Multi-Field Electrode Tissue Impedance Measurement
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Solution Overview
Problem
Existing devices for measuring dielectric properties of living tissue, such as glucose levels, face challenges with calibration efforts and drift due to environmental changes or displacement, limiting their accuracy.
Innovation Solution
A device with an electrode arrangement and signal source generates two spatially different electrical fields, measuring the difference in tissue responses to these fields, primarily focusing on deeper tissue regions by minimizing surface contributions through weighted calculations, allowing for improved accuracy and reduced impact from surface conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single electrical field is used for measurement, then the measurement process is simple, but the accuracy is limited due to inability to isolate deeper tissue regions from surface effects
Solution Approach 1:
The measurement process is segmented into multiple spatially distinct electrical fields (at least two different spatial distributions) that probe different tissue depths. By measuring responses to multiple fields and combining them through weighted differences, the system segments the contribution of surface tissue from deeper tissue, thereby isolating the desired measurement target and improving accuracy without requiring physical segmentation of the device itself.
Solution Approach 2:
The invention transitions from a single-field measurement approach to a multi-field approach, adding the dimension of spatial field distribution variation. By varying the spatial distribution of electrical fields and measuring responses across this additional dimension, the system can differentiate between contributions from different tissue depths, effectively using field spatial configuration as an additional measurement dimension to improve precision.
2Reliability
If environmental conditions change or device is displaced, then calibration drift occurs, but maintaining calibration accuracy requires substantial effort
Solution Approach 1:
The invention extracts and eliminates the confounding influence of surface tissue (epidermis) from the measurement by using differential measurement techniques. By measuring responses to multiple spatially distinct fields and calculating weighted differences, the system extracts only the signal from deeper tissue regions (dermis) while removing the surface contribution. This extraction of the desired signal component makes the measurement inherently more stable against environmental changes and displacement, reducing calibration drift without requiring frequent recalibration procedures.
Solution Approach 2:
The system changes the parameters of the electrical fields (spatial distributions, frequencies, or orientations) to create multiple measurement conditions. By varying these field parameters and measuring responses under different conditions, the system can differentiate between stable tissue properties and artifacts caused by environmental changes or displacement. This parameter variation approach enables the system to maintain reliability by identifying consistent signals across different field configurations.
3Measurement precision
If surface tissue contributions are included in measurement, then the measurement covers all tissue layers, but surface effects (temperature, surface conditions) interfere with deeper tissue measurement
Solution Approach 1:
The invention converts the harmful surface tissue contribution into a useful reference signal. By intentionally measuring the response to multiple spatially distinct fields where one field has significant surface contribution and another has minimal surface contribution, the system can use the surface-affected measurement as a reference to subtract out the surface interference. This transforms the previously harmful surface effect into a beneficial reference that enables isolation of the deeper tissue signal.
Solution Approach 2:
The system applies different spatial field distributions that create locally distinct measurement zones. By designing fields with specific spatial characteristics that concentrate energy at different depths, the system creates local measurement quality variations - some fields primarily probe surface tissue while others primarily probe deeper tissue. This local quality differentiation enables selective measurement of deeper tissue regions while minimizing surface interference through appropriate field selection and combination.
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 measurement accuracy by isolating dielectric properties of deeper tissue regions, reducing the influence of surface effects and environmental changes, thereby improving glucose level measurement precision.
Implementation Method 1
measuring the difference of the responses of the tissue to the electrical fields. This difference depends on the spatial difference between the electrical fields, i.e. it primarily depends on the dielectric properties of those regions within the tissue
Data Source
AI summary
A device for measuring a glucose level or some other parameter of living tissue that affects the dielectric properties of the tissue is disclosed. The device comprises an electrode arrangement (5) having a plurality of electrodes (5-i). The signal from a signal source (31) can be applied to the electrode arrangement via a switching assembly (39). The switching assembly (39) is designed to selectively connect a first and a second pattern of the electrodes (5-i) to the signal source, thereby generating a first and a second electrical field with different spatial distribution in the tissue. By using a differential method which relies on measuring the impedance of the electrode arrangement (5) for each field and on suitable subtraction of the measured results, surface effects can be reduced and the focus of the measurement can be offset to a point deeper inside the tissue.