Patent Application
20140318987
This application generally relates to the field of blood analyte measurement systems and more specifically to portable analyte meters that are configured to detect whether a test strip has been removed from the analyte meter after being inserted but before an analyte measurement has been completed.
Blood glucose measurement systems typically comprise an analyte meter that is configured to receive a biosensor, usually in the form of a test strip. Because many of these systems are portable, and testing can be completed in a short amount of time, patients are able to use such devices in the normal course of their daily lives without significant interruption to their personal routines. A person with diabetes may measure their blood glucose levels several times a day as a part of a self management process to ensure glycemic control of their blood glucose within a target range. A failure to maintain target glycemic control can result in serious diabetes-related complications including cardiovascular disease, kidney disease, nerve damage and blindness.
There currently exist a number of available portable electronic analyte measurement devices that are designed to automatically activate upon detecting an insertion of a test strip that is compatible with the analyte meter. Electrical contacts in the meter establish connections with contact pads on the test strip while a microcontroller in the meter determines whether the test strip is properly inserted for use in the meter. This determination may include measurements of analog and digital voltages that are produced by the test strip in response to various activation signals transmitted thereto from the meter. If the voltage response characteristics agree with expected values, the analyte meter makes the determination that the test strip is a type of test strip that is compatible with the analyte meter.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention (wherein like numerals represent like elements).
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
As used herein, the terms “patient” or “user” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment.
The term “sample” means a volume of a liquid, solution or suspension, intended to be subjected to qualitative or quantitative determination of any of its properties, such as the presence or absence of a component, the concentration of a component, e.g., an analyte, etc. The embodiments of the present invention are applicable to human and animal samples of whole blood. Typical samples in the context of the present invention as described herein include blood, plasma, red blood cells, serum and suspension thereof.
The term “about” as used in connection with a numerical value throughout the description and claims denotes an interval of accuracy, familiar and acceptable to a person skilled in the art. The interval governing this term is preferably ±10%. Unless specified, the terms described above are not intended to narrow the scope of the invention as described herein and according to the claims.
The electronic components of the analyte measurement system 100 can be disposed on, for example, a printed circuit board situated within the housing 11 and forming the data management unit 140 of the herein described system.
The analyte test strip 24 can be in the form of an electrochemical glucose test strip. The test strip 24 can include one or more working electrodes at one end of the test strip 24. Test strip 24 can also include a plurality of electrical contact pads at a second end of the test strip 24, where each electrode can be in electrical communication with at least one electrical contact pad, as described below in relation to
A display module 119, which may include a display processor and display buffer, is electrically connected to the processing unit 122 over the communication interface 123 for receiving and displaying output data, and for displaying user interface input options under control of processing unit 122. The structure of the user interface, such as menu options, is stored in user interface module 103 and is accessible by processing unit 122 for presenting menu options to a user of the analyte measurement system 100. An audio module 120 includes a speaker 121 for outputting audio data received or stored by the DMU 140. Audio outputs can include, for example, notifications, reminders, and alarms, or may include audio data to be replayed in conjunction with display data presented on the display 14. Such stored audio data can be accessed by processing unit 122 and executed as playback data at appropriate times. A volume of the audio output is controlled by the processing unit 122, and the volume setting can be stored in settings module 105, as determined by the processor or as adjusted by the user. User input module 102 receives inputs via user interface buttons 16 which are processed and transmitted to the processing unit 122 over the communication interface 123. The processing unit 122 may have electrical access to a digital time-of-day clock connected to the printed circuit board for recording dates and times of blood glucose measurements, which may then be accessed, uploaded, or displayed at a later time as necessary.
The display 14 can alternatively include a backlight whose brightness may be controlled by the processing unit 122 via a light source control module 115. Similarly, the user interface buttons 16 may also be illuminated using LED light sources electrically connected to processing unit 122 for controlling a light output of the buttons. The light source module 115 is electrically connected to the display backlight and processing unit 122. Default brightness settings of all light sources, as well as settings adjusted by the user, are stored in a settings module 105, which is accessible and adjustable by the processing unit 122.
A memory module 101, that includes but are not limited to volatile random access memory (“RAM”) 112, a non-volatile memory 113, which may comprise read only memory (“ROM”) or flash memory, and a circuit 114 for connecting to an external portable memory device, for example, via a USB data port, is electrically connected to the processing unit 122 over a communication interface 123. External memory devices may include flash memory devices housed in thumb drives, portable hard disk drives, data cards, or any other form of electronic storage devices. The on-board memory can include various embedded applications and stored algorithms in the form of programs executed by the processing unit 122 for operation of the analyte meter 10, as will be explained below. On board memory can also be used to store a history of a user's blood glucose measurements including dates and times associated therewith. Using the wireless transmission capability of the analyte meter 10 or the data port 13 such measurement data can be transferred via wired or wireless transmission to connected computers or other processing devices.
A wireless module 106 may include transceiver circuits for wireless digital data transmission and reception via one or more internal digital antennas 107, and is electrically connected to the processing unit 122 over communication interface 123. The wireless transceiver circuits may be in the form of integrated circuit chips, chipsets, programmable functions operable via processing unit 122, or a combination thereof. Each of the wireless transceiver circuits is compatible with a different wireless transmission standard. For example, a wireless transceiver circuit 108 may be compatible with the Wireless Local Area Network IEEE 802.11 standard known as WiFi. Transceiver circuit 108 may be configured to detect a WiFi access point in proximity to the analyte meter 10 and to transmit and receive data from such a detected WiFi access point. A wireless transceiver circuit 109 may be compatible with the Bluetooth protocol and is configured to detect and process data transmitted from a Bluetooth “beacon” in proximity to the analyte meter 10. A wireless transceiver circuit 110 may be compatible with the near field communication (“NFC”) standard and is configured to establish radio communication with, for example, an NFC compliant point of sale terminal at a retail merchant in proximity to the analyte meter 10. A wireless transceiver circuit 111 may comprise a circuit for cellular communication with cellular networks and is configured to detect and link to available cellular communication towers.
A power supply module 116 is electrically connected to all modules in the housing 11 and to the processing unit 122 to supply electric power thereto. The power supply module 116 may comprise standard or rechargeable batteries 118 or an AC power supply 117 may be activated when the analyte meter 10 is connected to a source of AC power. The power supply module 116 is also electrically connected to processing unit 122 over the communication interface 123 such that processing unit 122 can monitor a power level remaining in a battery power mode of the power supply module 116.
With reference to
The first working electrical contact 202 is connected to an input pin 215 of the microcontroller 122, which is connected to an analog-to-digital converter “ADC” 237 in microcontroller 122 for performing a test strip current measurement, such as a blood glucose current measurement for a blood sample provided in the test strip 24. A drain and source of an N-MOSFET 210 are connected between first electrical contact 202 and ground 212, respectively. A gate 216 of the N-MOSFET 210 is connected to control pin 218 of the microcontroller 122 whereby the microcontroller 122 can controllably switch N-MOSFET 210 by transmitting a signal over control pin 218. The strip-detect electrical contact 204 is connected to a microcontroller 122 input pin 234, which is monitored by the microcontroller 122 for detecting that a test strip has been inserted into strip port connector 22. The strip-detect electrical contact 204 is also connected to an input pin 238 which is connected to the ADC 237 in microcontroller 122 for performing a voltage measurement at strip-detect electrical contact 204 to identify the test strip 24 and to detect a removal of the test strip 24 during an assay of a blood sample provided therein. A drain and source of a P-MOSFET 224 is connected between strip-detect electrical contact 204 and pull-up resistor 222, respectively. Pull up resistor 222 is connected to voltage source 220 which is set at about 3 V. A gate 228 of the P-MOSFET 224 is connected to control pin 230 of the microcontroller 122 whereby the microcontroller 122 can controllably switch the P-MOSFET 224 by transmitting a signal over control pin 230.
Prior to insertion of the test strip 24 into test strip port connector 22, the microcontroller 122 is programmed to maintain the analyte measurement system 100 in a low power mode, thereby extending the lifetime of batteries 118. During the low power mode, microcontroller 122 maintains the voltage at control pin 218, connected to gate 216 of N-MOSFET 210, at a digital high level of about 3 V, e.g. equivalent to a logical “1”. This digital high signal activates N-MOSFET 210 thereby connecting first working electrical contact 202 to the ground 212. Also during the low power mode, microcontroller 122 maintains the control pin 230, connected to gate 228 of P-MOSFET 224, at a digital low level of about 0 V, e.g. equivalent to a logical “0”. This digital signal activates P-MOSFET 224 thereby maintaining a digital high voltage at microcontroller input pin 234 through pull up resistor 222.
When test strip 24 is inserted into strip port connector 22 the short between the first working electrical contact 202 and strip-detect electrical contact 204 switches a voltage at microcontroller input pin 234 from its digital high voltage to an approximate digital low voltage due to the test strip's shorting of the electrical contacts 202, 204 to ground 212 through the test strip resistance 208. The falling voltage at microcontroller input pin 234 signals the microcontroller that the test strip 24 has been inserted into the strip port connector 22. This signal activates a secondary programmed operation executed by microcontroller 122 to identify whether the test strip 24 is a proper type of test strip intended for use with the analyte meter 10. Test strips intended for use with analyte meter 10 may be configured such that test strip resistance 208 generates a bias voltage detectable at the strip-detect electrical contact 204 by the ADC 237 connected thereto. In one embodiment, a detectable predetermined bias voltage of about 400 mV may be configured by designing the voltage level driven from the first working electrical contact 202 through the test strip resistance 208 such that it indicates to the microcontroller 122 at its input pin 238 that a correct type of test strip 24 is present in the strip port 22. Although other types of test strips may be configured to short the electrical contacts 202, 204, they are not configured to generate the predetermined bias voltage of 400 mV provided by the combination of the test strip resistance 208 and the bias voltage level from the first working electrical contact 202, and so a reliable test strip identification mechanism may be configured as described above.
Upon recognizing the correct bias voltage at input pin 238, microcontroller 122 switches the analyte measurement system 100 into an active mode. At the start of the active mode, the microcontroller performs hardware integrity checks, calibration of impedance circuits with respect to voltage offsets and leakage currents, and the like, and both the N-MOSFET 210 and the P-MOSFET 224 are turned off, e.g. control pin 218 is switched to a digital low voltage and control pin 230 is switched to a digital high voltage. At this point, the analyte meter awaits application of a blood sample on the test strip 24, whereafter a current measurement may take place using the first working electrical contact 202 and the ADC 237 connected thereto, such as a blood glucose current measurement, as the test strip 24 and first working electrical contact 202 are properly isolated due to turning off the N-MOSFET 210 and the P-MOSFET 224. It is possible that the test strip 24 may be removed by a user prior to an application of a blood sample, therefore, the microcontroller 122 continues to periodically monitor the voltage at the strip-detect electrical contact 204. For example, the N-MOSFET 210 and the P-MOSFET 224 may be turned on periodically, e.g. every 60 ms, and if the voltage at the strip-detect electrical contact 204 is sensed to be at a digital high voltage level, i.e. the test strip has been removed, the microcontroller 122 returns the analyte measurement system 100 back to an inactive low power mode.
After a blood sample is applied to the test strip 24, as detected by strip port electrical contacts connected to contact pads on the test strip 24 which, in turn, are connected to at least one working electrode of the test strip physically touching the blood sample, the assay for measuring an analyte level in the sample begins. The microcontroller 122 thereafter keeps the N-MOSFET 210 and the P-MOSFET 224 deactivated. It is possible that the test strip 24 may be removed by a user prior to completion of the assay. Another algorithm for determining test strip removal during an assay is available to the microcontroller 122. This algorithm includes a sequence of measurements of the voltage present at the strip-detect electrical contact 204, which may be safely undertaken without affecting a current measurement, which is necessary for completing the assay, at the first working electrical contact 202. One method of accomplishing both measurements is to alternate, or interleave, the measurement of the voltage present at the strip-detect electrical contact 204 and the current measurement at the first working electrical contact 202.
With reference to
A blood sample is applied and received in blood sample inlet 302 and physically contacts reagent layer 330 and at least the first working electrodes 320, the second working electrode 322, and hematocrit electrodes 324, 326, forming an electrochemical cell therewith, wherein a glucose current traveling through the blood sample may be measured at the second working electrode, as described above. A voltage level between a preselected pair of electrodes that makes physical contact with the sample may be measured to detect the presence of the sample. The second working electrode contact pad 312 and strip-detect contact pad 317 are electrically connected due to their sharing of the electrode 322 and, when the test strip is inserted into test strip port 20, the first working electrical contact 202 and strip-detect electrical contact 204 are shorted, as described above, due to their electrical connection to the second working electrode contact pad 312 and the strip-detect contact pad 317. Exemplary embodiments of analyte meters employing test strips having various configurations of contact pads and electrodes are described in PCT Patent Application PCT/GB2012/053279 (Attorney Docket No. DDI5246PCT) entitled “Accurate Analyte Measurements for Electrochemical Test Strip Based on Sensed Physical Characteristic(s) of the Sample Containing the Analyte and Derived BioSensor Parameters” and PCT Patent Application PCT/GB2012/053276 (Attorney Docket No. DDI5220PCT) entitled “Accurate Analyte Measurements for Electrochemical Test Strip Based on Sensed Physical Characteristic(s) of the Sample Containing the Analyte”, both of which patent applications are incorporated by reference herein as if fully set forth herein.
With reference to
An alternative method of determining that the test strip 24 has been removed from the strip port 22 during an assay is to program the microcontroller 122 to monitor the current measurement taking place at the first working electrical contact 202. If the current there falls to zero, the microcontroller 122 can determine that the test strip has been removed.
With respect to
In terms of operation, one aspect of the analyte meter 10 may include a capability for detecting insertion of a proper type test strip 24 into strip port connector 22 intended for use in the analyte meter 10. Improper types of test strips will not activate the analyte meter 10. The presence, or subsequent removal, of the test strip, after its initial insertion, continues to be monitored before and after a blood sample is applied thereto. If the test strip 24 is removed at any point, the analyte meter 10 is returned to a low power mode.
As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method, or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “circuitry,” “module,” ‘subsystem” and/or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible, non-transitory medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code and/or executable instructions embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
Furthermore, the various methods described herein can be used to generate software codes using off-the-shelf software development tools. The methods, however, may be transformed into other software languages depending on the requirements and the availability of new software languages for coding the methods.
While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Therefore, to the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well.
