Systems and methods for electrochemical hematocrit determination by alternate current impedance phase angle determinations
Inventors
Hughes, Gary L. • Jesswein, Ryan D.
Assignees
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Publication Number
US-12270780-B2
Publication Date
2025-04-08
Expiration Date
Abstract
A system for determining a level of hematocrit includes a test strip configured to receive a sample; a meter configured to receive the test strip; and further including circuitry and a microprocessor, the circuitry and microprocessor configured to apply electrical energy to the test strip and the sample and determine an electrical property of the sample, either the impedance phase angle or the impendence magnitude of the test strip and the sample and, based on the electrical property, calculate the level of hematocrit in the sample.
Core Innovation
The invention relates to a method and a system for determining a level of hematocrit using a test strip and a meter. A sample is received at the test strip and inserted into the meter, where the meter applies electrical energy to the test strip and the sample. The circuitry and microprocessor determine an impedance phase angle for the test strip using the applied electrical energy.
The hematocrit level is calculated at the meter based on an amount of glucose in the sample that affects an impedance magnitude and the impedance phase angle at a different rate than the level of hematocrit. The calculation uses a level of glucose and the level of hematocrit, with the glucose and hematocrit each affecting the impedance magnitude and the impedance phase angle. This enables determining the hematocrit level at the meter while accounting for the effects of glucose on the electrical properties.
In the disclosed approach, hematocrit changes the impedance magnitude and the impedance phase shift during AC testing, and the impedance phase shift correlates with hematocrit and glucose. The disclosed observations indicate that the phase shift provides differentiation of unknown hematocrit samples after effects have levelled off. The document further provides exemplary calibration relationships for impedance magnitude and impedance phase angle as a function of hematocrit.
Claims Coverage
Independent claim clm-00001 describes a method that determines a hematocrit level at the meter using meter-driven AC impedance measurement and a glucose-affected interrelationship. The method’s core inventive features include 8 inventive features.
Meter-driven impedance phase angle determination using electrical energy
The system includes a meter with circuitry and a microprocessor configured to apply electrical energy to a test strip and the sample and determine an impedance phase angle of the test strip.
Hematocrit calculation using glucose-affected disparate-rate effects on impedance magnitude and impedance phase angle
Hematocrit is calculated in the meter based on an amount of glucose in the sample that affects an impedance magnitude and the impedance phase angle at a different rate than the level of hematocrit, using a level of glucose and the level of hematocrit.
Outputting a hematocrit level to a user
An output of the level of hematocrit is provided to a user.
Determining an impedance of the test strip and the sample
The method further includes determining, using the circuitry and microprocessor, an impedance of the test strip and the sample.
Determining an interrelationship that enables glucose and hematocrit being determinable
Hematocrit is determined from an interrelationship between impedance and the impedance phase angle, where glucose level and hematocrit affect impedance and phase angle in disparate but proportional ways, making both glucose level and hematocrit determinable.
Determining a glucose level in the sample
A glucose level in the sample is determined using the circuitry and the microprocessor.
Test strip having a first sample window with first and second electrodes
The test strip has a first sample window with a first electrode and a second electrode.
Using first and second electrode sets to measure impedance and impedance phase angle
A first set of electrodes measures impedance and a second set of electrodes measures impedance phase angle.
Across the disclosed independent method and its dependent refinements, the invention centers on meter-driven AC electrical testing of a test strip/sample to determine an impedance phase angle and impedance magnitude, then calculating hematocrit using a glucose-affected interrelationship where glucose and hematocrit affect impedance magnitude and impedance phase angle at different rates or in disparate but proportional ways. Dependent claims further refine the calculation basis by determining impedance and/or glucose level and by constraining electrode/sample-window measurement layouts.
Stated Advantages
Enables differentiation of unknown hematocrit samples after effects have levelled off.
Provides hematocrit determination by using impedance phase shift correlated with hematocrit and glucose.
Documented Applications
Hematocrit determination for providing a hematocrit level output to a user using a test strip and a meter.
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