(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2009/0085768 A1
`(43) Pub. Date:
`Apr. 2, 2009
`Patel et al.
`
`US 20090085768A1
`
`(54) GLUCOSE SENSORTRANSCEIVER
`
`Publication Classification
`
`(75) Inventors:
`
`Himanshu Patel, Northridge, CA
`(US); Wayne A. Morgan,
`Northridge, CA (US); Edward
`Chernoff, Frazier Park, CA (US);
`John J. Mastrototaro, Los
`Angeles, CA (US)
`
`Correspondence Address:
`LEE, HONG, DEGERMAN, KANG & WAIMEY
`660 S. FIGUEROASTREET, Suite 2300
`LOS ANGELES, CA 90017 (US)
`
`(73) Assignee:
`
`MEDTRONIC MINIMED, INC.
`
`(21) Appl. No.:
`
`12/056,651
`
`(22) Filed:
`
`Mar. 27, 2008
`
`Related U.S. Application Data
`(60) Provisional application No. 60/976,886, filed on Oct.
`2, 2007.
`
`(51) Int. Cl.
`(2006.01)
`GOSC 9/06
`(52) U.S. Cl. ................................................... 34O/870.05
`(57)
`ABSTRACT
`The present invention relates to a telemetered characteristic
`sensor transceiver for exchanging data with at least one
`remote device. The transceiver includes a housing detachably
`coupled to a sensor located on a body of a user, the sensor
`producing a signal indicative of a user characteristic. A pro
`cessor is formed within the housing and in communication
`with the sensor for processing the signal produced by the
`sensor. A transmitter is coupled to the processor for transmit
`ting data to at least one remote device while a receiver is
`coupled to the processor for receiving data from the at least
`one remote device. A memory is coupled to the processor for
`storing data, wherein the processor performs calculations
`using at least one of the signal produced by the sensor, the data
`received from the at least one remote device and the data
`stored in the memory, and performs at least one of storing the
`calculations in the memory and transmitting the calculations
`to the at least one remote device through the transmitter.
`
`COMPUTER
`
`COMMUNICATION
`STATION
`
`
`
`6
`
`8
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`
`
`100
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`
`TELEMETERED
`CHARACTERISTIC
`SENSORTRANSCEIVER
`
`SENSOR
`SET
`
`
`
`
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`Page 1 of 17
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`

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`Patent Application Publication
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`Apr. 2, 2009 Sheet 1 of 6
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`US 2009/0085768A1
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`106
`
`114
`
`FIG, 1
`
`16
`
`12
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`Page 2 of 17
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`

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`Patent Application Publication
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`Apr. 2, 2009 Sheet 2 of 6
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`US 2009/0085768A1
`
`
`
`
`
`sawwalutaww.wawhinn www.wawasawww.staxa
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`Page 3 of 17
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`Patent Application Publication
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`Apr. 2, 2009 Sheet 3 of 6
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`US 2009/0085768A1
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`106
`
`
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`122
`
`124
`
`126
`
`128
`
`RFFREQUENCY
`
`SENSOR
`INTERFACE
`
`PROCESSING
`ELECTROWICS
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`O
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`DATA
`FORMATTING
`ELECTROWICS
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`Page 4 of 17
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`Patent Application Publication
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`Apr. 2, 2009 Sheet 4 of 6
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`US 2009/0085768A1
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`100
`
`TELEMETERED
`CHARACTERISTIC
`SENSORTRANSCEIVER
`
`FIG 9
`
`
`
`
`
`RELAY/REPEATER
`
`
`
`CHARACTERISTIC
`MONITOR
`
`
`
`
`
`COMPUTER
`
`
`
`COMMUNICATION
`STATION
`
`FIG, 10
`
`100
`
`
`
`TELEMETERED
`CHARACTERISTIC
`SENSORTRANSCEIVER
`
`
`
`Page 5 of 17
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`Patent Application Publication
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`Apr. 2, 2009 Sheet 5 of 6
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`US 2009/0085768A1
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`BIOOd GIUCOSe
`Meter
`
`250
`
`X
`Characteristic
`Monitor
`
`200
`
`
`
`
`
`
`
`
`
`Sensor
`Transceiver
`
`Infusion Pump
`
`FIG 11
`
`Computer
`
`PDA
`
`Ce/PhOne
`
`210
`
`220
`
`230
`
`240
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`Page 6 of 17
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`Patent Application Publication
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`Apr. 2, 2009 Sheet 6 of 6
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`US 2009/0085768 A1
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`
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`to-
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`150
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`Page 7 of 17
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`US 2009/0085768 A1
`
`Apr. 2, 2009
`
`GLUCOSE SENSORTRANSCEIVER
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`0001. This application claims the benefit of earlier filing
`date and right of priority to U.S. Provisional Application Ser.
`No. 60/976,886 filed Oct. 2, 2007, the contents of which are
`hereby incorporated by reference.
`
`FIELD
`0002 The present invention relates to telemetered subcu
`taneous sensor devices and, more particularly, to devices for
`wireless communication between an implantable Subcutane
`ous sensor set at a selected insertion site within the body of a
`user and at least one of a plurality of remotely located
`therapy-related devices.
`
`BACKGROUND
`0003 Diabetes mellitus is the most common of endocrine
`disorders, and is characterized by inadequate insulin action.
`Diabetes mellitus has two principal variants, known as Type 1
`diabetes and Type 2 diabetes. The latter is also referred to as
`DM/II (diabetes mellitus type 2), adult-onset diabetes, matu
`rity-onset diabetes, or NIDDM (non-insulin dependent dia
`betes mellitus).
`0004 Over the years, body characteristics have been
`determined by obtaining a sample of bodily fluid. For
`example, diabetics often test for blood glucose levels. Tradi
`tional blood glucose determinations have utilized a finger
`prick method using a lancet to withdraw a small blood
`sample. These systems are designed to provide data at dis
`crete points but do not provide continuous data to show varia
`tions in the characteristic between testing times. These dis
`crete measurements are capable of informing a patient the
`state of his blood glucose values at a point in time. Thus, the
`patient has enough information to administer "correction'
`amounts of insulin to reduce his current blood glucose read
`ing at one point in time. However, these discrete readings are
`notable to provide enough information for any type of auto
`matic or semi-automatic system of administering insulin
`based on blood glucose values. Moreover, discrete blood
`glucose readings only give a limited understanding of one's
`blood glucose values over time, and thus may not give a
`patient a complete picture of how his/her blood glucose val
`ues vary between discrete measurements.
`0005 Recently, a variety of implantable electrochemical
`sensors have been developed for detecting and/or quantifying
`specific agents or compositions in a patient’s blood or inter
`Stitial fluid. For instance, glucose sensors are being developed
`for use in obtaining an indication of blood glucose levels in a
`diabetic patient. These glucose sensors connected (wired or
`wirelessly) to a blood glucose monitor can provide continu
`ous glucose readings overa period of time. Such as 3 to 5 days.
`Such readings are useful in monitoring and/or adjusting a
`treatment regimen which typically includes the regular
`administration of insulin to the patient.
`0006 Thus, continuous blood glucose readings improve
`medical therapies with 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 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 used in these continuous blood glucose monitors
`
`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.
`In addition, characteristic glucose monitors used to provide
`continuous glucose data are described in commonly assigned
`U.S. patent application Ser. No. 1 1/322,568 entitled “Tele
`metered Characteristic Monitor System and Method of Using
`the Same filed on Dec. 30, 2005, which is herein incorpo
`rated by reference in its entirety. In addition, infusion pumps
`receiving sensor data are described in commonly assigned
`U.S. patent application Ser. No. 10/867,529 entitled “System
`for Providing Blood Glucose Measurements to an Infusion
`Device' filed on Oct. 14, 2004, which is herein incorporated
`by reference in its entirety.
`0007. However, drawbacks associated with a prior glucose
`sensor System are that a sensor transmitter is only capable of
`one-way communication and has limited processing power.
`Hence, the sensor transmitter can only transmit raw sensor
`data and not calculate sensor blood glucose values itself.
`Accordingly, in the prior glucose sensor System, it is neces
`sary to couple the sensor transmitter to a specially pro
`grammed remote data receiving device. Such as a character
`istic monitor, to determine actual glucose sensor readings.
`Therefore, what is needed is a sensor transceiver for use with
`a blood glucose sensor that is capable of transmitting and
`receiving therapy-related data and independently calculating
`sensor blood glucose values.
`
`SUMMARY
`0008. The present invention relates to a telemetered char
`acteristic sensor transceiver for exchanging data with at least
`one remote device. The transceiver comprising a housing
`detachably coupled to a sensor located on a body of a user, the
`sensor producing a signal indicative of a user characteristic, a
`processor formed within the housing and in communication
`with the sensor for processing the signal produced by the
`sensor, a transmitter coupled to the processor for transmitting
`data to at least one remote device, a receiver coupled to the
`processor for receiving data from the at least one remote
`device, and a memory coupled to the processor for storing
`data. Preferably, the processor performs calculations using at
`least one of the signal produced by the sensor, the data
`received from the at least one remote device and the data
`stored in the memory, and performs at least one of storing the
`calculations in the memory and transmitting the calculations
`to the at least one remote device through the transmitter.
`0009. In accordance with an embodiment of the present
`invention, the transceiver exchanges data with a plurality of
`remote devices in a network structure. In one aspect, the
`transceiver exchanges data with the at least one remote device
`in a synchronous manner.
`0010. In accordance with another embodiment, the trans
`ceiver wakes up from a sleep mode prior to exchanging data
`with the at least one remote device, wherein the at least one
`remote device wakes up the transceiver. As such, the trans
`ceiver further comprises an ultrasonic sensor for receiving an
`ultrasonic signal from the at least one remote device when the
`at least one remote device transmits the ultrasonic signal to
`the transceiver to wake up the transceiver. Alternatively, the
`transceiver periodically wakes up independent of the at least
`one remote device.
`0011. In another aspect of the invention, the transceiver
`exchanges data with the at least one remote device in an
`asynchronous manner. Preferably, the data exchanged in the
`
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`

`US 2009/0085768 A1
`
`Apr. 2, 2009
`
`asynchronous manner comprises at least one of a blood glu
`cose value and a request for glucose history data.
`0012. In accordance with an embodiment of the present
`invention, the data exchanged between the transceiver and the
`at least one remote device comprises at least one of device
`configuration data, communication link configuration data,
`adaptive communication configuration data, glucose history
`data, and calibration data. Preferably, the device configura
`tion data comprises at least one of a device identification, user
`information, and time information. Preferably, the communi
`cation link configuration data comprises at least one of a
`communication rate, frequency information, and frequency
`hopping configuration information. Preferably, the glucose
`history data is exchanged according to a time interval. Pref
`erably, the calibration data comprises at least one of sensor
`initialization sequence and configuration information, and
`dynamic sensor initialization parameters.
`0013. In accordance with another embodiment of the
`present invention, the processor calculates sensor glucose
`values using at least one of the signal received from the
`sensor, the data received from the at least one remote device
`and the data stored in the memory. Preferably, a rate of
`exchanging data between the transceiver and the at least one
`remote device is dynamically changed depending on a char
`acteristic of the calculated sensor glucose values. Preferably,
`a glucose calculation algorithm for calculating the sensor
`glucose values is stored in the memory. Preferably, the pro
`cessor stores the calculated sensor glucose values in the
`memory or transmits the calculated sensor glucose values to
`the at least one remote device through the transmitter. Pref
`erably, the calculated sensor glucose values are secured via an
`encryption scheme before transmission to the at least one
`remote device.
`0014. In accordance with another embodiment of the
`present invention, the receiver receives calibration data from
`the at least one remote device and the processor stores the
`received calibration data in the memory. Preferably, the pro
`cessor performs a calibration using at least one of the calibra
`tion data stored in the memory, the signal received from the
`sensor and the calculated glucose sensor values. Preferably, a
`calibration algorithm for performing the calibration is stored
`in the memory.
`0015. In one aspect of the invention, transceiver comprises
`a display for displaying information processed by the proces
`sor. In another aspect, the transceiver comprises means for
`notifying the user that the at least one remote device is beyond
`a certain distance from the transceiver.
`0016. In a further aspect of the invention, a power for
`exchanging data between the transceiver and the at least one
`remote device is dynamically changed depending on a
`strength of a detected signal between the transceiver and the
`at least one remote device.
`0017. In another aspect of the invention, a rate of exchang
`ing data between the transceiver and the at least one remote
`device is dynamically changed depending on a power mode
`of at least one of the transceiver and the at least one remote
`device.
`0018. In accordance with the present invention, the hous
`ing is capable of detaching from the sensor and attaching to
`the at least one remote device. Preferably, the processor com
`municates with the sensor via wireless means.
`0019. In yet a further aspect of the invention, the housing
`comprises a single communication port for facilitating at least
`two of communication between the transceiver and the sen
`
`Sor, communication between the transceiver and the at least
`one remote device, and an electrical connection between the
`transceiver and a battery charger.
`0020. 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
`
`0021. A detailed description of embodiments of the inven
`tion will be made with reference to the accompanying draw
`ings, wherein like numerals designate corresponding parts in
`the several figures.
`0022 FIG. 1 is a perspective view illustrating a subcuta
`neous sensor insertion set and telemetered characteristic sen
`sor transceiver device embodying the novel features of the
`invention.
`0023 FIG. 2 is a longitudinal vertical section of the sub
`cutaneous sensor insertion set and telemetered characteristic
`sensor transceiver of FIG. 1.
`0024 FIG. 3 is an enlarged longitudinal sectional of a
`slotted insertion needle used in the insertion set of FIGS. 1
`and 2.
`0025 FIG. 4 is an enlarged transverse section taken gen
`erally on the line 4-4 of FIG. 3.
`0026 FIG. 5 is an enlarged transverse section taken gen
`erally on the line 5-5 of FIG. 3.
`0027 FIG. 6 is an enlarged fragmented sectional view of a
`needle inserted into a body in accordance with one embodi
`ment of the present invention.
`0028 FIG. 7 is an enlarged transverse section of a needle
`inserted into a body in accordance with one embodiment of
`the present invention.
`0029 FIG. 8A is a top plan and partial cut-away view of
`the telemetered characteristic sensor transceiver in accor
`dance with the embodiment shown in FIG. 1.
`0030 FIG. 8B is a simplified block diagram of a printed
`circuit board of the telemetered characteristic sensor trans
`ceiver in accordance with the embodiments shown in FIG.1.
`0031
`FIGS. 8C and 8D are top and bottom plan and partial
`cut-away views of the telemetered characteristic sensor trans
`mitter device in accordance with the embodiment shown in
`FIG 1.
`0032 FIG.9 is a simplified block diagram of a telemetered
`characteristic sensor transceiver and sensor set system in
`accordance with another embodiment of the present inven
`tion.
`0033 FIG. 10 is a simplified block diagram of a teleme
`tered characteristic sensor transceiver and characteristic
`monitor system in accordance with still another embodiment
`of the present invention.
`0034 FIG. 11 is a block diagram of a telemetered charac
`teristic sensor transceiver communicating with a variety of
`remote electronic devices in a network structure in accor
`dance with another embodiment of the present invention.
`0035 FIG. 12 illustrates a telemetered characteristic sen
`Sor transceiver capable of connecting to various devices in
`accordance with one embodiment of the present invention.
`
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`US 2009/0085768 A1
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`Apr. 2, 2009
`
`0036 FIG. 13 illustrates a communication port of a tele
`metered characteristic sensor transceiver capable of connect
`ing to various devices in accordance with one embodiment of
`the present invention.
`
`DETAILED DESCRIPTION
`0037. As shown in the drawings for purposes of illustra
`tion, the invention is embodied in a telemetered characteristic
`sensor transceiver coupled to a sensor set, that may be
`implanted in and/or through subcutaneous, dermal, Sub-der
`mal, inter-peritoneal or peritoneal tissue, that not only trans
`mits data from the sensor set to a remote therapy-related
`device. Such as a characteristic monitor for determining body
`characteristics, but may also receive data from the remote
`device. Although the telemetered characteristic sensor trans
`ceiver of the present invention is described below with regard
`to a characteristic monitor in particular, the transceiver need
`not operate with Such a device alone. The present invention
`contemplates the transceiver operating with other remote
`electronic devices. Such as infusion pumps, monitors, per
`Sonal computers and hospital system devices, for example.
`Moreover, the transceiver may be linked to a single electronic
`device or numerous devices in a network structure.
`0038. 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 trans
`ceiver and the monitor. However, it will be recognized that
`further embodiments of the invention may use a wired con
`nection or be used to determine the levels of other agents,
`characteristics or compositions, such as hormones, choles
`terol, medication concentrations, pH, oxygen Saturation, viral
`loads (e.g., HIV), or the like.
`0039. In other embodiments, the sensor set may also
`include the capability to be programmed or calibrated using
`data received and stored by the telemetered characteristic
`sensor transceiver, or may be calibrated at the monitor (or
`receiver). The telemetered characteristic sensor system is pri
`marily adapted for use in Subcutaneous human tissue. How
`ever, 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. Embodiments may
`provide sensor values to and/or receive therapy-related infor
`mation from a remote device on an intermittent or continuous
`basis.
`0040 FIG. 1 is a perspective view illustrating a subcuta
`neous sensor insertion set and telemetered characteristic sen
`sor transceiver device embodying the novel features of the
`invention. FIG. 2 is an enlarged longitudinal vertical section
`of FIG. 1. Referring to FIGS. 1 and 2, a telemetered charac
`teristic sensor System, in accordance with a preferred embodi
`ment of the present invention includes a percutaneous sensor
`set 10, a telemetered characteristic sensor transceiver device
`100 and a characteristic monitor 200. Description of the tele
`metered characteristic sensor is further found in commonly
`owned co-pending application Ser. No. 1 1/322.568 entitled
`“Telemetered Characteristic Monitor System and Method of
`Using the Same filed on Dec. 30, 2005, which is incorpo
`rated by reference in its entirety. Preferably, the telemetered
`characteristic sensor system provides for better treatment and
`glycemic control in an outpatient or home-use environment.
`For example, the sensor System can provide indications of
`glucose levels, hypoglycemia/hyperglycemia alerts and out
`patient diagnostics. It is also useful as an evaluation tool
`
`under a physician's Supervision or use in a hospital environ
`ment to monitor a patient's health status.
`0041. The percutaneous sensor set 10 utilizes an elec
`trode-type sensor, as described in more detail below. How
`ever, 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 embodi
`ments of a surface mounted sensor would utilize interstitial
`fluid harvested from underneath the skin.
`0042. The telemetered characteristic sensor transceiver
`100 generally includes the capability to transmit and receive
`data. For example, in a preferred embodiment, the sensor
`transmitter 100 will receive a calibration value (e.g. from a
`blood glucose meter, etc.), convert raw sensor signals into
`calibrated processed glucose values using algorithms stored
`in the sensor transceiver 100 and then transmit the calibrated
`glucose values to a third device which has a display to show
`the calibrated glucose values (e.g. a characteristic monitor
`200). The description of the telemetered characteristic sensor
`transceiver 100 will be covered in depth below.
`0043. In alternative embodiments, the characteristic
`monitor 200 may be replaced with a data receiver, storage
`and/or transmitting device for later processing of the trans
`mitted data or programming of the telemetered characteristic
`sensor transceiver 100. In other embodiments, the character
`istic monitor 200 is a bed-side monitor for monitoring body
`characteristics of a patient. In further embodiments, the tele
`metered characteristic sensor transceiver 100 can maintain
`multiple two-way communication links with other devices,
`Such as infusion pumps, monitors, personal computers and
`hospital system devices, for example.
`0044. In addition, referring to FIG.9, a relay or repeater 4
`may be used with the telemetered characteristic sensor trans
`ceiver 100 and the characteristic monitor 200 to increase the
`distance that the telemetered characteristic sensor transceiver
`100 can be used with the characteristic monitor 200. For
`example, the relay 4 could be used to provide information to
`parents of children using the telemetered characteristic sensor
`transceiver 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 embodiments, the relay 4 can include the
`capability to Sound an alarm. In addition, the relay 4 may be
`capable of providing telemetered characteristic sensor trans
`ceiver 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 relay 4
`may also be used to transfer information from a remote device
`to the transceiver 100.
`0045 Referring to FIG. 10, data may be exchanged
`between the transceiver 100 and a remotely located computer
`6 Such as a personal computer (PC), personal digital assistant
`(PDA), or the like, through a communication station 8 over
`communication lines (e.g., modem or wireless connection).
`In some embodiments, the communication station 8 may be
`omitted such that the transceiver 100 directly connects to the
`computer 6 via the modem or wireless connection. In further
`embodiments, the telemetered characteristic sensor trans
`ceiver 100 connects to an RF programmer, which acts as a
`relay, or shuttle, for data communication between the sensor
`set 10 and a PC, PDA, communication station, data processor,
`or the like. In further alternatives, the telemetered character
`
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`US 2009/0085768 A1
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`Apr. 2, 2009
`
`istic sensor transceiver 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 simultaneous
`monitoring of multiple sensors and/or include a sensor for
`multiple measurements.
`0046. In one embodiment, the telemetered characteristic
`sensor transceiver 100 may have and use an input port for
`direct (e.g., wired) connection formultiple purposes. Possible
`examples include the ability to directly connect to a program
`ming or data readout device and/or be used for calibration of
`the sensor set 10. Preferably, the input port is waterproof (or
`water resistant) or includes a water proof, or water resistant,
`removable cover.
`0047 Preferably, the telemetered characteristic sensor
`transceiver 100 takes characteristic information, such as glu
`cose data or the like, from the percutaneous sensorset 10 and
`transmits it via wireless telemetry to the characteristic moni
`tor 200, which displays and logs the received glucose read
`ings. Logged data can be downloaded from the characteristic
`monitor 200 to a PC, PDA, or the like, for detailed data
`analysis. Alternatively, in accordance with the present inven
`tion, glucose values may be calculated and logged by the
`transceiver 100. Accordingly, the logged data may be down
`loaded directly from the transceiver 100 by the PC, PDA,
`insulin pump or the like.
`0.048. In further embodiments, the telemetered character
`istic sensor system 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 charac
`teristic sensor transceiver 100 or characteristic monitor 200)
`to record data and events for later analysis, correlation, or the
`like. In addition, the telemetered characteristic sensor trans
`ceiver 100 may include a transmit/receive on/off button for
`compliance with safety standards and regulations to tempo
`rarily Suspend transmissions or receptions. Further buttons
`can include a sensor on/off button to conserve power and to
`assist in initializing the sensor set 10. The telemetered char
`acteristic sensor transceiver 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.
`0049 Referring to FIGS. 1-7, a percutaneous sensorset 10
`is provided for Subcutaneous placement of an active portion
`of a flexible sensor 12 (see FIGS. 6 and 7), or the like, at a
`selected site in the body 1000 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 inser
`tion, 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.
`0050. 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 condition.
`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.
`0051 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 insu
`lative material Such as polyimide film or sheet, and mem
`branes. 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. In alternative
`embodiments, other types of implantable sensors, such as
`chemical based, optical based, or the like, may be used.
`0052 Further description of flexible thin film sensors of
`this general type are be found in U.S. Pat. No. 5.391,250,
`entitled METHOD OF FABRICATING THIN FILM SEN
`SORS, which is herein incorporated by reference. A connec
`tion portion may be conveniently connected electrically to the
`monitor 200 or a telemetered characteristic sensortransceiver
`100 by a connector block (or the like) as shown and described
`in U.S. Pat. No. 5,482,473, entitled FLEX CIRCUIT CON
`NECTOR, which is also herein incorporated by reference.
`Thus, in accordance with embodiments of the present inven
`tion, Subcutaneous sensor sets 10 are configured or formed to
`work with either a wired or a wireless characteristic sensor
`system.
`0053. In accordance with the present invention, the proxi
`mal part of the sensor 12 is mounted in a mounting base 30
`adapted for placement onto the skin of a user. The mounting
`base 30 may be a pad having an underside surface coated with
`a suitable pressure sensitive adhesive layer, with a peel-off
`paper strip normally provided to cover and protect the adhe
`sive layer, until the sensor set 10 is ready for use. In preferred
`embodiments, the adhesive layer includes an anti-bacterial
`agent to reduce the chance of infection; however, alternative
`embodiments may omit the agent. In the illustrated embodi
`ment, the mounting base is generally oval, but alternative
`embodiments may be other shapes, such as rectangular, cir
`cular, hour-glass, butterfly, irregular, or the like.
`0054 An upper portion of the insertion needle 14 is
`adapted for slide-fit reception through a lowerbore 40 formed
`at an underside of the mounting base 30. As shown, the
`insertion needle 14 has a sharpened tip 44 and an open slot 46
`which extends longitudinally from the tip 44 at the underside
`of the needle 14 to a position at least within the bore 40. 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 sensorset 10 are found in U.S. Pat. No. 5,586,553, entitled
`TRANSCUTANEOUS SENSOR INSERTION SET and
`U.S. patent application Ser. No. 08/871,831, entitled “DIS
`POSABLE SENSOR INSERTIONASSEMBLY which are
`herein incorporated by reference.
`0055. The cannula 16 is best shown in FIGS. 6 and 7, and
`includes a first portion 48 having a partly-circular cross
`section to fit within the insertion needle 14that extends down
`wardly from the mounting base 30. In alternative embodi
`ments, the first portion 48 may be formed with a solid core,
`rather than a hollow core. In preferred embodiments, the
`cannula 16 is constructed from a suitable medical grade plas
`tic or elastomer, such as polytetrafluoroethylene, silicone, or
`the like. The cannula 16 also defines an open lumen 50 in a
`
`Page 11 of 17
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`US 2009/0085768 A1
`
`Apr. 2, 2009
`
`second portion 52 for receiving, protecting and guideably
`Supporting the sensing portion 18 of the sensor 12. The can
`nula 16 has one end fitted into the bore 40 formed at the
`underside of the mounting base 30, and the cannula 16 may be
`secured to the mounting base 30 by a suitable adhesive, ultra
`Sonic 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 inser
`tion needle 14, and terminates before the needle tip 44. At
`least one window 22 is formed in the lumen 50 near the