1. Field of the Invention
The present invention relates generally to methods and apparatus for determining the test type to be performed on various types of test elements. More particularly, this invention provides methods for distinguishing between different types of test elements, including analytical test strips with fluid samples applied to them, analytical test strips with control solution applied to them, and standard strips as measured by a reflectance-type testing device.
2. Background of the Invention
Monitoring analytes such as glucose, cholesterol, intoxicants, and other constituents is frequently desirable in fluids, such as blood, plasma, blood serum, saliva, urine, and other biological fluids. In healthcare applications, such monitoring affords the opportunity to make rapid diagnoses of a patient's condition and to take prophylactic or therapeutic measures necessary for maintaining proper health.
One such healthcare application that has benefited tremendously by analyte monitoring in recent years is the treatment of diabetes. Diabetics suffer from an impaired ability to regulate glucose levels in their blood. As a result, diabetics can have abnormally high blood sugar levels known as hyperglycemia. Chronic hyperglycemia may lead to long-term complications such as cardiovascular disease and degeneration of the kidneys, retinas, blood vessels and the nervous system. To minimize the risk of such long term complications, diabetics must strictly monitor and manage their blood glucose levels.
Diabetics that have glucose levels that fluctuate several times throughout the day require very close blood glucose level monitoring. Close monitoring of blood glucose levels is most easily obtained when a diabetic is able to monitor their glucose levels themselves. Many devices currently available allow diabetics to measure their own blood sugar levels.
Reflectance-based monitors comprise one category of personal, or home-use, glucose level monitoring devices. These monitors utilize an optical block which accepts test elements for photometric analysis.
The test elements are usually in the form of test strips, which contain analytical chemistry. Conventionally, these test strips are in the form of a disposable diagnostic test strip containing analytical chemistry upon which a fluid sample is deposited. Once the user applies the fluid sample to the test strip, and the sample has sufficiently penetrated the test strip, a chemical reaction occurs in the presence of a target analyte, e.g., glucose, to cause a change in the optical properties of the test strip. An optical photometric device then determines the analyte level of the sample by measuring an optical property, such as the intensity of reflected light at a certain wavelength from the test strip. For in vitro analysis in healthcare applications, the fluid sample is usually fresh whole blood. Periodically, however, it is desirable to run a test on a test element formed by applying a control solution of known analyte concentration to a test strip, in order to verify that the meter is performing within operational limits. It is also desirable for the user to insert a “standard strip”, which is a test element that has known optical properties, in order to verify that the meter is operating within operational limits.
Diagnostic test strips for testing analytes such as glucose levels of blood samples are well known in the art and comprise various structures and materials. Test strips typically include single or multi-layered porous membrane arrangements which receive a blood sample and undergo a change in an optical property, such as a color change, in response to the interaction of blood glucose with agents/reactants in the membrane. Examples of such multi-layer strips are described in U.S. Pat. No. 5,296,192 to Carroll and U.S. Pat. No. 6,010,999 to Carroll et al., the contents of both of which are incorporated herein by reference.
Prior to reaching the reactants, a whole blood sample can be filtered to eliminate potential optical interference by removing erythrocytes, or red blood cells. Some test strips operate to allow the applied blood sample to migrate to a reaction site in the membrane where the sample reacts with the agents/reactants, which is located in downstream capillary relation to the sample application site. The results of the reaction are often visible as a color change at the reaction site. However, the change may occur in invisible regions of the electromagnetic spectrum, such as infrared and ultraviolet. For the purposes of this application, the term “color change” will be understood to include variations in optical properties throughout the visible and invisible regions of the electromagnetic spectrum. As noted above, a color change can be correlated to the amount of glucose in the sample. Home-use glucose measuring devices that use a reflectance meter to measure the color change of the test strip correlate glucose levels to the change in the amount of light reflected from the reaction site of the test strip. As is well known in the art, strips can be formulated to produce a color change within a certain spectral region, and the meter designed to photometrically measure reflected, absorbed or transmitted light at a wavelength sensitive to the color change of the strip. While the present invention will be described with reference to reflectance based photometry, it would be known to one having ordinary skill in the art to apply the features of the invention to absorbance or transmittance based systems.
Desirable for maintaining the accuracy of blood glucose monitoring devices is the periodic checking of the device to ensure that it is within operational compliance. As mentioned above, certain periodic standardization tests performed by the user provide verification of the meter's accurate operation. Accuracy is required by regulatory authorities for medical devices such as diabetes testing monitors, where a patient's life can depend on proper operation of the monitoring system.
Common verification techniques are designed to periodically check whether the monitoring device is operating properly, and thus accurately measuring blood glucose levels. Verification techniques used in glucose level monitoring devices include inserting test elements having a known glucose or reflectance value into the monitoring unit and comparing the measured results with the known values. Test elements having known glucose levels (“Control Test Elements” hereinafter) are normally prepared by applying a glucose control solution having a known glucose concentration to a dry test strip that normally could be used to run a test with blood. The control test element is then inserted into the monitoring unit and a test is performed and the calculated glucose value of the test element is displayed. The calculated glucose value is then compared with a range of acceptable results provided by the manufacturer for the glucose control solution. If the results displayed by the device for the control test element fall with an acceptable range designated for the solution, the device is deemed to be appropriately functioning ready for testing a blood sample.
Another verification technique commonly used in glucose level monitoring devices includes inserting a strip with a known reflectance value into the monitoring unit (“Standard Test Element” of “Standard Strip” hereinafter). This standard test element does not receive a fluid sample, but is rather formed of a one piece rigid or semi-rigid material such as plastic having known optical properties. The standard reflectance strip can be stored in a compartment of the monitoring unit so that it is conveniently available for use throughout the life of the monitoring device. The standard reflectance strip is inserted into and measured by the device just as other test strips, and the measurement results are compared with a range of acceptable results provided with standard reflectance strip. As with the test using the glucose control test element, if the results of the measurement fall within an acceptable range, the device is ready for testing a blood sample.
The test run with the standard test element (“Standard Test” hereinafter) is intended to test the performance of the monitoring device only, while the test run with the control test element (“Control Test” hereinafter) is intended to check the entire monitoring process including the testing technique of the user. Conventional glucose monitoring devices are capable of performing both types of calibration techniques and will normally include instructions regarding when to initiate each type of calibration technique.
Of course, the monitoring device must also accept a test element formed by sample fluid, such as blood, applied to a test strip (“Analytical Test Element” hereinafter), and run an analytical test thereon to determine analyte concentration (“Analytical Test” hereinafter).
A problem with prior art devices has been that they have typically not been able to discriminate between the type of test element introduced into the meter, and therefore the type of test to run, without user intervention. For example, the standard test is instantaneous and need not ascertain that a reaction on a test strip has run to completion, as is required in the control test and the analytical test. It is also desirable that the historical results for all three tests should be stored separately, so that the user's results from the analytical tests are not mixed in or displayed with the standard test or control test results.
Conventional methods for differentiating the test type have required the user to perform an affirmative act, such as pressing a button on the device, to signal to the device that the test strip inserted includes a glucose control solution and not a blood sample.
The requirement that a user perform an affirmative act to signal to the monitoring device the type of sample tested allows the possibility for human error that can adversely affect the proper storing and monitoring of measurement results, and possibly the misinterpretation of stored results. For example, if a user were to fail to perform a required step indicating insertion of a test strip containing glucose control solution, such as failing to push a button or wait a specified time, the measurement results could be incorrectly stored in the memory of the device as an actual blood glucose level result, possibly resulting in, among others, false self-diagnosis of blood sugar levels or erroneous treatment regimens being prescribed by healthcare professionals.
Another prior art system is a “negative blood” approach, which uses two wavelengths. In such a system, a secondary LED which measures at a wavelength at which red blood cells are highly detectable. This measurement is used to formulate a correction factor used in running the glucose test in whole blood to subtract out optical interference caused by hemoglobin. This arrangement is usually necessary in conjunction with single-layer test strips, which are generally unable to adequately separate hemoglobin from whole blood sample as it flows to the opposite surface where the calorimetric reaction with the reagent is desired to be measured. If reflection from this secondary LED is not detected to achieve a certain threshold, that is if there is no hemoglobin detected, the meter automatically assumes that the test element is a control element. This methodology is in essence binary, and is limited to the distinction between “Blood” and “Not Blood” and is therefore not satisfactory if there are more than two possibilities.
The difficulties monitoring devices have in properly distinguishing the type of test element inserted also carries over to distinguishing between insertion of a test strip having a sample applied thereon, i.e. a control test element or an analytical test element, and insertion of a standard reflectance strip. Again, conventional monitoring devices have the drawback of requiring an affirmative act from the user to signal that a non-analytical test is being performed by the monitoring device. It is accordingly an object of the invention to provide a method for automatically distinguishing between the type of test performed by the device based on the test element inserted by the user, without the need for any affirmative act by the user.
In accordance with the invention, a method for automatically selecting test types in an analytical meter system is described, the method comprising the steps of:
providing a test element, said test element belonging to one of a plurality of test element types;
inserting said test element into an analytical meter system;
measuring a first optical property of the test element;
measuring a second optical property of the test element;
distinguishing said test element by identifying a predetermined relationship between said first and second optical properties;
selecting a test type based at least in part upon the results of said distinguishing step.
Also described is a meter system for performing one of a plurality of test types on a test element, where the test element is inserted into the meter system and belongs to one of a plurality of test element types, the meter system comprising:
a first light emitting diode selectively discharging light at a first wavelength;
a second light emitting diode selectively discharging light at a second wavelength;
at least one light detector for measuring light emitted from the first and second light emitting diodes and reflected from a test element; and
a processor for distinguishing said test element by identifying a predetermined relationship between first and second optical properties, and further for selecting a test type based at least in part upon the results of said distinguishing.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to an illustrative embodiment of the invention, which appears in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
With reference to the drawings,
The top and bottom support layers 32, 34 of test strip 30 each define an aperture or opening therethrough. These apertures or openings of the test strip 30 are oriented in vertical alignment with a test window (not shown) located along strip platform 24 (
Monitoring meter system 10 of the present invention includes a circuit assembly physically and electrically connected to a printed circuit board, an example of which is schematically depicted as the block diagram of
The circuit assembly can include a light intensity control circuit, represented as section 122 of the diagram, and a light detector circuit 124, discussed in further detail hereinbelow. An exemplary embodiment of the present invention operates using a DC offset (“virtual ground”) of 2.5V reference (not shown) and is powered from a 1.5V AAA battery (not shown), which may include a voltage divider circuit or other power management circuitry as is known in the art.
An analog to digital (A/D) converter 126 converts analog electrical output on line 128 from the light detector circuit 124 into digital information for the microprocessor 102. In an exemplary embodiment of the invention, a 12-bit A/D converter is employed. A temperature sensor 130 provides a voltage proportional to the temperature along line 132 to the A/D converter. The microprocessor 102 can make a determination as to whether the temperature of the testing environment is within predetermined thresholds, and prohibit a user from running a test if accuracy would be negatively affected.
The light intensity control circuit (LICC) 122 will now be described. In an exemplary embodiment, the circuit is supplied by a pulse width modulated signal along line 134 from the microprocessor 102. The circuit includes a low pass filter 136, a modulator 137, a flux biasing resistor 138, a reference photodiode 140, a control loop error amplifier 142, a feedback loop compensation capacitor 144, and LED drive transistors 146. The LICC controls the drive supplied to the LEDs 148, as will be described.
The LEDs, of which there are two in the exemplary embodiment, generate light, a component 150 of which will encounter the target 152, which is the test strip or other test element inserted into the meter. Another component 154 of the light strikes a chamber reflector 156 and a portion of which 158 is reflected toward reference photodiode 140. One of the LEDs is a 660 nm LED in the exemplary embodiment, which is appropriate for detecting glucose in a test strip marketed under the tradename PRESTIGE and sold by Home Diagnostics, Inc. of Ft. Lauderdale, Fla. The exemplary embodiment can be easily modified for detecting other anatytes or using other strips by changing the software and LED used to obtain a different wavelength. For instance, a 580 nm LED would be preferred for ketones using known analytical chemistry systems.
The light detector circuit (LDC) 124 will now be described. In an exemplary embodiment, the LDC includes a main photodiode 160, a transimpedance (current to voltage) amplifier 162, a high pass filter 164, an amplifier 166, and a negative gain amplifier 168. The output stage of the exemplary LDC includes a demodulator 170, a level shifting amplifier 172, and a low pass filter 174. The output stage provides a DC voltage to line 128, as set forth above. The LDC supplies an analog signal to the A/D converter, which when digitized is interpreted by the microprocessor to provide test results.
In the exemplary embodiment, input to the A/D converter is conventionally multiplexed, receiving input from lines 128 and 132, and from other signal lines not shown and not necessary to understand the present invention.
In the exemplary embodiment, two LEDs are employed, at 610 nm and 660 nm as described herein. The LEDs are selected according to the instruction code at appropriate times by the microprocessor 102 by a signal sent via line 176, which activates a switch 178. If additional LEDs are employed, then additional signal lines and switches can be added in conventional manner.
The operation of the exemplary circuit 100 will now be described. A pulse width signal is produced by the microprocessor 102 along line 134. As is well known, the pulse width modulation signal is basically a 2.5V signal delivered either on or off according to a duty cycle. In a perfect square wave, the duty cycle is 50%, so that the signal is 50% on, and 50% off. Accordingly, when the signal is on, it is delivered at 2.5 volts and when it's off, it is zero volts. The signal in line 134 is averaged by the low pass filter 136 to arrive at a drive voltage for the LEDs, which will in turn determine their output. For example, for a perfect 2.5V square wave, the average voltage, and thus the output of the low pass filter 136 will be 1.25V. In this way, the power delivered to the LEDs can be modified by the microprocessor by changing the duty cycle of the pulse width modulation signal. To increase the light power, the duty cycle of the signal would be increased.
In the exemplary embodiment, the duty cycle of the pulse width modulation signal is determined during factory calibration of the meter, and the duty cycle value is permanently stored in the EEPROM. Of course, periodic calibration routines known in the art could also be employed. Further, different LEDs may have different preferred drive requirements, so different duty cycles can be utilized based on the LED in operation.
The circuit 100 employs a modulation or “chopping” function controlled by the microprocessor 102. The microprocessor 102 supplies a modulation signal via line 180 to the modulator 137 of the LICC and, to the demodulator 170 of the LDC in synchrony. The chopping signal is essentially a square wave (on/off) signal supplied to drive the LEDs at a certain frequency, rather than at constant power, to eliminate noise in the signal output of the circuit. In the exemplary embodiment, a 2 kHz chop is employed. The chopping function allows the shifting of the frequency of the light signals LICC upward to a “quieter” region of the spectrum where ambient light effects can be minimized in the LDC. For example, while sunlight is 0 Hz (DC), incandescent lights have a frequency of 120 Hz. Fluorescent lights are also 120 Hz, but also have harmonic frequencies. By shifting the drive frequency of the LEDs above that of ambient light at the LICC, the LDC will be able to receive a signal at the matching frequency that is above the spectrum where most noise is encountered.
The LICC includes flux biasing resistor 138 which is in parallel with modulator 137. This resistor in parallel essentially inhibits the voltage from the low pass filter 136 from being completely turned off by the modulator 137. In this way, the chopping function, instead of modulating between full-on to full-off will modulate between full-on and low. The result is that the LEDs will be either full-on or dim, but never completely off. Several benefits are realized by this arrangement. First, because the LEDs are never dark, a positive bias is always present at the reference diode 140. As a result, when interfering ambient light reaches the reference diode 140, there is a tendency for the modulated signal to move toward ground. This positive bias helps to compensate for this tendency toward ground and allows the circuit to adapt without a change in peak-to-peak amplitude by keeping the modulated signal above ground. Second, the fact that a voltage is always present maintains control loop error amplifier 142 further above ground, which promotes better performance.
The control loop amplifier 142, in connection with the compensation capacitor 144 receives the output from the reference photodiode 140 to provide a feedback mechanism in determining the appropriate drive power for the LEDs 148.
When target 152 is, illuminated by light 150 from an LED 148, reflected light 153 is received by the main photodiode 160, producing a photocurrent based on the reflectance. The photocurrent output of the photodiode 160 is supplied to transimpedance amplifier 162, which converts the photocurrent to a voltage. This voltage is conditioned by high pass filter 164, which removes noise components of the signal below the chopping frequency. It is here that the noise components of artificial lighting are filtered out, although certain harmonics of fluorescent light are eliminated after demodulation by low pass filter 174. In the exemplary embodiment, a 400 Hz cutoff frequency is employed in high pass filter 164.
The signal emerging from high pass filter 164 is basically a square wave voltage. at the chopping frequency that is nominally 0.5V peak to peak maximum and centered about the virtual ground of 2.5V. To condition the output for the A/D converter, which in the exemplary embodiment operates at approximately 2.6V maximum, amplifier 166 and negative gain amplifier 168 are employed as follows. When the LED is on, the top half of the square wave is connected by level shifting amplifier 172; and when the LED is off, the bottom half of the square wave is amplified by minus unity and connected by level shifting amplifier 172. This inverts the bottom half of the square wave when the LED is off. The demodulator 170 selects between the amplifiers 166, 168 in synchrony with the modulation occurring in the LIDC at modulator 137. The resulting signal emerging from demodulator 170 is a DC signal proportional to the reflectance of the chemistry, in relation to the 2.5V reference voltage in the exemplary embodiment.
Level shifting amplifier 172, a differential amplifier, receives the DC signal from the demodulator 170, applies a gain and shifts the signal to a range acceptable to the A/D converter, which in the exemplary embodiment is approximately 2.6V maximum. Low pass filter 174 removes spiking introduced by the demodulation of the signal by amplifiers 166, 168, and also removes a large amount of the harmonics of artificial light that were shifted high by the demodulation. Further, Any DC offsets in the amplifier stages prior to the demodulations that were shifted up to the chopping frequency are also effectively filtered. The only noise left in the signal are harmonics of ambient light that are right around the chopping frequency, which in the exemplary embodiment of 2 kHz are minimal.
These remaining harmonics are of known frequency and their relationship to the chop frequency will determine their frequency. For example, the 17th harmonic of fluorescent lighting will be 120 Hz×17 =2040 Hz. If the chop frequency is 2048 Hz, which is more conveniently generated by binary digital systems than 2000 Hz, the strongest remaining interfering harmonic will be 8 Hz (|2048 Hz−2040 Hz|). Since this interfering signal is of known frequency, it can be further reduced by simple synchronous digital filtering techniques. In countries that use 50 Hz power grids, the strongest interfering frequency will be 2 Hz (the 25th harmonic of 100 Hz=2050 Hz, |2048 Hz−2050 Hz|=2 Hz). A simple synchronous digital filtering technique that “nulls-out” both 2 Hz and 8 Hz can be implemented.
Testing fluid samples for glucose levels according to the present invention generally includes insertion of test strip 30 containing a blood sample into meter system 10 within test chamber cover 22 along strip platform 24. Proper insertion of the test strip 30 in meter system 10 results in locating the reaction viewing port 46 of the test strip 30 directly 20 above the test window (not shown) of meter system 10. Once the test strip is properly inserted in meter system 10, the 660 nm LED discharges against viewing port 46 of test strip 30, and the reflectance from the discharge is registered by one or more light detectors. This process continues until the meter system, according to an algorithm, calculates the glucose level of the sample. A representative algorithm is described in commonly-assigned copending U.S. patent application Ser. No. 09/794,045 (entitled “Method for Determining the Concentration of an Analyte on a Test Strip”), filed on Feb. 28, 2001, now U.S. Pat. No. 6,541,266, issued on Apr. 1, 2003, the contents of which are incorporated herein by reference.
The microprocessor and algorithm software of meter system 10 perform calculations to arrive at the ultimate glucose measurement. It should be noted, however, that similar calculations may be used for deriving the amount of other analytes found in the test strip 30 so long as meter system 10 has been properly reconfigured and calibrated for the particular analyte of interest.
Meter system 10 according to an illustrative embodiment of the invention is intended to receive and automatically differentiate between at least three different types of test elements, as discussed hereinabove. The three types of tests include: (1) an analytical test; (2) a control test; and (3) a standard test. To avoid combining different types of test results, the results of each test type can be stored in separate locations in the memory of meter system 10. This categorizing of the test results would allow for separate recalling of test results for each type of test, but would not combine results from different types of tests. Access to different types of test results could also be determined by different protocols, for example allowing a user to view historical analytical test results, but limiting access to historical standard test results to service technicians. Alternatively, only the results of certain types of tests could be saved, and others not saved.
The present invention automatically differentiates between the three different types of tests by analyzing aspects of the spectral curve derived from reflectance measurements taken from a test element inserted into the meter system. Aspects of the spectral curve associated with an inserted test element can be ascertained by analyzing the percentage of reflectance of the test strip measured over certain predetermined wavelengths, or a range of wavelengths. An example of a spectral curve for an analytical element, using whole blood to test for glucose, according to the present invention and measured between a wavelength range of 500 nm to 900 nm is illustrated in
As illustrated in
This vertical displacement of the entire spectral curve for blood glucose tests presents challenges in differentiating test types, because absolute thresholds are not easily applied.
As described above, the illustrative embodiment uses a 660 nm wavelength LED to measure reflectance of a test element inserted into meter system 10. This wavelength has been selected based on numerous factors, including system components and type of test strip used, and is designed to correspond with a peak optical response, e.g., absorbance, of the reaction of analyte with reagent on the test strip. While the illustrative embodiment contemplates measuring reflectance with a LED having a wavelength of 660 nm, it is within the scope of the invention that any other wavelength could be used in association with a different test strip composition or system components.
Looking again at the spectral curve of the blood sample of
When using a chromogen as an analyte indicator such as with known dry chemistry test strips, the Kubelka-Munk K/S reflectance values can be used to draw a predictable quantitative relationship between color development and concentration of the analyte. The spectral curve of the glucose reaction on a given test strip that is measured is of a known shape and it is known that glucose concentrations can be calculated using K/S values. The effects of intentionally distorting the spectral curve shape of the reaction by adding a dye to the glucose control solution can also be measured using K/S. specifically the difference in K/S values at two different wavelengths. Therefore, K/S can be used to measure the spectral curve shape of both a blood glucose and glucose control reaction.
The advantage of using K/S values instead of raw % R in calculations is that using K/S values tend to provide a more consistent method of measurement from varying lots of chemistry strips, which vary from lot to lot. The advantage of using % R is that it tends to provide a more consistent method of measuring the effect of the dye in the glucose control solution. As a general proposition, it is easier to control the amount of dye in the glucose control from lot to lot than it is to control the optical properties of strips from lot to lot. As a result, K/S can be a more robust means of measuring the differences in the spectral curve shape from chemistry lot to chemistry lot. However, in some circumstances, Δ% R may hold a slight advantage over delta K/S, for example when measuring low glucose concentrations.
The use of K/S values in an exemplary practice of the present invention is described in the examples below, where Ch1 is 660 nm, and Ch2 is 610 nm,
Glucose Control detected when Ch2 % R is at least 3.5% R less than the Ch1 % R at the conclusion of the test.1 1 Actual % R cutoff value varies with dyes, chromogens and wavelengths used.
Pseudo Code
Glucose Glucose Control detected when Ch2 K/S is at least 0.3 less than that of Ch1 K/S at the conclusion of the test.2 2 Actual K/S cutoff value varies with dyes, chromogens and wavelengths used.
Pseudo Code
Glucose control solutions are manufactured at known glucose concentrations. Certain glucose concentrations can immediately be excluded from the need for spectral analysis by glucose concentration level alone. For example, blood detection is indicated, but when final glucose value exceeds 400 mg/dL, control solution is identified. In this case, no spectral curve shape analysis would be required.
Pseudo Code
In accordance with an illustrative embodiment of this invention, and as described above, meter system 10 incorporates a second LED having a wavelength of 610 nm. The second LED operates to measure a second point along the spectral curve of the test element inserted into the meter. It is this second LED, acting in conjunction with the strip sensor, that allows the meter system according to the illustrative embodiment to automatically differentiate between at least the three different types of tests described hereinabove to be conducted by meter system 10. The three types of tests are the analytical test, the standard test, and the control test.
In performing the standard test, a standard strip is inserted into the meter. This standard strip, as is known in the art, can be formed with a notch in the distal end (the end first inserted into the meter) so as not to trip the strip sensor upon full insertion. When inserted, the meter optics will detect the presence of the standard strip because reflectance values increase (with no test element in place, reflectance is, corrected for ambient light and noise, statistically equal to zero). Because the strip sensor will not indicate presence of a test strip because the notch on the standard strip will not trip the strip sensor, the meter will be able to ascertain that the test element inserted is the standard test element, and the test run is the standard test.
If the strip sensor is triggered, however, then the meter system will know that a test strip has been inserted. The test strip is common to both the analytical element and the control element. Distinguishing between the two, and thus between an actual blood sample and a glucose control solution, is facilitated by incorporating a dye within the glucose control solution that alters or distorts the spectral curve, or shape, of the control element. The dye preferably has a narrow spectral absorbance so that it does not significantly impact the glucose evaluation of the sample. The distortion of the spectral curve of the control element due to the dye provides a substantially different reflectance percentage value measured at 610 nm relative to that at 660 nm. As described above, the % R values returned at these two wavelengths are very nearly the same in blood. Accordingly, meter system 10 ascertains that a standardization and verification test using glucose control solution is being conducted when the reflectance percentage values using the 610 nm LED is measurably different relative to the 660 nm LED when the strip sensor is tripped. The amount of difference between reflectance percentage values between the 610 nm channel and the 660 nm channel is dependent on the type and amount of dye incorporated into the glucose control solution. The type and amount of dye used should be selected so that it does not exhibit significant absorbance at 660 nm. For example, a dye causing a six point absolute difference in reflectance percentage values between measurements by the two LEDs has been found sufficient to consistently and accurately distinguish the control solution from a blood sample. Because the dye affects the shape of the curve, the absolute reflectance measurement is not what is important. What is important is the relative difference between the reflectance percentages returned between the two wavelengths, which difference would remain substantially constant irrespective of the absolute values.
As indicated in the graph of
In accordance with the invention, any suitable dye can be used to modify the spectral curve of the glucose control solution, as long as it produces a detectable difference in measured results at the two selected LED wavelengths. Appropriate dyes include Bromophenol Blue and Crystal Violet. The amount of dye added to the control solution may be varied, in order to account for various factors understood by one having skill in the art, such as reagent system performance and monitor apparatus design considerations. Further, the spectral shape of a fluid sample may be altered by adding other ingredients which alter measurable optical properties, such as phosphorescing materials instead of dyes.
A representative control solution is formulated as shown in Table 1 in amounts sufficient to make 1000 mL of solution.
1Azophloxine [C18H13N3Na2O8S2]
23′,3″,5′,5″-Tetrabromophenolsulfonephthalein sodium salt [C19H9Br4NaO5S]
3Varies with product target level
Distinguishing the type of test being conducted in the meter system in the manner described above can be performed instantaneously in the case of the standard test, because the strip sensor is not tripped while reflectance values are being detected by the optical block of the monitor apparatus. Distinguishing between the analytical test and the control test generally takes place after a suitable incubation period has transpired between the sample fluid and the reagent system, such that reaction products can be formed and optically detected.
A decision table appears below as Table 2, summarizing the principles of operation of the illustrative embodiment described hereinabove:
In accordance with the invention, the above described spectral analysis can be applied to any type of test strip that has a distinct spectral shape for a given sample type. Of course, LED wavelengths may be selected from other than 660 nm and 610 nm, depending on the reagent system, to allow the meter to both accurately measure the level of analyte in the sample applied to the test strip, and provide distinguishable spectral curves between an analytical element and a control element, or even between different analytical elements. If different analytical elements were to be distinguished one from another, the reagent system of one type can contain dye particles embedded in the strip as is known in the art. In this way, tests between, for example, glucose and cholesterol might be distinguished using the principles described hereinabove. Also, additional LEDs can be integrated into the optical block, providing an additional data channel upon which a decision can be based.
Also, as shown above in table 1, the standard test is the only test which does not trip the strip sensor, therefore there is no need to ascertain whether the values returned on the 610 nm and 660 nm data channels are substantially equal. For example, if the standard test used a test element where the % R returned at 610 nm and 660 nm were substantially equal, another test type can be provided that would rely on a difference between 610 nm and 660 nm. As an example, a cholesterol test strip can have a notch in its leading edge so as to not trigger the strip sensor, and have a reagent system such that, at a decision point, there is a measurable relative difference between 610 nm and 660 nm. The standard test can be further identified by the absolute returns on the 610 nm and 660 nm channel, for example by providing reflectance values outside the range returned by analytical or control elements. Once the test type is identified as the standard test, which can be instantaneous due to the involvement of the strip sensor, the meter might display % R values instead of analytical values, and the verification by the user can be to compare the % R provided with the standard strip with the % R displayed by the device.
As described above, meter system 10 includes a memory for storing at least successive final glucose values. The memory may hold a collection of successive final glucose values, such as, for example, 365 values. With the capacity of modem subminiature memory chips, a very large amount of data can be reliably stored. These final values can be recalled by pressing a control button 16. Further, meter system 10 may include a data port or a modem assembly for downloading the stored final glucose values to another computer system. The computer system receiving the downloaded final glucose values could be a home PC, or that of a doctor, or a website operator, or any other person or organization for providing assistance to the user in monitoring their glucose levels, or for collecting data on diabetes management on a community regional national or international basis. The modem assembly can be of any configuration (e.g. TCP/IP or ATM), or those having wireless communication capabilities (e.g. those using GSM, WAP, CDMA, etc.). One such modem is described in copending commonly-assigned U.S. patent application Ser. No. 09/512,919, filed Feb. 25, 2000, now abandoned, the contents of which are hereby incorporated by reference.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This is a continuation of U.S. patent application Ser. No. 09/794,044, filed Feb. 28, 2001 now U.S. Pat. No. 6,562,625.
Number | Name | Date | Kind |
---|---|---|---|
2297248 | Rudolph | Sep 1942 | A |
2369499 | Treuhaft | Feb 1945 | A |
2893843 | Adams | Jul 1959 | A |
2893844 | Cook | Jul 1959 | A |
3061523 | Free | Oct 1962 | A |
3092465 | Adams | Jun 1963 | A |
3099605 | Free | Jul 1963 | A |
3127281 | Meyer | Mar 1964 | A |
3232710 | Rieckmann | Feb 1966 | A |
3298789 | Mast | Jan 1967 | A |
3413198 | Deutsch | Nov 1968 | A |
3443903 | Haack | May 1969 | A |
3483031 | Lauer | Dec 1969 | A |
3501009 | Jaworek | Mar 1970 | A |
3506126 | Serfass | Apr 1970 | A |
3509025 | Bergmeyer | Apr 1970 | A |
3511608 | Anderson | May 1970 | A |
3552925 | Fetter | Jan 1971 | A |
3552928 | Fetter | Jan 1971 | A |
3560161 | Webb | Feb 1971 | A |
3577162 | Gaehwiler | May 1971 | A |
3591480 | Neff | Jul 1971 | A |
3593568 | Schmitz | Jul 1971 | A |
3604815 | Clemens | Sep 1971 | A |
3607093 | Stone | Sep 1971 | A |
3620677 | Morison | Nov 1971 | A |
3630957 | Rey | Dec 1971 | A |
3650698 | Adler | Mar 1972 | A |
3653836 | Gruber | Apr 1972 | A |
3658480 | Kane | Apr 1972 | A |
3660638 | Oberli | May 1972 | A |
3663175 | Depositar | May 1972 | A |
3672838 | Trcka | Jun 1972 | A |
3677901 | Bergmeyer | Jul 1972 | A |
3690833 | Ferrari | Sep 1972 | A |
3703336 | Rosse | Nov 1972 | A |
3709612 | Clemens | Jan 1973 | A |
3713986 | Bergmeyer | Jan 1973 | A |
3715192 | Wenz | Feb 1973 | A |
3718439 | Rosse | Feb 1973 | A |
3723064 | Liotta | Mar 1973 | A |
3748044 | Liston | Jul 1973 | A |
3762609 | Hagen | Oct 1973 | A |
3765841 | Paulson | Oct 1973 | A |
3769178 | Rothermel | Oct 1973 | A |
3775058 | Bush | Nov 1973 | A |
3775595 | Rosse | Nov 1973 | A |
3778350 | Bergmeyer | Dec 1973 | A |
3785772 | Coggeshall | Jan 1974 | A |
3791933 | Moyer | Feb 1974 | A |
3795149 | Gillette | Mar 1974 | A |
3795484 | Daly | Mar 1974 | A |
3798004 | Zerachia | Mar 1974 | A |
3802843 | Kim | Apr 1974 | A |
3804593 | Smythe | Apr 1974 | A |
3811840 | Bauer | May 1974 | A |
3814582 | Rohrbaugh | Jun 1974 | A |
3819863 | Slaght | Jun 1974 | A |
3822285 | Werner | Jul 1974 | A |
3837339 | Aisenberg et al. | Sep 1974 | A |
3847553 | Verbeck | Nov 1974 | A |
3853472 | Rittersdorf | Dec 1974 | A |
3864166 | Barker | Feb 1975 | A |
3876374 | Burns | Apr 1975 | A |
3881992 | Raltson | May 1975 | A |
3897214 | Lange | Jul 1975 | A |
3901657 | Lightfoot | Aug 1975 | A |
3902052 | Amar | Aug 1975 | A |
3907503 | Betts | Sep 1975 | A |
3910701 | Henderson | Oct 1975 | A |
3915647 | Wright | Oct 1975 | A |
3917452 | Rittersdorf | Nov 1975 | A |
3917453 | Milligan | Nov 1975 | A |
3919051 | Koch | Nov 1975 | A |
3920580 | Mast et al. | Nov 1975 | A |
3926736 | Bucolo | Dec 1975 | A |
3929581 | de Fonseca-Wollheimn | Dec 1975 | A |
3933593 | Sternberg | Jan 1976 | A |
3936357 | Milligan | Feb 1976 | A |
3942995 | Ichikawa | Mar 1976 | A |
3950133 | Monte | Apr 1976 | A |
3954342 | Boeke | May 1976 | A |
3957436 | Murray | May 1976 | A |
3958560 | March | May 1976 | A |
3960497 | Acord | Jun 1976 | A |
3964870 | Tiedemann | Jun 1976 | A |
3971630 | Sandrock | Jul 1976 | A |
3973129 | Blumberg | Aug 1976 | A |
3973189 | Angel | Aug 1976 | A |
3975398 | Werner | Aug 1976 | A |
3979274 | Newman | Sep 1976 | A |
3980437 | Kishimoto | Sep 1976 | A |
3983005 | Goodhue | Sep 1976 | A |
3985508 | Williams | Oct 1976 | A |
3986833 | Mast | Oct 1976 | A |
3988208 | Werner | Oct 1976 | A |
3990849 | Lee | Nov 1976 | A |
3992158 | Przyblyowicz | Nov 1976 | A |
4009615 | Ruhl | Mar 1977 | A |
4011046 | Labes | Mar 1977 | A |
4014321 | March | Mar 1977 | A |
4015121 | Gagnon | Mar 1977 | A |
4022577 | Brooker | May 1977 | A |
4038485 | Johntson | Jul 1977 | A |
4040786 | Trivedi | Aug 1977 | A |
4042335 | Clement | Aug 1977 | A |
4043756 | Sommervold | Aug 1977 | A |
4050898 | Goffe | Sep 1977 | A |
4056468 | Breiter | Nov 1977 | A |
4057394 | Genshaw | Nov 1977 | A |
4059405 | Sodickson | Nov 1977 | A |
4061468 | Lange | Dec 1977 | A |
4061469 | DuBose | Dec 1977 | A |
4066362 | Carter | Jan 1978 | A |
4066403 | Bruschi | Jan 1978 | A |
4068169 | Angel | Jan 1978 | A |
4069017 | Wu | Jan 1978 | A |
4076502 | Dugle | Feb 1978 | A |
4095272 | Janzen | Jun 1978 | A |
4098574 | Dappen | Jul 1978 | A |
4101276 | Anderson | Jul 1978 | A |
4109159 | Onillon | Aug 1978 | A |
4110079 | Schaeffer | Aug 1978 | A |
4125327 | Margolis | Nov 1978 | A |
4125372 | Kawai | Nov 1978 | A |
4128628 | Brooker | Dec 1978 | A |
4135883 | McNeil | Jan 1979 | A |
4144306 | Figueras | Mar 1979 | A |
4152390 | Nosco | May 1979 | A |
4153668 | Hill | May 1979 | A |
4160646 | Furutani | Jul 1979 | A |
4165508 | Barter | Aug 1979 | A |
4176008 | Figueras | Nov 1979 | A |
4178153 | Sodickson | Dec 1979 | A |
4180060 | Kutter | Dec 1979 | A |
4199260 | Kusnetz | Apr 1980 | A |
4199261 | Tidd | Apr 1980 | A |
4211845 | Genshaw | Jul 1980 | A |
4217107 | Saito | Aug 1980 | A |
4218144 | Whitehouse et al. | Aug 1980 | A |
4219529 | Tersteeg | Aug 1980 | A |
4224032 | Glover | Sep 1980 | A |
4226537 | Colley | Oct 1980 | A |
4230456 | Wu | Oct 1980 | A |
4233029 | Columbus | Nov 1980 | A |
4238196 | Acuff | Dec 1980 | A |
4240912 | Stumpf | Dec 1980 | A |
4253846 | Smythe | Mar 1981 | A |
4254083 | Columbus | Mar 1981 | A |
4255384 | Kitajima | Mar 1981 | A |
4255788 | Schwartz | Mar 1981 | A |
4256693 | Kondo | Mar 1981 | A |
4257862 | Schnipelsky | Mar 1981 | A |
4258001 | Pierce | Mar 1981 | A |
4261041 | Starr | Apr 1981 | A |
4269938 | Frank | May 1981 | A |
4272482 | Jessop | Jun 1981 | A |
4273868 | Walter | Jun 1981 | A |
4274832 | Wu | Jun 1981 | A |
4276051 | Ginsberg | Jun 1981 | A |
4277561 | Monget | Jul 1981 | A |
4278439 | White | Jul 1981 | A |
4281062 | Kallis | Jul 1981 | A |
4283383 | Masson | Aug 1981 | A |
4283491 | Dappen | Aug 1981 | A |
4288228 | Oberhardt | Sep 1981 | A |
4292272 | Kitajima | Sep 1981 | A |
4297238 | Vormbrock | Oct 1981 | A |
4298345 | Sodickson | Nov 1981 | A |
4298688 | Kallies | Nov 1981 | A |
4299916 | Litman | Nov 1981 | A |
4300906 | Negersmith | Nov 1981 | A |
4302420 | Jakubowicz | Nov 1981 | A |
4303406 | Ross | Dec 1981 | A |
4303408 | Kim | Dec 1981 | A |
4303753 | Lam | Dec 1981 | A |
4308485 | Ignazio | Dec 1981 | A |
4310399 | Columbus | Jan 1982 | A |
4312834 | Vogel | Jan 1982 | A |
4318984 | Magers | Mar 1982 | A |
4318985 | Bauer | Mar 1982 | A |
4325910 | Jordan | Apr 1982 | A |
4330299 | Cerami | May 1982 | A |
4336330 | Bauer | Jun 1982 | A |
4337065 | Hiratsuka | Jun 1982 | A |
4338279 | Orimo | Jul 1982 | A |
4340669 | Bauer | Jul 1982 | A |
4353983 | Siddiqi | Oct 1982 | A |
4353984 | Yamada | Oct 1982 | A |
4361648 | Shuenn-tzong | Nov 1982 | A |
4363874 | Greenquist | Dec 1982 | A |
4366061 | Papanek et al. | Dec 1982 | A |
4366241 | Tom | Dec 1982 | A |
4370983 | Lichtenstein | Feb 1983 | A |
4373818 | Yamamoto | Feb 1983 | A |
4384042 | Milke | May 1983 | A |
4390343 | Walter | Jun 1983 | A |
4390621 | Bauer | Jun 1983 | A |
4391905 | Bauer | Jul 1983 | A |
4391906 | Bauer | Jul 1983 | A |
4399099 | Buckles | Aug 1983 | A |
4403984 | Ash | Sep 1983 | A |
4407959 | Tsuji | Oct 1983 | A |
4415700 | Betz | Nov 1983 | A |
4418037 | Katsuyama | Nov 1983 | A |
4420564 | Tsuji | Dec 1983 | A |
4420566 | Jessop | Dec 1983 | A |
4427632 | Okaniwa | Jan 1984 | A |
4427889 | Muller | Jan 1984 | A |
4430299 | Horne | Feb 1984 | A |
4430427 | Hopkins | Feb 1984 | A |
4430436 | Koyama | Feb 1984 | A |
4448207 | Parrish | May 1984 | A |
4449538 | Corbitt et al. | May 1984 | A |
4450153 | Hopkins | May 1984 | A |
4452887 | Kitajima | Jun 1984 | A |
4458539 | Bilstad | Jul 1984 | A |
4459358 | Berke | Jul 1984 | A |
4460684 | Bauer | Jul 1984 | A |
4464172 | Lichtenstein | Aug 1984 | A |
4472498 | Masuda | Sep 1984 | A |
4472505 | Manabe | Sep 1984 | A |
4476222 | Ohtani | Oct 1984 | A |
4477575 | Vogel | Oct 1984 | A |
4478942 | Katsuyama | Oct 1984 | A |
4478944 | Gross | Oct 1984 | A |
4483924 | Tsuji | Nov 1984 | A |
4492462 | Pross | Jan 1985 | A |
4499052 | Fulwyler | Feb 1985 | A |
4503385 | Haynes | Mar 1985 | A |
4503555 | Brimhall, Jr. | Mar 1985 | A |
4509859 | Markart | Apr 1985 | A |
4517160 | Galle | May 1985 | A |
4518259 | Ward | May 1985 | A |
4523853 | Rosenbladt et al. | Jun 1985 | A |
4528159 | Liston | Jul 1985 | A |
4532107 | Siddigi | Jul 1985 | A |
4534012 | Yokozawa | Aug 1985 | A |
4540670 | Arai | Sep 1985 | A |
4547460 | Eikenberry | Oct 1985 | A |
4551307 | Koyama | Nov 1985 | A |
4552458 | Lowne | Nov 1985 | A |
4553848 | Rosicke | Nov 1985 | A |
4554132 | Collins | Nov 1985 | A |
4557901 | Koyama | Dec 1985 | A |
4562148 | Sommer | Dec 1985 | A |
4567024 | Koyama | Jan 1986 | A |
4576793 | Koyama | Mar 1986 | A |
4578245 | Arai | Mar 1986 | A |
4578248 | Nagaoka | Mar 1986 | A |
4587100 | Amano | May 1986 | A |
4587220 | Mayamabala-Mwanika | May 1986 | A |
4592365 | Georgi | Jun 1986 | A |
4592893 | Poppe | Jun 1986 | A |
4594224 | Okaniwa | Jun 1986 | A |
4594327 | Zuk | Jun 1986 | A |
4595562 | Liston | Jun 1986 | A |
4602995 | Cassaday | Jul 1986 | A |
4603428 | Sandrik | Jul 1986 | A |
4604254 | Yamamoto | Aug 1986 | A |
4604264 | Rothe | Aug 1986 | A |
4604579 | Cannon | Aug 1986 | A |
4618475 | Wang | Oct 1986 | A |
4622207 | Wang | Nov 1986 | A |
4627014 | Lo | Dec 1986 | A |
4627445 | Garcia | Dec 1986 | A |
4632559 | Brunsting | Dec 1986 | A |
4637403 | Garcia | Jan 1987 | A |
4637978 | Dappen | Jan 1987 | A |
4642286 | Moldowan | Feb 1987 | A |
4647430 | Zweig | Mar 1987 | A |
4647432 | Wakatake | Mar 1987 | A |
4649123 | Charlton | Mar 1987 | A |
4661319 | Lape | Apr 1987 | A |
4668619 | Greenquist | May 1987 | A |
4669878 | Meier | Jun 1987 | A |
4670218 | Gantzer | Jun 1987 | A |
4671937 | Katsuyama | Jun 1987 | A |
4676653 | Strohmeier et al. | Jun 1987 | A |
4685059 | Yamamoto | Aug 1987 | A |
4686479 | Young | Aug 1987 | A |
4687329 | Schultz | Aug 1987 | A |
4693985 | Degen | Sep 1987 | A |
4703756 | Gough et al. | Nov 1987 | A |
4710458 | Maines | Dec 1987 | A |
4714341 | Hamaguri | Dec 1987 | A |
4717546 | Barnett | Jan 1988 | A |
4731726 | Allen | Mar 1988 | A |
4732736 | Kobayashi | Mar 1988 | A |
4734360 | Phillips | Mar 1988 | A |
4748114 | Kallies | May 1988 | A |
4772561 | Genshaw | Sep 1988 | A |
4773097 | Suzaki | Sep 1988 | A |
4774192 | Terminiello | Sep 1988 | A |
4775637 | Sutherland | Oct 1988 | A |
4780283 | Meinecke | Oct 1988 | A |
4782511 | Nemec et al. | Nov 1988 | A |
4787398 | Garcia | Nov 1988 | A |
4790979 | Terminiello | Dec 1988 | A |
4791461 | Kishimoto | Dec 1988 | A |
4803153 | Shibata | Feb 1989 | A |
4803159 | Smith-Lewis | Feb 1989 | A |
4803625 | Fu | Feb 1989 | A |
4810470 | Burkhardt | Mar 1989 | A |
4814142 | Gleisner | Mar 1989 | A |
4816224 | Vogel | Mar 1989 | A |
4818710 | Sutherland | Apr 1989 | A |
4820489 | Rothe | Apr 1989 | A |
4820649 | Kawaguchi | Apr 1989 | A |
4824639 | Hildenbrand | Apr 1989 | A |
4839297 | Freitag | Jun 1989 | A |
4849340 | Oberhardt | Jul 1989 | A |
4855108 | Masuda | Aug 1989 | A |
4857273 | Stewart | Aug 1989 | A |
4866836 | Von Brandt et al. | Sep 1989 | A |
4870005 | Akiyoshi | Sep 1989 | A |
4876204 | Inoue | Oct 1989 | A |
4876207 | Mack | Oct 1989 | A |
4877747 | Stewart | Oct 1989 | A |
4889131 | Salem et al. | Dec 1989 | A |
4889815 | Bradwell | Dec 1989 | A |
4900666 | Phillips | Feb 1990 | A |
4909260 | Salem et al. | Mar 1990 | A |
4913150 | Cheung et al. | Apr 1990 | A |
4914020 | Arai et al. | Apr 1990 | A |
4929561 | Hirschfeld | May 1990 | A |
4931384 | Layton et al. | Jun 1990 | A |
4935346 | Phillips | Jun 1990 | A |
4937050 | Meinecke et al. | Jun 1990 | A |
4943522 | Eisinger et al. | Jul 1990 | A |
4949400 | Leveen et al. | Aug 1990 | A |
4950454 | Masuda et al. | Aug 1990 | A |
4952373 | Sugarman et al. | Aug 1990 | A |
4952515 | Gleisner | Aug 1990 | A |
4962021 | Meserol et al. | Oct 1990 | A |
4965047 | Hammond | Oct 1990 | A |
4970172 | Kundu | Nov 1990 | A |
4974607 | Miwa | Dec 1990 | A |
4976724 | Nieto et al. | Dec 1990 | A |
4981779 | Wagner | Jan 1991 | A |
4985205 | Fritsche et al. | Jan 1991 | A |
4987085 | Allen et al. | Jan 1991 | A |
4994238 | Daffern et al. | Feb 1991 | A |
5004584 | Rayman | Apr 1991 | A |
5019574 | Miura et al. | May 1991 | A |
5023052 | Nagatomo et al. | Jun 1991 | A |
5023053 | Finlan | Jun 1991 | A |
5028542 | Kennamer et al. | Jul 1991 | A |
5029583 | Meserol et al. | Jul 1991 | A |
5035863 | Finlan et al. | Jul 1991 | A |
5036852 | Leishman | Aug 1991 | A |
5039225 | Uekusa | Aug 1991 | A |
5043269 | Theodoropulos | Aug 1991 | A |
5047206 | Dombrowski | Sep 1991 | A |
5047213 | Finlan et al. | Sep 1991 | A |
5047351 | Makiuchi et al. | Sep 1991 | A |
5049487 | Phillips et al. | Sep 1991 | A |
5055265 | Finlan | Oct 1991 | A |
5059394 | Phillips et al. | Oct 1991 | A |
5064619 | Finlan | Nov 1991 | A |
5067093 | Przybylowicz et al. | Nov 1991 | A |
5071746 | Wilk et al. | Dec 1991 | A |
5071769 | Kundu | Dec 1991 | A |
5079174 | Buck et al. | Jan 1992 | A |
5079715 | Venkataraman et al. | Jan 1992 | A |
5082626 | Grage, Jr. | Jan 1992 | A |
5096809 | Chen et al. | Mar 1992 | A |
5096836 | Macho et al. | Mar 1992 | A |
5104619 | de Castro et al. | Apr 1992 | A |
5104793 | Buck | Apr 1992 | A |
5104811 | Berger et al. | Apr 1992 | A |
5106758 | Adler et al. | Apr 1992 | A |
5110550 | Schlipfenbacher et al. | May 1992 | A |
5110724 | Hewett | May 1992 | A |
5114350 | Hewett | May 1992 | A |
5114673 | Berger et al. | May 1992 | A |
5116763 | Greene et al. | May 1992 | A |
5120507 | Sano et al. | Jun 1992 | A |
5124128 | Hildenbrand et al. | Jun 1992 | A |
5128171 | Gleisner | Jul 1992 | A |
5130231 | Kennedy et al. | Jul 1992 | A |
5130258 | Makino et al. | Jul 1992 | A |
5147606 | Charlton et al. | Sep 1992 | A |
5149505 | English et al. | Sep 1992 | A |
5152962 | Lackie | Oct 1992 | A |
5166051 | Killeen et al. | Nov 1992 | A |
5171688 | Hewett et al. | Dec 1992 | A |
5173261 | Krause et al. | Dec 1992 | A |
5174963 | Fuller et al. | Dec 1992 | A |
5179005 | Phillips et al. | Jan 1993 | A |
5183741 | Arai et al. | Feb 1993 | A |
5187100 | Matzinger et al. | Feb 1993 | A |
5188966 | Eikmeier et al. | Feb 1993 | A |
5188968 | Kano et al. | Feb 1993 | A |
5206177 | DeLaCroix et al. | Apr 1993 | A |
5207263 | Maier et al. | May 1993 | A |
5211914 | Vogel et al. | May 1993 | A |
5212060 | Maddox | May 1993 | A |
5215716 | Arai | Jun 1993 | A |
5217691 | Greene et al. | Jun 1993 | A |
5225997 | Lederer et al. | Jul 1993 | A |
5227310 | Sakamoto et al. | Jul 1993 | A |
5231576 | Suzuki et al. | Jul 1993 | A |
5246858 | Arbuckle et al. | Sep 1993 | A |
5251126 | Kahn et al. | Oct 1993 | A |
5252293 | Drbal et al. | Oct 1993 | A |
5279294 | Anderson et al. | Jan 1994 | A |
5281395 | Markart et al. | Jan 1994 | A |
5296192 | Carroll et al. | Mar 1994 | A |
5302348 | Cusack et al. | Apr 1994 | A |
5304468 | Phillips et al. | Apr 1994 | A |
5316727 | Suzuki et al. | May 1994 | A |
5321492 | Detwiler et al. | Jun 1994 | A |
5321618 | Gessman | Jun 1994 | A |
5339821 | Fujimoto | Aug 1994 | A |
5367555 | Isoyama | Nov 1994 | A |
5371020 | Frischauf | Dec 1994 | A |
5379214 | Arbuckle et al. | Jan 1995 | A |
5390238 | Kirk et al. | Feb 1995 | A |
5408535 | Howard, III et al. | Apr 1995 | A |
5410474 | Fox | Apr 1995 | A |
5416695 | Stutman et al. | May 1995 | A |
5418142 | Kiser et al. | May 1995 | A |
5424035 | Hones et al. | Jun 1995 | A |
5424545 | Block et al. | Jun 1995 | A |
5431880 | Kramer | Jul 1995 | A |
5452343 | Garland et al. | Sep 1995 | A |
5453360 | Yu | Sep 1995 | A |
5462051 | Oka et al. | Oct 1995 | A |
5467475 | Takashi et al. | Nov 1995 | A |
5470752 | Burd et al. | Nov 1995 | A |
5515170 | Matzinger et al. | May 1996 | A |
5518689 | Dosmann et al. | May 1996 | A |
5520883 | Charlton et al. | May 1996 | A |
5526120 | Jina et al. | Jun 1996 | A |
5529755 | Higashio et al. | Jun 1996 | A |
5545877 | Shelton | Aug 1996 | A |
5548633 | Kujawa et al. | Aug 1996 | A |
5554531 | Zweig | Sep 1996 | A |
5563042 | Phillips et al. | Oct 1996 | A |
5573506 | Vasko | Nov 1996 | A |
5576952 | Stutman et al. | Nov 1996 | A |
5579001 | Dempsey et al. | Nov 1996 | A |
5579775 | Dempsey et al. | Dec 1996 | A |
5581369 | Righter et al. | Dec 1996 | A |
5597532 | Connolly | Jan 1997 | A |
5605150 | Radons et al. | Feb 1997 | A |
5605837 | Karimi et al. | Feb 1997 | A |
5620863 | Tomasco et al. | Apr 1997 | A |
5622429 | Heinze | Apr 1997 | A |
5639672 | Burd et al. | Jun 1997 | A |
5666404 | Ciccotelli et al. | Sep 1997 | A |
5681529 | Taguchi et al. | Oct 1997 | A |
5695949 | Galen et al. | Dec 1997 | A |
5704364 | Saltzstein et al. | Jan 1998 | A |
5704366 | Tacklind et al. | Jan 1998 | A |
5715823 | Wood et al. | Feb 1998 | A |
5719034 | Kiser et al. | Feb 1998 | A |
5723284 | Ye | Mar 1998 | A |
5725774 | Neyer | Mar 1998 | A |
5728352 | Poto et al. | Mar 1998 | A |
5735285 | Albert et al. | Apr 1998 | A |
5745308 | Spangenberg | Apr 1998 | A |
5753452 | Smith | May 1998 | A |
5753519 | Durst et al. | May 1998 | A |
5754111 | Garcia | May 1998 | A |
5755942 | Zanzucchi et al. | May 1998 | A |
5758644 | Diab et al. | Jun 1998 | A |
5762871 | Neyer | Jun 1998 | A |
5764158 | Franklin et al. | Jun 1998 | A |
5770389 | Ching et al. | Jun 1998 | A |
5770839 | Ruebush et al. | Jun 1998 | A |
5772586 | Heinonen et al. | Jun 1998 | A |
5772963 | Cantatore et al. | Jun 1998 | A |
5780304 | Matzinger et al. | Jul 1998 | A |
5782878 | Morgan et al. | Jul 1998 | A |
5785650 | Akasaka et al. | Jul 1998 | A |
5789664 | Neel et al. | Aug 1998 | A |
5791342 | Woodard | Aug 1998 | A |
5795543 | Poto et al. | Aug 1998 | A |
5827180 | Goodman | Oct 1998 | A |
5837546 | Allen et al. | Nov 1998 | A |
5840020 | Heinonen et al. | Nov 1998 | A |
5841846 | Abbruscato | Nov 1998 | A |
5842975 | Illyes et al. | Dec 1998 | A |
5843692 | Phillips et al. | Dec 1998 | A |
5846486 | Pugh | Dec 1998 | A |
5850320 | Warmka et al. | Dec 1998 | A |
5861251 | Park et al. | Jan 1999 | A |
5866349 | Lilja et al. | Feb 1999 | A |
5872627 | Miers | Feb 1999 | A |
5885839 | Lingane et al. | Mar 1999 | A |
5922530 | Yu | Jul 1999 | A |
5945341 | Howard, III | Aug 1999 | A |
5962215 | Douglas et al. | Oct 1999 | A |
5968760 | Phillips et al. | Oct 1999 | A |
5986754 | Harding | Nov 1999 | A |
5989917 | McAleer et al. | Nov 1999 | A |
5995236 | Roth et al. | Nov 1999 | A |
5997817 | Crismore et al. | Dec 1999 | A |
6027690 | Bair et al. | Feb 2000 | A |
6027692 | Galen et al. | Feb 2000 | A |
6032352 | Furay et al. | Mar 2000 | A |
6040195 | Carroll et al. | Mar 2000 | A |
6067463 | Jeng et al. | May 2000 | A |
6084660 | Shartle | Jul 2000 | A |
6168957 | Matzinger et al. | Jan 2001 | B1 |
6193873 | Ohara et al. | Feb 2001 | B1 |
6201607 | Roth et al. | Mar 2001 | B1 |
6226082 | Roe | May 2001 | B1 |
6233471 | Berner et al. | May 2001 | B1 |
6268162 | Phillips et al. | Jul 2001 | B1 |
6562625 | Modzelewski et al. | May 2003 | B2 |
20020139692 | Tokunaga et al. | Oct 2002 | A1 |
Number | Date | Country |
---|---|---|
4503385 | Jan 1986 | AU |
7675887 | Feb 1988 | AU |
1117784 | Feb 1985 | CA |
1219797 | Mar 1987 | CA |
34 39 181 | Oct 1984 | DE |
39 21 391 | Jan 1991 | DE |
0 095 057 | Nov 1983 | EP |
0 110 173 | Jun 1984 | EP |
0 112 166 | Jun 1984 | EP |
0 113 896 | Jul 1984 | EP |
0 133 481 | Feb 1985 | EP |
0 140 337 | May 1985 | EP |
0 141 648 | May 1985 | EP |
0 159 727 | Oct 1985 | EP |
0 166 878 | Jan 1986 | EP |
0 169 055 | Jan 1986 | EP |
0 173 500 | Mar 1986 | EP |
0 174 247 | Mar 1986 | EP |
0 182 647 | May 1986 | EP |
0 183 524 | Jun 1986 | EP |
0 225 561 | Dec 1987 | EP |
0 256 806 | Feb 1988 | EP |
0 271 854 | Jun 1988 | EP |
0 295 526 | Dec 1988 | EP |
0 336 483 | Oct 1989 | EP |
0 345 781 | Dec 1989 | EP |
0 407 800 | Jun 1990 | EP |
0 414 563 | Feb 1991 | EP |
0 415 679 | Mar 1991 | EP |
0 473 241 | Mar 1992 | EP |
0 475 692 | Mar 1992 | EP |
0 479 394 | Apr 1992 | EP |
0 511 120 | Oct 1992 | EP |
0 555 045 | Aug 1993 | EP |
0 574 134 | Dec 1993 | EP |
0 735 369 | Mar 1995 | EP |
0 656 423 | Jul 1995 | EP |
0 759 555 | Aug 1995 | EP |
0 769 558 | Oct 1995 | EP |
0 779 367 | Dec 1995 | EP |
0 800 082 | Apr 1996 | EP |
0 764 271 | Mar 1997 | EP |
0 779 984 | Jun 1997 | EP |
0 781 405 | Jul 1997 | EP |
0 781 406 | Jul 1997 | EP |
0 799 896 | Oct 1997 | EP |
0 816 849 | Jan 1998 | EP |
0 823 634 | Feb 1998 | EP |
0 823 635 | Feb 1998 | EP |
0 823 636 | Feb 1998 | EP |
0 826 777 | Mar 1998 | EP |
0 832 691 | Apr 1998 | EP |
0 852 336 | Jul 1998 | EP |
0 960 946 | Dec 1999 | EP |
0 974 840 | Jan 2000 | EP |
2191734 | Feb 1974 | FR |
835551 | May 1960 | GB |
911181 | Nov 1962 | GB |
1037155 | Jul 1966 | GB |
1485506 | Sep 1977 | GB |
2029012 | Mar 1980 | GB |
2026160 | Jun 1980 | GB |
2039035 | Jul 1980 | GB |
2090659 | Jul 1982 | GB |
49-11395 | Jan 1974 | JP |
53-148522 | Dec 1978 | JP |
54-113383 | Sep 1979 | JP |
55-136957 | Oct 1980 | JP |
55-155235 | Dec 1980 | JP |
56-057937 | May 1981 | JP |
56-164941 | Dec 1981 | JP |
56-168148 | Dec 1981 | JP |
57-101760 | Jun 1982 | JP |
57-163848 | Oct 1982 | JP |
57-168144 | Oct 1982 | JP |
58-021544 | Feb 1983 | JP |
59-032850 | Feb 1984 | JP |
59-032851 | Feb 1984 | JP |
59-108942 | Jun 1984 | JP |
59-182347 | Oct 1984 | JP |
60-091265 | May 1985 | JP |
61-026842 | Feb 1986 | JP |
61-068539 | Apr 1986 | JP |
61-155849 | Jul 1986 | JP |
61-292540 | Dec 1986 | JP |
62-22066 | Jan 1987 | JP |
62-298765 | Dec 1987 | JP |
63-021558 | Jan 1988 | JP |
63-175749 | Jul 1988 | JP |
1-119743 | Jan 1989 | JP |
7-311196 | Jul 1995 | JP |
8-75735 | Mar 1996 | JP |
172088 | Dec 1965 | SU |
8100622 | Mar 1981 | WO |
8100912 | Apr 1981 | WO |
8300931 | Mar 1983 | WO |
8402578 | Jul 1984 | WO |
9212428 | Jul 1992 | WO |
9215861 | Sep 1992 | WO |
9402578 | Feb 1994 | WO |
9513536 | May 1995 | WO |
9607757 | Mar 1996 | WO |
9607892 | Mar 1996 | WO |
9607893 | Mar 1996 | WO |
9607907 | Mar 1996 | WO |
9607908 | Mar 1996 | WO |
WO 9607908 | Mar 1996 | WO |
9746878 | Dec 1997 | WO |
9946591 | Sep 1999 | WO |
Number | Date | Country | |
---|---|---|---|
20030138356 A1 | Jul 2003 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 09794044 | Feb 2001 | US |
Child | 10378797 | US |