Sham TMS Coil with Conductive Disrupting Elements
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Solution Overview
Problem
Existing TMS coil arrangements for sham or placebo treatments are bulky and easily distinguishable from active coils due to the need for thick ferromagnetic plates to reduce magnetic field saturation, leading to noise and altered appearance, making it difficult to create a convincing sham treatment without significant modifications.
Innovation Solution
Incorporating elongate conductive magnetic field disrupting elements adjacent to the windings, which induce currents opposing the magnetic field, allowing for significant cancellation of the magnetic field near the coil while maintaining the appearance and sound of an active coil, thus creating a sham TMS coil arrangement without major modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ferromagnetic plates are used to reduce magnetic field saturation, then magnetic field disruption is improved, but the device becomes bulky and easily distinguishable from active coils
Solution Approach 1:
The patent changes the material parameter from ferromagnetic to highly conductive non-ferromagnetic material (such as copper or aluminum), and changes the geometric parameter from thick plate to thin elongate element. This allows achieving magnetic field disruption without the bulkiness of traditional ferromagnetic plates, as the conductive material creates eddy currents that oppose the magnetic field change without requiring magnetic saturation.
Solution Approach 2:
The patent replaces the mechanical/magnetic approach of using ferromagnetic materials with an electromagnetic approach using highly conductive non-ferromagnetic materials. Instead of relying on magnetic saturation and thickness to disrupt the field, the solution uses induced eddy currents in the conductive material to generate an opposing magnetic field, achieving the same effect with much thinner elements.
2Object-affected harmful factors
If ferromagnetic plates are placed close to the winding, then magnetic field disruption is improved, but excessive noise is generated due to repulsive force
Solution Approach 1:
The patent changes the magnetic property parameter from ferromagnetic to non-ferromagnetic while maintaining high electrical conductivity. This eliminates the magnetic repulsion between the plate and the coil winding, thereby eliminating the noise caused by rapid deformation of ferromagnetic materials during coil operation, while still achieving magnetic field disruption through eddy current induction.
3Object-affected harmful factors
If thick ferromagnetic plates are used, then magnetic field saturation is reduced, but rapid heating occurs
Solution Approach 1:
The patent changes the material from ferromagnetic to highly conductive non-ferromagnetic material with lower magnetic losses. The thin elongate geometry combined with high electrical conductivity allows the material to dissipate induced eddy current energy more efficiently as opposed to thick ferromagnetic plates that experience rapid heating due to hysteresis losses and magnetic saturation effects.
4Object-generated harmful factors
If a gap greater than 5mm is maintained between winding and plate, then noise is reduced, but the device becomes bulky and requires redesign of packaging
Solution Approach 1:
The patent changes the material property from ferromagnetic to non-ferromagnetic highly conductive material, which eliminates magnetic repulsion and the associated noise. This allows the thin elongate disrupting element to be placed in close proximity to the winding (much less than 5mm gap) without generating excessive noise, thereby avoiding the need for bulky packaging and redesign of the coil arrangement.
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
The solution effectively reduces the magnetic field beneath the coil, allowing for a convincing sham treatment that mimics active TMS without cranial stimulation while still providing peripheral stimulation, maintaining the appearance and sound of an active coil, thus enhancing the authenticity of the placebo experience.
Implementation Method 1
the magnetic field produced by the winding and in particular the rate of change of magnetic field induces a current in the elongate conductive magnetic field disrupting element that runs in the opposite direction to that in the winding
Implementation Method 2
the magnetic field produced by the winding and in particular the rate of change of magnetic field induces a current in the elongate conductive magnetic field disrupting element
Data Source
Figure 1(A)~2(H)
Figure 3~4(a)
Figure 4(b)~5(D)
AI summary
The present invention relates to a magnetic stimulation (MS) and preferably transcranial magnetic stimulation (TMS) coil arrangement designed for use as a placebo treatment. Accordingly, the purpose of the invention is to reduce or remove the effect of the magnetic field generated in use by a magnetic stimulation coil arrangement whilst the appearance presented remains as expected from a MS coil arrangement. The invention comprises a radially wound conductive element having a plurality of turns forming at least one winding. There is further provided at least one conductive magnetic field disrupting element at least partially positioned adjacent to the at least one winding for disrupting a magnetic field generated in operation by the at least one winding. The conductive magnetic field disruptive element accordingly attenuates the generated magnetic field beneath the coil arrangement.