Reservoir with low fluid level sensor

Abstract

To provide a compact and more cost-efficient reservoir having a lower liquid amount detector for warning of the necessity of reservoir replacement.SOLUTION: A medical device having a low liquid amount sensor for subjecting a user to liquid medical agent treatment includes: a reservoir for storing the liquid medical agent supply: a rigid structure for carrying out fluid communication with the reservoir, which includes a chamber and an outlet / inlet; a plunger attached inside the chamber, which is designed to seal an end surface of the chamber and move in the chamber toward the outlet / inlet; and a sensor for detection the position of the plunger in the chamber, and detecting a low liquid amount of the liquid in the flexible reservoir. When a liquid amount level of the reservoir is low, the liquid medical agent extracted from the chamber and the reservoir causes the plunger to move toward the outlet / inlet. The movement of the plunger activates the sensor to transmit a signal indicating the low liquid amount in the flexible reservoir.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates generally to reservoirs for delivering liquids. Specific embodiments of the present invention relate to a flexible reservoir having a low fluid level sensor for delivering a liquid pharmaceutical product such as insulin. Additional embodiments provide a method of operating a flexible reservoir having a low fluid level sensor, including providing an alert that the flexible reservoir needs replacing. [Background technology]

[0002] Diabetes is a group of diseases characterized by high blood glucose levels due to the inability of diabetic patients to maintain adequate levels of insulin production when needed. People with diabetes will require some form of daily insulin treatment to maintain glucose levels under control. If untreated, diabetes can be dangerous for affected patients and can lead to serious health problems (complications) and premature death. However, such problems can be minimized by using one or more therapeutic options to help control diabetes and reduce the risk of problems.

[0003] Therapeutic options for diabetic patients include specialized diets, oral medications, and / or insulin therapy. The primary goal of diabetes treatment is to control the diabetic patient's blood glucose or sugar levels. However, maintaining proper diabetes control can be challenging because it must be balanced with the diabetic patient's activity.

[0004] In the treatment of type 1 diabetes, there are two main methods of daily insulin therapy. In the first method, the diabetic patient self-injects insulin when needed using a syringe or insulin pen. This method requires a needle puncture for each injection, and the diabetic patient may need three to four injections each day. The syringes and insulin pens used to inject insulin are relatively easy to use and cost-effective.

[0005] Another effective method of insulin therapy and diabetes management is insulin therapy using an insulin pump. Insulin pumps allow for the provision of continuous infusion of insulin at variable rates to diabetic patients to more closely match the function and behavior of a non-diabetic patient's properly operating pancreas to produce the required insulin. Insulin pumps also assist diabetic patients in maintaining their blood glucose levels within a target range based on the diabetic patient's individual needs.

[0006] There are generally two types of insulin pumps to facilitate insulin therapy: conventional pumps and patch pumps. Conventional pumps require the use of disposable components, typically called an infusion set, tubing set, or pump set, that deliver insulin from a reservoir within the pump to the skin of the user. In contrast, patch pumps are integrated devices in which most or all of the fluid components, including the fluid reservoir, pump mechanism, and a mechanism for automatically inserting a cannula, are integrated into a single housing that is adhesively affixed to the infusion site on the patient's skin, eliminating the need for the use of a separate infusion set or tubing set. Some patch pumps may wirelessly communicate with a separate controller (such as in devices sold under the OmniPod® brand by Insulet Corporation), while others are completely self-contained. Such devices are replaced frequently, such as every three days, when the insulin reservoir is depleted.

[0007] Because patch pumps are designed as freestanding units worn by diabetics, it is preferable for them to be as small as possible and not interfere with the user's activities. However, to minimize the overall size of the patch pump, the dimensions of its components must be reduced as much as possible. One such component is the reservoir that contains the insulin.

[0008] A conventional rigid reservoir, such as a syringe pump, controls the position of a plunger to deliver liquid. The main limitation of such a mechanism is size, since it must accommodate both the length of the reservoir and the length of the plunger. Thus, conventional rigid reservoirs are difficult to deploy in a compact configuration. Thus, there is a need for an improved reservoir that can be effectively deployed in a compact configuration to further reduce the overall size of the patch pump.

[0009] Detection of low fluid levels in the reservoir is important in ensuring that the patch pump system functions properly and / or to signal the need for reservoir or patch pump replacement. Various fill level detection systems have been proposed for a variety of different applications. Currently, there are two main methods for fill level detection. One provides electrical contacts to meter the dose. The other implements non-contact fill level detection using capacitance measurements.

[0010] Conventional fill level detection systems have many advantages when flow rate and fill level need to be constantly monitored and / or adjusted. Conventional fill level detection systems provide accurate fill level data at all times or at multiple points in time. Such systems are well suited when constant monitoring and adjustment is required. When only a low fluid warning is needed to indicate the need to change the reservoir, systems with fill level detection are unnecessarily costly and complex.

[0011] An approach to reducing the overall size of a patch pump is to replace the syringe-type administration mechanism with a downstream pump system that draws from a fluid reservoir. In such a device, a miniaturized pump is placed downstream of the fluid reservoir to create a negative pressure gradient that transports the fluid from the reservoir to its destination. Alternatively, a miniaturized pump can be placed to transport fluid from another larger fluid source into the reservoir to create a positive pressure gradient that fills the reservoir.

[0012] Therefore, there is a need in the art to provide a compact, more cost-effective reservoir with a low fluid level detector to alert of the need to replace the reservoir, thereby allowing more diabetic patients to access the benefits offered by patch pump systems. Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of an exemplary embodiment of the present invention to provide a flexible liquid reservoir having a low liquid detector. It is a further object of an exemplary embodiment of the present invention to provide notification of a low liquid level in the flexible reservoir. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a medical device having a low fluid level sensor for administering liquid drug therapy to a user, the medical device including a flexible reservoir for containing a supply of liquid drug, a rigid structure having a chamber and a side hole in fluid communication with the flexible reservoir, a plunger mounted inside the chamber and designed to seal one side of the chamber, and a sensor for detecting a low level of liquid in the flexible reservoir, wherein when an inner end of the plunger passes through the side hole the sensor is activated to send a signal indicative of a low level of liquid in the flexible reservoir.

[0015] A third aspect of the present invention provides a method for detecting a low level of liquid in a system and notifying a user of the time-to-empty, the system comprising: a flexible reservoir for containing a supply of liquid drug; a rigid structure having a chamber and a side hole in fluid communication with the flexible reservoir; a plunger mounted inside the chamber and designed to seal one side of the chamber; a sensor for detecting a low level of liquid in the flexible reservoir; and a control module in operative communication with the pump mechanism for controlling the operation of the pump mechanism, the plunger being adapted to detect the low level of liquid in the flexible reservoir and a control module in operative communication with the pump mechanism for controlling the operation of the pump mechanism. When the inner end of the plunger passes the side hole a sensor is activated sending a signal indicating a low level of liquid in the flexible reservoir, and the method includes the steps of providing a rigid structure having a chamber connected to the flexible reservoir, applying a negative pressure to end A of the rigid structure, withdrawing fluid from the flexible reservoir, detecting the moment the plunger loses contact with the switch, calculating an estimate of the time to empty from the current flow rate and the volume of the chamber and conduit, and warning a user that the level is low and informing them of an estimate of the time when the system will run out of liquid.

[0016] Other objects, advantages and salient features of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompany- ing drawings, discloses illustrative embodiments of the invention.

[0017] The above and other exemplary features and advantages of specific exemplary embodiments of the present invention will become apparent from the following description of specific exemplary embodiments of the present invention when taken in conjunction with the accompanying drawings.

[0018] Throughout the drawings, like reference numbers will be understood to refer to like elements, features and structures. [Brief description of the drawings]

[0019] [Figure 1] 1 depicts a medical device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram of the medical device of FIG. 1 in an empty state. [Diagram 3] FIG. 2 is a diagram of the medical device of FIG. 1 in a filled state. [Figure 4] FIG. 1 is a perspective view of a flexible reservoir implemented in a patch pump system. [Diagram 5] 5 is a schematic diagram of the fluid configuration and metering subsystem of the patch pump system of FIG. 4. [Figure 6] 1 is a flow chart illustrating a method for detecting low liquid volume and notifying a user of an estimated time to empty. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The matters exemplified herein are provided to assist in a comprehensive understanding of the exemplary embodiments of the present invention, and are referred to in the accompanying drawings. Those skilled in the art will recognize that various changes and modifications can be made in the exemplary embodiments described herein without departing from the scope and spirit of the claimed invention. In addition, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted.

[0021] As shown in FIG. 1, an exemplary embodiment of the present invention includes a flexible reservoir 101 for containing a supply of liquid drug, a rigid structure 120 having a chamber 102 and a side hole 104 in fluid communication with the flexible reservoir 101, and a plunger 105 mounted within the chamber and designed to seal one side of the chamber 102. The term "flexible reservoir" includes both reservoir structures that are fully flexible, such as collapsible fluid pouches or fluid sacs, and reservoir structures that are only partially flexible by virtue of having both flexible and rigid walls. An outlet / inlet 103 of the chamber 102 allows fluid to enter and exit the chamber 102. The plunger 105 can move in the axial direction of the chamber 102 from end A to end B to fill the chamber, or alternatively from end B to end A to drain the chamber. The plunger 105 is positioned within the chamber 102 to prevent leakage of liquid from the chamber. As the plunger 105 moves from end A to end B for filling, a fluid source is connected to end A. As the plunger 105 passes through the side hole 104, fluid fills the chamber 102 and flows into the flexible reservoir through the side hole 104 until the flexible reservoir 101 is full. At the same time, the sensor 106 is activated and sends a fluid level signal. As the plunger 105 moves from end B to end A for draining, the flexible reservoir 101 is first drained. As the plunger 105 passes through the side hole 104, the flexible reservoir 101 is empty. Again, the sensor 106 is activated and sends another fluid level signal indicating a low level of fluid in the reservoir.

[0022] Those skilled in the art will appreciate that the medical device shown in FIG. 1 is designed to be fully functional when the sensor 106 is an electrical switch. For example, when the plunger 105 passes through the side hole 104, an electrical signal is sent from the sensor 106 to indicate the fluid level information. Alternatively, the sensor 106 may be implemented using an optical sensor. For example, when the plunger 105 passes through the side hole 104, an optical signal is sent from the sensor 106 to indicate the fluid level information. Alternatively, the sensor 106 may be implemented using a magnetic sensor.

[0023] When draining the flexible reservoir 101 to empty it, a pump or means can be arranged downstream of the flexible reservoir 101 and chamber 102 to create a negative pressure that transports fluid from the flexible reservoir 101 to its destination. When filling the flexible reservoir 101, a similar means can be arranged to create a positive pressure that transports fluid from another fluid source through the outlet / inlet 103 into the flexible reservoir 101.

[0024] In one exemplary embodiment of the invention, the sensor 106 is an electrical switch aligned with end B of the chamber 102. A button or actuator 107 of the switch 106 faces the opening of the chamber 102. As the plunger 105 moves from end A toward end B and passes through the side hole 104, the end of the plunger 105 contacts the button 107 of the electrical switch, actuating the switch 106 to send a fluid level signal. One skilled in the art will appreciate that additional support and containment structures may be present to support or contain the above components.

[0025] FIG. 2 is an illustration of a low fluid state of the present invention with a pump mechanism. To empty the flexible reservoir 101, a pump mechanism 110 is placed downstream of the flexible reservoir 101. The initial position of the plunger 105 is position B. The pump mechanism creates a negative pressure on the fluid in the chamber 102 and the flexible reservoir 101. The fluid in the flexible reservoir 101 flows through the side hole 104 into the chamber 102 and through the chamber's outlet / inlet 103 to the conduit 111 to the pump mechanism 110. The negative pressure causes the flexible reservoir 101 to empty first. When the flexible reservoir 101 is empty, the continued negative pressure from the pump mechanism 110 moves the plunger 105 from position B towards position A, activating the button 107 of the switch 106 to send a low fluid signal to the control module 109. The control module 109 sends a low fluid warning signal to the user.

[0026] FIG. 3 is an illustration of the device of FIG. 2 in a high volume state. To fill the flexible reservoir 101, a filling syringe or other device is used to force fluid through the valve or seal and into the outlet / inlet 103. The initial position of the plunger 105 is position A. Positive pressure in the chamber 102 created by the filling device pushes the plunger 105 back. As the plunger 105 passes through the side hole 104 in the chamber 102, fluid begins to flow through the side hole 104 into the flexible reservoir 101. When the flexible reservoir 101 is full, the positive pressure increases, pushing the plunger 105 further down to position B, activating the button 107 of the switch 106 and sending a high volume signal to the control module 109. The pump means 110 can then begin to operate at a predetermined speed, and the liquid in the flexible reservoir 101 will be pumped to the user, and the flexible reservoir 101 will become empty as illustrated in FIG. 2, when the sensor 106 is activated and sends a low liquid level signal.

[0027] 4 is a perspective view of the flexible reservoir 101 implemented in the illustrated patch pump 1A without the cover. Such an arrangement may further reduce the outer dimensions of the patch pump 1A, with the flexible reservoir 101 filling the void within the patch pump. The patch pump 1A is illustrated with a cannula insertion device 7A for inserting a cannula into the surface of the user's skin. The patch pump 1A further includes a power source 5A in the form of a battery, a metering subsystem 41 that monitors the insulin level and includes low level detection means, control electronics 8A for controlling the components of the device, and a reservoir fill port 43 that receives a fill syringe 45 for filling the reservoir 101.

[0028] FIG. 5 is a diagram of the fluid configuration and metering subsystem of the patch pump 1A of FIG. 4. The power storage subsystem for the patch pump 1A includes a battery 5A. The control electronics 8A for the patch pump 1A may include a microcontroller 81, sensing electronics 82, a pump and valve controller 83, sensing electronics 85, and deployment electronics 87 that control the operation of the patch pump 1A. The patch pump 1A includes a fluid subsystem including a reservoir 101, a fluid level sensor 48 for the reservoir 101, and a reservoir fill port 43 for receiving a fill syringe 45 for filling the reservoir 4A. The fluid subsystem may include a metering system including a pump and valve actuator 411 and an integrated pump and valve mechanism 413. The fluid subsystem may further include an occlusion sensor 49, a deployment actuator or cannula loading device 7, as well as a cannula 47 for insertion into an injection site on the user's skin. In one embodiment of the invention, the fluid level sensor is implemented using sensor 106 of FIGS.

[0029] FIG. 6 is a flow chart illustrating a method for detecting low liquid levels and informing a user of an estimate of time to empty. In step 602, fluid flows out of the flexible reservoir 101 and through the chamber 102 as the flexible reservoir 101 is emptied by application of negative pressure to end A of the chamber 102. This continues until all of the fluid has been removed from the flexible reservoir 101 in step 603. At this point, the negative pressure builds up until it is sufficient to cause the plunger 105 to slide forward in the chamber 102. As the plunger 105 begins to move, the rear end of the plunger 105 loses contact with the button 107 of the switch, causing a low liquid level signal to be sent to the control module 109. In step 604, the moment the plunger 105 loses contact with the button 107 of the switch 106 is detected. The exact amount of liquid remaining in the system at this point is known. The volume is calculated as the volume of the chamber 102 not occupied by the conduit 111 and plunger 105 because it is equal to the volume of the portion of the chamber 102 not occupied by the conduit 111 and plunger 105. In step 605, this volume is divided by the current flow rate of the liquid, known from the operating speed of the pump mechanism, to obtain an estimate of the time left until the system is empty of fluid. In step 606, a user of the system is alerted that the liquid level is low. If the flow rate is known, in step 607 the user can be informed of an estimate of the time that the system will run out of liquid.

[0030] Those skilled in the art will appreciate that the features of the above exemplary embodiments may be similarly applied in numerous applications and are not limited to the above disclosure.

[0031] Although the present invention has been shown and described with reference to certain exemplary embodiments, the present invention is not bound to the exemplary embodiments, but only by the appended claims and their equivalents. It will be understood that those skilled in the art can change or modify the exemplary embodiments without departing from the scope and spirit of the present invention, and that features of separate embodiments and claims can be combined with each other unless they are mutually inconsistent.

Claims

1. 1. A medical device for administering a liquid drug therapy to a user, the medical device having a low fluid level sensor, the medical device comprising: a reservoir for containing a supply of liquid medicament; a rigid structure in fluid communication with the reservoir and having a chamber and an outlet / inlet; a plunger mounted within the chamber, sealing an end face of the chamber and designed to be movable within the chamber towards the outlet / inlet; a pump mechanism disposed downstream of the reservoir; a sensor for detecting the position of the plunger within the chamber and for detecting a low level of liquid within the reservoir; Including, the rigid structure is in fluid communication with a reservoir through a pore in the rigid structure; the pump mechanism creates a negative pressure on fluid within the chamber and the reservoir; the medical device has a flow path from the reservoir, through the bore, the chamber, the outlet / inlet, a conduit, to the pump mechanism; A medical device characterized in that when the fluid level in the reservoir is low, liquid medication withdrawn from the chamber and reservoir moves the plunger toward the outlet / inlet, and the movement of the plunger activates a sensor to send a signal indicating low fluid level in the reservoir.

2. The medical device of claim 1 , wherein the sensor comprises an electrical switch.

3. 3. The medical device of claim 2, wherein the electrical switch is activated by a button.

4. The medical device of claim 1 , wherein the sensor comprises an optical sensor.

5. The medical device of claim 1 , wherein the sensor comprises a magnetic sensor.

6. 10. The medical device of claim 1, further comprising a control module coupled to the sensor for receiving the low fluid level signal.

7. 10. The medical device of claim 1, further comprising an alarm system for warning of a low fluid level condition in the reservoir.

8. 8. The medical device of claim 7, wherein the alarm system transmits a light signal as a warning of a low fluid level condition in the reservoir.

9. 8. The medical device of claim 7, wherein the alarm system transmits an audible signal as a warning of a low fluid level condition in the reservoir.

10. 8. The medical device of claim 7, wherein the alarm system transmits a vibration signal as a warning of a low fluid level condition in the reservoir.

11. 8. The medical device of claim 7, wherein the alarm system transmits a combination of light, sound and vibration signals as a warning of a low fluid level condition in the reservoir.

12. 10. The medical device of claim 1, wherein the reservoir is flexible.

13. 1. A medical device for administering a liquid drug therapy to a user, the medical device having a low fluid level sensor, the medical device comprising: a reservoir for containing a liquid; a rigid structure having a chamber with an outlet / inlet and a hole in fluid communication with a reservoir; a pump mechanism in fluid communication with the chamber for pumping liquid from the chamber and the reservoir; a freely movable plunger within the chamber, the freely movable plunger moving in response to a negative pressure generated by the pump mechanism when the fluid level in the reservoir is low; a sensor for detecting when negative pressure from the pump mechanism causes the freely movable plunger to move relative to the sensor; a control module in operative communication with the sensor for receiving a fluid level signal from the sensor; Including, The medical device, wherein the plunger is in a first position in contact with the sensor, and movement of the plunger separates the plunger from the sensor and activates the sensor.

14. 14. The medical device of claim 13, wherein the reservoir is flexible.

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