Implantable Chemical Sensor Data Normalization via Fluid State
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Solution Overview
Problem
Implanted chemical sensors face challenges such as signal drift and inconsistent data due to changes in the patient's fluid state, including activity, posture, and respiration, which affect the accuracy of physiological analyte measurements.
Innovation Solution
The implementation of an implantable medical device system that includes a chemical sensor and a fluid state sensor, with normalization circuitry that adjusts and corrects chemical sensor data based on fluid state data, using techniques such as weighting, matching to templates, and discarding unreliable data to provide more reliable analyte measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical sensor data is collected continuously without normalization, then data collection simplicity is maintained, but measurement precision deteriorates due to fluid state changes
Solution Approach 1:
The patent introduces fluid state sensors (posture, activity, respiration sensors) as intermediary devices that detect physiological state changes. These sensors act as mediators between the chemical sensor and the normalization circuitry, providing information about fluid state changes that affect chemical sensor readings. The fluid state sensors enable the system to identify when normalization is needed without directly measuring the chemical analytes themselves.
Solution Approach 2:
The normalization circuitry implements a feedback mechanism where fluid state sensor data is continuously monitored and used to adjust chemical sensor data in real-time. When fluid state changes are detected (such as posture changes, activity level changes, or respiration changes), the normalization circuitry automatically applies correction algorithms to compensate for the expected impact on chemical sensor readings, creating a closed-loop system that continuously improves measurement accuracy.
2Measurement precision
If normalization processing is applied to all chemical sensor data, then measurement precision is improved, but loss of time increases due to data processing requirements
Solution Approach 1:
The normalization circuitry applies partial normalization by selectively processing only those chemical sensor data points that correspond to detected fluid state changes. Instead of normalizing every data point, the system identifies specific moments when fluid state transitions occur (such as posture changes or activity level changes) and applies normalization only to affected data segments. This approach maintains measurement precision for critical data while minimizing unnecessary processing time for stable periods.
Solution Approach 2:
The system performs preliminary detection of fluid state changes using dedicated fluid state sensors before chemical sensor data becomes corrupted. By detecting posture changes, activity level changes, or respiration changes in advance, the system can proactively apply normalization algorithms to prevent inaccurate data from being generated in the first place, rather than having to correct already-degraded measurements.
3Reliability
If fluid state sensors are added to the system, then reliability of chemical sensor data is improved, but device complexity increases
Solution Approach 1:
The patent designs the fluid state sensors and normalization circuitry to serve multiple functions within the implantable medical device. The same fluid state sensors that detect posture changes also detect activity level changes and respiration variations, enabling a single sensor system to address multiple sources of measurement error. The normalization circuitry similarly handles multiple types of corrections (posture-based, activity-based, respiration-based) using a unified processing architecture, reducing overall system complexity despite the added functionality.
Data Source
AI summary
Embodiments herein include implantable medical systems, devices and methods including chemical sensors. In an embodiment, an implantable medical device system includes a chemical sensor; a fluid state sensor such as a posture sensor; an activity sensor; and/or a respiration sensor. The implantable medical device system can further include normalization circuitry receiving data from the chemical sensor and the fluid state sensor and normalizing the chemical sensor data based on data from the fluid state sensor. In an embodiment, a method of operating an implantable medical device system is included. The method can include measuring the amount of a chemical analyte using a chemical sensor, measuring the fluid status in a patient using a fluid state sensor, and normalizing the measured amount of the chemical analyte as indicated by the chemical sensor using normalization circuitry based on data from the fluid state sensor. Other embodiments are also included herein.