(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0307916 A1
`Ramey et al.
`(43) Pub. Date:
`Dec. 9, 2010
`
`US 20100307916A1
`
`(54) TEMPERATURE ESTIMATIONS IN A BLOOD
`GLUCOSE MEASURING DEVICE
`
`(75) Inventors:
`
`Blaine Edward Ramey,
`Indianapolis, IN (US); Michael L.
`Brown, Greenwood, IN (US);
`James L. Pauley, JR. Fishers, IN
`(US)
`
`Correspondence Address:
`DINSMORE & SHOHL, LLP
`FIFTH THIRD CENTER
`ONE SOUTH MAIN STREET, SUITE 1300
`DAYTON, OH 45402 (US)
`
`(73) Assignee:
`
`ROCHE DAGNOSTICS
`OPERATIONS, INC.,
`Indianapolis, IN (US)
`
`(21) Appl. No.:
`
`12/479,212
`
`(22) Filed:
`
`Jun. 5, 2009
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`GOIN 27/26
`(2006.01)
`GOIK I3/2
`(52) U.S. Cl. .................. 204/402; 374/141; 374/E13.012
`(57)
`ABSTRACT
`Methods of estimating the temperature of a reaction site on a
`measurement Strip in a blood glucose measuring devices are
`provided. In one embodiment, a method includes determining
`an activation initiation time, an activation duration time, a
`thermal magnitude and a temperature elevation for heat gen
`erating components within a device. The temperature eleva
`tion for each of the heat generating components is determined
`at least in part by an impulse response matrix IX.), the acti
`Vation initiation time, the activation duration time and the
`thermal magnitude for each of the heat generating compo
`nents. The method further includes determining a total tem
`perature elevation of the glucose measuring device by Sum
`ming the temperature elevation of each of the heat generating
`components, reading a temperature value provided by the
`temperature measuring element, and determining a reaction
`site temperature estimation by Subtracting the total tempera
`ture elevation from the temperature value provided by the
`temperature measuring element.
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`US 2010/030791.6 A1
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`Dec. 9, 2010
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`TEMPERATURE ESTMLATIONS IN A BLOOD
`GLUCOSE MEASURING DEVICE
`
`TECHNICAL FIELD
`
`0001. The present invention generally relates to blood glu
`cose measuring devices and, more particularly, devices and
`methods for estimating the temperature of a blood glucose
`reaction site.
`
`BACKGROUND
`
`0002. As background, persons with diabetes suffer from
`either Type I or Type II diabetes in which the glucose level in
`the blood is not properly regulated by the body. As a conse
`quence, many persons with diabetes often carry specialized
`electronic monitors, called blood glucose (bC) monitors, to
`periodically measure their glucose level and take appropriate
`action, Such as administering insulin. Blood glucose monitors
`commonly comprise a base unit that houses control and test
`electronics required to test the glucose level in a sample of
`blood. Typical bg monitors may also have a measurement
`strip receptacle that accepts a disposable measurement strip.
`One end of the strip is inserted into the measurement strip
`receptacle while an exposed area contains a reaction site in
`which the user deposits a drop of blood, which is often
`obtained by pricking the skin with a lancet. Conductors run
`from the reaction site, which comprises various reagent
`chemicals, to the end inserted into base unit, thereby electri
`cally coupling the reaction site to the control and test elec
`tronics. For blood glucose measurement results to be valid,
`the temperature at the reaction site must be within established
`lower and upper bounds. Therefore, an accurate temperature
`reading at the reaction site is desired to necessarily validate a
`blood glucose measurement. Due to the fact that all but the
`base of the bC test strip is exposed to ambient air, the reaction
`site temperature closely follows the ambient air temperature.
`0003. In addition to the bC monitor, persons with diabetes
`may also carry a portable electronic device, such as a cellular
`phone, Smartphone, music player, personal digital assistant
`(PDA), or other similar devices. In order to reduce the number
`of electronic devices carried by persons with diabetes, there is
`a desire for integrating bg measuring functionality into
`another portable electronic device. For example, abC moni
`tor may be integrated into a cellular phone so that a diabetic
`only has to carry Such a single, multi-functional device.
`0004. However, many portable devices generate signifi
`cant internal heat resulting from active and passive compo
`nents within the device, such as power Supplies, resistors,
`integrated circuits, microcontrollers and the like. For
`example, the core temperature of a cellular phone can rise
`over 20 degrees Celsius above the ambient temperature dur
`ing continuous use over a period of twenty minutes. Blood
`glucose monitors commonly rely on an internal temperature
`sensor to determine the temperature at the reaction site. Dif
`ficulties arise when the temperature reading provided by the
`internal temperature sensor changes not due to changes in the
`ambient air, but rather due to the internal heating of electronic
`components inside the device. Furthermore, the internal heat
`generation may vary depending on how the portable elec
`tronic device is being used. Because the internal temperature
`of Such portable devices fluctuates greatly depending on
`device usage (e.g., cellphone talk times) and therefore influ
`ences the internal temperature, an internal temperature sensor
`
`maintained within the device is not capable of obtaining an
`accurate reaction site temperature to validate the blood glu
`COSe measurement.
`0005 Accordingly, a need exists for alternative tempera
`ture estimation methods and blood glucose measuring
`devices incorporating the same.
`
`SUMMARY
`0006. According to one embodiment, a method of estimat
`ing the temperature of a reaction site on a measurement Strip
`in a blood glucose measuring device having a plurality of heat
`generating components and a temperature measuring element
`is provided. The method includes determining an activation
`initiation time, an activation duration time, a thermal magni
`tude QX and a temperature elevation Ex for each of the heat
`generating components. The temperature elevation EX for
`each of the heat generating components is determined at least
`in part by an impulse response matrix X, for timest through
`t, the activation initiation time, the activation duration time
`and the thermal magnitude QX for each of the heat generating
`components. The method further includes determining a total
`temperature elevation E
`of the glucose measuring device
`by summing the temperature elevation Ex of each of the heat
`generating components, reading a temperature value T.
`provided by the temperature measuring element, and deter
`mining a reaction site temperature estimation T by Sub
`tracting the total temperature elevation E
`from the tem
`perature value T
`provided by the temperature measuring
`element. The method further includes preventing a blood
`glucose test if the reaction site temperature estimation T is
`greater than a maximum reaction site temperature T.
`0007 According to another embodiment, a blood glucose
`measuring device is provided. The blood glucose measuring
`device includes a plurality of heat generating components, a
`measurement strip port operable to receive a removable mea
`Surement strip having a reaction site for receiving a blood
`sample, and a temperature measuring element operable to
`measure an internal temperature of the blood glucose mea
`Suring device T
`and to provide an internal temperature
`signal that corresponds with the measured internal tempera
`ture. The blood glucose measuring device further includes a
`controller operable to receive the internal temperature signal
`from the temperature measuring element and to determine a
`temperature estimate of the reaction site T. based on blood
`glucose measuring device usage by applying a dynamic ther
`mal model. The dynamic thermal model determines a total
`temperature elevation E based at least on part on an acti
`Vation initiation time, an activation duration time and a ther
`mal magnitude QX of each heat generating component within
`a sample period. The controller calculates the temperature
`estimate of the reaction site T by subtracting the total
`temperature elevation E
`from the internal temperature
`T. provided by the internal temperature signal.
`0008 According to yet another embodiment, a blood glu
`cose measuring device including a controller, a temperature
`measuring element, a measurement Strip port, and a plurality
`of heat generating elements is provided. The measurement
`strip port is operable to receive a removable measurement
`strip having a reaction site positioned at an end. The tempera
`ture measuring element is in electrical communication with
`the controller and is operable to measure the temperature of
`the blood glucose measuring device and transmit a tempera
`ture signal corresponding to the temperature of the blood
`glucose measuring device to the controller. The controller is
`
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`Dec. 9, 2010
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`programmed to determine one or more activity characteristics
`within a sample period for each of the heat generating com
`ponents, calculate a total temperature elevation within the
`blood glucose measuring device due to the activity character
`istics of the heat generating elements within the sample
`period, and calculate a temperature estimation of the reaction
`site by subtracting the total temperature elevation from the
`temperature of the blood glucose measuring device corre
`sponding to the temperature signal received from the tem
`perature measuring element.
`0009. These and additional features provided by the
`embodiments of the present invention will be more fully
`understood in view of the following detailed description, in
`conjunction with the drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0010. The embodiments set forth in the drawings are illus
`trative and exemplary in nature and not intended to limit the
`inventions defined by the claims. The following detailed
`description of the illustrative embodiments can be understood
`when read in conjunction with the following drawings, where
`like structure is indicated with like reference numerals and in
`which:
`FIG. 1 depicts an exemplary portable electronic
`0011
`device capable of blood glucose measurement according to
`one or more embodiments shown and described herein;
`0012 FIG. 2A depicts an exemplary measurement strip
`according to one or more embodiments shown and described
`herein;
`0013 FIG. 2B depicts a cross section view of the exem
`plary measurement strip depicted in FIG.2A according to one
`or more embodiments shown and described herein;
`0014 FIG.3 depicts a schematic of a blood glucose mea
`Suring module according to one or more embodiments shown
`and described herein; and
`0015 FIG. 4 depicts a portion of a printed circuit board of
`a portable electronic device having a blood glucose measure
`ment module.
`
`DETAILED DESCRIPTION
`0016. The embodiments described herein generally relate
`to portable electronic devices which are capable of measuring
`blood glucose (bC) levels in a blood sample provided by an
`individual with diabetes. More particularly, embodiments
`described herein relate to estimations of the temperature at a
`bG measurement strip reaction site when the reaction site
`may be at a different temperature than the temperature of the
`bG measurement electronic circuitry. Heat generating com
`ponents within the bC measuring device (e.g., power sources,
`microcontrollers, resistors, etc.) may generate heat at varying
`levels depending on how the device is being used. It is desired
`to have an accurate estimation of the reaction site temperature
`to avoid unwarranted under or over-temperature lockout con
`ditions that would prevent proper use of the bC measuring
`device.
`0017 Embodiments described herein utilize a dynamic
`thermal model that uses a temperature sensor reading to
`dynamically estimate the reaction site temperature depending
`on how the portable electronic device is being used. As
`described in detail herein, the dynamic thermal model of
`particular embodiments utilize the linear Superposition of
`temperature elevation responses of a particular heat generat
`ing component over time to determine a total temperature
`
`elevation of the heat generating component. The dynamic
`thermal model further utilizes linear superposition of the total
`temperature elevations of eachheat generating components to
`determine a total internal temperature elevation that may then
`be subtracted from the temperature reading provided by the
`temperature sensor. The dynamic thermal model takes into
`account activity characteristics of the portable electronic
`device Such as an initiation time of when a component started
`generating heat, how long and at what thermal magnitude
`each component has been generating heat. In this manner, an
`estimation of the temperature of the reaction site on the mea
`Surement strip that takes into consideration device usage may
`be achieved.
`0018 Referring to FIG. 1, an exemplary bO measuring
`device 10 configured as a cellular phone is illustrated. It will
`be understood that the bC measuring device may be config
`ured as other types of portable electronic device, such as
`music players, personal digital assistants, Smartphones, insu
`lin pumps and others. The bC measuring device 10 comprises
`a measurement strip port 12 that may be operable to receive a
`measurement strip 14, which may be removably inserted into
`the measurement strip port 12. The measurement Strip port 12
`may be integrated into the housing of the cellular phone. The
`geometry of the port 12 may provide enough chamfer and
`guiding Surfaces to ease the insertion of the measurement
`strip 14 into the port 12. It will be understood that other
`embodiments of the slot and the strip port are also possible.
`The measurement strip 14 may be configured to receive a
`blood sample in the form of a blood drop at a reaction site 16
`located at a point along the measurement strip 12. Such as near
`the tip. The measurement Strip 14 may contain electronic
`circuitry and/or chemicals at the reaction site 16 which facili
`tate the measurement of the bC level of a blood sample.
`(0019 Referring to FIGS. 1, 2A and 2B, the measurement
`strip port 12 may have a plurality of electrical pads (not
`shown) which are configured to engage corresponding elec
`trical pads 18 at the base of the measurement strip 14 when
`installed in the measurement strip port 12. In one embodi
`ment, the measurement strip port 12 and measurement strip
`14 may have six electrical pads 18. In another embodiment,
`the Strip port and strip may have eight electrical pads 18.
`Electrodes 17 and 19, which may be made of a metal material
`Such as gold or palladium, may traverse the measurement
`strip 14 from the reaction site 16 to the base and electrical
`pads 18. The electrodes electrically couple the reaction site 16
`to the electrical pads 18 and measurement strip port 12.
`0020 FIG. 3 is a schematic of exemplary bO measuring
`circuitry 40 of a portable electronic device that is capable of
`measuring blood glucose, such as the cellular phone illus
`trated in FIG.1. It will be understood that the exemplary bO
`measuring circuitry 40 is only one configuration as other
`hardware and Software configurations may be utilized to
`effectuate the temperature estimation and dynamic thermal
`models described herein. The bC measuring circuitry 40 of
`the embodiment illustrated in FIG. 3 comprises an interface
`38, a bO microcontroller 34, an application specific inte
`grated circuit (ASIC) 32, a measurement strip port 12, a
`temperature measurement element 24 and memory 36. The
`bG measuring circuitry 40 may also comprise a code key port
`25 in which to receive a code key 25A containing calibration
`information. The bC measuring circuitry 40 may be integral
`with other dedicated circuitry of the portable electronic
`device, or the bC measuring circuitry 40 may be configured as
`an embeddable bC module that may be installed in an external
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`host having a host processor as disclosed in copending and
`commonly owned U.S. patent application Ser. No. 12/477,
`982, the entirety of which is hereby incorporated by reference
`herein. For example, when installed in an external host having
`a host processor, an embeddable bC module comprising the
`bG measuring circuitry 40 may be used as an embedded
`measurement engine for a glucose measurement system
`within the external host.
`0021 Referring still to FIG. 3, the bC microcontroller 34
`may be in electrical communication with the interface 38, the
`ASIC 32, and the temperature measuring element 24. The bC
`microcontroller 34 may be in electrical communication with
`other circuit modules of the portable electronics device
`“non-bC modules”) in which the bC measuring circuitry 40
`is implemented. As described below, the interface 38 may
`enable the bC microcontroller 34 to communicate with a
`cellular phone microcontroller (not shown), for example, to
`determine particular attributes of components operating
`within the cellular phone. In some embodiments, the interface
`38 may be incorporated directly into the bC microcontroller
`34 such that there is no dedicated interface 38 circuitry and
`the bC microcontroller 34 may communicate directly with
`other non-bg modules within the portable electronics device.
`0022. In one embodiment, the bC microcontroller 34 may
`be model MSP430CG4619, manufactured by Texas Instru
`ments, Inc. Other types and sizes of microcontrollers from
`Texas Instruments as well as other manufacturers may also be
`used. In this embodiment, the bG microcontroller 34 may
`contain a Universal Asynchronous Receiver Transmitter
`(UART), timers, programmable input/output (I/O) pins, data
`memory, program memory, and other functions which may
`facilitate its operation. The bC microcontroller 34 may
`execute a computer program, hereinafter called "bC measure
`ment software,” which defines and/or enables the functioning
`of the bC measurement circuitry 40. The bC measurement
`Software may be written in a computer language, such as “C”
`or assembly language, and may be stored in the program
`memory of the bC microcontroller 34.
`0023 The ASIC 32 may be in electrical communication
`with the bG microcontroller 34 as well as the measurement
`strip port 12. The ASIC 32 may be a mixed-signal device,
`having both digital and analog components. When a measure
`ment strip 14 is inserted into the measurement strip port 12,
`the ASIC 32 may be operable to electrically detect the inser
`tion and, Subsequently, communicate with the measurement
`strip port 12 such that the ASIC 32 may receive signals from
`the measurement strip 14 related to the blood glucose level of
`a blood sample placed on the reaction site 16. The ASIC 32
`may, after receiving the signals from the measurement strip
`14, process these signals and communicate information about
`the bClevel to the bG microcontroller 34. The bG microcon
`troller 34, in turn, may take this information and process it
`further in order to arrive at the final bG measurement result.
`Thus, the ASIC 32 and the bC microcontroller 34 may work
`together to perform the bC measurement function, with the
`ASIC 32 performing part of the function and the bC micro
`controller 34 performing part of the function. The ASIC 32
`may be housed in an electrical ball-grid array (BGA) package
`or other suitable package. The ASIC 32 may additionally
`perform other functions such as generating a fixed-frequency
`clock signal for the bC microcontroller 34. The ASIC 32 and
`bG microcontroller 34 may communicate with each other via
`a serial bus, such as IC or SPI, or via a parallel interface.
`
`0024. Referring still to FIG. 3, the bC measuring circuitry
`40 may also include a non-volatile configuration memory 36.
`This memory may be external to the bC microcontroller 34,
`as is depicted in FIG. 3, or may be integrated into the bC
`microcontroller 34. The memory 36 may be operable to store
`information relating to the operation of the module. Such as
`configuration parameters, calibration data for the measure
`ment strips, and so forth. Further, the memory may be oper
`able to store the dynamic thermal model and the impulse
`response matrix for each heat generating component, as
`describe in detail below. The memory 36 may in electrical
`communication with the bG microcontroller 34 such that the
`data stored in the memory may be read by the bC microcon
`troller 34. In addition, the bC microcontroller 34 may write
`data to the memory 36 such that the data is stored on the
`memory 36 in a non-volatile fashion. The memory 36, when
`it is external to the microcontroller, may be a 64 kilobit
`device, such as a 25AA640A device from Microchip Tech
`nology, Inc. Other types of memory, including flash memory,
`may also be utilized.
`0025. The interface 38 may employ a serial communica
`tion scheme to provide communication between the bC
`microcontroller 34 and non-bg module(s) of the portable
`electronics device. The serial data interface may employ a
`“hard-wired' scheme, such a UART or Universal Serial Bus
`(USB). In this embodiment, the communication signals
`between the bC measuring circuitry 40 and the non-bg mod
`ules may be implemented with electrical conductors. Further
`more, the connection may be made through an electrical
`connector. The UART may employ two signals: One signal
`may transmit data from the non-bg module to the bC measur
`ing circuitry 40, and the other signal may transmit data from
`the bC measuring circuitry 40 to the non-bg module. Other
`communications schemes, such as parallel or infrared com
`munication, may also be utilized.
`0026. The embeddable module 10 may also include a code
`key port 25. The code key port 25 may allow the user to install
`an external code key 25A which may contain calibration
`information related to the measurement site 16. This calibra
`tion information may permit the bC measuring circuitry 40 to
`improve the accuracy of the bC measurement due to, for
`example, slight variations in the measurement strip which
`may have been introduced during the manufacturing process.
`Thus, in order to improve the accuracy of the bC measure
`ment, the measurement strip 14 (or, typically, package of
`strips) may also include a code key 25A which is operable to
`store information relating to calibration data for the strip 14
`(or package of strips). When inserted into the code key port
`25, the calibration information contained on the code key 25A
`may be read by the bC microcontroller 34. As a result, when
`a bO measurement is performed, the code key 25A may
`provide calibration information which permits the bC micro
`controller 34 to improve the accuracy of the bC measurement.
`0027. Referring still to FIG. 3, the temperature measuring
`element 24 may be used to measure the internal temperature
`of the bC measuring device 10 and to estimate the tempera
`ture of the measurement strip 12. The temperature measuring
`element 24 may be in electrical communication with the bC
`microcontroller 34 such that the bC microcontroller 34 may
`request a temperature measurement during a bO measure
`ment session or any other time. In one embodiment, the
`temperature measuring element 24 may comprise a ther
`mistor, the resistance of which is a known function of tem
`perature. Other embodiments may use similar devices. Such
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`as semiconductor temperature sensors, resistance thermal
`devices (RTDs) and thermocouples. The temperature mea
`surement may be used to improve the accuracy of the bC
`measurement. As discussed in detail below, the temperature
`measurement provided by the temperature measuring ele
`ment 24 may also indicate conditions in which the bC mea
`Surement should not be made. Such as when the ambient
`temperature in which the bC measuring device 10 is operating
`is outside of the operating range of the measurement Strip 14.
`For example, a measurement strip 14 may be designed to
`operate from 10 degrees C. to 40 degrees C. Outside this
`range, the measurement strip 14 may not produce Sufficiently
`accurate results. Thus, when the ambient temperature falls
`outside this range, the bC measuring circuitry 40 may recog
`nize this condition and may refuse to take a measurement
`under Such conditions, since the result may not be sufficiently
`acCurate.
`0028. Although the primary components of the bC mea
`Suring circuitry 40 have been described (e.g., the microcon
`troller, the ASIC, etc.), the bC measuring circuitry 40 may
`comprise additional components, such as but not limited to
`resistors, capacitors, inductors, transformers, transistors, and
`diodes. These additional components may be used to facili
`tate the operation of the bC measuring device 10. For
`example, one or more capacitors may be electrically con
`nected to the power supply voltage in order to provide filter
`ing for the bC measuring circuitry 40. As another example,
`inductors may be placed between the bC microcontroller 34
`and the measurement strip port 12 so as to reduce the possi
`bility of damage to the bC microcontroller 37 due to an
`electrostatic discharge generated by the user when inserting
`the measurement strip 14 into the measurement Strip port 12.
`Additional electronic components may be used to perform
`similar functions.
`0029 Dynamic thermal models providing estimations of
`the temperature at a bO measurement strip reaction site 16
`when the reaction site 16 may be at a different temperature
`than the internal temperature of the bC measuring device 10
`will now be described. As discussed above, it may be impor
`tant to know the temperature at the measurement strip reac
`tion site 16 in order to avoid unwarranted under or over
`temperature lockout conditions that would prevent properuse
`of the bC measuring device 10. Referring to FIG. 1, in some
`embodiments, all but the base of the measurement strip 14 is
`exposed to the ambient air. It may be shown that the reaction
`site temperature is governed primarily by convective heat
`exchange with the ambient air and that the thermal conduc
`tivity of the strip is so low that the temperature of the inserted
`end of the measurement strip 14, which is close to the internal
`temperature of the bC measuring device 10, will have little
`measurable effect on the temperature at the other end of the
`strip 14 wherein the reaction site 16 is located. Therefore, the
`reaction site temperature closely follows the ambient air tem
`perature.
`0030 Embodiments described herein utilize a dynamic
`thermal model that uses a temperature sensor reading to
`dynamically estimate the reaction site temperature depending
`on how the portable electronic device is being used. As
`described in detail herein, embodiments utilize linear super
`position of temperature elevation responses of a particular
`heat generating component over time to determine a total
`temperature elevation of the particular heat generating com
`ponent based on the activity characteristics of each heat gen
`erating component. From this total temperature elevation and
`
`an internal temperature provided by the temperature measur
`ing element 24, an estimation of the temperature of the reac
`tion site 16 on the measurement strip 14 may be achieved.
`0031. Now referring to FIG. 4, a schematic of an exem
`plary bO measuring device printed circuit board (PCB) 20
`is illustrated. The PCB20, which may comprise several layers
`of copper and has a plurality of electronic components,
`including the bC microcontroller 34 and temperature sensor
`24. FIG. 4 is for illustrative purposes only and embodiments
`of the present disclosure are in no way limited thereto. It will
`be understood that additional PCBs may be located within the
`bG measuring device 10. Located on the PCB are a plurality
`of heat generating components A-J. The heat generating com
`ponents, may be any electrical component that generates heat,
`Such as microcontrollers, radio frequency power amplifiers,
`audio amplifiers, batteries, Voltage regulators, and the like.
`For example, heat generating component A may be a com
`munications microcontroller in a cellular phone application,
`while heat generating component F may be a resistor. The bC
`microcontroller 34 may also generate heat.
`0032. A number of factors may affect the temperature
`response of a given heat Source at the temperature measuring
`element 24. Within the device 10 enclosure, the heat source
`may be located on the same circuit board as the temperature
`measuring element 24 or on another circuit board, and it may
`be near the sensor or far from it. The heat generation of a
`particular electronic component may vary greatly during its
`various modes of operation. The corresponding temperature
`response at the temperature measuring element 24 may be
`measured with reasonable accuracy. Depending on the loca
`tion of the heat producing electronic component relative to
`the temperature measuring element 24 and the nature of the
`thermal pathways between them (e.g., the thermal resistance
`of the PCB substrate or substrates), the temperature response
`at the temperature measuring element 24 may vary a great
`deal from component to component. A heat generating com
`ponent near the temperature measuring element 24 (e.g., heat
`generating component B) may tend to produce a rapid rise in
`temperature as measured by the temperature measuring ele
`ment 24 after the heat is applied, followed by a rapid decline
`in temperature when the heat is removed. For a more distant
`heat generating component (e.g., heat generating component
`G), the rise and fall in temperature may be more gradual and
`more time may elapse before the peak temperature is reached.
`0033. Despite a temperature measuring element 24 that
`may be providing a signal to the bC microcontroller 34 that is
`changing at a rate that exceeds a specified threshold, embodi
`ments of the present disclosure may obtain an improved esti
`mate of the ambient air temperature, and hence the reaction
`site 16 temperature, by amplifying those changes in the tem
`perature measuring element 24 reading and formulating a
`new prediction based on a dynamic thermal model of the bC
`measuring device 10. As described above, difficulties may
`arise when the reading from the temperature measuring ele
`ment 24 is changing not due to changes in the ambient air, but
`rather due to the internal heating of electronic components
`inside the device containing the bC circuitry.
`0034. Using the cellular phone embodiment illustrated in
`FIG. 1 as an example, due to the high operating temperature
`of circuitry inside of a cellphone 10, the temperature readings
`from the temperature measuring element 24 may be unduly
`elevated. The internal heat caused by the heat generating
`components A-J may vary depending on how the cellphone
`10 is being used. For example, a recent and lengthy talk
`
`10
`
`

`

`US 2010/030791.6 A1
`
`Dec. 9, 2010
`
`session may cause a significant rise in internal temperature
`that should be accounted for. Similarly, the heat generated by
`a lengthy talk session that occurred forty-five minutes prior to
`the bC measurement test may have dissipated. Accurate tem
`perature estimation should continue even when the thermal
`characteristics of the device change with specific usage.
`0035 Embodiments of the present disclosure utilize a
`dynamic thermal model that provide for estimating the tem
`perature elevation due to any number of heat sources of arbi
`trary strength and arbitrary duration in a bO measuring
`device. Once the total expected temperature elevation has
`been determined from the dynamic thermal model, then this
`quantity may be subtracted from the temperature reading of
`the temperature measuring element 24 to furni