Coaxial Probe Hydration Sensor with Force Control
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Solution Overview
Problem
Current hydration sensing technologies are not sensitive enough to track small and slow changes in hydration status, leading to delayed detection of dehydration in patients, as they rely on inaccurate methods such as body weight measurement, blood analysis, or bioimpedance spectroscopy, which are impractical for daily monitoring.
Innovation Solution
A non-invasive skin contact sensor using a coaxial probe responsive to radio frequency signals for dielectric spectroscopy, which applies a repeatable force to measure changes in hydration levels by analyzing the frequency response of the tissue to determine the amount of liquid within the tissue, allowing for accurate tracking of hydration levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current hydration sensing technologies (body weight measurement, blood analysis, bioimpedance spectroscopy) are used, then hydration assessment can be performed, but measurement precision is insufficient to track small and slow changes in hydration status
Solution Approach 1:
The patent changes the measurement parameter from conventional methods (body weight, blood osmolality) to dielectric spectroscopy parameters (complex permittivity, conductivity) that are highly sensitive to water content. By measuring the frequency-dependent dielectric properties of tissue, the system can detect small changes in hydration status with high precision, directly resolving the measurement precision issue while maintaining reliability through multiple frequency point measurements.
2Measurement precision
If blood analysis is used for hydration sensing, then accurate hydration status can be determined, but ease of operation deteriorates due to requiring blood draws and clinical laboratories
Solution Approach 1:
The patent replaces the mechanical/invasive blood draw system with a non-invasive dielectric spectroscopy measurement system. The coaxial probe applies RF signals to the tissue and measures the dielectric response, eliminating the need for blood collection and laboratory analysis. This substitution maintains measurement accuracy while dramatically improving ease of operation for daily home monitoring.
Solution Approach 2:
The patent introduces dielectric spectroscopy as an intermediary measurement method that indirectly assesses hydration status through tissue dielectric properties rather than directly analyzing blood or other body fluids. This intermediary approach provides blood-test-level accuracy through a non-invasive proxy measurement, making daily monitoring practical.
3Ease of operation
If bioimpedance spectroscopy is used for non-invasive hydration measurement, then ease of operation improves, but measurement precision deteriorates due to variability from posture and electrode contact conditions
Solution Approach 1:
The patent changes from measuring impedance (real part only) to measuring complex permittivity (both real and imaginary parts across multiple frequencies). This parameter expansion provides more information about tissue composition and enables better discrimination between water and other tissues, improving measurement precision while maintaining the non-invasive convenience of bioimpedance spectroscopy.
Solution Approach 2:
The patent performs measurements at excessive frequency points (broad frequency spectrum) rather than at a single frequency. This excessive sampling approach provides redundant information that can be used to identify and compensate for variations due to posture and contact conditions, thereby improving measurement consistency while maintaining ease of operation.
4Ease of operation
If long electrical path bioimpedance spectroscopy is used, then non-invasive measurement is achieved, but measurement precision deteriorates because the path passes through gastrointestinal fluid volume which varies significantly with daily activity
Solution Approach 1:
The patent segments the measurement into localized tissue assessments using a coaxial probe that measures dielectric properties at a specific measurement site rather than requiring a long electrical path through the entire body. This segmentation eliminates the confounding effect of varying gastrointestinal fluid volume while maintaining non-invasive operation, enabling sensitive detection of local and systemic hydration changes.
Solution Approach 2:
The patent extracts the measurement from the confounding gastrointestinal fluid pathway by using a localized coaxial probe that measures dielectric properties directly at the tissue interface. This extraction isolates the measurement from the variable GI fluid volume, improving precision for detecting small hydration changes while preserving non-invasive operation.
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
Enables the detection of small variations in hydration levels over short periods, providing consistent and reliable measurements by isolating the liquid's electric response, thus improving the accuracy of hydration monitoring and enabling timely detection of dehydration.
Implementation Method 1
The coaxial probe can be configured to be responsive to radio frequency (RF) signals associated with dielectric spectroscopy
Implementation Method 2
exerting a repeatable force (i.e. applying substantially the same force a number of consecutive times) upon a portion of the coaxial probe
Data Source
AI summary
A system and method for measuring a hydration level in human tissue. The system includes a coaxial probe have a first end configured to be in contract with human tissue and configured to be emit and receive signals associated with a spectroscopic technique and having a second end adapted to be coupled to transmit and receive circuitry. The system further includes a patch or other means coupled to the coaxial probe and configured to be adhered to human tissue so as to provide a force upon at least a portion of the coaxial probe configured to be in contact with human tissue. In embodiments, the system may further include means coupled to receive signals from the coaxial probe, for determining an amount of liquid within a portion of human tissue in contact with the first end of the probe.