Implantable Glucose Sensor Electrode Spacing and Coil Placement
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Solution Overview
Problem
Existing implantable sensors face issues with inaccurate glucose concentration measurements due to body liquids affecting impedance readings, scar tissue interference, and energy transfer inefficiencies, which can lead to false insulin administration and reduced measurement accuracy.
Innovation Solution
Optimizing electrode spacing and coil placement to ensure impedance measurements are taken in healthy tissue, minimizing liquid interference and Eddy Currents, with current injecting electrodes spaced 5mm to 12mm apart and voltage sensing electrodes 1mm to 4mm from current injecting electrodes, and positioning the coil externally for improved energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are placed close together to reduce measurement distance, then measurement precision is improved, but body liquids and scar tissue interfere more significantly with the measurement
Solution Approach 1:
The patent applies local quality by creating a rounded housing shape with specific radius of curvature at the electrode interface. This local geometric modification ensures that current trajectories extend into healthy tissue rather than being confined to scar tissue, thereby improving measurement precision while reducing interference from body liquids and scar tissue in the specific local area where measurements are taken.
Solution Approach 2:
The patent employs spheroidality by designing the housing with a rounded shape and specific radius of curvature. This curvature is strategically designed to optimize current distribution and trajectories, ensuring that impedance measurements are taken through healthy tissue while minimizing the influence of scar tissue and body liquids, thus resolving the contradiction between measurement precision and harmful factor interference.
2Device complexity
If coil is placed inside or on the printed circuit board to simplify structure, then device complexity is reduced, but Eddy Currents are generated that affect measurement performance and energy transfer
Solution Approach 1:
The patent applies the taking out principle by extracting the coil from its conventional position on or inside the printed circuit board and relocating it to an external position. This separation removes the source of Eddy Currents that were generated when the coil was in close proximity to the PCB, thereby eliminating harmful electromagnetic interference while maintaining a relatively simple overall device structure.
3Measurement precision
If sensor is implanted to measure impedance in healthy tissue, then measurement precision is improved, but scar tissue develops around the sensor that interferes with measurements
Solution Approach 1:
The patent applies local quality by designing the housing with specific geometric characteristics (rounded shape with defined radius of curvature) that locally optimize current distribution. This ensures that even though scar tissue forms around the sensor, the current trajectories are directed through healthy tissue, maintaining measurement precision despite changes in tissue composition over time.
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
Enhances measurement accuracy by ensuring readings are taken in healthy tissue, reducing liquid interference, and improving energy transfer efficiency, thereby providing reliable glucose concentration data.
Implementation Method 1
a coil for receiving the electromagnetic energy from an external power source to power the implantable sensor
Implementation Method 2
two current injecting electrodes for injecting current into the tissue
Implementation Method 3
two voltage sensing electrodes for measuring impedance in the tissue
Data Source
Figure 1a~3
Figure 4~6
AI summary
Disclosed herein is an implantable sensor (1, 1′, 1ʺ, 1‴) for determining impedance in tissue of a living being, the implantable glucose sensor comprising: - a housing (2, 2'), - two current injecting electrodes (4, 4') for injecting current into the tissue, - two voltage sensing electrodes (5) for measuring impedance in the tissue, whereby the two voltage sensing electrodes (5) are arranged separately from the two current injecting electrodes (4, 4'), - a coil (7) for powering the implantable glucose sensor via a power source (10), - a circuit board (8) arranged within the housing (2, 2'), the circuit board (8) being electrically connected to the two voltage sensing electrodes (5) and the two current injecting electrodes (4, 4') and the coil (7), - a communication unit (9) for transferring and receiving data packages, the communication unit (9) being connected to the circuit board (8), - the housing (2) comprising the two voltage sensing electrodes (5) and the two current injecting electrodes (4, 4') on an outer surface. A distance (d, d') between the two current injecting electrodes (4, 4') on the outer surface is in a range from 5mm to 12mm, preferably about 6 to 10 mm and more preferably about 7 to 9mm.