TTFields Electrode Skin Temperature Control via Sensor Placement
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Solution Overview
Problem
Existing Tumor Treating Fields (TTFields) therapy systems face challenges in accurately monitoring skin temperature due to increased thermal gradients when using higher currents and heat exchangers, leading to potential skin temperature exceeding safety thresholds.
Innovation Solution
The system positions temperature sensors, such as thermistors, in front of the electrode elements and in direct thermal contact with the subject's body, reducing the thermal gradient and providing more accurate temperature readings. Additionally, a heat exchanger is used to remove heat from the electrode elements, and the system adjusts the alternating voltage and cooling fluid based on temperature readings to maintain safe skin temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher currents are used to increase treatment efficacy, then the therapeutic effect is improved, but the skin temperature exceeds safety thresholds causing thermal damage
Solution Approach 1:
A heat exchanger is introduced as an intermediary component between the electrode assembly and the subject's body. The heat exchanger includes a cooling fluid flow path that actively removes heat from the electrode assembly, allowing higher currents to be applied without exceeding skin temperature safety thresholds. This mediator enables the system to operate at higher power levels while maintaining safe thermal conditions.
Solution Approach 2:
Temperature sensors are positioned in thermal contact with the electrode assembly to provide real-time temperature feedback. This feedback signal is used by the control system to dynamically adjust the current amplitude, ensuring that the skin temperature remains below the safety threshold while maximizing treatment efficacy. The closed-loop control allows the system to operate at the highest safe current level.
2Device complexity
If temperature sensors are positioned behind the electrode elements, then the device structure is simplified, but the temperature measurement accuracy deteriorates due to thermal gradients
Solution Approach 1:
Instead of placing temperature sensors behind the electrode elements (conventional approach), the patent inverts the positioning by placing the temperature sensors in front of the electrode elements, in direct thermal contact with the subject's skin. This inverted positioning eliminates the thermal gradient issue and provides accurate skin temperature measurements, enabling precise thermal management.
3Ease of manufacture
If thermistors are positioned in holes within electrode elements, then the manufacturing process is simplified, but the temperature monitoring reliability is reduced due to thermal contact issues
Solution Approach 1:
The patent extracts the temperature sensing function from the electrode element structure itself. Instead of embedding thermistors in holes within the electrode elements, the temperature sensors are positioned separately in front of the electrode elements. This separation allows for better thermal contact with the skin and more reliable temperature monitoring, while the electrode elements maintain their original simple structure for easy manufacturing.
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 configuration allows for higher currents to be used without risking skin temperature exceeding safety thresholds, thereby increasing the efficacy of TTFields therapy while ensuring patient safety.
Implementation Method 1
a heat exchanger is used to remove heat from the electrode elements
Implementation Method 2
the heat exchanger can rely on a flow of a liquid to carry the heat away
Implementation Method 3
the plurality of temperature sensors will be situated between the front faces of the at least one electrode element and the subject's body, in thermal contact with the subject's body
Implementation Method 4
electrode assemblies (e.g., arrays of capacitively coupled electrodes, also called transducer arrays) placed on the subject's skin
Implementation Method 5
When an AC voltage is applied between opposing electrode assemblies, an AC current is coupled through the electrode assemblies and into the subject's body
Data Source
AI summary
Alternating electric fields (e.g., tumor treating fields or TTFields) can be applied to a subject's body by positioning electrode elements on opposite sides of a target region in the subject's body, and applying an AC voltage between the opposing electrode elements. Temperature sensors that are positioned in front of the electrode elements (i.e., between the electrode elements and the subject's skin) and in thermal contact with the subject's skin are used to monitor the temperature of the subject's skin. The current that is applied to the electrode elements is adjusted to the highest level possible that will not cause the subject's skin to exceed the safety threshold (e.g., 41° C.). Optionally, one or more heat exchangers is included to remove heat from the electrode elements, in which case it will be possible to drive larger currents through the electrode elements without exceeding the safety threshold.