupled to the shell component <NUM> in a number of manners including, for example, mechanically, through use of an adhesive, or through use of an adhesive tape or the like. The coupling of the flexible component <NUM> to the shell component <NUM> is a hermetic seal thereby forming the reservoir <NUM> that is able to contain the liquid drug or other fluid. The shell component <NUM> may be of any size or shape. As shown in <FIG>, the shell component <NUM> may form a bowl with an upper ridge or lip to support and provide coupling to the flexible component <NUM>.

<FIG> illustrates a top view and a corresponding side view of a second example of a drug reservoir. The drug reservoir <NUM> may be a particular implementation of the drug reservoir <NUM>. The drug reservoir <NUM> may include a rigid or semi-rigid shell component <NUM> and a flexible component <NUM>. The flexible component <NUM> may be formed from a thin flexible film, or the like. The shell component <NUM> may be an open shell. Although not shown in <FIG>, the flexible component <NUM> may be sealed (i.e., coupled to form hermetic seal) to the shell component <NUM> - for example, along a perimeter of the shell component <NUM>. For example, an adhesive, an adhesive tape or mechanical means, such as ultrasonic welding or the like, may be used to couple or affix the flexible film component to the shell component <NUM>. The sealing of the flexible component <NUM> to the shell component <NUM> is hermetic thereby forming the reservoir <NUM> that contains the liquid drug or other fluid. The side view shows the flexible component <NUM> in a deflated state <NUM>-<NUM> and in an inflated or expanded state <NUM>-<NUM> when filled with a fluid. When inflated or expanded, the flexible component <NUM> may provide a chamber <NUM> for storing a fluid.

The drug reservoir <NUM> may further include an opening or side port <NUM>. The side port <NUM> may be coupled to a fluid extraction component such as, for example, a pump (not shown). The side port <NUM> may also be coupled to a fluid path (not shown) coupled to a patient or user of a wearable drug device containing the drug reservoir <NUM>. The side port <NUM> may be formed as a portion of the shell component <NUM> or may be a separate component coupled to the drug reservoir <NUM>. A liquid drug or other fluid may enter and/or exit the drug reservoir <NUM> from the side port <NUM>.

As shown in the top view and the side view, the drug reservoir <NUM> may further include one or more recessed drainage channels <NUM>. The drainage channels <NUM> may be formed into the shell component <NUM>, for example, into an inner surface of the shell component <NUM>. In an alternative example, the drainage channels <NUM>, instead of being formed in the shell component <NUM>, may be formed into the flexible component <NUM>, for example, into an inner surface (i.e., inside the drug reservoir <NUM> at a surface that contacts the liquid) of the flexible component <NUM>. In yet another alternative example, the drainage channels <NUM> may be formed in the shell component <NUM> and the flexible component <NUM>, for example, in an inner surface of each of the shell component <NUM> and the flexible component <NUM>. The drainage channels <NUM> may improve drainage of the drug reservoir <NUM>, particularly as the drug reservoir <NUM> is nearly emptied of a stored liquid drug.

The drainage channels <NUM> may be formed in a number of ways to form any pattern or arrangement. In various examples, the drainage channels <NUM> may be formed to mimic venation patterns found on leaves. As an example, the drainage channels <NUM> may form a pinnate pattern or arrangement (e.g., a specific form of venation and may include a single mid-rib channel and secondary channels branching therefrom). In other examples, the drainage channels <NUM> may be a number of horizontal and vertical channels that are perpendicular to one another (e.g., a form of cross hatching), diagonal channels, or similar patterns of channels that facilitate drainage of the reservoir to minimize an amount of hold up volume (e.g., a volume of liquid) in the reservoir after the reservoir is drained. In addition, the channels may be a similar depth along the entire length of the channel or may have a graded depth to facilitate flow toward a port. Alternatively, or in addition, the interior of the reservoir on the film <NUM>, the shell <NUM> or both may have a textured surface, such as stippling (e.g., bumps), ridges, grooves, or the like, configured to minimize the surface area upon which surfaces of film <NUM> and shell <NUM> at the interior of the reservoir <NUM> may contact one another as the fluid evacuates the reservoir.

<FIG> illustrates a top view and a corresponding side view of a third example of a drug reservoir according to the disclosure. The drug reservoir <NUM> may include a rigid or semi-rigid shell component <NUM> and a flexible film component <NUM>. The flexible film component <NUM> may be sealed or coupled to the shell component <NUM> - for example, along a perimeter of the shell component <NUM>, to form a hermetic seal between the flexible film component <NUM> and the shell component <NUM>. The corresponding side view of drug reservoir <NUM> shows the flexible film component <NUM> in a deflated state <NUM>-<NUM> and in an inflated or expanded state <NUM>-<NUM>. When inflated or expanded, the flexible film component <NUM> may provide a chamber <NUM> for storing a fluid.

The drug reservoir <NUM> may further include an opening or central face port <NUM>. The central face port <NUM> may be coupled to a fluid extraction component such as, for example, a pump. The central face port <NUM> may also be coupled to a fluid path coupled to a patient or user of a wearable drug device containing the drug reservoir <NUM>. The central face port <NUM> may include a pierceable septum accessible from a bottom side of the drug reservoir <NUM>. The central face port <NUM> may be formed as part of the shell component <NUM> or may be a separate component coupled to the drug reservoir <NUM>. A liquid drug or other fluid may enter and/or exit from the central face port <NUM>.

The drug reservoir <NUM> may further include one or more recessed drainage channels <NUM>. The channels <NUM> may be formed into the shell component <NUM> (e.g., an inner surface of the shell component <NUM>). The channels <NUM> may improve drainage of the drug reservoir <NUM>, particularly as the drug reservoir <NUM> is nearly emptied of a stored liquid drug. For example, the circular region at the intersection of the channels <NUM> may be coupled to the pierce-able septum at the bottom of the pod and central face port <NUM> to allow the drug (not shown) to drain from the drug reservoir <NUM>.

The channels <NUM> may be formed in a number of ways to form any pattern or arrangement. In various examples, the channels <NUM> may be formed to mimic venation patterns found on leaves. As an example, the channels <NUM> may form a palmate pattern or arrangement (e.g., a specific form of venation to include multiple primary channels with additional subchannels branching from a central point). In other examples, the drainage channels <NUM> may be a pattern of a number of horizontal and vertical channels that are perpendicular to one another (e.g., a form of cross hatching), diagonal channels, or similar patterns of channels.

Overall, the channels <NUM> and <NUM> shown may be arranged in any manner according to any design or configuration. In various examples, the channels <NUM> and <NUM> may be optimized based on the number and size of the channels <NUM> and <NUM> to reduce hold-up volume that may be present as the drug reservoirs <NUM> and <NUM> are drained.

By joining an open rigid (or semi-rigid) shell component and a flexible film sealing the open rigid shell component, the drug reservoirs disclosed herein (e.g., the drug reservoirs <NUM>, <NUM>, and <NUM>) may provide a number of benefits including the following: more space efficient that a fully rigid reservoir; requires less pumping pressure than a fully rigid reservoir; and may provide more complex shapes than a fully rigid reservoir. For example, the drug reservoirs <NUM>, <NUM> and <NUM> may be configured to have layouts that conform to occupy otherwise "dead space", or unused space, within a wearable drug delivery device. In addition, depending upon the implementation, the example drug reservoirs <NUM>, <NUM> and <NUM> may be more robust; easier to secure; and easier to couple fluid path connections than a fully flexible reservoir. Furthermore, the intersection of the flexible film and the open rigid (or semi-rigid) shell component forms a natural hinge-like area around the open rigid shell that facilitates a controlled collapse of the flexible film into the open rigid shell component thereby allowing for a more uniform evacuation of the drug reservoir.

In various examples, the flexible film components <NUM>, <NUM> and <NUM> disclosed herein may be coupled or sealed to the shell components <NUM>, <NUM>, <NUM>, respectively, according to a number of processes including, for example: flame bonding; hot air gun; hot knife welding; hot plate welding; ultrasonic welding; an induction/impulse process; a dielectric-radio frequency process; solvent bonding, any combination thereof, or the like.

In various examples, the flexible film components <NUM>, <NUM> and <NUM> disclosed herein may be formed to provide a tight seal with the shell components <NUM>, <NUM>, <NUM>, respectively, disclosed herein to minimize any formed air gap. In various examples, the flexible film components <NUM>, <NUM> and <NUM> may be provided by thermoforming.

Each of the drug reservoirs disclosed herein (e.g., the drug reservoirs <NUM>, <NUM>, and <NUM>) may be included or used as a component of a drug delivery device including, for example, a wearable drug delivery device or an on-body drug delivery device that may store and dispense any type of drug, fluid, a therapeutic agent to a user including insulin, or the like. An example of a suitable drug delivery device in which the foregoing examples of drug reservoirs may be implemented is described in more detail with reference to the example of <FIG>.

<FIG> illustrates an example of a flexible reservoir system. The flexible reservoir system <NUM> may include a flexible reservoir <NUM> and an exoskeleton <NUM>. The flexible reservoir <NUM> may be made of any suitable non-rigid material that allows the flexible reservoir <NUM> to expand when filled with a liquid or fluid and to contract or collapse when emptied or drained. The flexible reservoir <NUM> may be configured to hold or store any liquid or fluid such as, for example, a liquid drug or other therapeutic agent.

The flexible reservoir system <NUM> may be integrated into a drug delivery device or system such as, for example, a wearable or on body drug delivery device such as that described with reference to <FIG>. The exoskeleton <NUM> may be formed of any suitable rigid or semi-rigid material such as, for example, metal or plastic. The exoskeleton <NUM> may be attached or coupled to the flexible reservoir <NUM> along all or a portion of the exoskeleton <NUM>. In various examples, the exoskeleton <NUM> may be detached or not coupled to the flexible reservoir <NUM>.

A rigid or semi-rigid exoskeleton <NUM> may surround the flexible reservoir <NUM> to guide the expansion and collapse of the flexible reservoir. The placement of the exoskeleton <NUM> creates impingement points or locations on the flexible reservoir <NUM> that guide the collapse or expansion as fluid leaves or is input to the flexible reservoir <NUM>. As a result, a volume of the liquid drug stored in the flexible reservoir <NUM> may be more easily determined to enable accurate fill gauging. For example, hold up volume may also be reduced based on the controlled and predictable manner of collapse of the flexible reservoir <NUM>.

<FIG> shows the flexible reservoir <NUM> in a filled or partially filled state. As shown, the flexible reservoir <NUM> may have a side cross-sectional shape resembling an arrowhead (or triangular) but is not so limited. In general, the flexible reservoir <NUM> may have any desired size and shape. The exoskeleton <NUM> may conform to the outer surfaces of the flexible reservoir <NUM> when filled and may operate or be similar to a stent. The exoskeleton <NUM> may have a material that has a higher elastic modulus than the material that forms the flexible reservoir <NUM>. As further shown in <FIG>, the exoskeleton <NUM> may form a cross-hatching or lattice arrangement (or cage) around the flexible reservoir <NUM>. In an unfilled or compressed state, the flexible reservoir <NUM> may lay substantially flat along with the exoskeleton <NUM> also being able to fold over, collapse, and/or lay substantially flat on top of and/or around the flexible reservoir <NUM>.

The flexible reservoir system <NUM> - by including the exoskeleton <NUM> - may improve control of the expansion and the collapse of the flexible reservoir <NUM> during filling and emptying of the flexible reservoir, respectively. The rigid and/or semi-shell components of the exoskeleton <NUM> may aid or guide the change of shape of the flexible reservoir <NUM> such that as it expands or collapses, it does so in a predictable and expected manner. By guiding the expansion and collapse of the flexible reservoir <NUM>, the exoskeleton <NUM> may improve operation of the flexible reservoir system <NUM>.

In particular, the exoskeleton <NUM> may improve fill gauge sensing in relation to the flexible reservoir system <NUM> as the exoskeleton <NUM> may ensure that the displacement of the flexible reservoir <NUM> as it is filled or emptied involves known displacement or movement, allowing the volume of the flexible reservoir to be determined more easily.

Additionally, the exoskeleton <NUM> may reduce hold up volume associated with the flexible reservoir <NUM> as the controlled collapse of the flexible reservoir <NUM> provided by the exoskeleton <NUM> is more predictable and consistent for each collapse.

<FIG> illustrates another example of a flexible reservoir system. The flexible reservoir system <NUM> may include a flexible reservoir <NUM> and rigid panels <NUM>. The flexible reservoir <NUM> may be made of any suitable non-rigid material that allows the flexible reservoir <NUM> to expand when filled with a liquid or fluid and to contract or collapse when emptied or drained. The flexible reservoir <NUM> may be configured to hold or store any liquid or fluid such as, for example, a liquid drug or other therapeutic agent.

The flexible reservoir system <NUM> may integrated into a drug delivery device or system such as, for example, a wearable or on body drug delivery device. The flexible reservoir system <NUM> may include one or more rigid panels <NUM>, with each rigid panel <NUM> attached a flat surface of the flexible reservoir <NUM> as shown. The rigid panels <NUM> may add structure to the flexible reservoir. As shown in <FIG>, hinge points <NUM> may be positioned at angled portions or crease portions (or vertices of the different angles) of the flexible reservoir <NUM>. The hinge points <NUM> may be introduced or created by attachment of the rigid panels <NUM> to the flexible reservoir <NUM>, or by use of the exoskeleton <NUM> of <FIG>.

The flexible reservoir <NUM> shown in <FIG> is in a filled or partially filled state (e.g., a side view of the flexible reservoir <NUM>). As shown, the flexible reservoir <NUM> may have a side cross-sectional shape resembling an arrowhead (or triangular) but is not so limited. In general, the flexible reservoir <NUM> may have any desired size and shape. The attachment and positioning of the rigid panels <NUM> to the flexible reservoir <NUM> may help determine the shape of the flexible reservoir <NUM> and may guide the expansion and collapse of the flexible reservoir <NUM> as it is filled or drained. In various examples, the rigid panels <NUM> may rotate about the hinge points <NUM> or rotate relative to one another as the flexible reservoir <NUM> is filled or emptied.

In various examples, the flexible reservoir <NUM> may be substantially the same as the flexible reservoir <NUM>. The placement of the rigid panels <NUM> may accommodate and guide movement of the flexible reservoir <NUM> in a controlled and predictable manner. The rigid panels <NUM> may be formed of any suitable material including, for example, metal or plastic. In general, the rigid panels <NUM> may be formed to be relatively thin in relation to a size of the flexible reservoir <NUM>. The rigid panels <NUM> may be attached to the flexible reservoir <NUM> by any suitable means.

The rigid panels <NUM> may facilitate volume determination of a fluid occupying the flexible reservoir <NUM>. For example, angles of the flexible reservoir <NUM>, angles of the created hinge points <NUM>, and/or movement or displacement of the rigid panels <NUM> (e.g., relative to one another or to a fixed reference point) may be used to estimate an amount of fluid contained within the flexible reservoir <NUM> as each of these components and features of the flexible reservoir system <NUM> change upon expansion and collapse. As with the flexible reservoir system <NUM>, the flexible reservoir system <NUM> may reduce hold up volume as the rigid panels provide controlled collapse of the flexible reservoir <NUM> during the evacuation of fluid from the flexible reservoir <NUM>, resulting in a more predictable and consistent collapse of the flexible reservoir <NUM>. The examples in <FIG> and <FIG> provide a reservoir system that fills and empties in a predictable manner due to the use of the exoskeleton. The predictability enables sensors to be used to provide reliable volume sensing (e.g., a fill gauge) so measurements of how much liquid drug remains, has been dispensed and other information related to the volume of the liquid drug, the reservoir or the operation of the wearable device may be provided to a user. The materials of the exoskeleton and the flexible reservoir may be the same, or different. To achieve the structural features that enable the predictable collapse or fill of the reservoir, different thicknesses of the same material and/or different materials having a different modulus of elasticity from one another may be used to form the illustrated examples.

In the various examples of <FIG> of another reservoir system, the reservoir systems in a wearable drug delivery system, for example, may also be configured to store a liquid drug.

<FIG> illustrates a first example of a reservoir. As shown in <FIG>, the reservoir <NUM> may include a reservoir <NUM> and peel-able restraints (or dividers) <NUM>. The reservoir <NUM> may couple to a fluid path component <NUM> that includes a flow sensor <NUM> and to a pumping mechanism <NUM> (not shown but described in more detail with reference to another example). The reservoir <NUM> may be a flexible thin film reservoir. The peel-able restraints <NUM> may be peel-able heat stakes or the like. For example, the peel-able restraints <NUM> may be held together with a weak adhesive having known holding properties or the like. The fluid path component <NUM> may be coupled to the reservoir <NUM>. The fluid path component <NUM> may include a fill port <NUM> and may also be coupled to a pumping mechanism <NUM>. As shown in another example, the flow sensor <NUM> may be positioned between the fill port <NUM> and the pumping mechanism <NUM>. The reservoir <NUM> may be part of a drug delivery device or system such as, for example, a wearable drug delivery device or system.

In various examples, the fill port <NUM> may provide access to a fluid such as, for example, a liquid drug. The pumping mechanism <NUM> (details not shown in <FIG> for simplicity) may be any type of pumping mechanism or system for extracting fluid from the reservoir <NUM>. The pumping mechanism <NUM> may be operated to provide stored fluid within the reservoir to, for example, a user or patient using the wearable drug delivery device of which the reservoir system <NUM> is a part.

In various examples, a first process may be used to form the reservoir <NUM> and a second or supplemental process may be used to form and position the peel-able restraints <NUM>. The peel-able restraints <NUM> may form zones within the reservoir <NUM>. The peel-able restraints <NUM> may seal or block off portions or sections of the reservoir <NUM> that may remain sealed until broken during a filling process. For example, the peel-able restraints <NUM> may seal off corresponding sections of the reservoir <NUM> and may be released or opened as more fluid enters the reservoir <NUM> during a filling process. A pressure/force from the fluid/filling process may cause the peel-able restraints <NUM> to open or break sequentially, thereby providing access to another corresponding sealed off section of the reservoir <NUM>. In this manner, a filling process of the reservoir <NUM> may be closely controlled - for example, to ensure that corresponding sections or zones determined by the peel-able restraints <NUM> are sequentially filled. In an operational example, one or more peel-able restraints <NUM> may be positioned on the reservoir <NUM> to seal off one or more corresponding sections (i.e., areas between respective peel-able restraints) of the reservoir <NUM>. In an example, each corresponding section of the one or more corresponding sections is completely filled with the liquid drug before a next section is opened for filling by breaking a next corresponding peel-able restraint. An initial section (e.g., the section of the reservoir <NUM> closest to the fluid path component <NUM>) of the reservoir <NUM> may be filled, eventually a first peel-able restraint (closest to the fluid path component <NUM>) of the peel-able restraints <NUM> may sequentially break, enabling the liquid drug to sequentially fill the corresponding section of the reservoir <NUM>. In this way, the reservoir <NUM> is filled in a predictable and controlled manner - with each section formed by the peel-able restraints filled one after another.

In various examples, the filling process may open any number of the peel-able restraints <NUM> but is not limited to opening all of the peel-able restraints <NUM>. That is, only a portion of the reservoir <NUM> may be filled such that some peel-able restraints <NUM> remain closed, thereby allowing certain corresponding sections of the reservoir <NUM> to remain sealed off. In general, the arrangement of the peel-able restraints <NUM> may guide the filling process of the reservoir <NUM> in a predictable and/or controlled manner.

As shown in <FIG>, the peel-able restraints <NUM> may have increasing widths (e.g., moving from an end of the reservoir <NUM> coupled to the fluid path component <NUM> to an end of the reservoir <NUM> not coupled to the fluid path component <NUM>). The increasing widths of the peel-able restraints <NUM> may provide increasing strengths for the peel-able restraints <NUM>, such that the peel-able restraints <NUM> having larger widths require more force to open than peel-able restraints <NUM> having smaller widths. This allows for tuning of the filling of the reservoir <NUM>. The arrangement and increasing widths of the peel-able restraints <NUM> as shown in <FIG> may ensure that the peel-able restraints <NUM> open sequentially in a controlled manner - for example, one at a time to provide the fluid to a current corresponding section to first fill completely before opening a next peel-able restraint <NUM>. In an example, increased pressure needed to break into the next corresponding section may provide a pressure "signature" that may be used for fill sensing. For example, the peel-able restraint between a first corresponding section and a second corresponding section may break at <NUM> pounds per square inch (psi), while the peel-able restraint between the second corresponding section and a third corresponding section may break at <NUM> psi, so on until the reservoir is filled to a desired volume. Alternatively, the respective pressure "signature" for each corresponding section may be the same (e.g. <NUM> psi). A fill sensing module, which may be a logic circuit or the like coupled to the flow sensor or pressure sensor (e.g., pressure gauge or the like), may detect pressure spikes and pressure drops to infer that a peel-able restraint broke and the liquid drug is flowing into a next corresponding section. Of course, other methods such as detecting changes in resistance or capacitance may also be used to provide fill sensing with use of a logic circuit.

The reservoir <NUM> may have any shape and/or form factor. The peel-able restraints <NUM> may also have any shape and may be arranged in any desired manner onto the reservoir <NUM>. In an example, the reservoir <NUM> may be circular and the peel-able restraints <NUM> may be formed in concentric circles on the reservoir <NUM>. In an example, the peel-able restraints <NUM> may be formed along a gradient (e.g., with increasing or decreasing sized corresponding sections).

The reservoir system <NUM> may provide several advantages. For example, by establishing separate fillable sections or zones within the reservoir, holdup volume, reservoir air volume, and vapor transmissivity may be reduced.

In some instances, the flexible films that form the reservoirs have vapor transmissivity that permits water vapor to pass through the flexible film after time. The exposure to water vapor over time can reduce the potency of a drug stored in the reservoir. As a further advantage of the reservoir <NUM> related to vapor transmissivity, at lower fill volumes, fewer compartments or sections formed by the peel-able restraints <NUM> may be filled by the fluid or drug. As a result, the interior surface area of the reservoir <NUM> that contacts the fluid may be reduced (e.g., in comparison to a flexible reservoir not having peel-able restraints <NUM>). By reducing the interior surface area of the reservoir <NUM> in contact with the fluid, the rate of vapor transmission to the stored fluid may be reduced (e.g., since the ratio of the surface area of the interior of the reservoir to the fill volume). For example, the reservoir <NUM> is to be filled with a volume of drug that is one-tenth of the capacity of the entire reservoir. Since reservoir <NUM> has the peel-able restraints <NUM>, by filling a first section or sections equal to the volume of drug, the exposure of the drug to an interior surface area of the reservoir remains at a consistent ratio of fill volume to surface area to which the drug is exposed. For example, a reservoir, such as <NUM>, may have an interior surface area of <NUM> square millimeters and assume a volume of drug equaling one-tenth of the fill capacity (i.e., volume of drug that the reservoir is capable of holding) of the reservoir is input into the reservoir. By using a reservoir <NUM> having the peel-able restraints <NUM>, the amount of the drug that is exposed to an interior surface of the reservoir may be limited to, for example, one-tenth of the interior surface area of the reservoir. By maintaining a consistent ratio of exposed interior surface area to liquid drug volume, the potency of the drug may be prolonged due to the reduced exposure to water vapor. The consistent ratio may be based on the particular drug and the material of the flexible film. In other examples, the solution of the liquid drug may pass through the reservoir <NUM> thereby leaving less liquid volume in the reservoir <NUM>. In addition, other proteins from the liquid drug may be left behind, which affects drug concentration and potency.

Furthermore, hold up volume may be reduced at lower fill volumes. The peel-able restraints <NUM> will also maintain a near vacuum state inside the reservoir <NUM> during storage, preventing trapped air from affecting performance of the reservoir system <NUM>.

The reservoir system <NUM> also may provide accurate fill sensing based on detected changes in pressure or flow rate when the peel-able restraints <NUM> break at known positions. For example, the arrangement of the peel-able restraints <NUM> may cause pressure pulses (e.g., when the dividers are broken) that may correspond to different fill volumes that may be detected by the flow sensor <NUM>. The detected flow volume may reflect the changes in pressure related to the fill volume. Alternatively, a pressure sensor could also be used in a similar location as the flow sensor <NUM> to estimate fill volume - for example, by detecting a pressure drop after each restraint (e.g., a peel-able restraint <NUM>) "breaks. " In general, the sensor <NUM> may detect changes in pressure and/or flow that may be related to fill volume of the reservoir <NUM> based on the known positions of the peel-able restraints <NUM> (and/or the known sizes of the different compartments formed by the peel-able restraints <NUM>). Other sensors could also be alternatively used to detect fill volume.

Often, the desire for a thin and flexible reservoir may make it challenging to make the reservoir less susceptible or prone to vapor transmission. <FIG> illustrates a subsequent exemplary reservoir system <NUM>. The reservoir system <NUM> provides a solution to these somewhat competing goals or requirements for a reservoir by using the thin film reservoir <NUM> and a separate membrane <NUM> as a vapor barrier. As shown in <FIG>, the reservoir system <NUM> includes a reservoir <NUM> and an outer membrane <NUM>. The reservoir <NUM> may be a flexible thin film reservoir. In an example, in configurations where an amount of free space or air volume is to be limited at maximum fill of the reservoir system <NUM>, the outer membrane <NUM> may be part of or integrated into the housing of wearable drug delivery device (not shown in this example). In another example, the outer membrane <NUM> may surround the inner thin film reservoir <NUM>. The inner thin film reservoir <NUM> may include a port or opening <NUM>. The outer membrane <NUM> may be a relatively thick membrane (e.g., in comparison to the thickness of the reservoir <NUM>) and/or have improved water vapor transmissivity than the inner thin film reservoir <NUM>. The outer membrane <NUM> may be configured to reduce or minimize vapor transmission. A top view and a corresponding side view of the reservoir system <NUM> are both shown in <FIG>.

By doing so, each component may be separately optimized to meet overall design requirements. In various examples, the reservoir <NUM> and the membrane <NUM> may be made of the same material (e.g., with different thicknesses). In various examples, the reservoir <NUM> and the membrane <NUM> may be made of different materials. In some examples, the reservoir <NUM> and the membrane <NUM> may not be laminated together, but in other example, the reservoir <NUM> and the membrane <NUM> may be laminated together.

<FIG> illustrates exemplary processes for forming a multilayer reservoir. The processes may be used to form the reservoirs <NUM> or <NUM>. In the top figure, a first membrane material <NUM> may be die cut by a cutter <NUM>. The first membrane material <NUM> may then be laminated to a second membrane material <NUM> by a laminator <NUM>. For example, the second material <NUM> may be configured to function as a localized stiffener. In an example, the first membrane material <NUM> may be a thin film that is easy to bend. In an example, the second membrane material <NUM> may provide a good vapor barrier and may be stiffer than the first membrane material <NUM>. Alternatively, in the top figure, the first membrane material <NUM> or the second membrane material <NUM> may be configured to contact the drug and be utilized as an interior surface of a reservoir.

The process shown in the top figure of <FIG> provides a technique for joining materials with different benefits to form a multilayer reservoir with localized stiffener. In an example, the second membrane material <NUM> may be polychlorotrifluoroethylene (PCTFE) (also referred to by the brand name Aclar®) or the like. The laminated result shown in the top process may provide localized areas that facilitate easier folding, manufacturing, and consistent collapse of a flexible reservoir, while maintaining desired vapor barrier properties across most of the surface area as a result of the lamination.

In the bottom figure of <FIG>, the top and bottom materials <NUM> may be of the same material as the first membrane material <NUM> in the top figure of <FIG> or the materials <NUM> may be a different. The middle material <NUM> may be a different material than the membrane material <NUM>. The material <NUM> on the top and bottom may be laminated together through die cut holes (e.g., formed by cutter <NUM>) formed in the middle material <NUM>. Again, in an example, the middle material <NUM> may provide enhanced vapor barrier properties. The process shown in this bottom figure of <FIG> may allow the formation of a multilayer reservoir using dissimilar materials that may be hard to laminate together - accordingly, holes in the middle layer material are formed such that lamination of the materials <NUM> to one another may form the multilayer reservoir by coupling the outer similar material <NUM> layers together. Such an arrangement may be beneficial because it provides both the flexibility required for a collapsible reservoir as well as the vapor barrier properties desired to mitigate against loss of potency of any liquid drug within the reservoir.

Examples of materials suitable for use in producing the respective flexible films of the examples shown in <FIG> include low-density polyethylene, polypropylene, polypropylene/ PCTFE laminate, PCTFE, Aclar CP or the like.

<FIG> illustrates an example of a wearable drug delivery device suitable for use with the reservoir examples of <FIG>. As shown in <FIG>, the wearable drug delivery device <NUM> includes housing <NUM>, a reservoir <NUM>, a fluid path component <NUM>, and a pump <NUM>. Although not shown, the wearable drug delivery device <NUM> may be attached to a user via an adhesive tape or the like. The housing <NUM> may also be a chassis for the wearable drug delivery device. The reservoir <NUM> may be a flexible thin film reservoir (as shown in the examples of <FIG>), a shell/flexible film hybrid reservoir (such as the examples shown in <FIG>), a flexible reservoir with exoskeleton (as shown in the examples of <FIG> and <FIG>), or the like. In examples in which the reservoir <NUM> includes a shell component, such as <NUM>, <NUM> and <NUM> of <FIG>, the shell component may be integrated into other parts of the wearable drug delivery device, such as the housing <NUM>, thereby enabling the rigid or semi-rigid shell component of the reservoir <NUM> to serve multiple purposes, such as a backside of a housing for the wearable drug delivery device <NUM>, or the like.

The fluid path component <NUM> may be coupled to the reservoir <NUM>. The fluid path component <NUM> may include a fill port <NUM> and may also be coupled to a pumping mechanism <NUM>. A flow sensor <NUM> suitable for use in determining a volume of drug delivered may be positioned within the fluid path component <NUM> between the fill port <NUM> and the pumping mechanism <NUM>. Alternatively, a flow sensor <NUM> may be near the entrance of the reservoir <NUM> so a drug volume input to the reservoir <NUM> may be determined.

In an example, the reservoir system of <FIG> may be used and may include a fluid path component <NUM> of the wearable drug delivery device <NUM> coupled to the reservoir <NUM> and a pumping mechanism, with the pumping mechanism configured to extract a fluid contained in the reservoir. In the example utilizing the reservoir system of <FIG>, a flow sensor <NUM> may be coupled between a fill port of the fluid path and the pumping mechanism and may detect a fill volume of the reservoir based on pressure changes or flow changes as the peel-able restraints sequentially break. Further, the breaking of peel-able restraints positioned at known locations may provide for fill sensing.

In addition, or in another example, a vapor barrier membrane, such as <NUM> in the example of <FIG>, may be positioned around the reservoir <NUM> to reduce vapor transmission.

In various examples, the fill port <NUM> may provide access to a fluid such as, for example, a liquid drug. The pumping mechanism <NUM> may be any type of pumping mechanism or system for extracting fluid from the reservoir <NUM>. Examples of pump mechanisms suitable for use as pump mechanism <NUM> may be found in <CIT> and <CIT>, the entire contents of each application incorporated herein by reference. Of course, other pump mechanisms may be used. The pump mechanism <NUM> may be coupled to a fluid path <NUM> and a needle or cannula <NUM>. The needle or cannula <NUM> may be configured to complete a fluid pathway from the fluid path <NUM> to a user by fluidly coupling to the fluid path <NUM> and penetrating the skin of the user (not shown). The pumping mechanism <NUM> may be operated to provide fluid stored within the reservoir <NUM> for example, via the fluid path <NUM> and needle/cannula <NUM> to a user or patient wearing the wearable drug delivery device <NUM>. An example of a system for delivering drugs is provided in <CIT>, which is herein incorporated by reference in its entirety.

The wearable drug delivery device <NUM> may also include a logic circuit and a power supply <NUM>. The logic circuit may be coupled to the pump mechanism <NUM>, the flow sensor <NUM> and optionally other components, such as the peel-able constraints, when the reservoir example of <FIG> is utilized. An example of a suitable power supply may be batteries, or the like. The logic circuit and power supply <NUM> may include a memory (not shown) for storing programming code and information. The logic circuit and power supply <NUM> may be configured to control and receive inputs from the pump mechanism <NUM>, the flow sensor <NUM> and other components, such as the peel-able constraints, if present. In addition, the logic circuit and power supply <NUM> may be configured to and perform calculations and processes based on inputs received from inputs from the pump mechanism <NUM>, the flow sensor <NUM>, and other components, such as the peel-able constraints, or the like.

Claim 1:
A reservoir (<NUM>, <NUM>) for storing a liquid drug, comprising:
a shell component (<NUM>, <NUM>) having an inner surface;
a flexible component (<NUM>, <NUM>) coupled to the shell component, wherein the coupling is a hermetic seal and the flexible component conforms to the inner surface of the shell
component when in a deflated state;
a port (<NUM>, <NUM>) configured to enable filling and/or emptying of the reservoir;
one or more drainage channels (<NUM>, <NUM>) formed into the inner surface of the shell component, wherein
the one or more drainage channels directly contact the liquid drug to reduce hold up volume of the drug reservoir that is present as the flexible component deflates and the drug reservoir is drained by guiding the liquid drug to the port.