Homogeneous Field Generators

FluxMetrix has developed a radio frequency (RF) magnetic field generator, which produces a highly homogeneous field. Field homogeneity is very important, to excite magnetic nanoparticles within a patient, without exposing healthy tissue to high levels of field, causing eddy-current heating.

Industrial RF magnetic induction-heating apparatus, for metal treatment, is unsuitable for this application. Metals readily conduct heat and so field homogeneity is not essential.

 

Solenoid coil laboratory equipment for developing and characterising nanoparticles has been produced. It has also been extended to coil diameters of 50 to 60mm, for in-vivo hyperthermia treatment experiments on small rodents.  Producing larger treatment volumes, has thwarted many researchers.

 

Existing techniques, such as solenoid, Helmholtz or Maxwell coils, produce a volume of homogeneous magnetic field. However, the high inductance of large coils, places severe limitations on the volume of RF magnetic field which can be produced. This is especially true at frequencies above 100kHz, suitable to excite magnetic nanoparticles.

 

FluxMetrix have invented a novel design that generates a homogeneous field with a much larger internal treatment volume.

 

We have built a demonstration unit with a diameter of 320mm and length of 250mm. The flux density within the working volume varies by no more than +/-10%, weakening only towards the open ends.  The field intensity is limited only by a 1.2kW bench power supply.  Under automatic software control of resonant frequency and field level, it produces a continuous field of 4mT rms (5.6mT peak).  Recent experiments with a 3kW power supply have seen 6mT rms (8.5mT peak).

 

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This Proof-of-Concept unit confirms that our calculations, simulations and measurements all agree.  Thus we have great confidence that simulations of larger units are eminently achievable.

 

FluxMetrix have now completed high power demonstration unit.  The cylinder volume is only 300mm diameter by 300mm long, but the field intensity is 10mT rms (14.1mT peak) with a homogeneity of +/-5% throughout the treatment zone. This has been tested with iron particles and again confirms our simulations .  Tests with saline solution further indicate that healthy tissue will not be affected. The limitation of this system is the 6kW output power, being the limit of current which can be drawn from a single-phase (cooker / shower) mains connection.

 

The following stage of development is to build a larger prototype, which would be 600mm diameter and 600mm long. This unit would be 'human-sized' and capable of clinical trials.  It would require a suitable three phase supply.

 

For this FluxMetrix seeks funding and support.

 

We believe this is a logical stepping-stone towards a routine clinical cancer

treatment unit.