Biosensor apparatus and method with sample type and volume detection

• US 7,199,594 B2
• Filed: 01/13/2005
• Issued: 04/03/2007
• Est. Priority Date: 12/12/2001
• Status: Expired due to Term

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Kermani, Mahyar Zardoshti
• Primary Examiner(s): Benson; Walter
• Application Number:
  US11/036,658
• Publication Number:
  US 20060119362A1
• Time in Patent Office: 810 Days
• Field of Search: 732/90, 731/49, 324/71.1, 324/692, 324/663, 324/171.1, 702/182, 205/777.5, 600/347
• US Class Current: 324/663
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24

Abstract

A biosensor apparatus and method with sample type and cell volume detection. The apparatus includes a sine wave generator to apply an AC signal to a biosensor cell containing a sample, a current-to-voltage converter, a phase shifter, a square wave generator, a synchronous demodulator, and a low pass filter which yields a signal proportional to the effective capacitance across the biosensor cell, which is proportional to the volume of the sample. In addition, the current-to-voltage converter yields a signal indicative of the type of sample contained within the biosensor cell. The method includes applying a sine wave to the biosensor cell, shifting the phase of the resultant signal, generating a square wave synchronous with the sine wave, demodulating the resultant signal with the square wave, and filtering the demodulated signal to produce a signal proportional to the effective capacitance across the biosensor cell. The biosensor apparatus and method are capable of determining sample type and measuring glucose levels over a wide range of sample volumes.

Claims

1. A glucose measurement method for use with a biosensor, said biosensor configured to receive a sample having a volume, said method comprising the steps of:

determining the volume of the sample through synchronous demodulation when the sample is received by deriving the volume based on a signal that is proportional to an effective capacitance across the biosensor cell; and

determining a glucose measurement for the sample if the volume is greater than a first level based on the determined volume of the sample.

2. The method of claim 1, further comprising the step of:

detecting whether the sample is of a specific type; and

storing the glucose measurement if the sample is said specific type.

3. A method for measuring glucose levels in a sample partially filling a biosensor cell, the biosensor cell having a filled effective capacitance, said method comprising the steps of:

determining a partially filled effective capacitance for the sample;

determining a first current level passing through the biosensor cell during a first pulse;

determining a second current level passing through the biosensor cell during a steady state portion of a second pulse;

multiplying said first current level by the ratio of the filled effective capacitance to said partially filled effective capacitance to generate a second compensated current level; and

calculating a glucose level for the partially filled sample based on said first and second compensated current levels.