Patent Application
20130002266
1. Field of the Invention
The present invention relates, in general, to medical devices and, in particular, to test meters and related methods.
2. Description of Related Art
The determination (e.g., detection and/or concentration measurement) of an analyte in a fluid sample is of particular interest in the medical field. For example, it can be desirable to determine glucose, ketone bodies, cholesterol, lipoproteins, triglycerides, acetaminophen and/or HbA1c concentrations in a sample of a bodily fluid such as urine, blood, plasma or interstitial fluid. Such determinations can be achieved using a hand-held test meter in combination with analytical test strips (e.g., electrochemical-based analytical test strips).
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings, in which like numerals indicate like elements, of which:
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 exemplary embodiments for the purpose of explanation only 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 “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.
In general, hand-held test meters for use with analytical test strips in the determination of an analyte (such as glucose) in a bodily fluid sample (for example, a whole blood sample) according to embodiments of the present invention include a housing, a test meter control circuit block (e.g. a microcontroller block), and an electromagnetic interference detection circuit block with an antenna configured to sense electromagnetic fields (for example, Radio Frequency [RF] fields including pulse modulated RF fields commonly created by GSM cellular phones and DECT cordless phones) of a predetermined frequency or frequency range (for example, electromagnetic fields in the frequency range of 800 MHz to 2200 MHz). In addition, the electromagnetic interference detection circuit block is configured to generate a signal (such as a demodulated signal) representative of an electromagnetic field sensed by the antenna and to provide that signal to the test meter control circuit block. Moreover, the test meter control circuit block is configured to interrupt operation of the hand-held test meter when the signal received from the electromagnetic interference detection circuit block represents a predetermined electromagnetic field that interferes with the hand-held test meter's operation.
Hand-held test meters according to embodiments of the present invention are beneficial in that the test meter's operation can be interrupted (for example, halted and/or modified by the display of a warning message to the hand-held test meter's user) when a predetermined electromagnetic field that deleteriously interferes with the hand-held test meter's operations is detected. For example, electrical circuit blocks within the hand-held test meter (such as, for example, analog-to-digital convertor circuit blocks) may generate a deleteriously noisy signal due to the presence of an external electromagnetic field. The accuracy of analyte determinations based on such a noisy signal can be degraded in comparison to analyte determinations based on a signal without such electromagnetic field generated noise. However, hand-held test meters according to embodiments of the present invention avoid the potential for such accuracy degradation by detecting electromagnetic fields that can interfere with the hand-held test meter's operation and then appropriately interrupting that operation.
A potential source of an electromagnetic field that could conceivably interfere with the accurate operation of a hand-held test meter is the electromagnetic field created by a nearby active cell phone. For example, the electromagnetic field strength directly beside the antenna surface of an active cell phone can be greater than 100 V/m. An electromagnetic field of such strength could interfere with the accurate operation of hand-held test meters including, for example hand-held test meters for the determination of glucose in a whole blood sample. However, hand-held test meters according to embodiments of the present invention include circuit blocks configured to sense electromagnetic fields and to interrupt operation of the hand-held test meter when an electromagnetic field that interferes with the hand-held test meter's operation is detected.
Once one skilled in the art is apprised of the present disclosure, he or she will recognize that an example of a hand-held test meter that can be readily modified as a hand-hand test meter according to the present invention is the commercially available OneTouch® Ultra® 2 glucose meter from LifeScan, Inc. (Milpitas, Calif.). Additional examples of hand-held test meters that can also be modified are found in U.S. Patent Application Publications No's. 2007/0084734 (published on Apr. 19, 2007) and 2007/0087397 (published on Apr. 19, 2007) and in International Publication Number WO2010/049669 (published on May 6, 2010), each of which is hereby incorporated herein in full by reference.
Hand-held test meter 100 includes a display 102, a plurality of user interface buttons 104, a strip port connector 106, a USB interface 108, and a housing 110 (see
Display 102 can be, for example, a liquid crystal display or a bi-stable display configured to show a screen image. An example of a screen image may include a glucose concentration, a date and time, an error message, an electromagnetic interference detection warning message, and a user interface for instructing an end user on how to perform a test.
Strip port connector 106 is configured to operatively interface with the analytical test strip (not depicted in the figures) such as an electrochemical-based analytical test strip configured for the determination of glucose in a whole blood sample. Therefore, the analytical test strip is configured for operative insertion into strip port connector 106. The analytical test strip can be any suitable analytical test strip including an electrochemical-based analytical test strip such as the commercially available OneTouch® Ultra® glucose test strip from LifeScan, Inc. (Milpitas, Calif.). Examples of analytical test strips can be found in U.S. Pat. Nos. 5,708,247; 5,951,836; 6,241,862; 6,284,125; 6,413,410; 6,733,655; 7,112,265; 7,241,265; and 7,250,105, each of which is hereby incorporate herein in full by reference.
USB Interface 108 can be any suitable interface known to one skilled in the art. USB Interface 108 is essentially a passive component that is configured to power and provide a data line to communications port block 116 of hand-held test meter 100.
Once an analytical test strip is interfaced with hand-held test meter 100, or prior thereto, a bodily fluid sample (e.g., a whole blood sample) is dosed into a sample-receiving chamber of the analytical test strip. The analytical test strip can include enzymatic reagents that selectively and quantitatively transforms an analyte into another predetermined chemical form. For example, the analytical test strip can include an enzymatic reagent with ferricyanide and glucose oxidase so that glucose can be physically transformed into an oxidized form.
Memory block 120 of hand-held test meter 100 includes a suitable algorithm that determines an analyte based on the electrochemical response of the analytical test strip.
Electromagnetic interference detection circuit block 112 includes an antenna (see antenna 122 of
Test meter control circuit block 114 is configured to interrupt operations of the hand-held test meter when the signal received from the electromagnetic interference detection circuit block is representative of a predetermined electromagnetic field that interferes with hand-held test meter operation. Such a predetermined electromagnetic field can be, for example, an electromagnetic amplitude-modulated (AM) or pulse-modulated electromagnetic field with a field strength of greater than 10 V/m and a frequency in the range of 800 MHz to 2200 MHz. Test meter control circuit block 114 can be any suitable test meter control circuit block known to one of skill in the art including, for example, a microcontroller block.
Referring to
Antenna 122 can be any suitable antenna known to one skilled in the art including, for example, a 10 mm diameter and approximately 12 nH loop antenna etched into a printed circuit board (not shown in the FIGs.) of the hand-held test meter. The combination of 2.7 pF first capacitor 124 and antenna 122 is configured to sense electromagnetic frequency bands from a GSM/UMTS cell phone in the range of 800 MHz to 2200 MHz. Diode 126 and second capacitor 128 are configured to serve as an AM demodulator that generates a 217 Hz pulse signal with a ⅛th duty cycle when electromagnetic interference detection circuit block 112 is in the presence of a GSM cell phone created electromagnetic signal. The amplitude of the 217 Hz signal (which is communicated to either of an analog input or a digital input (not shown in the figures) of microcontroller block 114) will be dependent on the electromagnetic field strength.
In the embodiment of
Electromagnetic interference detection circuit block 112 essentially demodulates amplitude modulated fields received by antenna 122 and creates a demodulated output voltage (i.e., a demodulated signal) that is proportional to the RF field strength multiplied by the amplitude modulation level. For example, for a GSM cell phone the amplitude modulation level is 100% (i.e., the RF is either fully on or fully off) with a 217 Hz interval.
Electromagnetic interference detection circuit block 112 includes an antenna 122′, a first capacitor 124′, a diode 126′, a second resistor 127, second capacitor 128′, a first resistor 130′ and a Zener diode 132. Electromagnetic interference detection circuit block 112′ is configured to detect AM modulated electromagnetic fields such as those generated by a GSM cell phone. In the embodiment of
Electromagnetic interference detection circuit block 112′ functions in a similar manner as that of electromagnetic interference detection circuit block 112. However, the value of second resistor 127 can be selected to match the sensitivity of the electromagnetic interference detection circuit block to a particular type and strength (e.g., field strengths greater than 10V/m) of electromagnetic field that is known to interfere with a hand-held test meter's operation. Resistor 127 forms a voltage divider with resistor 130′. As the higher the resistance value of resistor 127 is increased, the sensitivity of electromagnetic interference detection circuit block 112′ to an electromagnetic fields decreases. A typical but non-limiting resistance value for resistor 127 is 200,000 ohms.
Zener diode 132 is configured to protect microcontroller block 114 from being overloaded by a high voltage signal from electromagnetic interference detection circuit block 112′ and can be any suitable Zener diode including, for example, a 2.7V Zener Diode for a microcontroller block operated at supply voltage of 3.0V.
In the embodiments of
Once apprised of the present disclosure, one skilled in the art will recognize that the electromagnetic interference detection circuit blocks depicted in
Method 700 also includes interrupting operation of the hand-held test meter when the signal received by the test meter circuit control block from the electromagnetic interference detection block is representative of a predetermined electromagnetic field that interferes with hand-held test meter operation (see step 720 of
Such interruption can, for example, include displaying an electromagnetic interference warning message to a user via a display of the hand-held test meter. In such a scenario, the hand-held test meter's electromagnetic interference detection circuit and test meter control circuit block, as well as a display control block, are configured to control the display of such a warning message.
Methods according to embodiments of the present invention can, if desired, also include the steps of (i) applying a bodily fluid sample to an electrochemical-based analytical test strip; (ii) measuring an electrochemical response of the electrochemical-based analytical test strip using the hand-held test meter; and (iii) determining the analyte based on the measured electrochemical response. Moreover, once apprised of the present disclosure, one skilled in the art will recognize that method 700 can be readily modified to incorporate any of the techniques, benefits and characteristics of hand-held test meters according to embodiments of the present invention and described herein.
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that devices and methods within the scope of these claims and their equivalents be covered thereby.
