TTFields Electrode Array Wiring for Independent Thermal Current Control
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Solution Overview
Problem
Existing TTFields therapy systems face challenges in maintaining effective electrical contact between electrode elements and the body, leading to increased resistance and reduced treatment efficacy due to issues like hydrogel drying or hair growth, which necessitate reducing current across all elements, thereby decreasing electric field strength.
Innovation Solution
The system employs individual conductors for each electrode element, allowing independent control of current through each element using a controller and switches, without increasing the number of cables or requiring active components on the arrays, by measuring and adjusting the duty cycle based on real-time temperature readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual conductors are provided for each electrode element to enable independent current control, then treatment efficacy is improved by maintaining optimal current levels, but device complexity increases due to additional conductors and connectors
Solution Approach 1:
The patent divides the electrical connection system into separate individual conductors for each electrode element, allowing independent control of current to each element. This segmentation enables the system to respond to varying contact conditions (such as hydrogel drying or hair growth) at each specific electrode location without affecting other elements, thereby maintaining treatment efficacy through localized current adjustment.
Solution Approach 2:
The connector is designed with multiple functions: it provides individual current control paths for each electrode element while also serving as a common return path for all thermistors. This multi-functionality reduces the overall conductor count compared to having separate dedicated wires for each function, thus managing device complexity while maintaining the ability to individually control current and temperature monitoring.
2Temperature
If current is reduced across all electrode elements to compensate for increased resistance at one element, then temperature control is maintained, but electric field strength decreases
Solution Approach 1:
The patent implements independent current control for each electrode element through separate conductors, allowing the system to identify and respond to increased resistance at specific locations. When resistance increases due to hydrogel drying or hair growth at one element, the system can reduce current only to that specific element while maintaining full current delivery to other elements, thereby preserving overall electric field strength while controlling temperature.
Solution Approach 2:
The system incorporates thermistors at each electrode element to provide real-time temperature feedback. This feedback mechanism enables the control system to detect changes in contact conditions and adjust current delivery dynamically. When resistance increases at a particular element, the feedback from its thermistor allows the system to modulate current to that element specifically, maintaining temperature control without compromising the electric field strength generated by other functional elements.
3Measurement precision
If thermistors are positioned beneath each electrode element to enable individual temperature monitoring, then measurement precision is improved, but device complexity increases due to additional sensors and wiring
Solution Approach 1:
The patent merges the temperature monitoring function with the existing electrical connection infrastructure by positioning thermistors at the base of each electrode element where they can share the same conductor paths. The connector is designed to accommodate both current delivery conductors and thermistor return paths, combining multiple functions into a unified connection architecture. This merging approach enables precise individual temperature monitoring while minimizing the additional wiring complexity that would result from completely separate sensor wiring systems.
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 approach maintains optimal current levels across all electrode elements, ensuring consistent electric field strength and treatment efficacy by individually managing temperature and current distribution, reducing the need for widespread current reduction.
Implementation Method 1
Each of the thermistors has a first terminal and a second terminal, and each of the thermistors is positioned to sense a temperature at a corresponding respective one of the electrode elements
Implementation Method 2
The AC signal generator (a) sends an AC current through one pair of arrays 21, 22 during a first period of time, which induces an electric field with a first direction through the tumor
Implementation Method 3
Each electrode element includes an electrically conductive substrate with a dielectric layer (more specifically, a layer of ceramic material with a high dielectric constant) disposed thereon
Implementation Method 4
When placing the arrays on the patient, the medical gel conforms to the contours of the patient's skin and ensures good electric contact of the device with the body
Data Source
AI summary
Tumor treating fields (TTFields) can be delivered to a subject's body at higher field strengths by switching off one or more electrode elements in a transducer array that are overheating. This may be accomplished by using thermistors that sense the temperature of each electrode element. Portions of the wiring of each transducer array is shared between the electrode elements and the thermistors by using a plurality of conductors, each of which electrically connects (a) a pin of a connector, (b) a respective electrode element, and (c) a respective thermistor. In some embodiments, all of the thermistors are wired in series. In other embodiments, all the thermistors share a common connection.