Abstract:
A monitor system to monitor a characteristic of a user is disclosed. The monitor system includes a sensor to produce a signal indicative of a glucose characteristic measured in the user, the sensor further having a sensor port. The monitor system further includes a recorder within a recording housing, the recorder hosing also encompassing a batter. The recorder further includes a recorder port that interfaces with the sensor port in order to receive the produced signals from the sensor port. A recorder clock that assigns a time to the signals from the sensor is also defined within the recorder housing, as is a recorder processor that includes a recorder memory that is coupled to the recorder port to store the produced signals from the sensor. The recorder further includes a data port defined to interface with a dock receiver. A dock that is remotely located from the sensor and the recorder is also included with the monitor system. The dock includes the dock receiver that physically couples the recorder to the dock via the data port and a dock processor that is coupled to the dock receiver. The monitor system further includes a data processor defined to analyze the signals from the sensor that were stored in the recorder. The data processor includes: a data processor memory to store data from the recorder and a data processor clock. Further included with the data processor is a program to assign the time and date of the signals from the sensor by comparing the time and date on the data processor clock with the time assigned to the signals from the sensor by the recorder clock.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to monitor systems and, in particular embodiments, to devices and methods for monitoring of an sensor to determine a characteristic of a body. 
       BACKGROUND OF THE INVENTION 
       [0002]    Over the years, bodily characteristics have been determined by obtaining a sample of bodily fluid. For example, diabetics often test for blood glucose levels. Traditional blood glucose determinations have utilized a painful finger prick using a lancet to withdraw a small blood sample. This results in discomfort from the lancet as it contacts nerves in the subcutaneous tissue. The pain of lancing and the cumulative discomfort from multiple needle pricks is a strong reason why patients fail to comply with a medical testing regimen used to determine a change in characteristic over a period of time. Although non-invasive systems have been proposed, or are in development, none to date have been commercialized that are effective and provide accurate results. In addition, all of these systems are designed to provide data at discrete points and do not provide continuous data to show the variations in the characteristic between testing times. 
         [0003]    A variety of implantable electrochemical sensors have been developed for detecting and/or quantifying specific agents or compositions in a patient&#39;s blood. For instance, glucose sensors have been developed for use in obtaining an indication of blood glucose levels in a diabetic patient. Such readings are useful in monitoring and/or adjusting a treatment regimen which typically includes the regular administration of insulin to the patient. Thus, blood glucose readings improve medical therapies with semi-automated medication infusion pumps of the external type, as generally described in U.S. Pat. Nos. 4,562,751; 4,678,408; and 4,685,903; or automated implantable medication infusion pumps, as generally described in U.S. Pat. No. 4,573,994, which are herein incorporated by reference. Typical thin film sensors are described in commonly assigned U.S. Pat. Nos. 5,390,671; 5,391,250; 5,482,473; and 5,586,553 which are incorporated by reference herein, also see U.S. Pat. No. 5,299,571. However, the monitors for these continuous sensors provide alarms, updates, trend information and require sophisticated hardware to allow the user to program the monitor, calibrate the sensor, enter data and view data in the monitor and to provide real-time feedback to the user. This sophisticated hardware makes it most practical for users that require continuous monitoring with feedback to maintain tight control over their conditions. In addition, these systems require the user to be trained in their use, even if to be worn for short periods of time to collect medical data which will be analyzed later by a doctor. 
         [0004]    Doctors often need continuous measurements of a body parameter over a period of time to make an accurate diagnosis of a condition. For instance, Holter monitor systems are used to measure the EKG of a patient&#39;s heart over a period of time to detect abnormalities in the heart beat of the patient. Abnormalities detected in this manner may detect heart disease that would otherwise go undetected. These tests, while very useful are limited to monitoring of bio-mechanical physical changes in the body, such as a heart beat, respiration rate, blood pressure or the like. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    A monitor system to monitor a characteristic of a user is disclosed. The monitor system includes a sensor to produce a signal indicative of a glucose characteristic measured in the user, the sensor further having a sensor port. The monitor system further includes a recorder within a recording housing, the recorder hosing also encompassing a batter. The recorder further includes a recorder port that interfaces with the sensor port in order to receive the produced signals from the sensor port. A recorder clock that assigns a time to the signals from the sensor is also defined within the recorder housing, as is a recorder processor that includes a recorder memory that is coupled to the recorder port to store the produced signals from the sensor. The recorder further includes a data port defined to interface with a dock receiver. A dock that is remotely located from the sensor and the recorder is also included with the monitor system. The dock includes the dock receiver that physically couples the recorder to the dock via the data port and a dock processor that is coupled to the dock receiver. The monitor system further includes a data processor defined to analyze the signals from the sensor that were stored in the recorder. The data processor includes a data processor memory to store data from the recorder and a data processor clock. Further included with the data processor is a program to assign the time and date of the signals from the sensor by comparing the time and date on the data processor clock with the time assigned to the signals from the sensor by the recorder clock. 
         [0006]    Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, various features of embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A detailed description of embodiments of the invention will be made with reference to the accompanying drawings, wherein like numerals designate corresponding parts in the several figures. 
           [0008]      FIG. 1  is an exemplary illustration of components of a monitor system, in accordance with embodiments of the present invention. 
           [0009]      FIG. 2A  is an exemplary block diagram illustrating components within a recorder, in accordance with one embodiment of the present invention. 
           [0010]      FIGS. 2B-2D  illustrate various embodiments of a detail of a recorder port, in accordance with embodiments of the present invention. 
           [0011]      FIGS. 3A-3D  are schematic illustrations of connecting a dock to wall plug, in accordance with embodiments of the present invention. 
           [0012]      FIGS. 4A and 4B  are illustration showing the placement of the recorder onto the dock, in accordance with embodiments of the present invention. 
           [0013]      FIGS. 5A-5C  are exemplary illustrations of placement of a sensor and installation of the recorder onto the sensor, in accordance with embodiments of the present invention. 
           [0014]      FIG. 6A-6C  are exemplary schematics illustrating the removal of the recorder from the sensor and placement of the recorder back onto the dock, in accordance with embodiments of the present invention. 
           [0015]      FIG. 6D  is an illustration showing a recorder that contains recorded sensor data connected to a dock that is connected to a data processor via a cable, in accordance with embodiments of the present invention. 
           [0016]      FIGS. 7A-7D  are a series of illustrations that demonstrate actionable feedback provided by an icon cluster when the recorder is connected to a dock, in accordance with embodiments of the present invention. 
           [0017]      FIGS. 8A-8D  are larger illustrations of the icon cluster in accordance with embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    As shown in the drawings for purposes of illustration, the invention is embodied in a monitor system coupled to a subcutaneous implantable analyte sensor set to provide continuous data recording of the sensor readings for a period of time. The recorded data later being downloaded or transferred to a computing device to determine body characteristic data based on the data recording over the period of time. In embodiments of the present invention, the analyte sensor set and monitor system are for determining glucose levels in the blood and/or bodily fluids of the user without the use of, or necessity of, complicated monitoring systems that require user training and interaction. However, it will be recognized that further embodiments of the invention may be used to determine the levels of other analytes or agents, characteristics or compositions, such as hormones, cholesterol, medications concentrations, viral loads (e.g., HIV), or the like. In other embodiments, the monitor system may also include the capability to be programmed to record data at specified time intervals. The monitor system and analyte sensor are primarily adapted for use in subcutaneous human tissue. However, still further embodiments may be placed in other types of tissue, such as muscle, lymph, organ tissue, veins, arteries or the like, and used in animal tissue. The analyte sensors may be subcutaneous sensors, transcutaneous sensors, percutaneous sensors, sub-dermal sensors, skin surface sensors, or the like. Embodiments may record sensor readings on an intermittent or continuous basis. 
         [0019]      FIG. 1  is an exemplary illustration of components of a monitor system  10 , in accordance with embodiments of the present invention. A perspective view of a dock  100  illustrates icon cluster  106  and a dock receiver  108  that is configured to connect to a recorder data port  110  on the recorder  104 . The recorder port  110  of the recorder  104  is also configured to connect to a sensor port  112  that is included on a sensor  102 . The illustration of the sensor  102  is an exemplary top view of the sensor  102  after it has been inserted into a patient. In some embodiments, the sensor  102  is an assembly commonly known as a “sensor set” that includes, but it not limited to the sensor port  112 , sensor adhesive (not shown) covered by an adhesive backing  116 , an introducer needle (not shown in  FIG. 1 ), a sensing portion to be placed in a body (not shown), and a mounting base. In many embodiments the sensor set utilizes an electrode-type sensor that is used to monitor blood glucose levels. A data processor  114  is also included in the monitor system  10 . In some embodiments the data processor  114  is a general purpose computer such as a netbook, notebook computer or desktop computer that can connect to the dock  100 . In other embodiments, the data processor  114  can be more specialized computing devices such as smartphones or purpose built computers. In further embodiments, the data processor includes an Internet connection and employs an Internet-based server and Internet software application. 
         [0020]    In some embodiments the recorder  104  is a Holter-type recording device that can be interfaced with both the dock  100  and the sensor  102 . In one embodiment the sensor  102  utilizes an electrode-type sensor while in alternative embodiments, the sensor  102  may use other types of sensors, such as chemical based, optical based or the like. In further alternative embodiments, the sensor  102  may be of a type that is used on the external surface of the skin or placed below the skin layer of the user or placed in the blood stream of the user. Other embodiments of a surface mounted sensor would utilize interstitial fluid harvested from the skin. 
         [0021]    The recorder  104  generally includes the capability to record and store data as it is received from the sensor  102 , and includes a recorder port  110  that can be coupled with either the sensor  102  or the dock  100 . When the recorder  104  is coupled to the dock  100  and the dock  100  is in communication with the data processor  114 , data stored on the recorder  104  can be transferred to the data processor  114 . To enable data transfer between either the sensor  102  or the dock  100  the recorder  104  may include a recorder port  110  that is designed to establish communication between the sensor  102  or the dock  100 . 
         [0022]    Further description regarding the sensor and associated sensor set can be found in U.S. Pat. No. 6,248,067, entitled ANALYTE SENSOR AND HOLTER-TYPE MONITOR SYSTEM AND METHOD OF USING THE SAME, U.S. Pat. No. 5,586,553, entitled TRANSCUTANEOUS SENSOR INSERTION SET, and U.S. Pat. No. 5,594,643, entitled DISPOSABLE SENSOR INSERTION ASSEMBLY, all of which is herein incorporated by reference. 
         [0023]      FIG. 2A  is an exemplary block diagram illustrating components within the recorder  104 , in accordance with one embodiment of the present invention. A power supply  212  connected to power management  214  is found within the housing  202  of the recorder  104 . In some embodiments the power supply  212  is a battery assembly that uses a rechargeable battery chemistry to provide power to recorder  104 . In one embodiment the power supply  212  is made up of lithium ion battery cells. However, it is understood that alternate battery chemistries may be used, such as nickel metal hydride, alkaline or the like. Similarly, various embodiments can use a single battery cell while other embodiments use multiple battery cells. 
         [0024]    The power management  214  includes circuitry and programming to allow recharging of the power supply  212  via the recorder port  110 . In some embodiments power management  214  also includes circuitry and programming that enables a low battery warning alarm. In some embodiments the power supply  212  is capable of enabling the recorder  104  to record data for seven days. Additionally, after seven days of recording, the power supply further enables operation of an integrated clock in the recorder  104  for an additional seven days. Alternative embodiments may provide longer or shorter battery lifetimes, or include a power port or solar cells to permit recharging of the power supply  212 . 
         [0025]    The sensor  102  is connected via the sensor port  112  and the recorder port  110  to a signal conditioning circuit  200 , such as a potentiostat or the like, in a housing  202  of the recorder  104 . The signal conditioning circuit  200  is in turn connected to a current to frequency converter (I to F)  204 . The output of the current to frequency converter  204  is a digital frequency that varies as a function of the sensor signal produced by the sensor  102 . In alternative embodiments, other signals, such as voltage, or the like, may be converted to frequency. In one embodiment, the digital frequency is then counted by a digital counter  206 , and a value from the digital counter  206  is periodically read and stored with an indication of elapsed time, by a microprocessor  208 , into a non-volatile memory  210 . 
         [0026]    In some embodiments the microprocessor  208  includes an integrated clock that begins tracking elapsed time when the recorder  104  determines the sensor  102  is properly hydrated. The integrated clock is also used to determine when events occur such as periodic sample readings from the sensor  102 . The periodic readings from the sensor  102  are stored to the memory  210  with an elapsed clock reading from the integrated clock. In other embodiments, the clock is separate and distinct from the microprocessor  208  but is still contained within the housing  202 . In such embodiments, the microprocessor  208  is still programmed and configured to initiate the clock when the sensor  102  is properly hydrated. Additionally, the microprocessor  208  is programmed and configured to read and record the elapsed time of the clock. As will be discussed later, the elapsed clock time from the integrated clock of the recorder  104  can be used to retrospectively determine times of the periodic readings. 
         [0027]    In some embodiments, the recorder  104  provides power to drive the sensor  102  via the recorder port  110  and the sensor port  112 . Power from the recorder  104  may also be used to speed initialization of the sensor  102 , when it is first placed under the skin. The use of an initialization procedure can result in a sensor  102  providing stabilized data in an hour or less compared to requiring several hours before stabilized data is acquired without using an initializing procedure. One exemplary initialization procedure uses a two step process. First, a high voltage (preferably between 1.0-1.2 volts—although other voltages may be used) is applied to the sensor  102  for one to two minutes (although different time periods may be used) to initiate stabilization of the sensor  102 . Then, a lower voltage (preferably between 0.5-0.6 volts—although other voltages may be used) is applied for the remainder of the initialization procedure (typically 58 minutes or less). The initialization procedure described above is exemplary and other initialization procedures using differing currents, voltages, currents and voltages, different numbers of steps, or the like, may be used. 
         [0028]      FIGS. 2B-2D  illustrate various embodiments of detail  220  of the recorder port  110 , in accordance with embodiments of the present invention. Detail  220  shows top contacts  222  and bottom contacts  224  which together can simply be referred to as “the recorder contacts”. In the embodiment illustrated the recorder contacts are mounted to a circuit board  226  to which the components described in  FIG. 2A  are also mounted. The recorder contacts can be board mounted springs, or simple contact pads, or any other variety of contact that creates a reliable electrical connection. 
         [0029]    The configuration illustrated is intended to be exemplary and should not be construed to be limiting. For example, in alternative embodiments shown in  FIG. 2C , rather than a single recorder port  110  ( FIG. 2A ), the sensor  104  could have two separate ports with the first port  250  providing access to top contacts  222  while the second port  252  provides access to bottom contacts  224 . Similarly, other embodiments could use two separate ports while placing the bottom contacts  224  on the same side of the circuit board  226  as the top contacts  222 , as shown in  FIG. 2D . 
         [0030]    As illustrated the recorder contacts are protected from damage and/or fouling by being recessed within the recorder data port  110 . In alternative embodiments, the recorder contacts can be exposed on the exterior of the recorder  104  and rely on pins or pads from the both the sensor  102  ( FIG. 1 ) and the dock  100  ( FIG. 1 ) to make electrical contact. The recorder contacts are used for multiple purposes such as, but not limited to, allowing the power supply  212  ( FIG. 2A ) within the recorder  104  to provide power to the sensor  102  ( FIG. 1 ), transmitting data from the sensor  102  ( FIG. 1 ) to memory  210  within the recorder  104 , transmitting data stored in the memory  210  ( FIG. 2A ) of the recorder  104  to a data processor  114  ( FIG. 1 ), and recharging the power supply  212  ( FIG. 2A ) of the recorder  104 . In some embodiments the top contacts  222  are used to record sensor data and deliver power to the sensor  102 . Similarly, the bottom contacts  224  are used to charge the power supply  212  ( FIG. 2A ), transfer data from the recorder  104  to the data processor  114  and perform diagnostic tests of the recorder components shown in  FIG. 2A . The particular examples described above should be considered demonstrative and should not be construed as limiting the present invention. In other embodiments different combinations and configurations of recorder contacts may be used to perform various recorder functions and features. 
         [0031]      FIGS. 3A-3D  are schematic illustrations of connecting the dock  100  to wall plug  304 , in accordance with embodiments of the present invention.  FIG. 3A  illustrates plugging cable  302   a  into a dock port  300  where the dock port  300  is integrated into the dock  100 . In some embodiments the dock port  300  is chosen from a variety of standard ports in order to simplify manufacturing and distribution. As illustrated, the dock port  300  is a standard female mini-USB type connector while cable end  302   b  is the corresponding standard male mini-USB type connector. Alternate embodiments can use various connectors that are capable of supplying power and transmitting data. For example the cable end  302   b  could use a proprietary connector and dock port  300  could have a corresponding proprietary socket. Alternatively, a variety of USB connectors and socket could be used, including, but not limited to Type A, Type B, Mirco-AB and Micro-B.  FIG. 3B  illustrates plugging cable end  302   c  into the wall plug  304 . For simplicity of distribution,  FIG. 3B  shows cable end  302   c  as Type A USB plug while a plug receptacle  308  is a USB Type A receptacle. As described above, various plugs and receptacles can be used in place of those shown in  FIG. 3B . 
         [0032]      FIG. 3C  illustrates a single dock  100  being powered from a power strip  310 . The wall plug  304  is connected to the power strip  310  and power is transmitted to the dock  100  via the cable  302   a . In one embodiment, the dock  100  includes hardware and software to determine if enough power is being supplied to the dock  100 . In situations where the dock  100  is receiving appropriate levels of power the power indicator  306  will be constantly illuminated. The power indicator  306  is part of the icon cluster  106  which will be discussed in more detail during the description of  FIGS. 7 and 8 . 
         [0033]      FIG. 3D  is an exemplary illustration showing multiple docks  100  each drawing power from the power strip  310  via the wall plugs  304 . The ability to supply power to the dock  100  via the wall plug  304  or via a USB port from a data processor  114  ( FIG. 1 ) allows practitioners to use multiple docks  100  without requiring multiple data processors. This allows a practitioner to have a central location for multiple docks  100  separate and distinct from the data processor  114  ( FIG. 1 ). With many practitioners, data processors  114  ( FIG. 1 ) in their office may be located near a reception area that is separated from patient exam or consultation rooms. Thus, depending on placement of data processors in a given office, the ability to charge recorders  104  ( FIG. 1 ) using docks  100  that are simply plugged into a wall may be advantageous as the practitioner may have limited access to data processors  114  ( FIG. 1 ). 
         [0034]      FIGS. 4A and 4B  are illustration showing the placement of the sensor  104  onto the dock  100 , in accordance with embodiments of the present invention. As shown in  FIG. 1 , the dock  100  includes dock receiver  108 . The dock receiver  108  ( FIG. 1 ) includes electrical contacts that in one embodiment, interface with bottom contacts  224  ( FIG. 2B ). A hood  400  is included on the dock  100  in order to protect the electrical contacts on the dock receiver  108  ( FIG. 1 ). As shown in  FIG. 4A , the hood  400  extends over the dock receiver  108  ( FIG. 1 ) and protects the dock receiver  108  ( FIG. 1 ) from being deformed or rendered unable to couple with the recorder port  110 . In the embodiment illustrated in  FIG. 4A  the recorder  104  is pushed in direction D 1  onto the dock receiver  108  ( FIG. 1 ) which results in what is shown in  FIG. 4B . Note that the icon cluster  106  remains visible after the recorder  104  is coupled with the dock  100 . In some embodiments, an additional cleaning plug (not shown) is used to seal the recorder port  110  to prevent liquids from entering the recorder port  110  so the recorder  104  can be cleaned before the recorder  104  is coupled with the dock  100 . The additional step of cleaning the recorder port  110  can reduce or prevent fouling of the dock. 
         [0035]    As previously discussed, the dock  100  can draw power from either a wall plug  304  ( FIG. 3C ) or data processor  114  ( FIG. 1 ). When the dock  100  of  FIG. 4B  is connected to sufficient power via a wall plug  304  ( FIG. 3C ) or via a connection with the data processor  114  as shown in  FIG. 6D , hardware and software within the dock  100  will begin charging the power supply  212  ( FIG. 2A ) within the recorder  104 . As will be discussed in the description of  FIGS. 7 and 8 , a battery indicator  402  on the dock  100  provides actionable user feedback regarding the state of the power supply  212  ( FIG. 2A ) within the recorder  104 . 
         [0036]      FIGS. 5A-5C  are exemplary illustrations of placement of a sensor  102  and installation of the recorder  104  onto the sensor  102 , in accordance with embodiments of the present invention.  FIG. 5A  illustrates a sequence of typical steps used to place the sensor  102  within interstitial fluid of a patient. The leftmost panel of  FIG. 5A  is illustrative of using an inserter  500  to assist in the installation or placement of the sensor  102 . Commonly, inserters  500  are customized to accommodate a specific type of sensor  102 . For additional information regarding inserters  500  please see U.S. patent application Ser. No. 10/314,653 filed on Dec. 9, 2002, entitled INSERTION DEVICE FOR INSERTION SET AND METHOD OF USING THE SAME, U.S. Pat. No. 6,607,509, entitled INSERTION DEVICE FOR AN INSERTION SET AND METHOD OF USING THE SAME, and U.S. Pat. No. 5,851,197 entitled INJECTOR FOR A SUBCUTANEOUS INFUSION SET, all of which are herein incorporated by reference. 
         [0037]    The middle panel of  FIG. 5A  is an illustration showing the removal of the adhesive backing  116  to expose an adhesive that enables adhesion of the sensor  102  to the skin  504  of a patient. The rightmost panel of  FIG. 5A  is an illustration that depicts the removal of an introducer needle  506  that is used during the placement of the sensor  102 .  FIG. 5B  is an exemplary illustration showing the installation of the recorder  104  onto the sensor  102 . Direction arrows D 2  indicate that the recorder  104  is pushed onto the sensor  102  that was adhered to the patient, as shown in the middle panel of  FIG. 5A . In some embodiments, it is desirable to wait a predetermined period of time before installing the recorder  104  onto the sensor  102 . For example, it may be advantageous to wait for up to  15  minutes for the sensor  102  to be properly hydrated or wetted by the patient&#39;s interstitial fluid before attaching the recorder  104 . In other embodiments it may take longer before is sensor is considered properly hydrated. Being able to detect if an installed sensor  102  is properly hydrated can be used by a practitioner to help determine if the sensor was properly installed into the interstitial fluid. In other embodiments there is no minimum time required before attaching the recorder  104  to the sensor  102 . In still more embodiments, the sensor  102  need not be hydrated before the recorder  104  is connected. And in additional embodiments, the recorder may be integrated with the sensor before the sensor is inserted into a user. 
         [0038]    As illustrated in  FIG. 5C , some embodiments of the recorder  104  include a feedback indicator  502 . In one embodiment the feedback indicator  502  is a Light Emitting Diode (LED) that can be seen through a translucent or semi-translucent housing. In other embodiments, different light elements can be used, such as, but not limited to incandescent lights, fluorescent lights, Organic Light Emitting Diodes (OLED) or the like. In still other embodiments, the feedback indicator can be an audible tone or a vibration alarm similar to those in mobile phones. In embodiments with the feedback indicator, the recorder  104  can provide feedback regarding the hydration level of a connected sensor. For example, the recorder includes hardware and software that can determine if the sensor  102  is properly hydrated. The feedback indicator  502  can help a practitioner by narrowing the type of troubleshooting that needs to be performed. For example, the feedback indicator  502  can be programmed to flash a specific sequence or color to indicate that the sensor  102  is properly hydrated. Similarly, the feedback indicator  502  can be programmed to flash a different sequence or color to indicate that the sensor is not properly hydrated. In other embodiments, the feedback indicator  502  can further be programmed to flash a particular sequence or color that indicates to a practitioner that the sensor  104  is not fully charged or even that data needs to be transferred from the recorder  104  before additional data can be recorded. The examples provided are not intended to be exhaustive of conditions that can be reported by the feedback indicator  502 . The particular examples provided are intended to be exemplary and should not be construed as limiting the scope of the present invention. 
         [0039]    In some embodiments, the recorder  104  detects the connection of the sensor  102  and activates the recorder  104  for a specified monitoring period where sensor data is recorded onto the recorder  104 , such as 3 days, 4 days, 5 days, 6 days, 7 days, or more. In some embodiments, the recorder  104  will stop recording data after the specified monitoring period. In specific embodiments, the practitioner can program the recorder with a predefined duration that the recorder will operate before it stops collecting sensor data. In particular embodiments the recorder  104  will set an internal “study complete” flag when it stops collecting sensor data and the recorder  104  will not collect more sensor data until the “study complete” flag is removed. In some embodiments the “study complete” flag is removed when the sensor data in the recorder  104  is cleared from the recorder memory, such as by uploading the sensor data to the data processor  114  or by clearing the sensor data without downloading the sensor data first. In particular embodiments, the recorder  104  includes hardware and software to detect when a properly hydrated sensor is connected for the first time and begins to initialize the sensor  102 . Additionally, the recorder  104  can set a “study in process” flag, an internal flag such as a bit or switch, so the recorder  104  will not perform an initialization sequence again until after subsequently recorded data is retrieved or downloaded from the recorder  104 . Thus, if the sensor  102  is pulled out of the interstitial fluid of a patient, hardware and software within the recorder  104  will detect a change in capacitance measured across two or more sensor electrodes and set a “discard flag” so that all data recorded while the sensor is pulled out and be identified and ignored. Should the sensor be pushed back into the interstitial fluid of the patient, the recorder  104  is able to detect when the sensor  102  is rehydrated by the change in capacitance. Once a rehydrated sensor is detected, the recorder  104  will recognize that the “study in process” flag is set and will not reinitialize the sensor  102 . Rather, when a rehydrated sensor is detected, the recorder  104  will remove the discard flag. 
         [0040]    In alternative embodiments the recorder  104  will wait a pre-determined period of time for the sensor signal to stabilize before removing the discard flag. The “study in process” flag is removed when the sensor data is cleared from the recorder&#39;s memory such as by uploading the data to the data processor  114  or clearing the recorder&#39;s memory without uploading data. In some embodiments the pre-determined period of time to wait for sensor signal stabilization is approximately 30 minutes. In other embodiments, additional or less time can be afforded to sensor signal stabilization. Sensor life is improved by not re-initializing the sensor  102  after the sensor is rehydrated and furthermore, power draw from the recorder power supply  212  ( FIG. 2A ) is minimized. In other embodiments, the recorder  104  can determine if sensor data has been collected, and if sensor data is stored in the recorder&#39;s memory, then the recorder  104  will not reinitialize when a rehydrated sensor is detected. The recorder will initialize a sensor only after the sensor data has been cleared from the recorder&#39;s memory. For additional information regarding initialization and stabilization of a sensor please see U.S. patent application Ser. No. 12/345,354 filed on Dec. 29, 2008 entitled METHOD AND SYSTEMS FOR OBSERVING SENSOR PARAMETERS which is herein incorporated by reference. 
         [0041]    In one embodiment, the recorder  104  is programmed to record periodic sensor data for seven days, as timed by the recorder&#39;s internal clock. In one embodiment, the internal clock within the recorder is used to determine the periodic intervals for recording sensor data. Thus, after a predetermined period of time has elapsed after being connected to a hydrated sensor, data from the sensor is recorded with an associated time stamp from the internal clock. For example, if the recorder is programmed to record sensor data every 30 minutes after being connected to a properly hydrated sensor, the first record of sensor data will be time stamped as occurring after 30 minutes. After recording seven days of sensor data the power supply  112  will still have sufficient power to keep the internal clock running for an additional seven to 11 days. In other embodiments, the recorder  104  will supply power for more than  11  days after the sensor data is recorded. The additional seven to 11 days after recording of sensor data has ceased provides enough time for a patient to return to a practitioner&#39;s office to return the recorder  104  and give the practitioner time to download or retrieve the stored sensor data from the recorder  104 . To retrieve stored sensor data the recorder  104  is placed into a dock  100  that is connected to a data processor  114  ( FIG. 1 ). 
         [0042]      FIG. 6A-6C  are exemplary schematics illustrating the removal of the recorder  104  from the sensor  102  and placement of the recorder  104  back onto the dock  100 , in accordance with embodiments of the present invention.  FIGS. 6A and 6B  are illustrative of a two step procedure to remove the recorder  104  from the sensor  102 . As shown in  FIG. 6A  a practitioner or the patient squeezes the sensor  102  in the direction D 3  in order to release clips or snaps that help connect the recorder  104  to the sensor  102 . Subsequently, the recorder  104  is moved in the direction D 4  to remove or uncouple the recorder  104  from the sensor  102 . After the recorder  104  is removed from the sensor  102 , the sensor can be removed from the patient and the recorder  104  can be cleaned using the previously discussed cleaning plug before placing the recorder  104  on a dock  100  as shown in  FIG. 6C . 
         [0043]      FIG. 6D  is an illustration showing a recorder  104  that contains recorded sensor data connected to a dock  100  that is connected to a data processor  114  via cable  302   a , in accordance with embodiments of the present invention. A recorder  104  that contains recorded sensor data can be recharged using a dock  100  connected to a wall outlet, however as discussed above, the recorder  104  will have set an internal “study in process” flag that prevents the recorder  104  from performing an additional initialization sequence until the recorded data is retrieved or downloaded from the recorder  104 . Thus, it is preferable for recorders  104  with recorded sensor data to be placed on a dock  100  that is connected to a data processor  114 . In other embodiments, the recorder  104  will set the “study complete” flag when if the recorder  104  contains sensor data and is connected to the dock  100 . Thus, the recorder  104  will collect no additional data until the sensor data in the recorder is cleared, not even if the recorder is reconnected to a hydrated sensor. This helps to minimize the possibility of the recorder  104  containing data from a first patient and then being placed on a second patient before the data is cleared from the first patient. 
         [0044]    Furthermore, the recorder LED  502  will not flash when connected to a hydrated sensor if the “study complete” flag or the “study in process” flag is set. This tells the practitioner that the recorder  104  is not initializing the sensor. 
         [0045]    When the dock  100  is connected to a data processor  114  and the recorder  104  is connected to the dock,  100 , stored sensor data can be downloaded from the recorder  104  to the data processor  114 . As previously discussed, the stored sensor data includes time stamps regarding when the sensor data was recorded relative to the internal clock of the recorder  104 . The time stamped recorded data can be used in conjunction with a clock associated with the data processor  114  to retrospectively determine the actual time data was recorded. 
         [0046]    In one embodiment of the present invention, the recorder&#39;s internal clock does not stop when the recorder  104  is removed from the sensor  102 . Then the recorder  104  is connected to the dock  100  and the dock  100  is connected to the data processor  114  such as by using cable  302   a , the recorder can download sensor data to the data processor  114 . The recorder  104  provides sensor data that is time stamped with the age of the sensor readings. So, the data processor  114  can refer to a clock associated with the data processor  114  to determine the time and date when the sensor data is downloaded from the recorder  104 . Then the data processor  114  can compare the age of the last sensor reading to the time and date when the download occurred to determine the time and date that the sensor data was recorded. This can be done with each sensor reading. 
         [0047]    This process of retrospective time stamping can better be appreciated through the following example. In this example when sensor data was downloaded from the recorder  114  to the data processor  114  the clock associated with the data processor indicated 1:00:00 pm on Monday, The downloaded sensor data included the age of each sensor reading. The last sensor reading occurred  4  hours before the sensor data was downloaded to the data processor  114 . The data processor  114  subtracts 4 hours from the time and date that the download occurred to determine that the last sensor reading was recorded at 9 AM on Monday morning. The time and date of each sensor reading is calculated similarly. 
         [0048]    In an alternative embodiment, the recorder  104  is coupled with a dock  100  that is connected to a data processor  114 , the internal clock of the recorder  104  is stopped. In this example, the internal clock of the recorder is stopped at 10 days, 5 hours 15 minutes and 30 seconds. This means the recorder 104 detected a properly hydrated sensor 10 days, 5 hours, 15 minutes and 30 seconds ago. Additionally, 72 hours has elapsed on the internal clock since the last sensor data reading was recorded and the clock of the data processor  114  is reading 3 PM on Apr. 16, 2010. Thus, based on the present time and date reported by the data processor  114  and the elapsed time of the internal clock of the recorder  104 , it can be determined that the last sensor reading was taken on Apr. 13, 2010 at 3 PM. As all recorded sensor data includes a time stamp based on the elapsed time of the internal clock, similar retrospective calculations can be used to determine actual time based on the time reported by the data processor  114  for the other recorded sensor data. 
         [0049]    In still other embodiments, a Blood Glucose Meter (BGM) or other reference device could be used in conjunction with the sensor and monitor system  10  ( FIG. 1 ) to assist with calibration of sensor data. In one embodiment BGM data is downloaded from the BGM to the data processor  114  and retrospectively time stamped or calibrated similar to the sensor data. Thus, a practitioner will not need to set the proper time and date on the meter before the study. If the time and date of the BGM is incorrect, the data processor  114  can compensate by comparing the time and date of the data processor  114  to the incorrect time of the BMG. The data processor has access to the time and data of the BGM when BGM data is being downloaded from the BGM to the data processor  114 . The data processor  114  can apply the difference between the time and date as reported by the BGM and the time and date of the data processor  114  to determine the correct time and date for each BGM reading. 
         [0050]    While  FIG. 6D  and the above description describe data transfer between the recorder  104  and the data processor  114  via the cable  302   a , other embodiments allow the dock  100  to draw power through cable  302   a  while data transfer is conducted using wireless communications such as, but not limited to Wi-Fi, Bluetooth, ultrasonic frequencies, infrared or the like. Additionally, alternate embodiments of the dock  100  do not require the cable  302   a  to transfer power as the dock can include inductive power capabilities or the dock includes an internal power supply such as a battery. 
         [0051]      FIGS. 7A-7D  are a series of illustrations that demonstrate actionable feedback provided by the icon cluster  106  when the recorder  104  is connected to a dock  100 , in accordance with embodiments of the present invention. While the  FIG. 7A  shows the dock  100  connected to a data processor  114  the dock can include hardware and software that enables the dock  100  to perform the functions described below while being connected to a wall plug  304  ( FIG. 3B ).  FIG. 7B  is an exemplary illustration showing the state of icon cluster  106  as the recorder  104  is coupled to the dock  100 . Note that power indicator  306  is illustrated as being steadily illuminated while the battery indicator  402  and a warning indicator  700  are not illuminated or flashing. This condition is indicative that the dock  100  is receiving sufficient power from the data processor  114  and the dock  100  has not begun an initialization procedure. In  FIG. 7C  the recorder  104  has been coupled to the dock  100  and every element within the icon cluster  106 , the power indicator  306 , the battery indicator  402  and the warning indicator  700  are flashing. This condition indicates that the dock  100  is performing an initialization in response to the recorder  104  being coupled to the dock  100 . In one embodiment, if there is sufficient power, the power indicator remains illuminated while the battery indicator and warning indicator are turned off. Using a standard USB cable  302   a  to supply power to the dock  100  exposes the dock  100  to power inconsistencies from data processor  114  USB ports. Though the USB specification details the power requirement that are required from a USB port, various factors including, but not limited to, cable length, wire gauge within the cable, and the number of devices attached to the bus can affect the actual power supplied to a device. 
         [0052]    Notification that the dock  100  is receiving sufficient power is provided to a user by illuminating the power indicator  306 , which in one embodiment is a white LED. Thus, when the dock  100  is initialized by either being plugged in or upon detecting the presence of a recorder  104  and the power indicator  306  is not constantly illuminated, it is indicative that the dock  100  is not receiving sufficient power. To rectify the lack of power the user can be instructed to use a powered USB hub, or to try a different USB cable. In embodiments where the dock  100  includes a power indicator and associated hardware and/or software actionable feedback regarding the power supply to the dock  100  can be provided to the user. Without the actionable feedback provided by the power indicator  100  it could be more difficult to troubleshoot issues with both the dock  100  and the recorder  104 . 
         [0053]      FIG. 7D  is an illustration where the power indicator  306  is shown as illuminated while the battery indicator  402  is shown as flashing, in accordance with embodiments of the present invention. A flashing battery indicator  402  can be indicative of two conditions that can occur when the dock  100  is connected to either a wall plug  304  ( FIG. 3B ) or a data processor  114 . A flashing battery indicator  402  provides actionable feedback by indicating that the battery within the recorder  104  is being recharged or that the recorder  104  contains recorded sensor data that has not been downloaded to a data processor  114 . When the battery indicator  402  becomes steadily illuminated it is indicative that the battery within the recorder  104  is completely charged. However, if a recorder  104  has stored sensor data the battery indicator  402  will continue to blink even after the battery has been charged. This can notify a practitioner that the recorder  104  needs to be connected to a dock  100  that is connected to a data processor  114  so the stored sensor data can be transferred off of the recorder  104 . 
         [0054]    As previously discussed, it is only after stored sensor data is transferred or downloaded from the recorder  104  to the data processor  114 , that the recorder  104  can be used to record additional sensor data. Thus, it should be apparent to a practitioner that a prolonged flashing battery indicator  402  of a dock  100  may be indicative of a recorder  104  that is not available for use. In one embodiment, the battery indicator is a green LED that can be programmed to flash different sequences to distinguish between a dock  100  that is charging a recorder  104  and a dock  100  that has a recorder  104  containing sensor data. In alternative embodiments, the dock includes an indicator to show the status of the battery within the recorder  104  and a separate indicator to show the status of data stored on the recorder  104 . 
         [0055]    As mentioned above, the icon cluster  106  also includes a warning indicator  700 . This allows the dock  100  to provide actionable feedback regarding the operational readiness of a recorder  104 . In addition to providing feedback via the power indicator  306  and the battery indicator  402 , the dock  100  includes hardware and software that is able to perform diagnostic testing of a recorder  104  connected to the dock  100 . The results of the diagnostic test can be provided as feedback to a user via the warning indicator  700 . As previously discussed, the dock  100  includes dock receiver  108  ( FIG. 1 ) that couples with the recorder  104  to recharge the recorder power supply  212 , transfer data from the recorder  104 , and perform diagnostic tests of electronic components of the recorder  104 . As discussed above the recorder  104  includes a memory  210  and a processor  208 . In some embodiments, the dock  100  is programmed to perform a diagnostic test of communication between the memory  210  and the processor  208 . In other embodiments, the dock  100  performs a test to check the integrity of the memory  210  . In still other embodiments, the dock  100  performs tests of the recorder power supply  212 . In still other embodiments, the dock  100  verifies that the recorder  104  can communicate with the dock  100  therefore verifying that the recorder&#39;s microprocessor  208  is functioning properly and verifying that the connectors  224  in the recorder  104  are not damaged. 
         [0056]    While specific types of diagnostic tests have been described above, the types of tests should not be construed as limiting. In other embodiments the dock  100  can be programmed to perform any number of tests only limited by hardware access and programmers inventiveness. A failure of any of the diagnostic tests performed by the dock  100  results in the warning indicator flashing at periodic intervals. Alternatively, the warning indicator can be constantly illuminated if there is a failure of any of the diagnostic tests. In still another embodiment, in order to reduce troubleshooting the warning indicator can flash in specific sequences to indicate which diagnostic test was failed. In particular embodiments, the warning indicator will turn on if the recorder&#39;s power supply  212  is too low or is taking too long to charge. In other embodiments, the warning indicator will turn on if the sensor connectors  220  are damaged or if the electronics in the recorder  104  used to operate the sensor are not functioning properly. To convey the seriousness of a failed diagnostic test, in some embodiments the warning indicator  700  is a red LED. 
         [0057]      FIGS. 8A-8D  are larger illustrations of icon cluster  106  in accordance with embodiments of the present invention.  FIG. 8A  is an example of the icon cluster  106  where the power indicator  306 , the battery indicator  402  and the warning indicator  700  are flashing during initialization of the dock  100 .  FIG. 8B  is an example of the icon cluster  106  when the power indicator  306  is steadily illuminated while the battery indicator  402  and the warning indicator  700  are not illuminated or flashing. This provides feedback to a user by indicating that sufficient power being supplied to the dock  100  and the recorder  104  is not connected to the dock  100 .  FIG. 8C  is an example of the icon cluster  106  when the power indicator  306  is steadily illuminated, the battery indicator  402  is flashing, and the warning indicator  700  is not illuminated nor flashing. This feedback indicates to a user that the dock  100  is receiving sufficient power and either the recorder&#39;s power supply  212  is charging or that the recorder  104  contains recorded sensor data that has not been downloaded.  FIG. 8D  is an example of the icon cluster where the power indicator  306  is steadily illuminated, the battery indicator  402  is steadily illuminated, and the warning indicator  700  is not illuminated nor flashing. Such exemplary feedback is indicative that the recorder  104  in the dock  100  is fully charged and is ready to be connected to a sensor. 
         [0058]    The icon cluster is used to provide actionable feedback to a user with the intent of minimizing difficulty when troubleshooting the system while ensuring integrity of data stored on the recorder  104 . The use of three different colored LEDs for the power indicator  306 , the battery indicator  402  and the warning indicator  700  should not be construed as limiting as a single multicolored LED may be used or combinations of various lighting types. Additionally, the use of only visual feedback should not be construed as limiting. Other embodiments of the dock  100  can include both visual feedback as discussed above along with audible feedback of various frequencies and rhythms. 
         [0059]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. 
         [0060]    The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.