Multi-Frequency Glucose Measurement Using Interdigital Electrodes
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Solution Overview
Problem
Existing devices for determining glucose levels in living tissue using electrical fields face accuracy issues due to the influence of state variables other than glucose on electric and dielectric responses, requiring improved measurement methodologies to isolate glucose modulation effectively.
Innovation Solution
The device applies AC signal voltages at multiple frequencies (1 kHz to 200 kHz, 0.2 MHz to 100 MHz, and at least 1 GHz) to measure specific electric parameters, combines these with temperature measurements, and uses distinct electrode configurations to isolate glucose signals from other tissue parameters, employing interdigital and coplanar waveguide electrodes to achieve depth-resolved information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-frequency electrical measurements are used to determine glucose levels, then the measurement process is simple, but accuracy is reduced due to influence from non-glucose tissue state variables
Solution Approach 1:
The measurement process is segmented into multiple frequency components (first frequency range for sweat effects, second frequency range for glucose modulation, third frequency range for water content). Each frequency range targets specific tissue parameters, allowing isolation of glucose signal from confounding factors through frequency-domain segmentation.
Solution Approach 2:
The patent changes the frequency parameter of the applied electrical field to selectively probe different tissue properties. By varying frequency across three distinct ranges, the system exploits frequency-dependent tissue response to differentiate glucose effects from other physiological variables, transforming a single-parameter measurement into a multi-parameter characterization.
2Measurement precision
If measurements are taken at multiple frequencies to isolate glucose signals, then glucose determination accuracy improves, but the device complexity increases
Solution Approach 1:
The electrode arrangement is designed with multi-functionality, where the same electrode structure serves multiple measurement purposes across different frequency ranges. The electrodes are configured to simultaneously enable measurement of sweat effects at low frequencies, glucose modulation at mid frequencies, and water content at high frequencies, eliminating the need for separate electrode sets for each measurement type.
3Measurement precision
If temperature compensation is added to multi-frequency measurements, then measurement accuracy further improves, but energy consumption increases
Solution Approach 1:
The system uses self-service by leveraging the existing multi-frequency electrical field measurements to simultaneously obtain both glucose information and temperature data. The electrical measurements serve dual purposes: characterizing tissue electrical properties for glucose determination and detecting temperature-induced changes in dielectric properties, thereby deriving temperature compensation information without requiring separate measurement systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances glucose level determination accuracy by eliminating the influence of non-glucose tissue state variables, improving precision through the use of multi-frequency measurements and direct temperature compensation, while accounting for changes in water content and sweat effects.
Implementation Method 1
This type of device exploits the fact that the glucose level affects the dielectric and electric response of the same
Implementation Method 2
glucose mainly modulates the beta-dispersion in the frequency range 0.2 MHz to 100 MHz
Implementation Method 3
The third electric parameter is also best measured by means of a dedicated third pair of electrodes, which can be optimized for measurements at the Gigahertz range, e.g. be being designed as coplanar waveguides
Implementation Method 4
the first electric parameter is measured by means of a first pair of electrodes designed as interdigital electrodes because the separation gap needs to be very small to allow measuring only surface effects
Implementation Method 5
the temperature of the tissue affects all the electrically measured parameters, therefore a direct temperature measurement allows to improve the accuracy further
Data Source
AI summary
A method and device for determining the glucose level in living tissue are based on measuring the response of the tissue an electric field as well as temperature measurements. In order to improve accuracy, it has been found that measurements in at least three frequency ranges between 1 kHz and 200 kHz, 0.2 MHz an 100 MHz as well as above 1 GHz should be combined since the response of the tissue in these different frequency ranges is ruled by differing mechanisms.