EIT Electrode Assembly with Shift Register Control
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Solution Overview
Problem
Current electrical impedance tomography (EIT) systems face issues with poor reliability due to electrode disconnection, high cost, and the inability to exclude non-functioning electrodes from measurements, leading to artefacts and potentially incorrect diagnoses.
Innovation Solution
A belt-like electrode assembly with a double shift register arrangement allows for sequential activation of electrodes, enabling independent control of current injection and voltage readout patterns, and a safety unit to prevent excessive current injection, while excluding faulty electrodes from measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EIT systems use multiple electrodes for current injection and voltage measurement, then imaging capability is achieved, but electrode disconnection and poor contact reliability occur leading to measurement artefacts
Solution Approach 1:
The patent divides the electrode system into two independent functional groups: current-injecting electrodes and voltage-measuring electrodes. This segmentation allows independent monitoring and control of each function, reducing the impact of electrode disconnection on overall system reliability. Current electrodes are monitored for proper current injection, while voltage electrodes are separately monitored for proper contact, allowing selective exclusion of faulty electrodes from measurements.
Solution Approach 2:
The patent implements feedback mechanisms by monitoring the actual current injected through current-injecting electrodes and the voltages measured at voltage-measuring electrodes. This feedback allows the system to detect electrode disconnection or poor contact conditions and adjust or exclude affected electrodes from the measurement process, preventing artefact generation and maintaining reliable imaging.
2Productivity
If sequential electrode activation is implemented using shift register arrangement, then measurement efficiency and speed are improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical switching systems with electronic shift register circuits for sequential electrode activation. The shift registers use simple D-flip-flops and logic gates to generate sequential activation patterns for current-injecting and voltage-measuring electrodes, achieving fast switching without mechanical components. This substitution maintains measurement speed while reducing mechanical complexity and improving reliability.
Solution Approach 2:
The patent employs periodic activation patterns generated by clocked shift registers to sequentially activate current-injecting electrodes and voltage-measuring electrodes in a repeating cycle. This periodic action enables efficient time-multiplexed measurements where multiple electrode combinations are activated in sequence, increasing measurement throughput and productivity through systematic temporal organization.
3Reliability
If current injection is performed without independent control of injection and measurement patterns, then system operation is simplified, but safety risks and measurement accuracy deteriorate
Solution Approach 1:
The patent segments the control system into independent control paths for current injection and voltage measurement. Current-injecting electrodes are controlled by one set of activation signals while voltage-measuring electrodes are controlled by another set, allowing independent optimization of each function. This segmentation enables precise control over which electrodes perform which function in each measurement cycle, improving measurement accuracy and safety.
Solution Approach 2:
The patent implements dynamic electrode assignment where the functional role of electrodes (current injection vs. voltage measurement) can change from cycle to cycle based on shift register states. This dynamic reconfiguration allows the system to adaptively optimize measurement patterns, exclude faulty electrodes, and maintain accurate measurements while managing control complexity through systematic temporal variation.
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 solution enhances the reliability and cost-effectiveness of EIT imaging by allowing faster and more efficient measurements, reducing artefacts, and ensuring safe current injection, thereby providing accurate medical imaging.
Implementation Method 1
A control unit ensures that an electrical signal, for example a current is applied to one or several pairs of electrodes on the skin to establish an electrical field
Implementation Method 2
With the remaining electrodes, the resulting voltages are measured and subsequently used to estimate the distribution of electric impedance within the thorax
Data Source
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AI summary
An electrode assembly for an EIT scanning device (11) including an electrode (15), a current supply unit (17), a voltage buffer unit (19), a switch logic unit (21), and lines for connecting the different elements, whereby the switch logic unit (21) comprises at least one element of a first shift register (27) and at least one element of a second shift register (29). A belt-like device comprising a plurality of said electrode assemblies. A method of measuring an EIT-image using such electrode assemblies preferably arranged in such a belt-like device.