Bio-impedance Ratio for Wearable Sensor Contact Validation
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Solution Overview
Problem
Biometric information detection technologies face challenges in maintaining accuracy and reproducibility due to variable sensor positioning and contact states, especially in wearable devices, which can lead to noise in optical measurements and affect the reliability of health monitoring data.
Innovation Solution
A method and device using biometric electrode pairs to measure bio-impedance ratios, where a reference electrode pair and a measurement electrode pair are used to determine the validity of detected biometric information based on impedance ratios within predetermined ranges, ensuring stable contact and accurate data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a biometric sensor is used to detect biometric information in a wearable device, then the convenience and portability are improved, but the measurement accuracy and reproducibility deteriorate due to variable sensor positioning and contact states
Solution Approach 1:
The patent changes the parameter being measured from absolute optical signal intensity to the ratio of bio-impedance values. This ratio parameter is insensitive to sensor contact state variations, thereby maintaining measurement accuracy while preserving wearable convenience. The bio-impedance ratio remains stable even when contact pressure or positioning changes.
Solution Approach 2:
The patent introduces bio-impedance measurement as an intermediary parameter to indirectly assess contact state. By measuring bio-impedance through electrode pairs and using its ratio as a reference, the system creates a mediator that reflects contact conditions without being directly affected by optical measurement noise.
2Adaptability or versatility
If the sensor contact state varies due to user motion, then the adaptability to different conditions is improved, but the measurement reproducibility deteriorates
Solution Approach 1:
The patent transforms the measurement parameter from absolute values to ratios. The bio-impedance ratio of measurement electrodes to reference electrodes remains consistent across different contact states and motion conditions, thereby maintaining reproducibility while adapting to varying user activities.
Solution Approach 2:
The patent creates an equipotential reference system using reference electrode pairs that experience similar contact state variations. By comparing measurement electrodes against these reference electrodes, the system eliminates common-mode variations caused by motion, ensuring reproducible measurements across different conditions.
3Device complexity
If optical measurement signals are used without contact state verification, then the measurement process is simplified, but noise increases due to variable facing states
Solution Approach 1:
The patent introduces bio-impedance ratio as an intermediary indicator to assess contact state quality. This intermediary parameter provides feedback about measurement conditions without significantly increasing system complexity, enabling noise reduction through contact state verification.
Solution Approach 2:
The patent implements feedback by using bio-impedance ratio to evaluate contact state and determine measurement validity. When the bio-impedance ratio indicates poor contact, the system can flag or reject the optical measurement, thereby reducing noise while maintaining relatively simple device architecture.
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 the accuracy and reproducibility of biometric data by identifying and maintaining optimal sensor contact states, reducing noise, and ensuring the validity of measured biometric information, thereby improving the reliability of health monitoring data from wearable devices.
Implementation Method 1
measuring a bio-impedance of the subject using a first biometric electrode pair
Data Source
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Figure 2
AI summary
An apparatus for biometric information detection includes a housing, a biometric sensor (e.g. an optical sensor) disposed on a surface of the housing, and configured to detect biometric information of a subject, and an impedance measurer including at least two electrode pairs disposed around the biometric sensor, the impedance measurer being configured to measure bio-impedances of the subject using the electrode pairs. The apparatus further includes a processor configured to determine a bio-impedance ratio of the measured bio-impedances, and to determine validity of the detected biometric information, based on the determined bio-impedance ratio.