Introduction to Impedance Spectroscopy
Electrochemical Impedance Spectroscopy (EIS) is a non-invasive diagnostic technique used to detect biofouling in Continuous Glucose Monitors (CGMs). Biofouling refers to the accumulation of proteins and other substances on the sensor surface, leading to decreased accuracy and reliability of glucose readings [1].
Principles of EIS
EIS operates by applying a small amplitude AC signal to the sensor and measuring the resulting current. The impedance spectrum is then analyzed to determine the presence of biofouling. The technique utilizes two primary mechanisms:
- High-frequency AC signals assess the integrity of the sensor membrane, ensuring its stability and functionality.
- Low-frequency AC signals measure the diffusion resistance caused by the body's immune response, affecting the sensor's ability to accurately detect glucose levels.
Applications of EIS in CGMs
The integration of EIS in CGMs offers several benefits:
- Improved accuracy: EIS enables the detection of biofouling, allowing for adjustments to be made to maintain accurate glucose readings [2].
- Enhanced reliability: EIS helps to identify sensor failures and alerts the user to potential issues, ensuring timely intervention and maintenance [3].
- Increased user convenience: By reducing the need for frequent calibrations, EIS enhances the overall user experience and adherence to CGM therapy [4].
Challenges and Limitations
While EIS significantly enhances the performance of CGMs, it also introduces additional computational complexity and power consumption. Furthermore, the technique faces challenges during the initial
References
- Method and apparatus for providing sensor diagnostics (Medtronic Patent)Source