Abstract:
A pump controllably moves a small quantity of fluid from a fluid chamber to an outlet port with a small inexpensive actuator powered for a very short amount of time, thereby optimizing cost, size, and battery efficiency. Multiple pumps can be housed in a single enclosure, allowing multiple drugs to each be injected through a single cannula or needle.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/947,032 filed Mar. 3, 2014 entitled Fluid Delivery Damping and Delivery Pump, which is hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Insulin pumps are medical devices used for the administration of insulin in the treatment of diabetes, which is known as continuous subcutaneous insulin infusion therapy. Typically, insulin pumps include a pump mechanism, a disposable reservoir for insulin, and a disposable infusion set (e.g., a cannula for insertion under the user&#39;s skin). 
         [0003]    In an attempt to increase battery efficiency and safety, a variety of different pump mechanisms have been contemplated in battery powered insulin pumps. For example, such pump mechanism include servomotors with gear trains; nitinol wires that deform when electrically stimulated; heated wax that changes volume or actuates a check valve, and MEMS valves whose diaphragm motion open and close check valves. These methods however typically require complex, large, and expensive mechanical arrangements, as well as having substantial power consumption, requiring a large battery and/or frequent recharging. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect of the present invention, a pump controllably moves a small quantity of fluid from a fluid chamber to an outlet port with a small inexpensive actuator powered for a very short amount of time, thereby optimizing cost, size, and battery efficiency. 
         [0005]    In another aspect of the present invention, the pump includes a fail-safe position such that component failure will not result in free flow between the fluid chamber and the patient. 
         [0006]    Another aspect of the present invention includes a method of pumping a fluid in which a pulse of a device such as an electrical solenoid pushes on a piston to controllably move a small quantity of fluid by hydraulically filling a pressurized delivery chamber. The delivery chamber slowly dispenses the fluid by adding a restriction to the flow out of the outlet port to dampen the fluid flow rate between actuations to prevent sudden spikes of liquid. 
         [0007]    Another aspect of the present invention includes a pump enclosure having multiple pump mechanisms, which can each be configured to pump a different drug to a patient. 
         [0008]    Yet another aspect of the present invention includes a method of delivering different drugs to a patient from a single pump enclosure. 
         [0009]    Yet another aspect of the present invention includes measuring sensor data from within an air chamber open to the atmosphere within a pump enclosure and determining a volume of fluid remaining in a fluid chamber. 
         [0010]    Another aspect of the present invention includes calibrating a pump enclosure for measuring an accurate volume of fluid in a fluid chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which 
           [0012]      FIGS. 1A-5  illustrate one embodiment of a fluid pump according to the present invention. 
           [0013]      FIGS. 6A-11B  illustrate another embodiment of a fluid pump according to the present invention. 
           [0014]      FIGS. 12A-16B  illustrate another embodiment of a fluid pump according to the present invention. 
           [0015]      FIGS. 17-26  illustrate an embodiment of a pump enclosure having multiple fluid chambers and pumps. 
           [0016]      FIGS. 26-30  illustrate various options of materials within fluid chambers of the pump enclosure according to  FIGS. 17-26 . 
           [0017]      FIG. 31  illustrates a feedback system for a pump enclosure. 
           [0018]      FIG. 32  illustrates an example pressure measurement from the feedback system in  FIG. 31 . 
           [0019]      FIG. 33  illustrates a flow chart of a method for determining a liquid volume via the feedback system of  FIG. 31 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
       Pump Mechanism and Operation 
       [0021]    One aspect of the present invention is directed to a pump mechanism and method of use. Specifically, a displacement mechanism is used deliver small quantities of fluid (e.g., insulin) to a patient or to another pumping application. While the present specification primarily describes a solenoid as the displacement mechanism, it should be understood that a number of other devices can also be used, such as a motor, electromagnet, cam actuators, ultrasonic motors, magnets with shielding, Nitinol wire phase change materials, expanding/contracting materials, or similar devices. 
         [0022]      FIGS. 1A-5  discloses one embodiment of a pump mechanism  100  that is actuated by a solenoid  106 . When the solenoid  106  is operated, fluid (e.g., insulin) from a fluid chamber  112  is pumped into the input port  104 A, through input lumen  104 , and ultimately out the output port  116 . 
         [0023]    The solenoid  106  is preferably located within a chamber of a pump housing  102  and, when activated, moves a plunger  108  against a compressible elastomer film or flexible sheet  110 . The film  110  is preferably connected around or near its outer edges and is fitted to have slack (i.e., is not pulled tight), allowing the film  110  to deform or bend. In this respect, when the plunger  108  is extended (i.e., moved to the left), the film  110  is pressed against an end port  104 B of the input passage  104 , closing off the port  104 B and preventing any further liquid to enter the pump  100 . 
         [0024]    The pump  100  also includes a delivery piston  118  that moves laterally between a larger diameter pump chamber  102 A and a smaller diameter pump chamber  102 B (seen best in  FIG. 1B ). The delivery piston  118  includes a cylindrical portion  118 A which has diameter that is slightly smaller than the chamber  102 B, allowing the cylindrical portion  118 A to slide within the chamber  102 B. A disk portion  118 C is connected to the cylindrical portion by an elongated connection portion  118 B, and has a diameter that is slightly smaller than the chamber  102 A. 
         [0025]    The piston  118  is biased towards the solenoid  106  by a spring  114 . The spring  114  is preferably connected to the cylindrical portion  118 A and to a location left of the piston, such as the septum  113  or to the wall of the chamber  102 B. Since the fast action of the on/off cycle of a solenoid  106  (or similar actuator mechanism) can delivery fluid faster than the patient&#39;s tissue can absorb, creates sheer forces on the fluid molecules (e.g., insulin) potentially disrupting their efficacy, and can potentially injure the patient at the injection site, the spring helps dampen the solenoid force. Specifically, as the solenoid causes the delivery piston  118  to move to the left, the spring  114  helps reduce the speed of the piston  118  to create a more gentle movement, as well as stores some of the energy create by the solenoid  106 . While a spring  114  is described, it should be understood that a variety of different dampening mechanisms are possible, such as magnetic dampening mechanisms and elastomeric members. 
         [0026]    To allow movement of the delivery piston  118  and injection of fluid via the septum  113 , the smaller diameter pump chamber  102 B includes one or more fluid return ports  103  (e.g., 3 or 6 ports), which connect the pump chamber  102 B with the fluid chamber  112 . 
         [0027]    With regard to the operation of the pump  100 ,  FIGS. 1A and 1B  illustrates the pump in a neutral position in which the delivery position  118  covers the entrance  116 A to the output port  116 . 
         [0028]    Turning to  FIG. 2 , power is applied to the solenoid  106 , causing the plunger  108  move to the right, against the plunger return spring  107 . The delivery plunger  118  also moves to the right, maintaining the output port  116  in a blocked or closed configuration and pressing against the film  110  so as to open the input lumen  104 . In this respect, fluid from the fluid chamber  112  passes into input port  104 A, along input passage  104 , out the end port  104 B, and into the larger diameter chamber  102 A. 
         [0029]    Once the larger diameter chamber  102 A has filled with fluid, the solenoid  106  is powered off, allowing the plunger release spring  107  to begin moving fluid towards the left of the pump  100 , thereby causing the fluid to move the piston  118  to the left, as seen in  FIG. 3 . As such, the end port  104 B becomes covered or blocked by the film  110 , preventing further passage of fluid through the input passage into the chamber  102 A. 
         [0030]    As seen in  FIG. 4A , the continued movement of the plunger  108  to the left against the film  110 , causing the fluid in the chamber  102 A to press against the displacement piston  118 , moving the piston  118  further to the left. At this position, the cylindrical portion  118 A no longer blocks the output port  116  and a portion of the fluid in the smaller diameter chamber  102 B (e.g., portion  102 C in  FIG. 4B ). In other words, the entire contents of both chambers  102 A and  102 B do not empty out of the output port  116 ; instead only a fraction of that fluid is displaced. Additionally, the piston  118  has compressed against the spring  114 , storing some of the energy imparted via the solenoid  106  and displacing some of the fluid on the left side of the piston  118  out the fluid return ports  103 . 
         [0031]    It should be understood that the amount and rate of fluid leaving the chamber  102 B in this position can be controlled by a number of factors. For example, the diameter and length of the output port  116  can both be increased or decreased to adjust an amount and/or rate of displaced fluid per cycle. Other factors may also influence this, such as the compressibility of the springs  114  and  107 , the size of the chambers  102 A and  102 B, the diameter holding the fluid in the film, and the strength and actuation time/speed of the solenoid  106 . 
         [0032]    Referring to  FIG. 5 , with a portion of the fluid displaced, the spring  114  begins to push back the piston  118 , closing the output port  116  and returning to a neutral (i.e., nonmoving position). In this position, both the output port  116  and the end port  104  of the input passage  104  are closed. In this respect, if the solenoid  106  or other components controlling the solenoid  106  break, or if the piston sticks, the pump will not allow constant flow of insulin through the pump  100  and into the patient. 
         [0033]      FIGS. 6A-11B  illustrate another embodiment of a pump  130  that is constructed and operates in a generally similar manner to the previously described pump  100 . However, instead of single piston and a film, the present pump  130  includes a solid, cylindrical delivery piston  132 , a tubular fill piston  134 , and a cylindrical refill piston  136 . 
         [0034]    The cylindrical delivery piston  132  is preferably sized slightly smaller in diameter than smaller diameter chamber  102 B and moves laterally to selectively block the output port  116 . The tubular fill piston  134  is sized slightly smaller in diameter than the larger chamber  102 A and moves laterally to selectively open and close the input passage  104 . The tubular fill piston  134  also includes a passage therethrough in which the cylindrical refill piston  136  slides during operation, creating a small refill chamber. 
         [0035]      FIGS. 6A and 6B  illustrate the pump  130  in a neutral position in which neither the solenoid  106 , nor the spring  114  are actively creating motion of the components within the pump  130 . The delivery piston  132  can be seen closing off the delivery port  116 , preventing fluid from passing to the patient. The fill piston  134  can be seen moved to the right, allowing fluid to enter from the input passage into the area around the delivery piston  132  within the larger chamber  102 A. 
         [0036]    In  FIGS. 7A and 7B , the solenoid  106  is actuated (i.e., power is applied), causing the plunger  108  to move to the left. As the plunger moves  108 , pressure builds within the chamber  102 A, causing the refill piston  136  to push back, to the right. As the fill piston  134  continues to move to the left, it closes of the input port  104 , creating a small, somewhat pressurized chamber of fluid within the fill piston  134 . 
         [0037]    As seen in  FIGS. 8A and 8B , the plunger  108  continues to move left, moving with it the fill piston  134 , the refill piston  136  and the delivery piston  132 . In this position, the delivery piston  132  has moved far enough to the right so as to open output port  116 , thereby allowing some of the fluid to be discharged from the pump  130 . 
         [0038]    In  FIGS. 9A and 9B , the power to the solenoid  106  is turned off so that the plunger  108  no longer applies leftward pressure. With reduced fluid in the pump chambers and a lack of force from the plunger  108 , the compressed spring  114  pushes the delivery piston  132  rightward, thereby blocking off the delivery port  116 . 
         [0039]    In  FIGS. 10A and 10B , the delivery piston  132  continues to move to the right, contacting and pushing the fill piston  134 . As seen best in  FIG. 10B , the delivery piston  132  and fill piston  134  stop their movement as a hydraulic lock point is created by the chamber formed at location  135 . This hydraulic lock point is eliminated as fluid from within the chamber within the fill piston  134  migrates into area  135  (e.g., via a small gap formed between the right side of the delivery piston  132  and the left side of the fill piston  132 ). As the fluid moves to area  135 , the refill piston  136  moves further to the left while the delivery piston  132  and fill piston  134  move to the right, as seen in  FIGS. 11A and 11B . Eventually, the fill piston  134  moves far enough to the right to open the input passage  104  and the pump cycle can begin again. 
         [0040]      FIGS. 12-16  illustrate another embodiment of a pump  140  according to the present invention. The pump  140  is generally similar to the previously described pumps  100  and  130 . However, the pump  140  includes an elastomeric fill sleeve  144  disposed around the fill piston  142 , selectively opening and closing the input passage  104  during operation. 
         [0041]    In  FIG. 12A , the solenoid  106  remains unactuated (i.e., no power is applied) and the plunger  108  is fully retracted to the right. The delivery piston  132  is positioned to block the output port  116  and the fill piston is positioned against the plunger  108  and the delivery piston  132 . As described below, during a normal cycle, hydraulic lock pressure is created in the chamber formed between the delivery piston  132  and the elastomeric fill sleeve  144 . This force pulls the elastomeric sleeve  144  away from a bypass channel  141  (seen in  FIG. 12B ) that connects between the input passage  104  and the larger diameter chamber  102 A, thereby opening the input passage  104  and allowing fluid to be sucked into the pump  140 . 
         [0042]    In  FIG. 13A , fluid has entered the chamber  102 A. As the solenoid  106  is actuated, the plunger begins to exert pressure on the fill piston  142  and thereby create pressure within the chamber  102 A. As seen in  FIG. 13B , this pressure pushes the elastomeric sleeve upwards into the bypass channel  141 , filling the channel  141  and closing of the input passage  104 . 
         [0043]    In  FIG. 14 , the plunger  108  moves further to the left, increasing pressure within the chambers  102 A and  102 B. This increased pressure causes the delivery piston  132  to slide to the left, past the output port  116 , causing a portion of the fluid in the pump  140  to be expelled. 
         [0044]    As the fluid leaves the chamber  102 B, the pressure in the chamber  102 B reduces. Additionally, the power to the solenoid  106  is deactivated, allowing the compressed spring  114  to push the delivery piston  132  back to the right, closing the output port  116  as seen in  FIG. 15 . 
         [0045]    As seen in  FIGS. 16A and 16B , as the delivery piston  132  continues to move to the right, an area  143  is created between the delivery piston  132  and the elastomeric sleeve  144 , creating a hydraulic lock. The force of the hydraulic lock pulls downward on the elastomeric sleeve  144 , away from the channel  141 , pulling additional fluid into the chamber  102 A. This ultimately results in the configuration seen in  13 A and allows the pump cycle to be repeated. 
       Pump Enclosure with Multiple Chambers 
       [0046]    In another embodiment according to the present invention,  FIGS. 17-26  illustrate various aspects of a pump enclosure  150  having multiple chambers to accommodate multiple pumps. While this embodiment of the pump enclosure  150  accommodates up to 4 fluid pumps, it should be understood that the enclosure could also be configured for different numbers of pumps, such as 2, 3, 5, and 6. Any of the pumps previously described in this specification (or variations thereof) lend themselves particularly well to use in the present pump enclosure  150 , due to the relatively small size of the pumps and the relatively low power consumption afforded by the solenoid  106  (or similar actuator mechanism). 
         [0047]      FIG. 17  illustrates the pump enclosure  150 , having a lower housing member  154 , an upper housing cover  152 , a cannula  156  (or rigid needle), and a plurality of septums  113  from each of the pumps within the enclosure  150 .  FIG. 18  illustrates the enclosure  150  with the upper housing cover  152  removed, exposing a top sealing cover or film  164 , a plurality of solenoids  106  that drive each of the pumps, a battery  158 , and a circuit assembly  160  comprising a plurality of electrical components that control and operate the enclosure  150 . 
         [0048]      FIG. 19  illustrates a similar view of the enclosure  150  as the prior figure, except that the film  164  has been removed to expose four pump chambers  166 . Each chamber  166  includes pump housings  165  (also seen in  FIG. 21 ) that are similarly shaped to those of the pump housing  102 , as described in previously described pump embodiments. In this regard, the pump components shown in  FIG. 20  (e.g., the septum  113 , spring  114 , and chambers  102 A,  102 B) are located within passage created within each housing  165 . 
         [0049]    In one embodiment, the walls of the chambers  166  and the film  164  create the fluid chamber (e.g., fluid chamber  112 ). Alternately, a flexible bag or container can be located within the each chamber  166  to act as the fluid chamber. 
         [0050]    The output ports  116  of each of the pumps are connected to apertures  172  in the lower housing member  154 , as seen best in  FIGS. 23-25 . These apertures  172  each connect to a channel  176  on the lower side of the housing member  154  that connects to a single aperture  174 . These channels  176  can be formed into a sealed passage system with a lower plate or film  162  fixed over both the channels  176  and the aperture  174 , as seen in  FIG. 22 . As best seen in  FIGS. 25 and 26 , the aperture  177  connects with a curved septum passage  168 , which allows the cannula  156  (or rigid needle) to connect with the pump enclosure and receive the fluid from any/all of the pumps. 
         [0051]    In an alternate embodiment, the output port of one or more of the pumps can be directly connected to a fluid chamber of an adjacent pump, allowing the contents of one fluid chamber to be delivered to the fluid chamber of another pump. 
         [0052]    It should be understood that the circuit assembly  160  includes a variety of circuitry to operate the pumps of the controller, as well as any other electrical components that may be present. For example, the circuit assembly  160  may include a microprocessor or microcontroller, a memory, software stored in the memory and executed by the microprocessor/microcontroller, sensors (e.g., pressure sensor, temperature sensor), and a communications port. 
         [0053]    It should be understood that a variety of different drugs and combinations of drugs are possible for each of the fluid chambers of the pump enclosure  150 . Several enclosure examples and methods of use are discussed below, however, each of these drugs can be mixed and matched in many different configurations, all of which are contemplated in the present invention. 
         [0054]    In one embodiment, multiple fluid chambers may have two or more types of insulin with different pharma kinetic actions. In one example seen in  FIG. 26 , at least one fluid chamber of the enclosure may contain a fast acting insulin  180 , such as lispro, aspart, and glulisine, and another chamber may contain a slow acting insulin  182 , such as insulin glargine or insulin detemir. In another example seen in  FIG. 27 , an intermediate acting insulin may also be included in another chamber of the enclosure  150 , such as NPH. 
         [0055]    Emergency rescue pens are used by diabetics when their glucose goes low and they begin to show signs of hypoglycemia. These pens combine liquid and lyophilized powder to form a glucagon fluid that is stable for about 24 hours. Typically, all of the fluid is immediately used. 
         [0056]    Another configuration of the enclosure  150  can combine the functionality of such an emergency rescue pens with typical insulin pump functionality. For example,  FIG. 28  illustrates a first chamber containing insulin  186  for normal insulin pump operation, a lyophilized powder  188  in a second chamber, a diluent  190  in a third chamber, and saline  192  in a fourth chamber. The output port of the third pump can be configured to lead only to the second chamber, allowing the third chamber&#39;s pump to move into the second chamber with the lyophilized powder to create glucagon. The second chamber&#39;s pump can then be activated to output glucagon to the patient. Finally, the saline  192  of the fourth chamber can be used to rinse the cannula/needle of any glucagon residue. 
         [0057]      FIG. 29  illustrates a similar example to that of  FIG. 28 , except that instead of mixing both a powder and diluent, a liquid stable glucagon is used in a second chamber. 
         [0058]      FIG. 30  illustrates another configuration of the enclosure  150  in which amylin  196  is included in one of the chambers to slow post prandial emptying to better regulate the speed of insulin activation and thereby better match glucose uptake. 
         [0059]    As mentioned above, a pump enclosure may include one or more, or even all of the following in different fluid chambers of the enclosure: Fast acting insulin, slow acting insulin, intermediate acting insulin, lyophilized powder, diluent, saline, liquid stable glucagon, and/or amylin. Again, the saline can be used to flush the channels of the enclosure and the cannula/needle to remove any residual drugs and prevent an inadvertent mixing during delivery. 
         [0060]    In another embodiment of the present invention, one of the pumps of the pump enclosure  150  can be configured for measuring glucose. Specifically, one pump is configured to move fluid from the cannula  156  to a testing chamber in the pump. Unlike traditional CGMS needles that require a separate stick, by waiting between interstitial drug dosages, the interstitial fluid washes through the drug. During this time, a small amount of fluid inside the cannula and outside the cannula could be drawn in to test the level of glucose at the site and correlate it back to a blood plasma glucose level. Furthermore, the cannula could have the glucose oxidase inside of it with electrodes to measure within the cannula. 
         [0061]    In another aspect of the present invention, the enclosure  150  includes a plurality of indicators  151 , such as LED lights, that correspond to and are located near a specific pump and septum  113  within the enclosure  150 . In this respect, activation of the indicator  151  may be used to indicate a status of a pump. For example, the indicator  151  may indicate that a fluid reservoir is empty or that a pump has become broken. The indicator  151  may be capable of illuminating a single color or multiple colors, each of which indicate a different status (e.g., green means operational, yellow means empty fluid reservoir, and red means a broken pump). 
         [0062]    In another aspect of the present invention, the enclosure may include a single indicator  151  that illuminates in several different colors that each correspond to a color of a septum  113 . For example, the first septum  113  may be green and the second may be blue. When the indicator  151  illuminates in either of these colors, the user is made aware that the fluid reservoir for that pump is empty and therefore requires filling. Alternately, each septum  113  could have a different shape (e.g., circle, square, triangle), number, or other indicator, and a display on the enclosure may also display these indicators as necessary to indicate empty fluid reservoirs. 
       Pump Feedback 
       [0063]    One further benefit of the pump embodiments and pump enclosure embodiments of the present invention is that they can allow various aspects of pump cycles to be measured, so as to allow onboard circuitry to determine if the pump mechanism is operating properly. For example, with certain measurements, pump enclosure circuitry may determine if the pump mechanism is delivering the proper or expected quantity of fluid. 
         [0064]      FIG. 31  illustrates an embodiment of a pump enclosure  200  having a pressure sensor  202 , a temperature sensor  204 , and a gas restrictor  206 , all of which are either located in or are in communication with a gas or air chamber  208 . As the pump  140  operates, it increases and decreases the amount of fluid in its flexible fluid chamber  112 . For example, the pump  140  may initially increase the amount of fluid in the fluid chamber  112  during its filling portion of its cycle and then decrease the amount of fluid during delivery of the fluid to the patient. These increases and decreases in volume of the fluid within the air chamber  208  of the enclosure  200  increase or decrease the air pressure within the air chamber  208  (e.g., as seen in  FIG. 32 ). 
         [0065]    By measuring the pressure and temperature of the air/gas within the air chamber  208 , the enclosure&#39;s onboard circuitry can determine the volume of the air chamber  208  that is not occupied by the fluid chamber  112  with Boyle&#39;s Law. This volume can be subtracted from the known volume of the air chamber  208  with an empty fluid chamber  112  to determine the fluid volume. 
         [0066]    If the air chamber  208  was completely sealed, a vacuum could be created within the chamber  208  as fluid is pumped out of the fluid chamber  112 . Since such a vacuum could ultimately hinder operation of the pump  140 , an air restrictor  206  can be used to slowly vent and thereby slowly equalize the air chamber  208  with the atmosphere. The previously described fluid volume calculations can still be performed by also compensating for the resistance to airflow through the restrictor  206  using Poiseuille&#39;s Law. Poiseuille&#39;s Law of fluid flow determines the amount of fluid that passes through a restriction as a function of the viscosity, pressure differences, size of the restriction and length. By adding a restriction of known physical characteristics and measuring the pressure on one side (and knowing the pressure on the other side by measuring it during static conditions), the changes in the gas and liquid volume can be measured and determined dynamically. 
         [0067]    These measurements and calculations by the onboard circuitry/software could identify how quickly the actuator (e.g., solenoid  106 ) is moving the pump elements, how far the delivery piston has moved due to the displacement of fluid, how much fluid has returned to the fluid chamber when the motion begins at the neutral position and the rate of flow from the delivery chamber to the output. This occurs because there are two functions at work, the displacement of fluid out of the delivery chamber and the flow of gas through the restriction due to the pressure differentials. 
         [0068]    In this respect, the present invention contemplates a method of a pump enclosure measuring pressure and temperature within an air chamber  208  (step  210 ), compensating for airflow through a restrictor  206  connected to the air chamber  208  (step  212 ), and determining a volume of fluid in a fluid chamber  112  (step  214 ), as seen in  FIG. 33 . 
         [0069]    The restrictor  206  can be made of rigid materials, such as, rubies, diamonds, glass, plastic, and other materials commonly used in the practice. The flow characteristics of the restrictor  206  can be characterized or calibrated during the initial pumps (by the onboard circuitry/software) when the volume in the fluid chamber  112  is known and the air chamber  208  is known. The enclosure may also be calibrated by performing volume calculations via the circuitry/software, injecting a known volume of liquid into the fluid chamber  206 , inputting the volume into an interface associated with the enclosure, performing a second volume measurement, and then comparing the difference between the injected amount and the calculated amount. In the case of either method, the changes in pressure can be used to determine the resistance caused by the restrictor  206 , accounting for variations in manufacturing and dirt or other changes that may change the behavior of the restrictor  206  over time. 
         [0070]    Preferably, the restrictor  206  is sized small enough such that the small pressure created in the movements internally are insufficient to pull liquid into the air chamber  208 , due to the surface tension characteristics of the restrictor  206 . This may prevent water and other fluids from being sucked into the air chamber  208  during cleaning, showers, and swimming, for example. 
         [0071]    It should be understood that by monitoring fluid volume in the fluid chamber  112 , a variety of different diagnostics and alerts are possible. For example,  FIG. 34  illustrates a method of determining if a fluid pump is pumping an expected amount of fluid. First, a pump cycle is actuated as explained with regard to several of the different pump embodiments of the present specification (step  216 ). Next, the electronics and software of the pump enclosure  200  compare a calculated fluid volume of the fluid chamber  112  from before the previous pump cycle to a calculated fluid volume after the pump cycle (step  218 ). Finally, the electronics and software of the pump enclosure  200  determine if the expected fluid decrease matches the measured fluid decrease (step  220 ). If the two fluid volume decreased do not “match” (e.g., are not within 5% of each other), the electronics and software of the pump enclosure  200  may generate a warning (e.g., on an interface on the pump enclosure or a separate interface connected to the pump enclosure via a wired or wireless communications protocol). 
         [0072]    While pressure measurement can be used to monitor pumping cycles, the pumping cycles could also be monitored by including a cycle counting sensor. For example, a Reid or Hall effect sensor could be used to monitor movement of various pistons in the pump. In this respect, the pump enclosure&#39;s electronics and software could alert the user when an expected pump fails to occur or when a greater number of pump cycles occur than expected. 
         [0073]    In one aspect of the present invention, the pump enclosure  200  may include a multicolor light (e.g. a tricolor LED) that indicates the cycle of a pump within the pump enclosure. For example, a yellow light may indicate a pressure increases to an acceptable level, a green light may indicate that the pressure has dissipated due to deliver of the fluid, and a red light may indicate that an unexpected sensor/pressure/volume value. 
         [0074]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.