Blood glucose reflectance meter including a null prompting means and a device for providing a constant brightness light

• US 5,277,870 A
• Filed: 08/11/1992
• Issued: 01/11/1994
• Est. Priority Date: 01/07/1991
• Status: Expired due to Term

• Current Assignee: UMM Electronics, Inc. (Nortech Systems, Inc.)
• Original Assignee: United Medical Manufacturing Co. (Nortech Systems, Inc.)
• Inventors: Fuller, Maurice D., Riedel, Richard A.
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): WALLENHORST, MAUREEN
• Application Number:
  US07/929,168
• Time in Patent Office: 518 Days
• Field of Search: 422/56, 422/68.1, 422/82.01, 422/82.02, 422/82.05, 422/82.12, 436/95, 436/169, 356/446, 250/238
• US Class Current: 422/82.05
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G01N 2201/1211 for temperature
• CPC Class Codes: G01N 2201/12738 Selectively initiating check
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A portable blood chemistry monitoring meter that employs an analog circuit in conjunction with a manually adjustable potentiometer to locate a null position that balances the measure taken of the blood chemistry-induced changes in the chemistries of disposable test strips. The meter displays in pre-printed, man-readable format blood chemistry concentrations that are individually calibrated to the specific batch-lot chemistries of the disposable test strips used with the meter. In a preferred embodiment, the meter is a blood glucose monitoring meter.

Claims

1. In a portable blood glucose monitoring meter having an analog circuit with a variable potentiometer and a reflectance measuring system, including a light source, to measure blood glucose-induced color changes in the chemistries of disposable test strips to determine blood glucose concentrations, the improvements comprising:

a light emitting diode as the light source within said reflectance measuring system; and

first circuit means connected to said light emitting diode for providing a current signal to said light emitting diode that varies in accordance with variations in ambient temperature to maintain a constant intensity brightness signal from said light emitting diode.

2. The meter of claim 1 wherein said first circuit means includes means for detecting a change in ambient temperature and producing a compensating signal in response thereto, and amplifier means responsive to said compensating signal for varying said current signal accordingly.

3. The meter of claim 2 wherein said means for detecting a change in ambient temperature includes at least one diode.

4. The meter of claim 3 wherein said amplifier means includes an operational amplifier and wherein at least one diode is forward biased with the cathode of said diode connected to an input of said operational amplifier, said amplifier means further including a transistor, said transistor connected in a feedback loop with said operational amplifier with the base of said transistor connected to the output of said operational amplifier, and wherein said transistor produced said current signal.

5. In a portable blood chemistry monitoring meter having an analog circuit with a variable potentiometer to measure blood chemistry-induced changes in an enzyme-based blood analysis system utilizing disposable test strips to determine blood chemistry concentrations, the improvements comprising:

dial means to vary manually the resistance of said potentiometer to locate a null position that balances the measure of the blood chemistry-induced changes in the chemistries of the disposable test strips; and

calibration means integral with said dial means to receive replaceable, pre-printed, man-readable blood chemistry concentrations that correspond to the null positions located by said dial means and that are empirically calibrated to the batch lot variations in the chemistries of the disposable test strips used in the meter.

6. The portable blood chemistry monitoring meter of claim 5 and further comprising null prompting means to indicate the manual variation of said dial means required to achieve a null position.

7. The portable blood chemistry monitoring meter of claim 5 wherein said dial means includes a manually rotatable dial.

8. The portable blood chemistry monitoring meter of claim 7 wherein said manually rotatable dial supports a replaceable, man-readable, pre-printed calibration disk.

9. The portable blood chemistry monitoring meter of claim 8 wherein said calibration disk displays man-readable blood chemistry concentrations about its periphery that are calibrated by their position about the periphery to the specific batch-lot chemistries applied to the disposable test strips to be used with the meter.

10. The portable blood chemistry monitoring meter of claim 5 wherein the enzyme-based blood analysis system is a blood glucose analysis system.

11. In a portable blood glucose monitoring meter having an analog circuit with a variable potentiometer to measure blood glucose-induced changes in the chemistries of disposable test strips to determine blood glucose concentrations, the improvements comprising:

a sliding pointer with means to vary manually the resistance of the potentiometer to locate a null position that balances the measure of the blood glucose-induced changes in the chemistries of disposable test strips; and

slot means to receive disposable test strips, the disposable test strips bearing calibration means that will be in registered juxtaposition with said sliding pointer when received by said slot means, said calibration means including man-readable blood glucose concentrations that correspond to the null positions located by said sliding pointer and that have been empirically calibrated to the batch lot variations in the chemistries of the disposable test strips.

12. The portable blood glucose monitoring meter of claim 11 wherein said analog circuit includes a reflectance measuring system having at least one light emitting diode and temperature compensation means to vary the current supplied to said light emitting diode as temperature varies to achieve constant light emitting diode brightness within the reflectance measuring system in the absence of a microprocessor.

13. In a portable blood chemistry monitoring meter having an analog circuit with a variable potentiometer to measure blood chemistry-induced changes in an enzyme-based blood analysis system utilizing disposable test strips to determine blood chemistry concentrations, the improvements comprising:

a sliding pointer with means to vary manually the resistance of the potentiometer to locate a null position that balances the measure of the blood chemistry-induced changes in the chemistries of disposable test strips; and

slot means to receive disposable test strips, the disposable test strips bearing calibration means that will be in registered juxtaposition with said sliding pointer when received by said slot means, said calibration means including man-readable blood chemistry concentrations that correspond to the null positions located by said sliding pointer and that have been empirically calibrated to the batch lot variations in the chemistries of the disposable test strips.

14. The portable blood chemistry monitoring meter of claim 13 wherein the enzyme-based blood analysis system is a blood glucose analysis system.

15. The portable blood chemistry monitoring meter of claim 13 wherein the enzyme-based blood analysis system is a blood cholesterol analysis system.

16. In a disposable test strip for a portable blood chemistry monitoring meter having an analog circuit with a variable potentiometer to measure blood chemistry-induced changes in an enzyme-based blood analysis system applied to the test strip to determine blood chemistry concentrations, the improvements comprising:

calibration means to calibrate the batch lot variations in the chemistries of the enzyme-based blood analysis system in a man-readable format, said calibration means including pre-printed, man-readable blood chemistry concentrations registered directly on the test strip in positions corresponding to blood chemistry concentrations located by empirical testing with known blood chemistry concentrations.

17. The disposable test strip of claim 16 wherein the enzyme-based blood analysis system is a blood glucose analysis system.

18. The disposable test strip of claim 16 wherein the enzyme-based blood analysis system is a blood cholesterol analysis system.