System and method of increasing sample throughput by estimation of a sensor endpoint

• US 9,113,834 B2
• Filed: 10/02/2013
• Issued: 08/25/2015
• Est. Priority Date: 08/16/2011
• Status: Active Grant

• Current Assignee: Instrumentation Lab Co (Instrumentation Lab)
• Original Assignee: Instrumentation Lab Co (Instrumentation Lab)
• Inventors: Mansouri, Sohrab, Cervera, Jose Maria
• Primary Examiner(s): HARWARD, SOREN T
• Application Number:
  US14/044,111
• Publication Number:
  US 20140100794A1
• Time in Patent Office: 692 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: C12Q 1/002 Electrode membranes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 2035/00702 Curve-fitting; Parameter matching; Calibration constants
• CPC Class Codes: G01N 2035/0097 monitoring reactions as a function of time
• CPC Class Codes: G01N 27/327 Biochemical electrodes , e.g. electrical or mechanical details for in vitro measurements
• CPC Class Codes: G01N 33/48792 Data management, e.g. communication with processing unit for in vivo diagnostics A61B5/0002; transmission systems for measured values G08C
• CPC Class Codes: G01N 33/50 Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing measuring or testing processes involving enzymes or microorganisms, compositions or test papers therefor; processes for forming such compositions, condition responsive control in microbiological or enzymological processes C12Q
• CPC Class Codes: G16H 10/40 for data related to laboratory analysis, e.g. patient specimen analysis

Abstract

Technologies for increasing sample throughput by predicting the end point response time of a sensor for the analysis of an analyte in a sample are disclosed. In one aspect, a system includes a sensor that generates data signals associated with the measurement of an analyte within the sample. A processor records appropriate data points corresponding to the signals, converts them to a logarithmic function of time scale, and plots the converted data points. The processor then determines a curve that fits the plotted data points and determines a curve fitting equation for the curve. Once the equation is determined, the processor extrapolates an end point response of the sensor using the equation. A value, such as analyte concentration, is then calculated using the extrapolated end point response.

Claims

1. A non-transitory computer storage medium storing an analyte concentration measurement application to increase sample throughput, the application comprising:

a sensor communication module that causes a processor to receive data signals from one or more sensors;

a data point reporting module that causes the processor to capture and record data points from said data signals;

a data point selection module that causes the processor to select predetermined data points from said data points;

a curve fitting module that causes the processor to obtain a logarithmic function of time corresponding to the predetermined data points;

the logarithmic function of time being obtained from a curve fitting equation of the form s(t)=a*(log(t))^2+b*log(t)+c, wherein t represents time, s(t) represents data point at time t, and a, b and c are fit parameters for a second order polynomial that are determined based on the predetermined data points;

an extrapolation module that causes the processor to extrapolate an end point response of a sensor from the one or more sensors;

a validation module that causes the processor to validate said end point response; and

an analyte concentration reporting module that causes the processor to determine a concentration of an analyte within a sample using said end point response, thereby increasing sample throughput.

2. The non-transitory computer storage medium storing art analyte concentration measurement application of claim 1 wherein said data point selection module is further configured to select said predetermined data points such that said predetermined data points are within a kinetic region of the response of said sensor.

3. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 2 wherein the kinetic region extends from a first time when the sensor is first exposed to an analyte to a second time when said data signals generated by the sensor are substantially similar to an actual end point response of the sensor.

4. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 3 wherein the kinetic region begins at approximately fifteen seconds after the sensor is exposed to the analyte.

5. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 3 wherein the kinetic region ends approximately thirty seconds after the sensor is exposed to an analyte.

6. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 1 wherein said data point selection module is further configured to record the data points at equal time intervals.

7. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 1 wherein said curve fitting module is further configured to plot said predetermined data points.

8. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 1 wherein said extrapolation module is further configured to extrapolate said end point response using said curve fitting equation.

9. The analyte non-transitory computer storage medium storing an concentration measurement application of claim 1 wherein said extrapolation module is further configured to evaluate said curve fitting equation at a time within an equilibrium region of a response curve of said sensor.

10. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 1 wherein said validation module is further configured to determine a coefficient of variation and a coefficient of determination.

11. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 10 wherein the coefficient of variation (CV) is given by

CV=(a standard deviation of observed values)/(paean of observed values);

and wherein the coefficient of determination (R²) is given by

R²=1−

Σ

(y_i−

f_i)²/Σ

(y_i−

y)²

wherein y_i is the ith observed value (data signal),

y is the mean (average) value of y, and

f_i is the ith value calculated from the curve fitting equation.

12. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 10 wherein said validation module is further configured to determine whether said coefficient of variation and said coefficient of determination are within predetermined acceptable limits.

13. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 12 wherein said analyte concentration reporting module is further configured to, when it is determined that said coefficient of variation and said coefficient of determination are not within said predetermined acceptable limits, report the concentration of the analyte and a flag indicating that said coefficient of variation and said coefficient of determination are not within said predetermined acceptable limits.

14. The non-transitory computer storage medium storing an analyte concentration measurement application of claim 12 wherein said analyte concentration reporting module is further configured to, when it is determined that said coefficient of variation and said coefficient of determination are within said predetermined acceptable limits, report the concentration of the analyte.