Abstract:
Disclosed is a medical infusion device, such as an externally worn insulin pump, capable of being in remote communication with a controller or data acquisition unit such as a blood glucose meter. The disclosed medical infusion device includes a dual frequency antenna to facilitate communication with the remote device and the antenna is mounted using a spring-design that inhibits transmission of vibration to the antenna.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates, in general, to drug delivery systems and, more particularly, to a communications system for a drug delivery device that may be remotely controlled. The present invention also relates to methods of assembling such a drug delivery device in a manner that improves reliability and reduces mechanical vibrations in the device. 
       BACKGROUND OF THE INVENTION 
       [0002]    Diabetes mellitus is a chronic metabolic disorder caused by an inability of the pancreas to produce sufficient amounts of the hormone insulin so that the metabolism is unable to provide for the proper absorption of sugar and starch. This failure leads to hyperglycemia, i.e. the presence of an excessive amount of glucose within the blood plasma. Persistent hyperglycemia causes a variety of serious symptoms and life threatening long term complications such as dehydration, ketoacidosis, diabetic coma, cardiovascular diseases, chronic renal failure, retinal damage and nerve damages with the risk of amputation of extremities. Because healing is not yet possible, a permanent therapy is necessary which provides constant glycemic control in order to always maintain the level of blood glucose within normal limits. Such glycemic control is achieved by regularly supplying external insulin to the body of the patient to thereby reduce the elevated levels of blood glucose. 
         [0003]    External insulin was commonly administered by means of multiple, daily injections of a mixture of rapid and intermediate acting insulin via a hypodermic syringe. While this treatment does not require the frequent estimation of blood glucose, it has been found that the degree of glycemic control achievable in this way is suboptimal because the delivery is unlike physiological insulin production, according to which insulin enters the bloodstream at a lower rate and over a more extended period of time. Improved glycemic control may be achieved by the so-called intensive insulin therapy which is based on multiple daily injections, including one or two injections per day of long acting insulin for providing basal insulin and additional injections of rapidly acting insulin before each meal in an amount proportional to the size of the meal. Although traditional syringes have at least partly been replaced by insulin pens, the frequent injections are nevertheless very inconvenient for the patient, particularly those who are incapable of reliably self-administering injections. 
         [0004]    Substantial improvements in diabetes therapy have been achieved by the development of the insulin infusion pump, relieving the patient of the need syringes or insulin pens and the administration of multiple, daily injections. The insulin pump allows for the delivery of insulin in a manner that bears greater similarity to the naturally occurring physiological processes and can be controlled to follow standard or individually modified protocols to give the patient better glycemic control. 
         [0005]    Infusion pumps can be constructed as an implantable device for subcutaneous arrangement or can be constructed as an external device with an infusion set for subcutaneous infusion to the patient via the transcutaneous insertion of a catheter or cannula. External infusion pumps are mounted on clothing, hidden beneath or inside clothing, or mounted on the body and are generally controlled via a user interface built-in to the device. 
         [0006]    Regardless of the type of infusion pump, blood glucose monitoring is required to achieve acceptable glycemic control. For example, delivery of suitable amounts of insulin by the insulin pump requires that the patient frequently determines his or her blood glucose level and manually input this value into a user interface for the external pumps, which then calculates a suitable modification to the default or currently in-use insulin delivery protocol, i.e. dosage and timing, and subsequently communicates with the insulin pump to adjust its operation accordingly. The determination of blood glucose concentration is typically performed by means of a measuring device such as a hand-held electronic meter which receives blood samples via enzyme-based test strips and calculates the blood glucose value based on the enzymatic reaction. 
         [0007]    Since the blood glucose meter is an important part of an effective glycemic control treatment program, integrating the measuring aspects of the meter into an external pump or the remote of a pump is desirable. Integration eliminates the need for the patient to carry a separate meter device, it offers added convenience and safety advantages by eliminating the manual input of the glucose readings, and may reduce instances of incorrect drug dosaging resulting inaccurate data entry. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
           [0009]      FIG. 1  is an illustrative schematic view of elements of a drug delivery system according to an exemplary embodiment of the invention. 
           [0010]      FIG. 2  is a block diagram of a drug delivery system according to an exemplary embodiment of the invention. 
           [0011]      FIG. 3  is a perspective view of a drug delivery device according to an exemplary embodiment of the invention. 
           [0012]      FIG. 4  is a perspective, cross-sectional view of the drug delivery device shown in  FIG. 3  with the drug reservoir cap, bolus button, battery cap, battery and vibrator removed. 
           [0013]      FIG. 5  is a perspective view of a housing for a drug delivery device according to an exemplary embodiment with the drug reservoir cap, bolus button, battery cap and navigational buttons removed. 
           [0014]      FIG. 6  is a perspective view of another housing for a drug delivery device with the display cover removed according to an exemplary embodiment. 
           [0015]      FIG. 7  is a perspective view of a radio frequency module according to an exemplary embodiment of the invention. 
           [0016]      FIGS. 8A and 8B  are top and bottom views, respectively, of an antenna according to an exemplary embodiment of the invention. 
           [0017]      FIGS. 9A ,  9 B and  9 C are various views of spring connector configurations on the circuit board of the radio frequency module according to an exemplary embodiment of the invention. 
           [0018]      FIG. 10  is a simplified schematic view of the drug delivery device shown in  FIG. 3  according to an exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIGS. 1 and 2  illustrate a drug delivery system  100  according to an exemplary embodiment. Drug delivery system  100  includes a drug delivery device  102 , a remote controller  104  and an optional processing station  106 . Drug delivery device  102  is configured to transmit and receive data to and from remote controller  104  by, for example, radio frequency communication  108 . Drug delivery device  102  may also function as a stand-alone device with its own built in controller. In one embodiment, drug delivery device  102  is an insulin infusion device and remote controller  104  is a hand-held blood glucose metering system. In such an embodiment, data transmitted from drug delivery device  102  to remote controller  104  may include insulin delivery data. Data transmitted from remote controller  104  to drug delivery device  102  may include glucose test results and a food database to aid in calculating the amount of insulin to be delivered by drug delivery device  102 . In another embodiment (not shown), remote controller  104  is a continuous metering system for detecting glucose in blood or interstitial fluid. 
         [0020]    Drug delivery device  102  may also be configured for bi-directional wireless communication with processing station through, for example, an infrared signal  110 . Remote controller  104  and processing station  106  may be configured for bi-directional wired communication through, for example, a universal serial bus (USB) cable  112 . Processing station  106  may be used, for example, to download upgraded software to drug delivery device  102  and to process information from drug delivery device  102 . Examples of processing station  106  may include, but are not limited to, a personal or networked computer, a personal digital assistant or a mobile telephone. 
         [0021]    Referring to  FIG. 2 , drug delivery device  102  includes processing electronics  114  including a central processing unit and memory elements for storing control programs and operation data, a radio frequency module  116  for sending and receiving communication signals (i.e., messages) to/from remote controller  104 , a display  118  for providing operational information to the user, a plurality of navigational buttons  120  for the user to input information, a battery  122  for providing power to the system, an alarm  124  for providing feedback to the user, a vibrator  126  for providing feedback to the user, a drug delivery mechanism  128  (e.g. an insulin pump and drive mechanism) for forcing a drug from a drug reservoir  130  (e.g., an insulin cartridge) through a side port  132  connected to an infusion set  134  and into the body of the user. 
         [0022]    As illustrated in  FIG. 3 , drug delivery device  102  further includes a first housing  136 , a second housing  138 , a backlight button  140 , an up button  142 , a drug reservoir cap  144 , a first primary vent  146 , a bolus button  148 , a down button  150 , a battery cap  152  with a second primary vent  154 , an OK button  156  and a display cover  158 . First housing  136  and second housing  138  are typically formed from a durable plastic material. 
         [0023]    Referring to  FIGS. 4 ,  5  and  6 , first housing  136  is nested at least partially within second housing  138  and includes a grooved portion  159  that receives a tongue portion  160  of second housing  138 . First housing  136  houses drug reservoir  130 , drug delivery mechanism  128 , processing electronics  114 , battery  122 , and a transceiver  162  mounted on a first surface  163  of a circuit board  164 . Drug reservoir  130 , drug delivery mechanism  128  with the electronics and battery  122  are each encased in sealed compartments in first housing  136 . In one embodiment, a drug delivery mechanism/electronics compartment  166  of drug delivery device  102  is located between a drug reservoir compartment  168  and a battery compartment  170 . 
         [0024]    Located on a distal end  172  of first housing  136 , circuit board  164  is connected to a gear plate  174  in drug delivery mechanism  128  and is operatively connected to the main circuit board of drug delivery device  102  through a board connector  176  (see  FIGS. 4 and 5 ). Transceiver  162  is also operatively connected to an antenna  178  in second housing  138  by at least one spring connector  180  (e.g., a pogo pin). At least one spring connector  180  allows for ease of assembly of drug dispensing device. Together, transceiver  162  mounted on circuit board  164  and antenna  178  form radio frequency module  116  (see  FIG. 7 ). Second housing  138  also includes vibrator  126  operatively connected to battery  122  by, for example, a spring clip  186  (see  FIG. 6 ). 
         [0025]    Referring to  FIGS. 7 ,  8 A and  8 B, antenna  178  includes a substrate  188 , a conductive trace  190  (i.e., the resonating portion), and a signal feed region  192 . Trace  190  is electrically connected to a first conductive pad  194  in signal feed region  192  at or adjacent to a first end  196  of substrate  188 . Substrate  188  provides a support for trace  190  and is manufactured from a dielectric material or a flexible material. For example, a small fiberglass-based printed circuit board may be used. Other examples of materials that may be used for substrate  188  include, but are not limited to, FR4 plastic, phenolic material and fiberglass reinforced Teflon. The use of a thin substrate  188  provides the advantage of being deformable and easily mounted in place. 
         [0026]    Trace  190  is formed from a conductive material such as, for example copper, brass, aluminum, silver or gold. Trace  190  may be deposited onto substrate  188  using a technique known to those skilled in the art such as, but not limited to, photo-etching of a conductive material on a dielectric or insulated substrate, plating of a conductive material on a substrate, or adhering a conductive material, such as a thin plate of metal, on a substrate with adhesive. 
         [0027]    The length of trace  190  primarily determines the resonant frequency of antenna  178 . Trace  190  is sized appropriately for a particular operating frequency. Traces  190  used to form the antenna  178  are deposited to provide a conductive element that is approximately ¼ an effective wavelength (λ) for the frequency of interest. Those skilled in the art will readily recognize the benefits of making the length slightly greater or less than λ/4, for purposes of matching the impedance to corresponding transmit or receive circuitry. In addition, connecting elements such as exposed cables, wires, or the spring connector  180  contribute to the overall length of antenna  178 , and are taken into account when choosing the dimensions of trace  190 . 
         [0028]    Where antenna  178  is used with a wireless device capable of communicating at more than one frequency, the length of trace  190  is based on the relationship of the frequencies. That is, multiple frequencies can be accommodated provided they are related by fractions of a wavelength. For example, the λ/4 length for one frequency corresponds to 3×/4 or λ/2 for the second frequency. 
         [0029]    The width of trace  190  is less than a wavelength in the dielectric substrate material so that higher-order modes will not be excited. In the embodiment shown in  FIGS. 7 and 8B , width of trace  190  is between about 0.5 to 2.0 millimeters, typically about 1.5 millimeters. In the subject invention, the length and width of trace  190  is sized so that antenna  178  is capable of receiving and transmitting signals having a frequency range between about 850 MHz and about 950 MHz. In one embodiment, antenna  178  may transmit and receive signals in the frequency range between about 869.70 MHz and about 870 MHz. In another embodiment, antenna  178  may transmit and receive signals in the frequency range between about 902 MHz and about 928 MHz. 
         [0030]    The thickness of trace  190  is usually on the order of a small fraction of the wavelength, in order to minimize or prevent transverse currents or modes, and to maintain a minimal antenna  178  size (i.e., thickness). The selected value is based on the bandwidth over which antenna  178  must operate. 
         [0031]    The total length of trace  190  is approximately λ/4, but it should be noted that trace  190  may be folded, bent, or otherwise redirected, to extend back along the direction it came so that the overall antenna  178  size is reduced. As shown in  FIG. 8B , trace  190  extends along the length and edge of substrate  188  such that it is redirected back toward first conductive pad  194 . This allows antenna  178  to have a shorter overall length. The thin conductor dimensions combined with a relatively thin support substrate  188  and λ/4 total length allows a reduction in the overall size of antenna  178  compared to conventional strip or patch antennas, making it more desirable for use in portable medical devices. In one embodiment, the length of antenna  178  is about 41 millimeters and the widest portion of antenna  178  is about 13 millimeters. 
         [0032]    As illustrated in  FIGS. 7 and 8B , a first conductive pad  194  is positioned in signal feed region  192  and electrically coupled or connected to trace  190 . Generally, first conductive pad  194  and trace  190  are formed from the same material, possibly as a single unified body or structure, using the same manufacturing technique, although this is not required. First conductive pad  194  simply needs to make good electrical contact with trace  190  for purposes of signal transfer without adversely impacting antenna impedance or performance. 
         [0033]    In the antenna embodiment illustrated in  FIGS. 7 ,  8 A and  8 B, which is a planar inverted-F antenna, trace  190  faces away from transceiver  162  such that substrate  188  is positioned between trace  190  and transceiver  162 . In this situation, first conductive pad  194  is positioned on the side of substrate  188  that does not readily accept a signal directly from transceiver  162 . Thus, as shown in  FIG. 8A , a second conductive pad  198  may be used on the opposing side of substrate  188  and conductive vias (not shown) may be used to transfer signals through substrate  188 . 
         [0034]    The use of first conductive pad  194  and second conductive pad  198  allows antenna  178  to be installed and operated in a manner that provides for convenient electrical connection and signal transfer through the at least one spring connector  180  (e.g., pogo pins). This simplifies construction and manufacture of drug delivery device  102  by eliminating the need for manual installation of specialized connectors, or having to manually insert antenna  178  within a contact structure. To assemble radio frequency module, first housing  136  and second housing  138  are simply snap-fitted together (e.g. tongue portion  160  of second housing  138  is fit into grooved portion  159  of first housing  136 ). To ensure a watertight fit, first housing  136  and second housing  138  may then be adhered together by adhesive. Having spring connectors also eliminates the need for a separate antenna housing that would be attached (e.g., glued) to drug delivery device  102  in an additional manufacturing step. Because a separately attached antenna housing is not needed, a possible source of water ingress is eliminated. 
         [0035]    Antenna  178  is mounted in drug delivery device  102  adjacent to transceiver  162  and is placed substantially parallel to the ground plane provided by circuit board  164 . Second conductive pad  198  is positioned adjacent to and electrically coupled to circuit board  164  using at least one spring connector  180 . At least one spring connector  180  is mounted on circuit board  164  by, for example, soldering or conductive adhesives. As illustrated in  FIGS. 7 and 9A , at least one spring connector  180  may be mounted near a first end  200  of circuit board  164 . At least one spring connector  180  may also be mounted near a first edge  202  of circuit board  164  or near a second edge  204  of circuit board  164 , depending on where antenna  178  is located in drug delivery device  102  (see  FIGS. 9B and 9C ). Generally, a distance D 1  between two spring connectors  180  is between about 2.5 millimeters and about 4 millimeters. A distance D 2  from two spring connectors to an edge of circuit board  164  parallel to a line through two spring connectors  180  is between about 1.5 millimeters and about 5 millimeters. A distance D 3  from a spring connector to an edge of circuit board  164  perpendicular to a line through two spring connectors  180  is between about 5 millimeters and about 13 millimeters. 
         [0036]    At least one spring connector  180  is electrically connected on one end to appropriate conductors or conductive vias to transfer signals to and from circuit board  164 . The other end of at least one spring connector  180  is generally free floating and extends from circuit board  164  toward contact pad of antenna  178 . At least one spring connector  180  may be formed from a metallic material such as copper or brass. 
         [0037]    As illustrated in  FIGS. 4 and 6 , antenna  178  is sized to occupy the entire inner surface of a distal end of second housing  138  to maximize the signal transmitted and received. Antenna  178  may be located on any inner surface of drug delivery device  102  as long as the signal transmitted and received is not blocked. In one embodiment, the location and size are such that the signal range of antenna  178  is about 3 meters when drug delivery device  102  is not held in the user&#39;s hand and is about 1 meter when drug delivery device  102  is held in the user&#39;s hand. The thickness of antenna  178  is such that length of drug delivery device  102  is kept to a minimum. In one embodiment, the thickness of antenna  178  is between about 0.6 and about 0.8 millimeters, typically about 0.76 millimeters, and the length of drug delivery device  102  is between about 7 and 9 centimeters, typically about 8 centimeters. 
         [0038]    At least one protrusion  206  on an inner surface of second housing  138  protrudes through at least one hole  208  in substrate  188  of antenna  178 . At least one protrusion  206  positions vibrator  126  above antenna  178  such that vibration generated by vibrator  126  does not interfere significantly with signals transmitted and received by antenna  178 . In one embodiment, antenna  178  is located between about 4 millimeters and about 7 millimeters (typically about 5 millimeters) from the bottom edge of vibrator  126 . At least one protrusion  206  serves as a conduit for vibration to be transferred to second housing  138 . At least one protrusion  206  also serves as a simple mounting mechanism for positioning antenna  178  within distal end of second housing  138  of drug delivery device  102 . An optional nodule  209  on the inner surface of the distal end of second housing  138  may also aid in positioning antenna within drug delivery device  102 . Nodule  209  may protrude through a substrate opening  210  in antenna  178 . A half cradle  211  formed from a plurality of ribs  212  in second housing  138  also supports vibrator  126  and transfers vibration radially from vibrator  126  to second housing  138  without interfering significantly with signals transmitted and received by antenna  178 . 
         [0039]    First housing  136  also includes a plurality of vents with water impermeable membranes to protect the internal components of drug delivery device  102  from water damage during such user activities as, for example, swimming. The water impermeable membranes are also air permeable to ensure rapid pressure equilibration between the interior of drug delivery device  102  and atmosphere that could cause unexpected and undesirable delivery of a drug to the user. A rapid pressure change may occur, for example, when a user flies in an airplane. 
         [0040]    Referring to  FIG. 10 , first primary vent  146  is located in first housing  136  near drug reservoir cap  144  and vents the drug reservoir compartment to atmosphere through a first opening  214  into drug reservoir compartment  168 . First primary vent  146  vents drug reservoir compartment  168  to atmosphere to ensure that there is no differential pressure between drug reservoir compartment  168  and atmosphere, which could result in unwanted dispensing of the drug from drug reservoir  130 . Second primary vent  154  is located in battery cap  152  and vents battery compartment  170  to atmosphere. Second primary vent  154  prevents uncontrolled pressure build up of gas in battery compartment  170 . For example, hydrogen gas resulting from a chemical reaction in battery  122  may build up in battery compartment  170 . 
         [0041]    A first secondary vent  216  is located between drug reservoir compartment  168  and drug delivery mechanism/electronics compartment  166  to equalize pressure inside drug delivery device  102 . First secondary vent  216  vents the inside of drug delivery device  102  through a second opening  218  into drug reservoir compartment  168  (see  FIG. 10 ). A second secondary vent  220  is located in distal end of battery compartment  170 , i.e., near the positive terminal. Second secondary vent  220  provides a vent between battery compartment  170  and the drug delivery mechanism/electronics compartment  166  to equalize pressure inside drug delivery device  102 . 
         [0042]    Redundancy created by the presence of first primary vent  146 , second primary vent  154 , first secondary vent  216  and second secondary vent  220  ensures venting and pressure equilibration of all drug delivery device compartments (i.e., drug delivery mechanism/electronics  166 , drug reservoir compartment  168  and battery compartment  170 ), even during abnormal situations such as occlusion of any of the primary or secondary vents. 
         [0043]    The water impermeable membrane (e.g, a hydrophobic membrane) included in all the primary and secondary vents is selected such that the water entry pressure exceeds a fluid pressure at a selected depth, i.e., the depth to which the membrane can reasonably expect to be exposed upon immersion in water. For example, in the case in which a test pressure of 5.2 pounds per square inch (psi) is requested (i.e., water pressure at a depth of 12 feet below the surface), a selected water entry pressure of approximately 10 to 15 psi provides an exemplary design margin. Exemplary membrane materials include, but are not limited to, Emflon® and Mupor® polytetrafluoroethylene (PTFE). 
         [0044]    While embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. 
         [0045]    It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.