Automatic Electrode Localization Using 3D Impedance Models
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Solution Overview
Problem
Existing methods for localizing electrodes on a conductive body, such as for physiological signal measurements, often require costly and invasive procedures like MRI or CT scans, or dedicated setups like cameras and transparent beds, and suffer from inaccuracies and logistical challenges.
Innovation Solution
A system and method using impedimetric measurements to determine the spatial position of electrodes on a conductive body by injecting electrical currents at landmark electrodes with known positions and measuring voltages at measurement electrodes, utilizing a 3D electrical impedance model to process these measurements and calculate the electrodes' positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If optical methods (cameras, 3D depth cameras) are used for electrode localization, then localization can be performed without invasive procedures, but the error between optical localization and reference localization (CT, MRI) is about 1 cm and dedicated setups are required
Solution Approach 1:
The patent introduces an intermediary electrical impedance model that acts as a mediator between the measured voltages and the electrode positions. By using the body's electrical impedance properties as an intermediary, the system achieves higher precision localization without invasive procedures, resolving the contradiction between non-invasiveness and accuracy
Solution Approach 2:
The patent replaces the mechanical/optical camera-based localization system with an electrical measurement system. By substituting optical methods with electrical impedance measurements and inverse problem solving, the system achieves superior precision while maintaining non-invasiveness
2Measurement precision
If MRI or CT scans are used to determine electrode location, then accurate localization is achieved, but the procedures are costly, potentially harmful, and logistically challenging
Solution Approach 1:
The patent enables the physiological measurement system to self-determine electrode positions using its own measurement electrodes and electrical impedance measurements. The system performs self-localization through inverse problem solving on the electrical impedance model, eliminating the need for separate MRI or CT scan procedures and reducing logistical complexity
Solution Approach 2:
The patent makes the measurement electrodes serve dual functions: both physiological signal measurement and spatial localization. This multi-functionality eliminates the need for separate localization procedures (MRI/CT), reducing cost and logistical complexity while maintaining accuracy
3Ease of operation
If transparent bed or soft material imprint methods are used to determine back electrode positions, then localization of back electrodes is achieved, but dedicated setups and additional apparatuses are required
Solution Approach 1:
The patent enables the measurement system to automatically determine back electrode positions through electrical impedance measurements and inverse problem solving, without requiring external assistance from transparent beds or imprint materials. The system self-determines all electrode positions including those on the back
4Measurement precision
If additional instruments (ultra-sound transducers, radiological imaging devices) are used for electrode localization, then electrode positions can be determined, but the setups become more complex and costly
Solution Approach 1:
The patent makes the existing measurement electrodes perform the additional function of spatial localization. By using the same electrodes for both physiological measurement and position determination through electrical impedance measurements, the system eliminates the need for additional localization instruments, reducing apparatus complexity while maintaining localization capability
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 accurate and cost-effective localization of electrodes without additional setups, allowing continuous and concurrent physiological measurements, reducing the need for invasive procedures and improving localization reliability.
Implementation Method 1
impedimetric measurements to determine the spatial position of electrodes on a conductive body by injecting electrical currents at landmark electrodes with known positions and measuring voltages at measurement electrodes
Data Source
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Figure 4~5A
AI summary
A system (1) for the automatic localization of electrode spatial position on the surface of a conductive body (2), having a processing unit (10), which: in response to electrical current injections at first electrodes (4), acquires voltages (ui,m) measured at second electrodes (5) on the surface of the conductive body; using an electrical impedance model of the conductive body, simulates the electrical current injections at the first electrodes (4) and estimates, for each electrical current injection, a resulting body surface potential on the surface of the conductive body; and performs a combined processing of the voltages (ui,m) measured at the second electrodes (5) and of the estimated body surface potential, in order to determine the locations of the second electrodes (5) on the surface of the conductive body.