(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0202859 A1
`(43) Pub. Date:
`Sep. 14, 2006
`Mastrototaro et al.
`
`US 20060202859A1
`
`(54) TELEMETERED CHARACTERISTIC
`MONITOR SYSTEMAND METHOD OF
`USING THE SAME
`
`(76) Inventors: John J. Mastrototaro, Los Angeles,
`CA (US); Edward Chernoff, Frazier
`Park, CA (US); David Y. Choy, San
`Gabriel, CA (US); James L. Henke,
`Simi Valley, CA (US); Richard E.
`Purvis, Pasadena, CA (US); Peter I.
`Hong, Santa Clarita, CA (US)
`Correspondence Address:
`MEDTRONIC MINIMED, INC.
`18000 Devonshire Street
`Northridge, CA 91325-1219 (US)
`(21) Appl. No.:
`11/322,568
`
`(22) Filed:
`
`Dec. 30, 2005
`Related U.S. Application Data
`(63) Continuation-in-part of application No. 10/898.589,
`filed on Jul. 23, 2004, which is a continuation of
`application No. 09/465,715, filed on Dec. 17, 1999,
`now Pat. No. 6,809,653, which is a continuation of
`application No. 09/377,472, filed on Aug. 19, 1999,
`now abandoned.
`
`(60) Provisional application No. 60/103,812, filed on Oct.
`8, 1998.
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`H04O 9/00
`(2006.01)
`GOSC 9/22
`(52) U.S. Cl. ........................................................ 34O/870.07
`
`(57)
`
`ABSTRACT
`
`A telemetered characteristic monitor system includes a
`remotely located data receiving device, a sensor for produc
`ing signal indicative of a characteristic of a user, and a
`transmitter device. The transmitter device includes a hous
`ing, a sensor connector, a processor, and a transmitter. The
`transmitter receives the signals from the sensor and wire
`lessly transmits the processed signals to the remotely located
`data receiving device. The processor coupled to the sensor
`processes the signals from the sensor for transmission to the
`remotely located data receiving device. The data receiving
`device may be a characteristic monitor, a data receiver that
`provides data to another device, an RF programmer for a
`medical device, a medication delivery device (Such as an
`infusion pump), or the like.
`
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`Page 1 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 1 of 12
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`US 2006/0202859 A1
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`Page 2 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 2 of 12
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`US 2006/0202859 A1
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`Page 3 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 3 of 12
`
`US 2006/0202859 A1
`
`
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`Page 4 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 4 of 12
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`US 2006/0202859 A1
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`204
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`FIG. 12
`
`Page 5 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 5 of 12
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`US 2006/0202859 A1
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`CHARACTERISTIC
`MONITOR
`
`2OO
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`F.G. 13
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`TELEMETERED
`CHARACTERISTIC
`1001 MONITORIAANSMITTER
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`1001 MONITORTRANSMITTER
`
`FIG. 14
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`Patent Application Publication Sep. 14, 2006 Sheet 6 of 12
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`US 2006/0202859 A1
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`Patent Application Publication Sep. 14, 2006 Sheet 7 of 12
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`US 2006/0202859 A1
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`Patent Application Publication Sep. 14, 2006 Sheet 8 of 12
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`US 2006/0202859 A1
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`1118
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`1122
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`FIG. 19
`
`
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`Patent Application Publication Sep. 14, 2006 Sheet 9 of 12
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`US 2006/0202859 A1
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`Page 10 of 25
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`Patent Application Publication Sep. 14, 2006 Sheet 11 of 12
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`US 2006/0202859 A1
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`Patent Application Publication Sep. 14, 2006 Sheet 12 of 12
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`US 2006/0202859 A1
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`Page 13 of 25
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`US 2006/0202859 A1
`
`Sep. 14, 2006
`
`TELEMETERED CHARACTERISTIC MONITOR
`SYSTEMAND METHOD OF USING THE SAME
`
`RELATED APPLICATIONS
`0001. This application is a continuation-in-part of U.S.
`patent application Ser. No. 10/898.589, filed on Jul. 23,
`2004, which is a continuation of U.S. patent application Ser.
`No. 10/465,715, filed on Dec. 17, 1999 and issued as U.S.
`Pat. No. 6,809,653 on Oct. 26, 2005, which is a continuation
`of U.S. patent application Ser. No. 09/377,472, filed on Aug.
`19, 1999 and later abandoned, which claimed priority from
`U.S. Provisional Application Ser. No. 60/103,812, filed on
`Oct. 8, 1998, each of which are herein incorporated by
`reference.
`
`FIELD OF THE INVENTION
`0002 This invention relates to telemetered subcutaneous
`sensor devices and, in particular embodiments, to devices
`and methods for wireless communication between an
`implantable Subcutaneous sensor set at a selected insertion
`site within the body of a user and a remotely located
`characteristic monitor.
`
`BACKGROUND OF THE INVENTION
`0003 Over the years, a variety of implantable electro
`chemical sensors have been developed for detecting and/or
`quantifying specific agents or compositions in a patients
`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 implant
`able medication infusion pumps, as generally described in
`U.S. Pat. No. 4,573.994, which are herein incorporated by
`reference.
`0004 Generally, small and flexible electrochemical sen
`sors can be used to obtain periodic readings over an
`extended period of time. In one form, flexible subcutaneous
`sensors are constructed in accordance with thin film mask
`techniques in which an elongated sensor includes thin film
`conductive elements encased between flexible insulative
`layers of polyimide sheets or similar material. Such thin film
`sensors typically include a plurality of exposed electrodes at
`one end for Subcutaneous placement with a users interstitial
`fluid, blood, or the like, and a corresponding exposed
`plurality of conductive contacts at another end for conve
`nient external electrical connection with a suitable monitor
`ing device through a wire or cable. 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 incor
`porated by reference herein. See also U.S. Pat. No. 5,299,
`571.
`0005 Drawbacks to the use of implantable sensors arise
`from the use of a wired connection between the implantable
`sensor set and the monitor. The use of the wire or cable is an
`additional inconvenience to users that already utilize an
`external infusion pump that includes an infusion insertion
`set and tube to infuse the medication. Also, the preferred site
`
`for some sensing device may be, inconvenient for connec
`tion by wire to a characteristic monitor. For implantable
`pumps, the wire or cable negates the very benefit of having
`an internal device without external wires or cables. For Type
`2 diabetics, who do not necessarily need or use an infusion
`pump, the use of a cable is seen as an inconvenience that
`may inhibit use of the device. In addition, the use of a wire
`or cable limits a users ability to position the monitor, since
`it can be placed no further away than the ultimate length of
`the wire or cable. Thus, the user must normally wear the
`monitor, which can be problematic. For example, removal of
`the monitor for sleeping can be difficult, since a user would
`tend to become “tangled in the wire or cable, between the
`sensor and the monitor, during the normal tossing and
`turning that occurs during sleep. Furthermore, the more
`connections the user must deal with (e.g., infusion pump and
`catheter and/or monitor with wire to sensor), the more
`complicated it is to use the devices, and the less likely the
`user will maintain compliance with the medical regimen due
`to perceived and actual difficulties with all of the wires and
`cables.
`
`SUMMARY OF THE DISCLOSURE
`It is an object of an embodiment of the present
`0006.
`invention to provide an improved telemetered implantable
`sensor set (such as a Subcutaneous or percutaneous sensor)
`and monitor connection device, which obviates for practical
`purposes, the above mentioned limitations.
`0007 According to an embodiment of the invention, a
`telemetered characteristic monitor System includes a
`remotely located data receiving device, a sensor for produc
`ing signal indicative of a characteristic of a user, and a
`transmitter device. In preferred embodiments, the transmit
`ter device includes a housing, a sensor connector, a proces
`Sor, and a transmitter. A potentiostat within the transmitter
`device may be coupled to the sensor connector and applies
`power to the sensor. The sensor connector receives the
`produced signals from the sensor. The processor is coupled
`to the sensor connector and processes the signals from the
`sensor for delivery to the remotely located data receiving
`device. The transmitter is coupled to the processor for
`wirelessly transmitting the processed signals to the remotely
`located data receiving device. In preferred embodiments, the
`data receiving device is a characteristic monitor. However,
`in other embodiments, the data receiving device is a data
`receiver that provides data to another device, an RF pro
`grammer, a medication delivery device (Such as an infusion
`pump), or the like.
`0008. In particular embodiments, the transmitter of the
`transmitter device transmits the processed signals by radio
`frequencies. In other embodiments, the sensor may be
`implanted in and/or through Subcutaneous, dermal, Sub
`dermal, intra-peritoneal or peritoneal tissue, and the sensor
`connector of the transmitter device includes a cable that is
`connected to the sensor. Also, the implantable sensor can be
`configured for a wired connection to a characteristic moni
`tor, and the sensor connector of the transmitter device is
`formed to connect to the configured implantable sensor. Still
`further embodiments of the transmitter device include a
`receiver to receive data and instructions from the character
`istic monitor, or the like.
`0009 Embodiments of the transmitter device (when used
`with a subcutaneous or percutaneous sensor) may include a
`
`Page 14 of 25
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`US 2006/0202859 A1
`
`Sep. 14, 2006
`
`bio-compatible adhesive to secure the housing to a skin
`surface of the user. Preferably, the housing of the transmitter
`device is less than about 3.0 inches in diameter by 0.5 inches
`thick. In addition, the housing is resistant to fluids when
`immersed in a fluid, operable in a temperature range of 0°C.
`to 50° C., and has an operable life of at least 3 months. If the
`sensor is fully implanted, the transmitter that is connected to
`the sensor may be secured by Sutures, sewing rings, or the
`like.
`0010. 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 embodi
`ments of the invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0.011) 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.
`0012 FIG. 1 is a is a perspective view illustrating a
`Subcutaneous sensor insertion set and telemetered charac
`teristic monitor transmitter device embodying the novel
`features of the invention;
`0013 FIG. 2 is an enlarged longitudinal vertical section
`taken generally on the line 2-2 of FIG. 1;
`0014 FIG. 3 is an enlarged longitudinal sectional of a
`slotted insertion needle used in the insertion set of FIGS. 1
`and 2.
`FIG. 4 is an enlarged transverse section taken
`0.015
`generally on the line 4-4 of FIG. 3;
`0016 FIG. 5 is an enlarged transverse section taken
`generally on the line 5-5 of FIG. 3:
`0017 FIG. 6 is an enlarged fragmented sectional view
`corresponding generally with the encircled region 6 of FIG.
`2; and
`0018 FIG. 7 is an enlarged transverse section taken
`generally on the line 7-7 of FIG. 2.
`0.019
`FIG. 8(a) is a top plan and partial cut-away view
`of the telemetered characteristic monitor transmitter device
`in accordance with the embodiment shown in FIG. 1.
`0020 FIG. 8(b) is a simplified block diagram of the
`printed circuit board of the telemetered characteristic moni
`tor transmitter device in accordance with the embodiments
`shown in FIG. 1.
`0021
`FIG. 9 is a timing diagram illustrating an embodi
`ment of a message and timing format used by the teleme
`tered characteristic monitor transmitter device shown in
`F.G. 1.
`0022 FIG. 10 is a simplified block diagram of a char
`acteristic monitor used in accordance with an embodiment
`of the present invention.
`0023 FIG. 11 is a timing diagram for the characteristic
`monitor shown in FIG. 10.
`0024 FIG. 12 is another timing diagram for the charac
`teristic monitor shown in FIG. 10.
`
`0025 FIG. 13 is a simplified block diagram of a teleme
`tered characteristic monitor transmitter and sensor set sys
`tem in accordance with another embodiment of the present
`invention.
`0026 FIG. 14 is a simplified block diagram of a teleme
`tered characteristic monitor transmitter and characteristic
`monitor system in accordance with still another embodiment
`of the present invention.
`0027 FIG. 15 is a perspective view illustrating another
`preferred embodiment of the subcutaneous sensor insertion
`set and telemetered characteristic monitor transmitter device
`when mated together in relation to the characteristic monitor
`system.
`0028 FIG. 16 is a top view of the subcutaneous sensor
`insertion set and telemetered characteristic monitor trans
`mitter device when separated.
`0029 FIGS. 17 and 18 are two perspective views of the
`characteristic monitor transmitter in accordance with the
`embodiment shown in FIG. 16.
`0030 FIGS. 19 and 20 are top and bottom plan and
`partial cut-away views of the telemetered characteristic
`monitor transmitter device in accordance with the embodi
`ment shown in FIG. 16.
`0031
`FIG. 21 is a side view of the charger associated
`with telemetered characteristic monitor transmitter device.
`0032 FIG. 22 is a perspective view of the charger
`associated with telemetered characteristic monitor transmit
`ter device.
`0033 FIG. 23 is a perspective view of the charger mated
`with telemetered characteristic monitor transmitter device.
`0034 FIGS. 24 and 25 are simplified block diagrams of
`the charger system used to charge the telemetered charac
`teristic monitor transmitter device.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0035. As shown in the drawings for purposes of illustra
`tion, the invention is embodied in a telemetered character
`istic monitor transmitter coupled to a sensorset, that may be
`implanted in and/or through Subcutaneous, dermal, Sub
`dermal, inter-peritoneal or peritoneal tissue, that transmits
`data from the sensor set to the characteristic monitor for
`determining body characteristics. In preferred embodiments
`of the present invention, the sensor set and monitor are for
`determining glucose levels in the blood and/or body fluids of
`the user without the use of, or necessity of a wire or cable
`connection between the transmitter and the monitor. How
`ever, it will be recognized that further embodiments of the
`invention may be used to determine the levels of other
`agents, characteristics or compositions, such as hormones,
`cholesterol, medication concentrations, pH, oxygen satura
`tion, viral loads (e.g., HIV), or the like. In other embodi
`ments, the sensor set may also include the capability to be
`programmed or calibrated using data received by the tele
`metered characteristic monitor transmitter device, or may be
`calibrated at the monitor device (or receiver). The teleme
`tered characteristic monitor System is primarily adapted for
`use in subcutaneous human tissue. However, still further
`embodiments may be placed in other types of tissue. Such as
`
`Page 15 of 25
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`
`Sep. 14, 2006
`
`muscle, lymph, organ tissue, veins, arteries or the like, and
`used in animal tissue. Embodiments may provide sensor
`readings on an intermittent or continuous basis.
`0036) The telemetered characteristic monitor system 1, in
`accordance with a preferred embodiment of the present
`invention include a percutaneous sensor set 10, a teleme
`tered characteristic monitor transmitter device 100 and a
`characteristic monitor 200. The percutaneous sensor set 10
`utilizes an electrode-type sensor, as described in more detail
`below. However, in alternative embodiments, the system
`may use other types of sensors, such as chemical based,
`optical based or the like. In further alternative embodiments,
`the sensors may be of a type that is used on the external
`surface of the skin or placed below the skin layer of the user.
`Preferred embodiments of a surface mounted sensor would
`utilize interstitial fluid harvested from underneath the skin.
`The telemetered characteristic monitor transmitter 100 gen
`erally includes the capability to transmit data. However, in
`alternative embodiments, the telemetered characteristic
`monitor transmitter 100 may include a receiver, or the like,
`to facilitate two-way communication between the sensorset
`10 and the characteristic monitor 200. The characteristic
`monitor 200 utilizes the transmitted data to determine the
`characteristic reading. However, in alternative embodi
`ments, the characteristic monitor 200 may be replaced with
`a data receiver, storage and/or transmitting device for later
`processing of the transmitted data or programming of the
`telemetered characteristic monitor transmitter 100.
`0037. In addition, a relay or repeater 4 may be used with
`a telemetered characteristic monitor transmitter 100 and a
`characteristic monitor 200 to increase the distance that the
`telemetered characteristic monitor transmitter 100 can be
`used with the characteristic monitor 200, as shown in FIG.
`13. For example, the relay 4 could be used to provide
`information to parents of children using the telemetered
`characteristic monitor transmitter 100 and the sensor set 10
`from a distance. The information could be used when
`children are in another room during sleep or doing activities
`in a location remote from the parents. In further embodi
`ments, the relay 4 can include the capability to Sound an
`alarm. In addition, the relay 4 may be capable of providing
`telemetered characteristic monitor transmitter 100 data from
`the sensor set 10, as well as other data, to a remotely located
`individual via a modem connected to the relay 4 for display
`on a monitor, pager or the like. The data may also be
`downloaded through a Communication-Station 8 to a
`remotely located computer 6 such as a PC, lap top, or the
`like, over communication lines, by modem or wireless
`connection, as shown in FIG. 14. Also, Some embodiments
`may omit the Communication Station 8 and uses a direct
`modem or wireless connection to the computer 6. In further
`embodiments, the telemetered characteristic monitor trans
`mitter 100 transmits to an RF programmer, which acts as a
`relay, or shuttle, for data transmission between the sensorset
`10 and a PC, laptop, Communication-station, a data proces
`sor, or the like. In further alternatives, the telemetered
`characteristic monitor transmitter 100 may transmit an alarm
`to a remotely located device, such as a communication
`station, modem or the like to Summon help. In addition,
`further embodiments may include the capability for simul
`taneous monitoring of multiple sensors and/or include a
`sensor for multiple measurements.
`
`0038 Still further embodiments of the telemetered char
`acteristic monitor transmitter 100 may have and use an input
`port for direct (e.g., wired) connection to a programming or
`data readout device and/or be used for calibration of the
`sensor set 10. Preferably, any port would be water proof (or
`water resistant) or include a water proof, or water resistant,
`removable cover.
`0039 The purpose of the telemetered characteristic
`monitor system 1 (see FIG. 2) is to provide for better
`treatment and control in an outpatient or a home use envi
`ronment. For example, the monitor System 1 can provide
`indications of glucose levels, a hypoglycemia/hyperglyce
`mia alert and outpatient diagnostics. It is also useful as an
`evaluation tool under a physician’s Supervision.
`0040. The monitor system 1 also removes inconvenience
`by separating the monitor electronics into two separate
`devices; a telemetered characteristic monitor transmitter
`100, which attaches to the implantable sensor set 10; and a
`characteristic monitor 200 (or other receiver), which is
`carried like a pager. This provides several advantages over
`wire connected devices. For instance, the user can more
`easily conceal the presence of the monitor System 1, since a
`wire will not be visible (or cumbersome), within clothing.
`Such remote communication also provides greater conve
`nience and flexibility in the placement of the sensor. It also
`makes it is easier to protect the characteristic monitor 200,
`which can be removed from the user's body during showers,
`exercise, sleep or the like. In addition, the use of multiple
`components (e.g., transmitter 100 and characteristic monitor
`200) facilitates upgrades or replacements, since one module
`or the other can be modified or replaced without requiring
`complete replacement of the monitor system 1. Further, the
`use of multiple components can improve the economics of
`manufacturing, since Some components may require
`replacement on a more frequent basis, sizing requirements
`may be different for each module, there may be different
`assembly environment requirements, and modifications can
`be made without affecting the other components.
`0041. The telemetered characteristic monitor transmitter
`100 takes characteristic information, Such as glucose data or
`the like, from the percutaneous sensor set 10 and transmits
`it via wireless telemetry to the characteristic monitor 200,
`which displays and logs the received glucose readings.
`Logged data can be downloaded from the characteristic
`monitor 200 to a personal computer, laptop, or the like, for
`detailed data analysis. In further embodiments, the teleme
`tered characteristic monitor system 1 may be used in a
`hospital environment or the like. Still further embodiments
`of the present invention may include one or more buttons (on
`the telemetered characteristic monitor transmitter 100 or
`characteristic monitor 200) to record data and events for
`later analysis, correlation, or the like. In addition, the
`telemetered characteristic monitor transmitter 100 may
`include a transmit on/off button for compliance with safety
`standards and regulations to temporarily Suspend transmis
`sions. Further buttons can include a sensor on/off button to
`conserve power and to assist in initializing the sensor set 10.
`The telemetered characteristic monitor transmitter 100 and
`characteristic monitor 200 may also be combined with other
`medical devices to combine other patient data through a
`common data network and telemetry system.
`0042. Further embodiments of the percutaneous sensor
`set 10 would monitor the temperature of the sensor set 10,
`
`Page 16 of 25
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`Sep. 14, 2006
`
`which can then be used to improve the calibration of the
`sensor. For instance, for a glucose sensor, the enzyme
`reaction activity may have a known temperature coefficient.
`The relationship between temperature and enzyme activity
`can be used to adjust the sensor values to more accurately
`reflect the actual characteristic levels. In addition to tem
`perature measurements, the oxygen Saturation level can be
`determined by measuring signals from the various electrodes
`of the sensor set 10. Once obtained, the oxygen saturation
`level may be used in calibration of the sensor set 10 due to
`changes in the oxygen saturation levels, and its effects on the
`chemical reactions in the sensor set 10. For instance, as the
`oxygen level goes lower the sensor sensitivity may be
`lowered. The oxygen level can be utilized in calibration of
`the sensor set 10 by adjusting for the changing oxygen
`saturation. In alternative embodiments, temperature mea
`Surements may be used in conjunction with other readings to
`determine the required sensor calibration.
`0043. As shown in FIGS. 1-7, a percutaneous sensor set
`10 is provided for subcutaneous placement of an active
`portion of a flexible sensor 12 (see FIG. 2), or the like, at a
`selected site in the body of a user. The subcutaneous or
`percutaneous portion of the sensor set 10 includes a hollow,
`slotted insertion needle 14, and a cannula 16. The needle 14
`is used to facilitate quick and easy Subcutaneous placement
`of the cannula 16 at the subcutaneous insertion site. Inside
`the cannula 16 is a sensing portion 18 of the sensor 12 to
`expose one or more sensor electrodes 20 to the user's bodily
`fluids through a window 22 formed in the cannula 16. After
`insertion, the insertion needle 14 is withdrawn to leave the
`cannula 16 with the sensing portion 18 and the sensor
`electrodes 20 in place at the selected insertion site.
`0044) In preferred embodiments, the percutaneous sensor
`set 10 facilitates accurate placement of a flexible thin film
`electrochemical sensor 12 of the type used for monitoring
`specific blood parameters representative of a user's condi
`tion. Preferably, the sensor 12 monitors glucose levels in the
`body, and may be used in conjunction with automated or
`semi-automated medication infusion pumps of the external
`or implantable type as described in U.S. Pat. No. 4,562,751:
`4,678.408; 4,685,903 or 4,573.994, to control delivery of
`insulin to a diabetic patient.
`0045 Preferred embodiments of the flexible electro
`chemical sensor 12 are constructed in accordance with thin
`film mask techniques to include elongated thin film conduc
`tors embedded or encased between layers of a selected
`insulative material Such as polyimide film or sheet, and
`membranes. The sensor electrodes 20 at a tip end of the
`sensing portion 18 are exposed through one of the insulative
`layers for direct contact with patient blood or other body
`fluids, when the sensing portion 18 (or active portion) of the
`sensor 12 is subcutaneously placed at an insertion site. The
`sensing portion 18 is joined to a connection portion 24 (see
`FIG. 2) that terminates in conductive contact pads, or the
`like, which are also exposed through one of the insulative
`layers. In alternative embodiments, other types of implant
`able sensors, such as chemical based, optical based, or the
`like, may be used.
`0046. As is known in the art, and illustrated schemati
`cally in FIG. 2, the connection portion 24 and the contact
`pads are generally adapted for a direct wired electrical
`connection to a suitable monitor 200 for monitoring a user's
`
`condition in response to signals derived from the sensor
`electrodes 20. Further description of flexible thin film sen
`sors of this general type are be found in U.S. Pat. No.
`5,391,250, entitled METHOD OF FABRICATING THIN
`FILM SENSORS, which is herein incorporated by refer
`ence. The connection portion 24 may be conveniently con
`nected electrically to the monitor 200 or a telemetered
`characteristic monitor transmitter 100 by a connector block
`28 (or the like) as shown and described in U.S. Pat. No.
`5,482.473, entitled FLEX CIRCUIT CONNECTOR, which
`is also herein incorporated by reference. Thus, in accordance
`with embodiments of the present invention, Subcutaneous
`sensor sets 10 are configured or formed to work with either
`a wired or a wireless characteristic monitor system.
`0047 The proximal part of the sensor 12 is mounted in a
`mounting base 30 adapted for placement onto the skin of a
`user. As shown, the mounting base 30 is a pad having an
`underside Surface coated with a Suitable pressure sensitive
`adhesive layer 32, with a peel-off paper strip 34 normally
`provided to cover and protect the adhesive layer 32, until the
`sensor set 10 is ready for use. As shown in FIGS. 1 and 2.
`the mounting base 30 includes upper and lower layers 36 and
`38, with the connection portion 24 of the flexible sensor 12
`being sandwiched between the layers 36 and 38. The con
`nection portion 24 has a forward section joined to the active
`sensing portion 18 of the sensor 12, which is folded angu
`larly to extend downwardly through a bore 40 formed in the
`lower base layer 38. In preferred embodiments, the adhesive
`layer32 includes an anti-bacterial agent to reduce the chance
`of infection; however, alternative embodiments may omit
`the agent. In the illustrated embodiment, the mounting base
`is generally rectangular, but alternative embodiments may
`be other shapes, such as circular, oval, hour-glass, butterfly,
`irregular, or the like.
`0048. The insertion needle 14 is adapted for slide-fit
`reception through a needle port 42 formed in the upper base
`layer 36 and further through the lower bore 40 in the lower
`base layer 38. As shown, the insertion needle 14 has a
`sharpened tip 44 and an open slot 46 which extends longi
`tudinally from the tip 44 at the underside of the needle 14 to
`a position at least within the bore 40 in the lower base layer
`36. Above the mounting base 30, the insertion needle 14 may
`have a full round cross-sectional shape, and may be closed
`off at a rear end of the needle 14. Further description of the
`needle 14 and the sensor set 10 are found in U.S. Pat. No.
`5,586,553, entitled “TRANSCUTANEOUS SENSOR
`INSERTION SET and co-pending U.S. patent application
`Ser. No. 08/871,831, entitled “DISPOSABLE SENSOR
`INSERTIONASSEMBLY,” which are herein incorporated
`by reference.
`0049. The cannula 16 is best shown in FIGS. 6 and 7.
`and includes a first portion 48 having partly-circular cross
`section to fit within the insertion needle 14 that extends
`downwardly from the mounting base 30. In alternative
`embodiments, the first portion 48 may be formed with a
`solid core; rather than a hollow core. In preferred embodi
`ments, the cannula 16 is constructed from a Suitable medical
`grade plastic or elastomer, such as polytetrafluoroethylene,
`silicone, or the like. The cannula 16 also defines an open
`lumen 50 in a second portion 52 for receiving, protecting
`and guideably Supporting the sensing portion 18 of the
`sensor 12. The cannula 16 has one end fitted into the bore 40
`formed in the lower layer 38 of the mounting base 30, and
`
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`US 2006/0202859 A1
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`Sep. 14, 2006
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`the cannula 16 is secured to the mounting base 30 by a
`Suitable adhesive, ultrasonic welding, Snap fit or other
`selected attachment method. From the mounting base 30, the
`cannula 16 extends angularly downwardly with the first
`portion 48 nested within the insertion needle 14, and termi
`nates before the needle tip 44. At least one window 22 is
`formed in the lumen 50 near the implanted end 54, in general
`alignment with the sensor electrodes 20, to permit direct
`elec